OXIDE MIXTURE AND COMPLEX OXIDE COATINGS FOR CATHODE MATERIALS

[0001] This patent application claims the benefit under 35 U.S.C. § 119(e) of U.S. Patent Application Ser. No. 62/713,715, entitled “OXIDE MIXTURE AND COMPLEX OXIDE COATINGS FOR CATHODE MATERIALS,” filed on Aug. 2, 2018, which is incorporated herein by reference in its entirety.

[0002] This invention was made with U.S. government support under NVFO Proposal No. 85F59. This invention was made under a CRADA 1500801 between Apple Inc. and Argonne National Laboratory operated for the United States Department of Energy. The U.S. government has certain rights in the invention.

[0003] This disclosure relates generally to batteries, and more particularly to cathode active materials for lithium-ion batteries.

[0004] A commonly used type of rechargeable battery is a lithium battery, such as a lithium-ion or lithium-polymer battery. As battery-powered devices become increasingly small and more powerful, batteries powering these devices need to store more energy in a smaller volume. Consequently, use of battery-powered devices may be facilitated by mechanisms for improving the volumetric energy densities of batteries in the devices.

[0005] Lithium cobalt metal oxides or lithium transition metal oxides can be used in cathode active materials for lithium-ion batteries. The lithium transition metal oxides are derivations of lithium cobalt oxide. The lithium cobalt metal oxides or transition metal oxides can be in the form of powder.

[0006] In Li-ion batteries, the cathode materials of different compositions tend to react chemically or electrochemically with the liquid electrolyte that consists of a lithium salt (LiPF₆) in organic solvents (such as ethylene carbonate, ethyl-methylene carbonate), especially when Li is extracted from the cathodes during charging. This is one of the major reasons for causing short cycle life of the batteries. A coating, such as aluminum oxide (Al₂O₃), is normally applied to the cathode particles in order to mitigate the reaction between the cathode and electrolyte and to prevent dissolution of the transition metals from the cathode into the electrolyte. Although the aluminum oxide coating renders necessary pretention, the coating often causes energy density loss for the battery. There remains a need to develop coatings for improved battery performance.

[0007] In one aspect, the disclosure is directed to a cathode active material including a plurality of cathode active compound particles. A coating is disposed over each of the cathode active compound particles. The coating can include ZrO₂, La₂O₃, a mixture of Al₂O₃ and ZrO₂ or a mixture of Al₂O₃ and La₂O₃.

[0008] In another aspect, the coating is a mixture of Al₂O₃ and ZrO₂. In some variations, the cathode active material can have less than or equal to 5000 ppm Zr. The cathode active material can have less than or equal to 5000 ppm Al.

[0009] In another aspect, the coating can include a mixture of La₂O₃ and Al₂O₃. In some variations, the molar ratio of La to Al is from 0.01 to 5.0. In some variations, aluminum is an amount from 20 ppm to 5000 ppm and lanthanum is in an amount from 20 ppm to 5000 ppm.

[0010] In further aspects, the disclosure is directed to a battery cell. The battery cell can include an anode comprising an anode current collector and a cathode including the cathode active material described herein. A separator disposed between the anode and the cathode.

[0030] The following description is presented to allow any person skilled in the art to make and use the embodiments, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. Thus, the disclosure is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

[0031] As used herein, all compositions referenced for cathode active materials represent those of as-prepared materials (i.e., “virgin” materials) unless otherwise indicated. Materials of these compositions have not yet been exposed to additional processes, such as de-lithiation and lithiation during, respectively, charging and discharging of a lithium-ion battery.

[0032] Overview

[0033] The disclosure provides the use of various oxides mixture or complex oxides as coatings for the cathode active compound particles of lithium-ion (Li-ion) batteries or other types of Li batteries. The coated cathode active materials have improved properties over an aluminum oxide coating and an uncoated cathode active material. Lithium cobalt oxides or lithium transition-metal oxides can be used in cathode active materials for commercial lithium-ion batteries. The lithium transition-metal oxides are variations or derivatives of lithium cobalt oxides. The performance of such cathode active materials can be increased by improving its discharge capacity, average voltage, discharge energy, and energy retention.

[0034] The disclosure provides surface coatings for cathode materials of Li-ion batteries and other Li batteries that demonstrate improved energy and/or energy retention. The surface coatings may include mixed oxides, such as a mixture of Al₂O₃ and ZrO₂. The surface coatings may also include complex oxides, such as ZnAl₂O₄. Without limitation, these coating compositions are applied to the cathodes of Li-ion batteries or other types of Li batteries (e.g., substituted lithium cobalt oxides or lithium manganese cobalt nickel oxides), the batteries can demonstrate either improved discharge capacity, increased average discharge voltage, increased energy, and/or energy retention over the uncoated cathode active compound particles, and the conventional alumina coating on the cathode active compound particles.

[0035] The performance of batteries can be improved using coatings on cathode active materials that provide increased discharge capacity, average voltage, discharge energy, and energy retention. These and other needs are addressed by the disclosure herein.

[0036] FIG. 1 presents a top-down view of a battery cell 100 in accordance with an embodiment. The battery cell 100 may correspond to a lithium-ion or lithium-polymer battery cell that is used to power a device used in a consumer, medical, aerospace, defense, and/or transportation application. The battery cell 100 includes a stack 102 containing a number of layers that include a cathode with a cathode active material, a separator, and an anode with an anode active material. More specifically, the stack 102 may include one strip of cathode active material (e.g., aluminum foil coated with a lithium compound) and one strip of anode active material (e.g., copper foil coated with carbon). The stack 102 also includes one strip of separator material (e.g., conducting polymer electrolyte) disposed between the one strip of cathode active material and the one strip of anode active material. The cathode, anode, and separator layers may be left flat in a planar configuration or may be wrapped into a wound configuration (e.g., a “jelly roll”).

[0037] Enclosures can include, without limitations, pouches, such as flexible pouches, rigid containers, and the like. Returning to FIG. 1, during assembly of the battery cell 100, the stack 102 is enclosed in an enclosure. The stack 102 may be in a planar or wound configuration, although other configurations are possible. Flexible pouch can be formed by folding a flexible sheet along a fold line 112. For example, the flexible sheet may be made of aluminum with a polymer film, such as polypropylene. After the flexible sheet is folded, the flexible sheet can be sealed, for example, by applying heat along a side seal 110 and along a terrace seal 108. The flexible pouch may be less than 120 microns thick to improve the packaging efficiency of the battery cell 100, the density of battery cell 100, or both.

[0038] The stack 102 can also include a set of conductive tabs 106 coupled to the cathode and the anode. The conductive tabs 106 may extend through seals in the enclosure (for example, formed using sealing tape 104) to provide terminals for the battery cell 100. The conductive tabs 106 may then be used to electrically couple the battery cell 100 with one or more other battery cells to form a battery pack.

[0039] Batteries can be combined in a battery pack in any configuration. For example, the battery pack may be formed by coupling the battery cells in a series, parallel, or a series-and-parallel configuration. Such coupled cells may be enclosed in a hard case to complete the battery pack, or may be embedded within an enclosure of a portable electronic device, such as a laptop computer, tablet computer, mobile phone, personal digital assistant (PDA), digital camera, and/or portable media player.

[0040] FIG. 2A presents a side view of a set of layers for a battery cell (e.g., the battery cell 100 of FIG. 1) in accordance with the disclosed embodiments. The set of layers may include a cathode current collector 202, a cathode active material 204, a separator 206, an anode active material 208, and an anode current collector 210. The cathode current collector 202 and the cathode active material 204 may form a cathode for the battery cell, and the anode current collector 210 and the anode active material 208 may form an anode for the battery cell. To create the battery cell, the set of layers may be stacked in a planar configuration, or stacked and then wrapped into a wound configuration.

[0041] As mentioned above, the cathode current collector 202 may be aluminum foil, the cathode active material 204 may be a lithium compound, the anode current collector 210 may be copper foil, the anode active material 208 may be carbon, and the separator 206 may include a conducting polymer electrolyte.

[0042] It will be understood that the cathode active materials described herein can be used in conjunction with any battery cells or components thereof known in the art. For example, in addition to wound battery cells, the layers may be stacked and/or used to form other types of battery cell structures, such as bi-cell structures. All such battery cell structures are known in the art.

[0043] In further variations, a cathode active material comprises a cathode active compound particle and a coating. FIG. 2B is a sectional view of a coated particle including a cathode active particle and a coating in accordance with an illustrative embodiment. As shown, a coated cathode active compound particle 212 can include a cathode active compound particle or a cathode active compound particle 216 and a coating 214.

[0044] The coating can be an oxide material. In some variations, the coating may be a layer of material in contact with a surface of the cathode active compound particle or a reaction layer formed along the surface of the cathode active compound particle. In some variations, the coating can include an oxide mixture (e.g. a mixture of Al₂O₃ and ZrO₂, or a mixture of Al₂O₃ and La₂O₃). In some variations, the coating can include a complex oxide, such as ZnAl₂O₄.

[0045] In various embodiments, the performance of batteries including the cathode active material can increase battery capacity and/or reduce the loss of available power in a fully charged battery over time.

[0046] The coating can be in any amount known in the art. In some variations, amount of coating may be less than or equal to 7 wt. % of the total particle. In some variations, amount of coating may be less than or equal to 5 wt. % of the total particle. In some variations, amount of coating may be less than or equal to 0.8 wt. % of the total particle. In some variations, amount of coating may be less than or equal to 0.6 wt. % of the total particle. In some variations, amount of coating may be less than or equal to 0.4 wt. % of the total particle. In some variations, amount of coating may be less than or equal to 0.3 wt. % of the total particle. In some variations, amount of coating may be less than or equal to 0.2 wt. % of the total particle. In some variations, amount of coating may be less than or equal to 0.1 wt. % of the total particle. In various aspects, the amount can be chosen such that a capacity of the cathode active material is not negatively impacted.

[0047] The coating may include multiple layers of coating material. The coating may also be a continuous coating or a discontinuous coating. Non-limiting examples of discontinuous coatings include coatings with voids or cracks and coatings formed of particles with gaps there between. Other types of discontinuous coatings are possible.

[0048] A powder comprising the particles described herein can be used as a cathode active material in a lithium ion battery. Such cathode active materials can tolerate voltages equal to or higher than conventional materials (i.e., relative to a Li/Li⁺ redox couple) without capacity fade. Capacity fade degrades battery performance and may result from a structural instability of the cathode active material, a side reaction with electrolyte at high voltage, surface instability, dissolution of cathode active material into the electrolyte, or some combination thereof.

[0049] In various aspects, the cathode active materials described herein can result in lithium ion batteries that can be charged at high voltages without capacity fade. Without wishing to be held to a specific mechanisms or mode of action, the compounds may impede or retard structural deviations from an α-NaFeO₂ crystal structure during charging to/at higher voltages.

[0050] Batteries having cathode active materials that include the disclosed coatings can show improved battery performance. For example, the mixture oxide coatings particles provide for an increased battery capacity and an increase average voltage and also an increased discharge energy over cycles.

[0051] Mixture of Al₂O₃ and ZrO₂

[0052] In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 5.0. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 4. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 2. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 1. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.5. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.28. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.26. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.23. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.20. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.17. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.13. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.11. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.09. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.07. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.06. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.05. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.04. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.03. In some variations, the molar ratio of Al to Zr for the mixture of Al₂O₃ and ZrO₂ is equal to or less than 0.02.

[0053] In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 3000 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 2000 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 1000 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 500 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 300 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 230 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 200 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 170 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 135 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 120 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 100 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 90 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 80 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 65 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 50 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 45 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 35 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 15 ppm aluminum.

[0054] In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 10 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 20 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 30 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 40 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 55 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 60 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 70 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 85 ppm aluminum. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 95 ppm aluminum.

[0055] In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 100 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 200 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 500 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 600 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 700 ppm zirconium. In certain variations, the mixture Al₂O₃ and ZrO₂ has equal to or greater than 800 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 900 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 1000 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 1100 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 1200 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 1300 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or greater than 1400 ppm zirconium.

[0056] In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 2000 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 1500 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 1400 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 1300 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 1200 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 1100 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 1000 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 900 ppm zirconium. In certain variations, the mixture of Al₂O₃ and ZrO₂ has equal to or less than 800 ppm zirconium.

[0057] In certain variations, a battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has a discharge energy of at least 710 Wh/kg after 25 cycles. In certain variations, a battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has a discharge energy of at least 712 Wh/kg after 25 cycles. In certain variations, a battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has a discharge energy of at least 714 Wh/kg after 25 cycles. In certain variations, a battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has a discharge energy of at least 716 Wh/kg after 25 cycles. In certain variations, a battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has a discharge energy of at least 718 Wh/kg after 25 cycles. In certain variations, a battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has a discharge energy of at least 720 Wh/kg after 25 cycles.

[0058] In some variations, the battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has an energy retention of at least 85% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has an energy retention of at least 90% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has an energy retention of at least 91% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has an energy retention of at least 92% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has an energy retention of at least 93% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has an energy retention of at least 94% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has an energy retention of at least 95% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has an energy retention of at least 96% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has an energy retention of at least 97% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and ZrO₂ coated cathode active materials has an energy retention of at least 98% after 30 charge-discharge cycles.

[0059] Mixture of Al₂O₃ and La₂O₃

[0060] In some variations, the mole ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or less than 5. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or less than 4. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or less than 3. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or less than 1.0. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or less than 0.9. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or less than 0.8. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or less than 1.2. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or less than 1.1. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or less than 1.0. In some variations, the molar ratio of La to Al for the mixture of A Al₂O₃ and La₂O₃ is equal to or less than 0.9. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or less than 0.8.

[0061] In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or greater than 0.1. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or greater than 0.2. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or greater than 0.3. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or greater than 0.4. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or greater than 0.5. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or greater than 0.6. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or greater than 0.7. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or greater than 0.8. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or greater than 0.9. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or greater than 1.0. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or greater than 1.1. In some variations, the molar ratio of La to Al for the mixture of Al₂O₃ and La₂O₃ is equal to or greater than 1.2.

[0062] In certain variations, the mixture of Al₂O₃ and La₂O₃ has aluminum from 20 ppm to 5000 ppm.

[0063] In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 20 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 40 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 60 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 80 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 100 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 120 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 150 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 200 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 250 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 300 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 500 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 1000 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 2000 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 3000 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 4000 ppm aluminum.

[0064] In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 5000 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 4000 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 3000 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 2500 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 2000 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 1000 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 500 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 340 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 300 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 250 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 200 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 150 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 100 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 80 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 60 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 40 ppm aluminum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has lanthanum from 20 ppm to 5000 ppm.

[0065] In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 20 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 50 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 100 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 200 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 300 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 400 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 500 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 600 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 700 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 800 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 900 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 1000 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 1100 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 1200 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 1300 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 1400 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 1500 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 2000 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 2500 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 3000 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or greater than 4000 ppm lanthanum.

[0066] In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 5000 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 4000 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 3000 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 2500 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 2000 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 1500 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 1300 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 1100 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 900 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 700 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 500 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 300 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 200 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 100 ppm lanthanum. In certain variations, the mixture of Al₂O₃ and La₂O₃ has equal to or less than 50 ppm lanthanum.

[0067] In certain variations, a battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has a discharge energy of at least 710 Wh/kg after 25 cycles. In certain variations, a battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has a discharge energy of at least 715 Wh/kg after 25 cycles. In certain variations, a battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has a discharge energy of at least 720 Wh/kg after 25 cycles. In certain variations, a battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has a discharge energy of at least 725 Wh/kg after 25 cycles. In certain variations, a battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has a discharge energy of at least 730 Wh/kg after 25 cycles. In certain variations, a battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has a discharge energy of at least 735 Wh/kg after 25 cycles.

[0068] In some variations, the battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has an energy retention of at least 85% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has an energy retention of at least 90% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has an energy retention of at least 91% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has an energy retention of at least 92% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has an energy retention of at least 93% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has an energy retention of at least 94% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has an energy retention of at least 95% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has an energy retention of at least 96% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has an energy retention of at least 97% after 30 charge-discharge cycles. In some variations, the battery including a mixture of Al₂O₃ and La₂O₃ coated cathode active materials has an energy retention of at least 98% after 30 charge-discharge cycles.

[0069] In certain variations, a battery including a complex oxide ZnAl₂O₄ coated cathode active materials has a discharge energy of at least 715 Wh/kg after 25 cycles. In certain variations, a battery including a complex oxide ZnAl₂O₄ coated cathode active materials has a discharge energy of at least 720 Wh/kg after 25 cycles. In certain variations, a battery including a complex oxide ZnAl₂O₄ coated cathode active materials has a discharge energy of at least 725 Wh/kg after 25 cycles. In certain variations, a battery including a complex oxide ZnAl₂O₄ coated cathode active materials has a discharge energy of at least 730 Wh/kg after 25 cycles. In certain variations, a battery including a complex oxide ZnAl₂O₄ coated cathode active materials has a discharge energy of at least 735 Wh/kg after 25 cycles. In certain variations, a battery including a complex oxide ZnAl₂O₄ coated cathode active materials has a discharge energy of at least 740 Wh/kg after 25 cycles.

[0070] In some variations, the battery including a complex oxide ZnAl₂O₄ coated cathode active materials has an energy retention of at least 85% after 30 charge-discharge cycles. In some variations, the battery including a complex oxide ZnAl₂O₄ coated cathode active materials has an energy retention of at least 90% after 30 charge-discharge cycles. In some variations, the battery including a complex oxide ZnAl₂O₄ coated cathode active materials has an energy retention of at least 91% after 30 charge-discharge cycles. In some variations, the battery including a complex oxide ZnAl₂O₄ coated cathode active materials has an energy retention of at least 92% after 30 charge-discharge cycles. In some variations, the battery including a complex oxide ZnAl₂O₄ coated cathode active materials has an energy retention of at least 93% after 30 charge-discharge cycles. In some variations, the battery including a complex oxide ZnAl₂O₄ coated cathode active materials has an energy retention of at least 94% after 30 charge-discharge cycles. In some variations, the battery including a complex oxide ZnAl₂O₄ coated cathode active materials has an energy retention of at least 95% after 30 charge-discharge cycles. In some variations, the battery including a complex oxide ZnAl₂O₄ coated cathode active materials has an energy retention of at least 96% after 30 charge-discharge cycles. In some variations, the battery including a complex oxide ZnAl₂O₄ coated cathode active materials has an energy retention of at least 97% after 30 charge-discharge cycles. In some variations, the battery including a complex oxide ZnAl₂O_{4 coated cathode active materials has an energy retention of at least} 98% after 30 charge-discharge cycles,

[0071] The coated powder can be used as a cathode active material for lithium ion batteries, as described herein. These cathode active materials assist energy storage by releasing and storing lithium ions during, respectively, charging and discharging of a lithium-ion battery.

[0072] Without wishing to be limited to a specific mechanism or mode of action, the characteristics of the powder can provide improved battery performance when the powder is used as a cathode active material. The powder comprising the disclosed oxide mixture coatings or complex oxide coating described herein have increased capacity and increased stability over an oxide coating, such as an Al₂O₃ coating or a ZrO₂ coating. Batteries comprising the powder as a cathode active material have an increased discharge capacity, an increased average voltage, an increased discharge energy, and an increased energy retention.

[0073] Cathode Active Compounds

[0074] The coating is disposed over cathode active compounds. Specifically, in various aspects, the coating is disposed over cathode active compound particles. The coated cathode active compounds can be used as cathode active materials in lithium-ion batteries.

[0075] In some variations, this disclosure is directed to a cathode active precursor compound, or particles (e.g., a powder) comprising the cathode active precursor compound, represented by Formula (Ia):

Ni_aMn_bCo_cM¹_dO_e  (Ia)

In Formula (Ia), M¹ is selected from B, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ru, Ag, In, La and any combination thereof; 0≤a≤1; 0≤b≤1; 0≤c≤1; a+b+c>0; 0≤d≤0.5; a+b+d>0; and 1≤e≤5. Compounds of Formula (Ia) include at least one of Ni, Mn, or Co (i.e., a+b+c>0). Moreover, the compounds include at least one of Ni, Mn, or M¹ (i.e., a+b+d>0).

[0076] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by Formula (Ib):

Li_1+fNi_aMn_bCo_cM¹_dO_e  (Ib)

It will be appreciated that the lithiated mixed-metal oxides may be prepared using the mixed-metal oxides associated with Formula (Ia), as will be discussed below. In Formula (Ib), M¹ is selected from B, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ru, Ag, In, La and combinations thereof; −0.1≤f≤1.0; 0≤a≤1; 0≤b≤1; 0≤c≤1; a+b+c>0; 0≤d≤0.5; a+b+d>0; and 1.9≤e≤3. Compounds of Formula (Ib) include at least one of Ni, Mn, or Co (i.e., a+b+c>0). Moreover, the compounds include at least one of Ni, Mn, or M¹ (i.e., a+b+d>0). As used herein, all compounds referenced for the lithiated mixed-metal oxides represent those of as-prepared materials (i.e., “virgin” materials) unless otherwise indicated. Such compounds have not yet been exposed to additional chemical processes, such as de-lithiation and lithiation during, respectively, charging and discharging. In some instances, 0≤f≤0.5. In some instances, 1.9≤e≤2.7. In further instances, 1.9≤e≤2.1.

[0077] In some instances, 0≤f≤1.0 and d=0. In these instances, no content associated with M¹ is present in the particles. Further, in some instances, d=0 and f≥0.20. In some instances, d=0 and f≥0.40. In some instances, d=0 and f≥0.60. In some instances, d=0 and f≥0.80. In some instances, d=0 and f≥0.80. In some instances, d=0 and f≥0.60. In some instances, d=0 and f≥0.40. In some instances, d=0 and f≥0.20. In some instances, d=0 and e≥2.20. In some instances, d=0 and e≥2.40. In some instances, d=0 and e≥2.60. In some instances, d=0 and e≥2.80. In some instances, d=0 and e≤2.80. In some instances, d=0 and e≤2.60. In some instances, d=0 and e≤2.40. In some instances, d=0 and e≤2.20. It will be understood that, in the aforementioned instances, the boundaries off and e can be combined in any variation as above.

[0078] In some instances, M¹ can include one or more cations with an average oxidation state of 4+, i.e., M¹₁. M¹ also can include more than one cation with a combined oxidation state of 3+, i.e., M¹₁M¹₂. M¹₁ is selected from Ti, Mn, Zr, Mo, and Ru and may be any combination thereof. M¹₂ is selected from Mg, Ca, V, Cr, Fe, Cu, Zn, Al, Sc, Y, Ga, and Zr and may be any combination thereof. A stoichiometric content associated with M¹₁, i.e., d₁, and a stoichiometric content associated with M¹₂, i.e., d₂, equals d (i.e., d₁+d₂=d). In these instances, a+b+c+d₁+d₂=1. Further, in some instances, d₁≥0.1. In some instances, d₁≥0.2. In some instances, d₁≥0.3. In some instances, d₁≥0.4. In some instances, d₁≤0.1. In some instances, d₁≤0.2. In some instances, d₁≤0.3. In some instances, d₁≤0.4. It will be understood that, in the aforementioned instances, the boundaries of d₁ can be combined in any variation as above.

[0079] In some instances, −0.05≤f≤0.10; M¹=Al; 0≤d≤0.05; a+b+c=1; 0<a+b<0.5; and 1.95≤e≤2.6. In further instances, 0.01≤d≤0.03. In still further instances, 0.02≤d≤0.03. In instances where d≠0 (i.e., aluminum is present), a distribution of aluminum within each particle may be uniform or may be biased to be proximate to a surface of each particle. Other distributions are possible.

[0080] In some instances, −0.05≤f≤0.10; d=0; a=0, b+c=1; and 1.9≤e≤2.2. Further, in some instances, 0.0≤f≤0.10. In some instances, 0.0≤f≤0.05. In some instances, 0.01≤f≤0.05 and 0.02≤b≤0.05. In some instances, 0.01≤f≤0.05 and b=0.04.

[0081] In some variations, this disclosure is directed to a cathode active precursor compound, or particles (e.g., a powder) comprising the cathode active precursor compound, represented by Formula (IIa):

M²O_g  (IIa)

wherein M²=Co, Mn, Ni, and any combination thereof; and 0.9≤g≤2.6. In some variations, 0.9≤g≤1.1. In some variations, g=1. In some variations, 1.4≤g≤1.6. In some variations, g=1.5. In some variations, 1.9≤g≤2.1. In some variations, g=2. In some variations, 2.4≤g≤2.6. In some variations, g=2.5.

[0082] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by Formula (IIb):

Li_hM²O_g  (IIb)

wherein M²=Co, Mn, Ni, and any combination thereof, 0.95≤h≤2, and 2≤g≤3. In some variations, 1≤h≤2. In some variations, 1.20≤h. In some variations, 1.40≤h. In some variations, 1.60≤h. In some variations, 1.80≤h. In some variations, h≤1.8. In some variations, h≤1.6. In some variations, h≤1.4. In some variations, h≤1.2. In some variations, h≤1.8. Further, in some variations, 2.2≤g. In some variations, 2.4≤g. In some variations, 2.6≤g. In some variations, 2.8≤g. In some variations, g≤2.8. In some variations, g≤2.6. In some variations, g≤2.4. In some variations, g≤2.2. It will be understood that the boundaries of h and g can be combined in any variation as above.

[0083] In some variations, this disclosure is directed to a cathode active precursor compound, or particles (e.g., a powder) comprising the cathode active precursor compound, represented by Formula (IIIa):

M³_iM⁴_1-iO_j  (IIIa)

wherein M³ is selected from Ti, Mn, Zr, Mo, Ru, and any combination thereof; M⁴ is selected from B, Na, Mg, Ti, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga, Zr, Ru, Mo, and any combination thereof; 0≤i≤1; and 0.9≤j≤2.6. In some variations, M³ has an average oxidation state of 4+(i.e., tetravalent). In some variations, M⁴ has an average oxidation state of 3+(i.e., trivalent). In some variations, 0<i<1. In specific variations, M³ is Mn. In specific variations, M⁴ is Co. In specific variations, M⁴ is a combination of Co and Mn. In further variations, a proportion of Co is greater than a proportion of Mn in the combination of Co and Mn.

[0084] In some variations, 1.4≤j≤2.1. In some variations, 1.5≤j≤2.0. In some variations, 1.6≤j≤1.9. In some variations, 0.9≤j≤1.1. In some variations, j=1. In some variations, 1.4≤j≤1.6. In some variations, j=1.5. In some variations, 1.9≤j≤2.1. In some variations, j=2. In some variations, 2.4≤j≤2.6. In some variations, j=2.5.

[0085] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by Formula (IIIb):

(i)[Li₂M³O₃].(1−i)[LiM⁴O₂]  (IIIb)

wherein M³ is one or more cations with an average oxidation state of 4+(i.e., tetravalent), M⁴ is one or more cations with an average oxidation state of 3+ (i.e., trivalent), and 0≤i≤1. In some variations, M³ is selected from Ti, Mn, Zr. Mo, Ru, and a combination thereof. In specific variations, M³ is Mn. In some variations, M⁴ is selected from B, Na, Mg, Ti, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga, Zr, Ru, Mo and a combination thereof. In specific variations, M⁴ is Co. In specific variations, M⁴ is a combination of Co and Mn. In further variations, a proportion of Co is greater than a proportion of Mn in the combination of Co and Mn. In variations where M⁴ includes cobalt, cobalt may be a predominant transition-metal constituent.

[0086] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by Formula (IIIc):

(i)[Li₂M³O₃].(1−i)[L_1-kM⁴O₂]  (IIIc)

wherein M³ is one or more cations with an average oxidation state of 4+(i.e., tetravalent), M⁴ is one or more cations, 0≤i≤1, and 0≤k≤1. In some variations, M³ is selected from Ti, Mn, Zr, Mo, Ru, and a combination thereof. In specific variations, M³ is Mn. In some variations, M⁴ is selected from B, Na, Mg, Ti, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga, Zr, Ru, Mo, and any combination thereof. In specific variations, M⁴ is Co. In specific variations, M⁴ is a combination of Co and Mn. In further variations, a proportion of Co is greater than a proportion of Mn in the combination of Co and Mn. In variations where M⁴ includes cobalt, cobalt may be a predominant transition-metal constituent which allows high voltage, and high volumetric energy density for cathode active materials employed in lithium-ion batteries.

[0087] In some variations, 0≤k≤0.16. In some variations, 0≤k≤0.14. In some variations, 0≤k≤0.12. In some variations, 0≤k≤0.10. In some variations, 0≤k≤0.08. In some variations, 0≤k≤0.06. In some variations, 0≤k≤0.04. In some variations, 0≤k≤0.02. In some variations, k=0.15. In some variations, k=0.14. In some variations, k=0.13. In some variations, k=0.12. In some variations, k=0.11. In some variations, k=0.10. In some variations, k=0.09. In some variations, k=0.08. In some variations, k=0.07. In some variations, k=0.06. In some variations, k=0.05. In some variations, k=0.04. In some variations, k=0.03. In some variations, k=0.02. In some variations, k=0.01.

[0088] In some variations, this disclosure is directed to a cathode active precursor compound, or particles (e.g., a powder) comprising the cathode active precursor compound, represented by Formula (IVa):

Co_1-lM⁵_lAl_mO_n  (IVa)

wherein M⁵ is B, Na, Mn, Ni, Mg, Ti, Ca, V, Cr, Fe, Cu, Zn, Al, Sc, Y, Ga, Zr, Mo, Ru, and any combination thereof, 0<l<0.50; 0≤m≤0.05; and 0.9≤n≤2.6. In some variations, M⁵ is Mn, Ni, and any combination thereof.

[0089] In some variations, 1.4≤n≤2.1. In some variations, 1.5≤n≤2.0. In some variations, 1.6≤n≤1.9. In some variations, 0.9≤n≤1.1. In some variations, n=1. In some variations, 1.4≤n≤1.6. In some variations, n=1.5. In some variations, 1.9≤n≤2.1. In some variations, n=2. In some variations, 2.4≤n≤2.6. In some variations, n=2.5.

[0090] In some variations, 0.01≤m≤0.03. In some variations, 0.001≤m≤0.005. In some variations, 0.002≤m≤0.004. In some variations, m=0.003. In some variations, 0.02≤m≤0.03. In variations of Formula (IVa) where m #0 (i.e., aluminum is present), a distribution of aluminum within the particle may be uniform or may be biased to be proximate to a surface of the particle. Other distributions of aluminum are possible. In some variations, Al is at least 500 ppm. In some variations, Al is at least 750 ppm. In some variations, Al is at least 900 ppm. In some variations, Al is less than or equal to 2000 ppm. In some variations, Al is less than or equal to 1500 ppm. In some variations, Al is less than or equal to 1250 ppm. In some variations, Al is approximately 1000 ppm. In an optional alternative, the compound can be expressed as Co_1-lM⁵_lO_n and Al expressed in ppm.

[0091] In some variations, 0.9≤n≤1.1. In some variations, n=1. In some variations, 1.4≤n≤1.6. In some variations, n=1.5. In some variations, 1.9≤n≤2.1. In some variations, n=2. In some variations, 2.4≤n≤2.6. In some variations, n=2.5. In some variations, 1.4≤n≤2.1. In some variations, 1.5≤n≤2.0. In some variations, 1.6≤n≤1.9.

[0092] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by Formula (IVb):

Li_oCo_1-lM⁵_lAl_mO_n  (IVb)

wherein M⁵ is B, Na, Mn, Ni, Mg, Ti, Ca, V, Cr, Fe, Cu, Zn, Al, Sc, Y, Ga, Zr, Mo, Ru, and any combination thereof; 0.95≤o≤1.10; 0≤l≤0.50; 0≤m≤0.05; and 1.95≤n≤2.60. In some variations, M⁵ is Mn, Ni, and any combination thereof.

[0093] In some variations, 0.01≤m≤0.03. In some variations, 0.001≤m≤0.005. In some variations, 0.002≤m≤0.004. In some variations, m=0.003. In some variations, 0.02≤n≤m 0.03. In variations of Formula (IVb) where m #0 (i.e., aluminum is present), a distribution of aluminum within the particle may be uniform or may be biased to be proximate to a surface of the particle. Other distributions of aluminum are possible. In some variations, Al is at least 500 ppm. In some variations, Al is at least 750 ppm. In some variations, Al is at least 900 ppm. In some variations, Al is less than or equal to 2000 ppm. In some variations, Al is less than or equal to 1500 ppm. In some variations, Al is less than or equal to 1250 ppm. In some variations, Al is approximately 1000 ppm. In additional variations of Formula (IVb), 1.02≤o≤1.05 and 0.02≤l≤0.05. In further variations of Formula (4b), 1.03≤o≤1.05 and l=0.04. It will be recognized that the components as described above can be in any combination. In some instances, when Al is expressed in ppm, in one aspect, the compound can be represented as Li_oCo_1-lM⁵_lO_n and the amount of Al can be represented as Al in at least a quantity in ppm, as described herein.

[0094] The various compounds of Formulae (IIb), (IIIb), (IIIc), and (IVb) can include Mn⁴⁺. Without wishing to be limited to any theory or mode of action, incorporating Mn⁴⁺ can improve a stability of oxide under high voltage charging (e.g., 4.5V) and can also help maintain an R³ m crystal structure (i.e., the α-NaFeO₂ structure) when transitioning through a 4.1-4.3V region (i.e., during charging and discharging).

[0095] In some variations, this disclosure is directed to a cathode active precursor compound, or particles (e.g., a powder) comprising the cathode active precursor compound, represented by Formula (Va):

Co_1-pMn_pM⁶_qO_r  (Va)

wherein M⁶ is at least one element selected from the group consisting of B, Na, Mg, Ti, Ca, V, Cr, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga, Zr, Ru, and Mo; 0≤p≤0.30; 0≤q≤0.10; and 0.9≤r≤2.6. In some variations, q=0. In some variations, M⁶ is Al.

[0096] In some variations, 1.4≤r≤2.1. In some variations, 1.5≤r≤2.0. In some variations, 1.6≤r≤1.9. In some variations, 0.9≤r≤1.1. In some variations, r=1. In some variations, 1.4≤r≤1.6. In some variations, r=1.5. In some variations, 1.9≤r≤2.1. In some variations, n=r. In some variations, 2.4≤r≤2.6. In some variations, r=2.5.

[0097] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by Formula (Vb):

Li_sCo_1-pMn_pO_r  (Vb)

wherein 0.95≤s≤1.10, 0≤p≤0.10, and 1.90≤r≤2.20. In some variations, 0<p≤0.10. In some variations, 0.98≤s≤1.01. In some variations of Formula (Vb), 0.98≤s≤1.01 and p=0.03. In some variations of Formula (Vb), 1.00≤s≤1.05. In some variations, the disclosure is directed to a compound represented by Formula (Vb), wherein 0.95≤s≤1.05 and 0.02≤p≤0.05. In a further aspect, the disclosure is directed to a compound represented by Formula (Vb), wherein 0.95≤s≤1.05 and p=0.04. In some variations, p=0.03. In further variations of Formula (Vb), 1.01≤s≤1.05 and 0.02≤p≤0.05. In still further variations of Formula (Vb), 1.01≤s≤1.05 and p=0.04. In some variations of Formula (Vb), 1.00<s≤1.10. In other variations of Formula (Vb), 1.00<s≤1.05. In a further aspect, the disclosure is directed to a compound represented by Formula (Vb), wherein 0.98≤s≤1.01, p=0.03, and r=2.

[0098] It will be appreciated that s represents a molar ratio of lithium content to total transition-metal content (i.e., total content of Co and Mn). In various aspects, increasing lithium content can increase capacity, improve stability, increase gravimetric density of particles comprising the compound, increase particle density, and/or increase particle strength of the cathode active material. In various aspects, decreasing lithium content can increase capacity, improve stability, increase gravimetric density of particles comprising the compound, increase particle density, and/or increase particle strength of the cathode active material.

[0099] In some variations, the compound of Formula (Vb) may be represented as a solid solution of two phases, i.e., a solid solution of Li₂MnO₃ and LiCoO₂. In these variations, the compound may be described according to Formula (Vc):

(p)[Li₂MnO₃].(1−p)[LiCoO₂]  (Vc)

where Mn is a cation with an average oxidation state of 4+(i.e., tetravalent) and Co is a cation with an average oxidation state of 3+(i.e., trivalent). A more compact notation for Formula (Vc) is given below:

Li_1+pCo_1-pMn_pO_2+p  (Vd)

In Formula (Vd), p can describe both Mn and Co. Due to differing valences between Mn and Co, the inclusion of Mn may influence a lithium content and an oxygen content of the compound.

[0100] Referring back to Formula (Vb), ‘p’ can be 0≤p≤0.10. In such variations, the lithium content can be from 1 to 1.10 (i.e., 1+p), and the oxygen content can be from 2 to 2.10 (i.e., 2+p). However, the compounds disclosed herein have lithium contents and oxygen contents that may vary independently of p. For example, and without limitation, the lithium and oxygen contents may vary from stoichiometric values due to synthesis conditions deliberately selected by those skilled in the art. As such, subscripts in Formulas (Vc) and (Vd) are not intended as limiting on Formula (Vb), i.e., s is not necessarily equal to 1+p, and r is not necessarily equal 2+p. It will be appreciated that one or both of the lithium content and the oxygen content of compounds represented by Formula (Vb) can be under-stoichiometric (i.e., s<1+p; r<2+p) or over-stoichiometric (i.e., s>1+l; r>2+p) relative to the stoichiometric values of Formula (Vd).

[0101] In some variations, the compound of Formula (Vb) may be represented as a solid solution of two phases, i.e., a solid solution of Li₂MnO₃ and LiCoO₂. In these variations, the compound may be described according to Formula (Ve):

(t)[Li₂MnO₃].(1−t)[Li_(1−u)Co_(1−u)Mn_uO₂]  (Ve)

where Mn is a cation with an average oxidation state of 4+(i.e., tetravalent) and Co is a cation with an average oxidation state of 3+(i.e., trivalent). A unified notation for Formula (Ve) is given below:

Li_1+t−u−tuCo_{(1−t)(1−u)}Mn_(t+u−tu)O_2+t  (Vf)

In Formula (Vf), t and u can describe both Mn and Co. Without wishing to be held to a particular mechanism or mode of action, because of differing valences between Mn and Co, inclusion of Mn may influence lithium content and oxygen content of the compound.

[0102] Comparing Formulas (Vb) and (Vf) shows s=1+t−u−tu, p=t+u−tu, r=2+t. In compounds represented by Formula V(f), the lithium content can be any range described herein for Formula (Vb). In some variations, Li can be from 0.95 to 1.10. In some variations, oxygen content can be from 2 to 2.20.

[0103] In other variations, this disclosure is directed to a compound, or particles (e.g., a powder) comprising a compound, represented by Formula (Vg):

Li_sCo_1−p−qMn_pM⁶_qO_r  (Vg)

wherein 0.95≤s≤1.30, 0≤p≤0.30, 0≤q≤0.10, and 1.98≤r≤2.04, and M⁶ is at least one element selected from the group consisting of B, Na, Mg, Ti, Ca, V, Cr, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga, Zr, Ru, and Mo. The compound of Formula (Vg) is single phase. The compound can have a trigonal R³m crystal structure. In further variations, 0.98≤s≤1.16 and 0<p≤0.16. In some variations 0.98≤s≤1.16, 0<p≤0.16, and 0<q≤0.05.

[0104] In other variations, this disclosure is directed to a compound, or particles (e.g., a powder) comprising a compound, represented by Formula (Vh):

Li_sCo_1−p−qMn_pAl_qO_r  (Vh)

wherein 0.95≤s≤1.30, 0≤p≤0.30, 0≤q≤0.10, and 1.98≤r≤2.04. In some variations, 0.96≤s≤1.04, 0≤p≤0.10, 0≤q≤0.10, and 1.98≤r≤2.04. In some variations, the compounds represented by Formula (Vh) have 0.98≤s≤1.01, 0.02≤p≤0.04, and 0≤q≤0.03. The compound of Formula (Vh) is a single phase. The compound can have trigonal R³m crystal structure.

[0105] In some variations, this disclosure is directed to a cathode active precursor compound, or particles (e.g., a powder) comprising the cathode active precursor compound, represented by Formula (VIa):

(v)[M⁷O₂].(1−v)[Co_1−σM⁸_σO₂]  (VIa)

wherein M⁷ is one or more elements with an average oxidation state of 4+(i.e., tetravalent); M⁸ is one or more monovalent, divalent, trivalent, and tetravalent elements; 0.01≤v<1.00, and 0≤σ≤0.05. In some variations, M⁷ is selected from Mn, Ti, Zr, Ru, and a combination thereof. In some variations, M⁸ is selected from B, Na, Mg, Ti, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga, Zr, Ru, Mo and a combination thereof. In some variations, M⁷ is Mn. In some variations, M⁸ is Al.

[0106] In some embodiments, 0.01≤v≤0.50. In some embodiments, 0.01≤v<0.50. In some embodiments, 0.01≤v≤0.30. In some embodiments, 0.01≤v<0.10. In some embodiments, 0.01≤v<0.05. In some variations, 0<σ≤0.05. In some variations, 0<σ≤0.03. In some variations, 0<σ≤0.02. In some variations, 0<σ≤0.01. In some variations, 0.01≤v<0.05, and 0<σ≤0.05.

[0107] In some variations, Al is at least 500 ppm. In some variations, Al is at least 750 ppm. In some variations, Al is at least 900 ppm. In some variations, Al is less than or equal to 2000 ppm. In some variations, Al is less than or equal to 1500 ppm. In some variations, Al is less than or equal to 1250 ppm. In some variations, Al is less than or equal to 1000 ppm. In some variations, Al is less than or equal to 900 ppm. In some variations, Al is less than or equal to 800 ppm. In some variations, Al is less than or equal to 700 ppm. In some variations, Al is less than or equal to 600 ppm. In some instances, when M⁸ (e.g., Al) is expressed in ppm, in optional variations, the compound can be represented as (v)[Li₂M⁷O₃].(1−v)[Li_αCo_wO₂] and the amount of M⁸ can be represented as M⁸ in at least a quantity in ppm, as otherwise described above. In some embodiments, 0.5≤w≤1. In some embodiments, 0.8≤w≤1. In some embodiments, 0.96≤w≤1. In some embodiments, 0.99≤w≤1. In some embodiments, w is 1.

[0108] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by (VIb):

(v)[Li₂M⁷O₃].(1−v)[Li_αCo_1-σM⁸_σO₂]  (VIb)

wherein M⁷ is one or more elements with an average oxidation state of 4+(i.e., tetravalent); M⁸ is one or more monovalent, divalent, trivalent, and tetravalent elements; 0.95≤α≤1.05, 0.95≤α≤0.99, 0.01≤v<1.00, and 0.5≤w≤1, and 0≤σ≤0.05. In some variations, M⁷ is selected from Mn, Ti, Zr, Ru, and a combination thereof. In some variations, M⁸ is selected from B, Na, Mg, Ti, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga, Zr, Ru, Mo and a combination thereof. In some variations, M⁷ is Mn. In some variations, M⁸ is Al.

[0109] In some embodiments, 0.01≤v≤0.50. In some embodiments, 0.01≤v<0.50. In some embodiments, 0.01≤v≤0.30. In some embodiments, 0.01≤v<0.10. In some embodiments, 0.01≤v<0.05. In some variations, 0<σ≤0.05. In some variations, 0<σ≤0.03. In some variations, 0<σ≤0.02. In some variations, 0<σ≤0.01. In some variations, 0.95≤α≤1.05, 0.95≤α<0.99, 0.01≤v<0.05, 0.96≤w<1, and 0<σ≤0.05.

[0110] In some variations, M⁸ (e.g., Al) is at least 500 ppm. In some variations, M⁸ (e.g., Al) is at least 750 ppm. In some variations, M⁸ (e.g., Al) is at least 900 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 2000 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 1500 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 1250 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 1000 ppm. In some variations, M (e.g., Al) is less than or equal to 900 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 800 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 700 ppm. In some variations, M (e.g., Al) is less than or equal to 600 ppm. In some instances, when M⁸ (e.g., Al) is expressed in ppm, the compound can be represented as (v)[Li₂M⁷O₃].(1−v)[Li_αCo_wO₂] and the amount of M⁸ can be represented as M⁸ in at least a quantity in ppm, as otherwise described above. In some variations, 0.5≤w≤1. In some variations, 0.8≤w≤1. In some variations, 0.96≤w≤1. In some variations, 0.99≤w≤1. In some variations, w is 1.

[0111] In some variations, the disclosure is directed to a cathode active material for lithium ion batteries that includes a lithium nickel oxide (LiNiO₂) having one or more tetravalent metals selected from Mn, Ti, Zr, Ge, Sn, and Te and/or one or more divalent metals selected from Mg, Be, Ca, Sr, Ba, Fe, Ni, Cu, and Zn. In these materials, the trivalent Ni ion can serve as host to supply the capacity. Without wishing to be limited to any theory or mode of action, a tetravalent ion such as Mn⁴⁺, and a divalent ion such as Mg²⁺, can stabilize the structure and help Ni ion stay trivalent for typical layer LiNiO₂ oxide.

[0112] The lithium nickel oxide may also include a stabilizer component, Li₂MeO₃, in which Me is one or more elements selected from Mn, Ti, Ru, and Zr. Without wishing to be limited to any theory or mode of action, Li₂MeO₃ can stabilize a layered crystal structure and improve a reversible capability of the lithium nickel oxide in a voltage window of a lithium-ion cell. Representative examples of Me include Mn, Ti, Ru, Zr, and any combination thereof.

[0113] In some variations, this disclosure is directed to a cathode active precursor compound, or particles (e.g., a powder) comprising the cathode active precursor compound, represented by Formula (VIIa):

Ni_xM⁹_yM¹⁰_zO_α  (VIIa)

where M⁹ is selected from Mn, Ti, Zr, Ge, Sn, Te, and any combination thereof; M¹⁰ is selected from Mg, Be, Ca, Sr, Ba, Fe, Ni, Cu, Zn, and any combination thereof; 0.7<x<1; 0<y<0.3; 0<z<0.3; x+y+z=1; and 0.9≤α≤2.6. In some variations of Formula (VIIa), M⁹ is Mn and M¹⁰ is Mg. In some variations of Formula (VIIa), 0.05<y<0.3 and 0.05<z<0.3.

[0114] In some variations, 1.4≤α≤2.1. In some variations, 1.5≤α≤2.0. In some variations, 1.6≤α≤1.9. In some variations, 0.9≤α≤1.1. In some variations, α=1. In some variations, 1.4≤α≤1.6. In some variations, α=1.5. In some variations, 1.9≤α≤2.1. In some variations, α=2. In some variations, 2.4≤α≤2.6. In some variations, α=2.5.

[0115] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by Formula (VIIb):

Li_βNi_xM⁹_yM¹⁰_zO₂  (VIIb)

where M⁹ is selected from Mn, Ti, Zr, Ge, Sn, Te, and a combination thereof; M¹⁰ is selected from Mg, Be, Ca, Sr, Ba, Fe, Ni, Cu, Zn, and a combination thereof; 0.9<β<1.1; 0.7<x<1; 0<y<0.3; 0<z<0.3; and x+y+z=1. In some variations of Formula (VIIb), 0.05<y<0.3 and 0.05<z<0.3.

[0116] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by Formula (VIIc):

Li_βNi_xMn_yMg_zO₂  (VIIc)

where 0.9<β<1.1; 0.7<x<1; 0<y<0.3; <z<0.3; and x+y+z=1. In some variations of Formula (VIIc), 0.05<y<0.3 and 0.05<z<0.3.

[0117] In compounds of Formula (VIIc), a valence of Mg remains 2+ and a valence of Mn remains 4+. Again, without wishing to be held to a particular theory or mode of action, the valence of Mg remains 2+ to stabilize a layered crystal structure and improve electrochemical performance of the cathode active materials represented by Formula (VIIc). As compared to known cathode formulae, the amount of Ni²⁺ can be reduced to achieve charge balance. Unlike Ni²⁺, which can transition electronically to Ni³⁺, Mg²⁺ represents a stable divalent ion in the cathode active material. Thus, in order to maintain an average transition-metal valence of 3+, a presence of Mg²⁺ in the cathode active material biases Ni away from Ni²⁺ to Ni³⁺. Such bias towards Ni³⁺ decreases the availability of Ni²⁺ to occupy a Li⁺ site, which decreases performance of the cathode active material.

[0118] In some variations, Ni is an active transition metal at a higher stoichiometric amount than in conventional materials. In further variations, the active transition metal of Ni is trivalent in the material (i.e., 3+). During an electrochemical charge/discharge process in a cell, the redox couple between Ni³⁺/Ni⁴⁺ influences a capacity of the cell.

[0119] The compounds of Formulae (VIIb) and (VIIc) as disclosed herein have properties that are surprisingly improved over properties of known compositions.

[0120] In some variations, this disclosure is directed to a cathode active precursor compound, or particles (e.g., a powder) comprising the cathode active precursor compound, represented by Formula (VIIIa):

M¹¹_γNi_(1−γ)δM¹²_(1−γ)εM¹³_(1−γ)ζO_η  (VIIIa)

where M¹¹ is selected from Mn, Ti, Ru, Zr, and any combination thereof; M² is selected from Mn, Ti, Zr, Ge, Sn, Te, and any combination thereof; M¹³ is selected from Mg, Be, Ca, Sr, Ba, Fe, Ni, Cu, Zn, and any combination thereof; 0≤γ≤0.3; 0.7<δ<1; 0<ε<0.3; 0≤ζ<0.3; δ+ε+ζ=1; and 0.9≤η≤2.6.

[0121] In some variations of Formula (VIIIa), 0.05<ε<0.3 and 0.05<ζ<0.3. In some variations, 1.4≤η≤2.1. In some variations, 1.5≤η≤2.0. In some variations, 1.6≤η1.9. In some variations, 0.9≤η1.1. In some variations, η=1. In some variations, 1.4≤η≤1.6. In some variations, η=1.5. In some variations, 1.9≤η≤2.1. In some variations, η=2. In some variations, 2.4≤η≤2.6. In some variations, η=2.5.

[0122] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by Formula (VIIIb):

γLi₂M¹¹O₃.(1−γ)Li_θNi_δM¹²_εM¹³_ζO₂  (VIIIb)

In Formula (VIIIb), Li_θNi_δM¹²_εM¹³_ζO₂ serves as the active component and Li₂M¹¹O₃ serves as the stabilizer component. The compound of Formula (VIIIb) corresponds to integrated or composite oxide material. A ratio of the components is governed by γ, which ranges according to 0≤γ≤0.3. For the Li₂M¹¹O₃ stabilizer component, M¹¹ is selected from Mn, Ti, Ru, Zr, and any combination thereof. For the Li_θNi_δM¹²_εM¹³_ζO₂ active component, M¹² is selected from Mn, Ti, Zr, Ge, Sn, Te, and any combination thereof; M¹³ is selected from Mg, Be, Ca, Sr, Ba, Fe, Ni, Cu, Zn, and any combination thereof; 0.9<θ<1.1; 0.7<δ<1; 0<ε<0.3; 0<ζ<0.3; and δ+ε+ζ=1. In some variations of Formula (VIIIb), 0.05<ε<0.3 and 0.05<ζ<0.3.

[0123] In some variations, this disclosure is directed to a cathode active precursor compound, or particles (e.g., a powder) comprising the cathode active precursor compound, represented by Formula (IXa):

(v)[M⁷O₂].(1−v)[Co_1-σM⁸_σO₂]  (IXa)

wherein M⁷ is one or more elements with an average oxidation state of 4+(i.e., tetravalent); M⁸ is one or more monovalent, divalent, trivalent, and tetravalent elements; 0.01≤v<1.00, and 0.5≤ and 0≤σ≤0.05. In some variations, M⁷ is selected from Mn, Ti, Zr, Ru, and a combination thereof. In some variations, M⁸ is selected from B, Na, Mg, Ti, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga, Zr, Ru, Mo and a combination thereof. In some variations, M⁷ is Mn. In some variations, M⁸ is Al.

[0124] In some embodiments, 0.01≤v≤0.50. In some embodiments, 0.01≤v<0.50. In some embodiments, 0.01≤v≤0.30. In some embodiments, 0.01≤v<0.10. In some embodiments, 0.01≤v<0.05. In some variations, 0≤σ≤0.05. In some variations, 0<σ≤0.05. In some variations, 0<σ≤0.03. In some variations, 0<σ≤0.02. In some variations, 0<σ≤0.01. In some variations, 0.01≤v<0.05 and 0<σ≤0.05.

[0125] In some variations, Al is at least 500 ppm. In some variations, Al is at least 750 ppm. In some variations, Al is at least 900 ppm. In some variations, Al is less than or equal to 2000 ppm. In some variations, Al is less than or equal to 1500 ppm. In some variations, Al is less than or equal to 1250 ppm. In some variations, Al is less than or equal to 1000 ppm. In some variations, Al is less than or equal to 900 ppm. In some variations, Al is less than or equal to 800 ppm. In some variations, Al is less than or equal to 700 ppm. In some variations, Al is less than or equal to 600 ppm. In some instances, when M⁸ (e.g., Al) is expressed in ppm, in optional variations, the compound can be represented as (v)[Li₂M⁷O₃].(1−v)[Li_αCo_wO₂] and the amount of M⁸ can be represented as M⁸ in at least a quantity in ppm, as otherwise described above. In some embodiments, 0.5≤w≤1. In some embodiments, 0.8≤w≤1. In some embodiments, 0.96≤w≤1. In some embodiments, 0.99≤w≤1. In some embodiments, w is 1.

[0126] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by Formula (IXb):

(v)[Li₂M⁷O₃].(1−v)[Li_αCo_1-σM⁸_σO₂]  (IXb)

wherein M⁷ is one or more elements with an average oxidation state of 4+ (i.e., tetravalent); M⁸ is one or more monovalent, divalent, trivalent, and tetravalent elements; 0.95≤α≤1.05, 0.95≤α<0.99, 0.01≤v<1.00, and 0.5≤w≤1, and 0≤σ≤0.05. In some variations, M⁷ is selected from Mn, Ti, Zr, Ru, and a combination thereof. In some variations, M⁷ is selected from Mn, Ti, Zr, and Ru. In some variations, M⁸ is selected from B, Na, Mg, Ti, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga, Zr, Ru, Mo and a combination thereof. In some variations, M⁸ is selected from B, Na, Mg, Ti, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga, Zr, Ru, and Mo. In some variations, M⁷ is Mn. In some variations, M⁸ is Al.

[0127] In some embodiments, 0.01≤v≤0.50. In some embodiments, 0.01≤v<0.50. In some embodiments, 0.01≤v≤0.30. In some embodiments, 0.01≤v<0.10. In some embodiments, 0.01≤v<0.05. In some variations, 0≤σ≤0.05. In some variations, 0<σ≤0.05. In some variations, 0<σ≤0.03. In some variations, 0<σ≤0.02. In some variations, 0<σ≤0.01. In some variations, 0.95≤α≤1.05, 0.95≤α<0.99, 0.01≤v<0.05, 0.96≤w<1, and 0<σ≤0.05.

[0128] In some variations, M⁸ (e.g., Al) is at least 500 ppm. In some variations, M⁸ (e.g., Al) is at least 750 ppm. In some variations, M⁸ (e.g., Al) is at least 900 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 2000 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 1500 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 1250 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 1000 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 900 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 800 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 700 ppm. In some variations, M⁸ (e.g., Al) is less than or equal to 600 ppm. In some instances, when M⁸ (e.g., Al) is expressed in ppm, the compound can be represented as (v)[Li₂M⁷O₃].(1−v)[Li_αCo_wO₂] and the amount of M⁸ can be represented as M⁸ in at least a quantity in ppm, as otherwise described above. In some variations, 0.5<w<1. In some variations, 0.8<w<1. In some variations, 0.96<w<1. In some variations, 0.99<w<1. In some variations, w is 1.

[0129] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by Formula (X):

Li_αCo_1−x−yM_yMn_xO_δ  (X)

wherein 0.95≤α≤1.30, 0.95≤α≤1.05, 0<x≤0.30, 0≤y≤0.10, and 1.98≤δ≤2.04, and M is at least one element selected from the group consisting of B, Na, Mg, Ti, Ca, V, Cr, Fe, Co, Ni, Cu, Zn, Al, Sc, Y, Ga, Zr, Ru, and Mo. The compound of Formula (VII) is single phase. The compound can have a trigonal R³m crystal structure. In further variations, 0.98≤α≤1.16 and 0<x≤0.16. In some variations 0.98≤α≤1.16, 0<x≤0.16, 0<y≤0.05, 1.98≤δ≤2.04.

[0130] In some variations, this disclosure is directed to a cathode active compound, or particles (e.g., a powder) comprising the cathode active compound, represented by Formula (XI):

Li_αCo_1−x−yAl_yMn_xO_δ  (XI)

wherein 0.95≤α≤1.05, 0.95≤α≤1.05, 0<x<0.30, 0≤y≤0.10, and 1.98≤δ≤2.04. In some variations, 0.96≤α≤1.04, 0<x≤0.10, 0≤y≤0.10, and 1.98≤δ≤2.04. In some variations, the compounds represented by Formula (XI) have 0.98≤α≤1.01, 0.02≤x≤0.04, 0≤y≤0.03, and 1.98≤δ≤2.04. The compound of Formula (XI) is a single phase. The compound can have trigonal R³m crystal structure.

[0131] In other instances, the compounds represented by Formulae (X) and (XI), in any combination of variables described above, have 0.95≤α. In some instances, α≤1.05. In some instances, α≤1.04. In some instances, α≤1.03. In some instances, α≤1.02. In some instances, α≤1.01. In some instances, α≤1.00. In some instances, α≤0.99. In some instances, α≤0.98. In some instances, 0.5≤α≤0.98. In some instances, 0.95≤α≤0.99. In some instances, 0.95≤α≤1.00. In some instances, 0.95≤α≤1.01. In some instances, 0.95≤α≤1.02. In some instances, 0.95≤α≤1.03. In some instances, 0.95≤α≤1.04. In some instances, the compounds represented by Formulae (X) and (XI) have α>1+x. In some instances, the compounds represented by Formulae (X) and (XI) have α>1+x. In some instances, α<1+x. As such, a in Formulae (X) and (XI) can deviate from α==1+x, which may be associated with a solid-solution between Li₂MnO₃ and (1−x)LiCo_1−yM_yO₂. This solid solution can be represented by xLi₂MnO₃.(1−x)LiCo_1−yM_yO₂, and xLi₂MnO₃.(1−x)Li1−yCo_1−yM_yO₂, or in compact notation, Li_1+xCo_1−x−y+xyM_(1−x)*_yMn_xO_2+x or Li_1+x−y+xyCo_1−x−y+xyM_(1−x)*yMn_xO_2+x.

[0132] Methods of Making the Cathode Active Material

[0133] The disclosure is further directed to methods of making the cathode active material. The coatings of oxide mixtures or complex oxides are prepared by mixing a cathode active compound particles with a solution mixture that contains the precursors of the metals that are found in the coatings. After drying, the mixture is calcined at elevated temperatures to decompose the precursors into oxides or to promote formation of the complex oxides on the cathode active compound material. The coated cathode active material is then tested as cathode in coin cells that use a Li foil anode, a separator, and flooded electrolyte solution.

[0134] In certain variations, a wet impregnation method was used to form an oxide (e.g. Al₂O₃, ZrO₂, or mixture) coating over a particular cathode active material. A predetermined amount of the cathode active material was weighed out into a glass beaker.

[0135] In some variations, to form Al₂O₃ coating, an amount of aluminum precursor needed for the desired amount of coating (e.g., 0.5 wt. %) was calculated based on the weighed amount of base powder. The aluminum precursor included various aluminum salts such as aluminum nitrate, aluminum acetate, or other aluminum salts, which are soluble in water or alcohol. The aluminum precursor was dissolved in a small amount of water or alcohol to form a first clear solution. A desired amount of lithium precursor was calculated using a molar ratio of Li to Al between 0.25 and 1.05. The lithium precursor used was lithium hydroxide, lithium nitrate, lithium acetate, or other lithium salts soluble in water or alcohol. The desired amount of lithium precursor was dissolved in a small amount of water or alcohol to form a second clear solution. The first and second clear solutions were mixed together. This mixed solution was then added drop-wise to the base powder while stirring. The volume of solution added was such that the base powder became incipiently wet but not watery (i.e., exhibited a damp consistency). After drying at 50-80° C., the dried base powder was then heat-treated to 500° C. for 4 h in stagnant air. The pH of the first clear solution (i.e., the aluminum solution) can also be varied to improve coating properties such as coating density and uniformity.

[0136] In some variations, zirconium precursor includes various zirconium salts, such as zirconium acetate, may be used to form ZrO₂ coating.

[0137] In some variations, aluminum precursor including various aluminum salts, such as aluminum nitrate, aluminum acetate, and zirconium precursor includes various zirconium salts, such as zirconium acetate, may be used to form a mixture of Al₂O₃ and ZrO₂.

[0138] In some variations, aluminum precursor including various aluminum salts, such as aluminum nitrate, aluminum acetate, and lanthanum precursor including lanthanum salts, such as lanthanum nitrates may be used to form a mixture of Al₂O₃ and La₂O₃.

[0139] In some variations, aluminum precursor including various aluminum salts, such as aluminum nitrate, aluminum acetate, and zinc precursor includes various zinc salts, such as zinc nitrate, may be used to form a complex oxide ZnAl₂O₄.

[0140] In a dry processing, a predetermined amount of cathode active compound particles (e.g. Li(Co_0.97Mn_0.03)O₂) was weighed out and poured into a dry coater (Nobilta, NOB-130, Hosokawa Micron Ltd). Next, the powder was weighed out according to a desired amount of coating on the predetermined base powder (e.g., 0.1 wt. %). The weighed powder was poured into the dry coater. For a 0.1 wt. % coating, 0.5 g of oxide (e.g. Al₂O₃, ZrO₂, or mixture) was mixed thoroughly with 500 g of base powder. The speed was controlled at 4000 rpm. After 5 min, an oxide-coated base powder was formed.

[0141] Cathode Disk

[0142] In some variations, the cathode disks can be formed from the coated powder. A ball mill may be used to grind powder into finer powder. The density of the cathode disk may increase by reducing the size of the powder.

[0143] The porosity of the cathode may affect the performance of an electrochemical cell. A hydraulic press may be used to compact powder to obtain a cathode disk of desired thickness and density during cold pressing. For example, the coated cathode active material was placed in a die that can be compressed up to 5000 lbs. The press includes two plates that are hydraulically forced together to create a pressure.

[0144] Testing Methods

[0145] The cathode disks were assembled into button cell (coin cell) batteries with a Li disk anode, a Celgard 2325 separator (25 μm thick), and the electrolyte consisting of 1.2 M LiPF6 in ethyl carbonate (EC) and ethyl methyl carbonate (EMC) (EC:EMC=3:7 w/w). Galvanostatic charge/discharge cycling was conducted in the 3.0-4.5 V range at 25° C. The test procedure includes three formation cycles at a ˜C/5 rate with the 1 C capacity assumed to be 185 mAh/g, followed by aging cycles at a C/5 rate with the 1 C capacity calculated based on the third cycle discharge capacity. The batteries are aged for 30 to 50 cycles.

[0146] An electrochemical tester (e.g. Maccor 4200) provides a user with a variety of options in testing of batteries. Multiple channels can be plugged into the electrochemical tester to allow for multiple batteries to be tested simultaneously. These tests allow the user to measure parameters of the batteries, such as voltage, current, impedance, and capacity, to fully understand the effectiveness of the electrochemical cell being tested. The tester can be attached to a computer to obtain digital testing values.

[0147] The following examples are for illustration purposes only. It will be apparent to those skilled in the art that many modifications, both to materials and methods, may be practiced without departing from the scope of the disclosure.

[0148] Although ZrO₂ has been used as coatings for lithium (Li)-ion batteries cathodes, a mixture of Al2O3 and ZrO2 has not been used as coatings for battery cathode materials.

[0149] The mixture coatings were applied to three molar percent manganese (Mn) to substitute cobalt (Co) in LiCoO₂ (Li(Co_0.97Mn_0.03)O₂). The preparation method included mixing of the cathode active compound particles with a dilute acetic acid aqueous solution containing zirconium acetate and aluminum nitrate. The preparation method also included drying the resulting wet powder at 80° C. overnight, and calcining the dried powder at 450° C. for four hours in stagnant air. As a result, the particles were coated with a mixture of Al₂O₃ and ZrO₂. The cathode active material was used to form a cathode in a coin cell against Li foil anode.

[0150] The coatings including several ratios of the mixture of the Al₂O₃ and ZrO₂ were prepared and tested. Tests were performed by the disclosed methods to determine discharge capacity, average voltage, discharge energy, and energy retention of the battery cell.

[0151] The electrochemical performance of the cathode was compared with that of the uncoated cathode active compound particles alone, Al₂O₃ coated cathode active compound particles, and ZrO₂ coated cathode active compound particles. The composition of coatings is shown in Table 1.

TABLE 1
Coating compositions of Al2O3 and ZrO2
		Metal content
	Al2O3:ZrO2	in coating
Coating type	molar ratio	Al, ppm	Zr, ppm
Al2O3	1.00	0.00	265	0
Mixture of Al2O3 and ZrO2	0.287	0.713	265	1111
Mixture of Al2O3 and ZrO2	0.091	0.909	66	1111
Mixture of Al2O3 and ZrO2	0.092	0.908	133	2221
ZrO2	0.00	1.00	0	2221

[0152] As shown in Table 1, a first mixture of Al₂O₃ and ZrO₂ had a molar ratio of 0.287 to 0.713 for Al₂O₃ to ZrO₂, which has a value of 0.403. The coating formed from the first mixture included 265 ppm aluminum and 1111 ppm zirconium. A second mixture of Al₂O₃ and ZrO₂ had a molar ratio of 0.091 to 0.909 for Al₂O₃ to ZrO₂, which has a value of 0.100. The coating formed from the second mixture included 66 ppm aluminum and 1111 ppm zirconium. A third mixture of Al₂O₃ and ZrO₂ had a molar ratio of 0.092 to 0.908 for Al₂O₃ to ZrO₂, which has a value of 0.101. The coating formed from the third mixture included 133 ppm aluminum and 2221 ppm zirconium.

[0153] FIG. 3 is a plot of discharge capacity versus cycle count for cathode active materials including a mixture of Al₂O₃ and ZrO₂ coating on Li(Co_0.97Mn_0.03)O₂ compared with Al₂O₃ coating or ZrO₂ coating on Li(Co_0.97Mn_0.03)O₂, according to an illustrative embodiment. FIG. 3 illustrates the effect of a mixture of Al₂O₃ and ZrO₂ coating on the discharge capacity of a battery. As shown, the ZrO₂ coating provides a first-cycle discharge capacity of 188 mAh/g, but loses capacity faster than the Al₂O₃ coating. In other words, the Al₂O₃ coating is more stable than the ZrO₂ coating, but starts with a lower first-cycle discharge capacity of 186 mAh/g than the ZrO₂ coating.

[0154] As shown, the second mixture of Al₂O₃ and ZrO₂ coating including 1111 ppm Zr and 66 ppm Al provides a first-cycle discharge capacity of about 186 mAh/g, and stabilizes the discharge capacity of the battery by demonstrating a less steep slope for the curve of discharge capacity versus cycle count such that the discharge capacity drops to about 179 mAh/g, slightly more than that of the ZrO₂ coating. However, the first mixture of Al₂O₃ and ZrO₂ coating including 1111 ppm Zr and 265 ppm Al decreases the discharge capacity to about 184.5 mAh/g, but stabilizes the capacity of the battery with a less steep slope such that the discharge capacity drops to about 177 mAh/g after 26 cycles, which is lower than that of the ZrO₂ coating. Also, the third mixture of Al₂O₃ and ZrO₂ coating including 2221 ppm Zr and 133 ppm Al has a similar capacity of 186 mAh/g to Al₂O₃ coating, but does not stabilize the discharge capacity of the battery such that the discharge capacity drops to about 177 mAh/g after 26 cycles, which is lower than that of the ZrO₂ coating. As such, the second mixture of Al₂O₃ and ZrO₂ coating including 1111 ppm Zr and 66 ppm Al provides the surprising result of achieving both enhanced discharge capacity and improved stability over cycles.

[0155] FIG. 4 is a plot of average voltage versus cycle count for cathode active materials including a mixture of Al₂O₃ and ZrO₂ coating on Li(Co_0.97Mn_0.03)O₂ compared with Al₂O₃ coating or ZrO₂ coating on Li(Co_0.97Mn_0.03)O₂, according to an illustrative embodiment. As shown in FIG. 4, the ZrO₂ coating provides a boost to the average voltage up to about 4.04 V after 5 cycles, but does not sustain good retention, as shown by a relatively steep slope such that the voltage drops to 3.98 V after 26 cycles.

[0156] The first mixture of Al₂O₃ and ZrO₂ coating including 1111 ppm Zr and 265 ppm Al reduces the slope of the curve of average voltage vs. cycle count and thus increases the energy retention. The first mixture of Al₂O₃ and ZrO₂ coating provides an average voltage of about 4.01 V after 4 cycles, which is lower than that of ZrO₂ coating and close to that of Al₂O₃ coating for the same cycles.

[0157] The third mixture of Al₂O₃ and ZrO₂ coating including 2221 ppm Zr and 133 ppm Al provides a boost to the average voltage of about 4.03 V after 4 cycles, but the voltage decreases to 3.98 after 26 cycles, which does not improve the energy retention over the ZrO₂.

[0158] The second mixture of Al₂O₃ and ZrO₂ coating including 1111 ppm Zr and 66 ppm Al) provides a boost to the average voltage up to about 4.04 V after 5 cycles, and also reduces the slope of the curve of average voltage vs. cycle count such that the voltage drops to about 4.00 after 26 cycles, which thus increases the energy retention to be higher than that of the ZrO₂ coating. As such, the second mixture of Al₂O₃ and ZrO₂ of the coating including 1111 ppm Zr and 66 ppm Al provides the surprising result of achieving both enhanced average voltage and improved energy retention.

[0159] FIG. 5 is a plot of discharge energy versus cycle count for cathode active materials including a mixture of Al₂O₃ and ZrO₂ coating on Li(Co_0.97Mn_0.03)O₂ compared with Al₂O₃ coating or ZrO₂ coating on Li(Co_0.97Mn_0.03)O₂, according to an illustrative embodiment. The discharge capacity and average voltage are combined to define the discharge energy (Wh/kg) of a battery. As shown in FIG. 5, the ZrO₂ coating provides increased discharge energy in comparison to the Al₂O₃ coating. However, the ZrO₂ alone cannot sustain the discharge energy without the addition of Al₂O₃ (e.g. the mixture including 1111 ppm Zr and 66 ppm Al).

[0160] FIG. 6 is a plot of energy retention versus cycle count for cathode active materials including a mixture of Al₂O₃ and ZrO₂ coating on Li(Co_0.97Mn_0.03)O₂ compared with Al₂O₃ coating or ZrO₂ coating on Li(Co_0.97Mn_0.03)O₂, according to an illustrative embodiment. The energy retention is defined as the normalized discharge energy with respect the discharge energy after 4 cycles. The energy retention clearly shows the effects of stability of the mixture of Al₂O₃ and ZrO₂ coating on Li(Co_0.97Mn_0.03)O₂ over the individual oxide coatings.

[0161] As shown, only the mixture including a small amount of Al₂O₃ (e.g. 66 ppm) helps stabilize the ZrO₂.

[0162] FIG. 7 is a phase diagram of Al₂O₃ and ZrO₂ from Powder Metall. Mt. Ceram., Vol. 33, 1994, p 486-490. As shown in FIG. 7, the oxides Al₂O₃ and ZrO₂ do not combine to form a ternary oxide. Instead, the oxides Al₂O₃ and ZrO₂ maintain their individual oxide phases and demonstrate a negligible solubility in each other. However, a more recent publication [A. T. Ravichandran et al., Superlattices and Microstructures, 75 (2014) 533-542] revealed that 2 to 10 at % Al can be doped into tetragonal ZrO₂ nano-powders by solution combustion method using glycine as the fuel in a preheated furnace around 500° C., which reduces the ZrO₂ crystallite's size and stabilizes the ZrO₂ tetragonal phase.

[0163] The mixture including Al₂O₃ and La₂O₃ were applied to the Li(Co_0.97Mn_0.03)O₂ cathode active compound particles. The mixture on Li(Co_0.97Mn_0.03)O₂ were prepared by mixing the cathode active compound particles with aqueous mixture solution of aluminum and lanthanum nitrates, followed by drying at 80° C. overnight and calcining at 450° C. for four hours in air. As a result, the particles were coated with a mixture of Al₂O₃ and La₂O₃. The cathode active material used to form a cathode in a coin cell against Li foil anode. The coatings including several ratios of the mixture of the Al₂O₃ and La₂O₃ were prepared. The coin cells or battery cells were tested to determine the electrochemical performance of the cathode.

[0164] The electrochemical performance of the cathode is compared with that of the cathode active compound particles alone, and cathode active compound particles coated with Al₂O₃ alone. The composition of coatings is shown in Table 2.

TABLE 2
Coating compositions of Al2O3 and La2O3
		Metal content
	Al2O3:La2O3	in coating
Coating type	molar ratio	Al, ppm	La, ppm
Al2O3	1	0	265	0
Mixture of Al2O3 and La2O3	1	1	63	325
Mixture of Al2O3 and La2O3	1	1	126	649
Mixture of Al2O3 and La2O3	1	1	252	1296

[0165] As shown in Table 2, a first mixture of Al₂O₃ and La₂O₃ had 63 ppm Al and 325 ppm La. A second mixture of Al₂O₃ and La₂O₃ included 126 ppm Al and 649 ppm La. A third mixture of Al₂O₃ and La₂O₃ included 252 ppm Al and 1296 ppm La. The first, second and third mixtures have about the same molar ratio 1:1 for La₂O₃ to Al₂O₃. Also, the first, second and third mixtures have Al less than 265 ppm of the Al₂O₃ coating.

[0166] FIGS. 8-11 reveal a significant enhancement in the electrochemical performance of the oxide mixture coating over the Al₂O₃ coating on Li(Co_0.97Mn_0.03)O₂, including increased discharge capacity and increased average discharge capacity, increased discharge energy associated with increased discharge capacity and average discharge capacity, and enhanced energy retention. Variations in the level of mixture coatings on Li(Co_0.97Mn_0.03)O₂ particles do not seem to affect the cathode electrochemical performance much as long as the molar ratio remains unchanged.

[0167] FIG. 8 is a plot of discharge capacity versus cycle count for cathode active materials including a mixture of Al₂O₃ and La₂O₃ coating on Li(Co_0.97Mn_0.03)O₂ with different loadings at 1:1 molar ratio of La₂O₃ to Al₂O₃ compared with uncoated Li(Co_0.97Mn_0.03)O₂ and Al₂O₃ coating on Li(Co_0.97Mn_0.03)O₂, according to an illustrative embodiment. As shown in FIG. 8, all the three mixture coatings including 325 ppm La, 649 ppm La, and 1296 ppm La reveal a discharge capacity of about 186 mAh/g after 5 cycles, which is higher than that of the Al₂O₃ coating, and also higher than that of the uncoated cathode active compound particles. Also, the mixture coatings provide a discharge capacity of about 178 mAh/g after 30 cycles, which is higher than that of the Al₂O₃ coating and that of the uncoated cathode active compound particles.

[0168] FIG. 9 is a plot of average discharge voltage versus cycle count for cathode active materials including a mixture of Al₂O₃ and La₂O₃ coating on Li(Co_0.97Mn_0.03)O₂ with different loadings at 1:1 molar ratio of La₂O₃ to Al₂O₃ compared with uncoated Li(Co_0.97Mn_0.03)O₂ and Al₂O₃ coating on Li(Co_0.97Mn_0.03)O₂, according to an illustrative embodiment. FIG. 10 is a plot of discharge energy versus cycle count for cathode active materials including a mixture of Al₂O₃ and La₂O₃ coating on Li(Co_0.97Mn_0.03)O₂ with different loadings at 1:1 molar ratio of La₂O₃ to Al₂O₃ compared with uncoated Li(Co_0.97Mn_0.03)O₂ and Al₂O₃ coating on Li(Co_0.97Mn_0.03)O₂, according to an illustrative embodiment. FIG. 11 is a plot of energy retention versus cycle count for cathode active materials including a mixture of Al₂O₃ and La₂O₃ coating on Li(Co_0.97Mn_0.03)O₂ with different loadings at 1:1 molar ratio of La₂O₃ to Al₂O₃ compared with uncoated Li(Co_0.97Mn_0.03)O₂ and Al₂O₃ coating on Li(Co_0.97Mn_0.03)O₂, according to an illustrative embodiment. As shown in FIGS. 9-11, all the first, second, and third mixtures reveal improved performance over the Al₂O₃ coating, similar to that shown in FIG. 8.

[0169] FIG. 12 is a phase diagram of Al₂O₃ and La₂O₃(J. Alloys Compd., Vol. 179, 1992, p 259-28). As shown in FIG. 12, the Al₂O₃ and La₂O₃ oxides may combine to form a Perovskite phase, e.g. LaAlO₃, at high temperatures. The LaAlO₃ has the same type of crystal structure as CaTiO₃, which is known as the Perovskite structure. The Perovskite phase may also be formed at lower temperatures when the Al₂O₃ and La₂O₃ are in nanoparticles forms and mixed at atomic scales, with amount increasing with the molar ratio of La:Al. (J. Phys. Chem. C2015, 119, 25053-25062). However, it is difficult to identify the perovskite phase in these coatings by XRD, as the coating quantity is too low to warrant detection of the coating phases.

[0170] Zinc oxide (ZnO) was investigated as coatings for Li-ion battery cathodes, particularly for the Co-rich cathodes, which was shown to improve the cathode performance to certain extent. However, there are no literature investigations used a complex oxide ZnAl₂O₄, a combination of zinc oxide and aluminum oxide in a spinel structure, as coating for Co-rich cathodes.

[0171] The complex oxide ZnAl₂O₄ was used as a coating applied onto Co-containing cathode material, Li(Co_0.97Mn_0.03)O₂. The coating was prepared by mixing the cathode active compound particles with an aqueous mixture solution of Zn and Al nitrates at Zn to Al molar ratio of 1:2, followed by drying at 80° C. and calcining at 700° C. for four hours in air. As a result, the particles were coated with a complex oxide ZnAl₂O₄. The cathode active compound material was used to form a cathode in a coin cell against Li foil anode. The tests were performed to evaluate the electrochemical performance of the coating.

[0172] FIGS. 13-16 illustrate the improvement of the complex oxide coating over Al₂O₃ coating on Li(Co_0.97Mn_0.03)O₂. Compared to the Al₂O₃ coating, the complex oxide ZnAl₂O₄ coating increases not only discharge capacity, but also average discharge voltage, leading to the increased discharge energy.

[0173] FIG. 13 is a plot of discharge capacity versus cycle count for cathode active materials including the complex oxide ZnAl₂O₄ coating on Li(Co_0.97Mn_0.03)O₂ compared with uncoated Li(Co_0.97Mn_0.03)O₂ and Al₂O₃ coating on Li(Co_0.97Mn_0.03)O₂, according to an illustrative embodiment. As shown in FIG. 13, the complex oxide ZnAl₂O₄ coating provides a boost to the discharge capacity to about 187 mAh/g after 1 cycle, which is higher than about 184 mAh/g for the Al₂O₃ coating. The complex oxide ZnAl₂O₄ coating provides a boost to the discharge capacity to about 180 mAh/g after 30 cycles, which is higher than about 176 mAh/g for the Al₂O₃ coating after 30 cycles.

[0174] FIG. 14 is a plot of average discharge voltage versus cycle count for cathode active materials including the complex oxide ZnAl₂O₄ coating on Li(Co_0.97Mn_0.03)O₂ compared with uncoated Li(Co_0.97Mn_0.03)O₂ and Al₂O₃ coating on Li(Co_0.97Mn_0.03)O₂, according to an illustrative embodiment. As shown in FIG. 14, the complex oxide ZnAl₂O₄ coating provides a boost to the average voltage to about 4.03 V after 4 cycles, which is higher than about 4.0 V for the Al₂O₃ coating. Also, the complex oxide ZnAl₂O₄ coating provides a boost to the average voltage to about 4.00 V after 30 cycles, which is higher than about 3.95 V for the Al₂O₃ coating.

[0175] FIG. 15 is a plot of discharge energy versus cycle count for cathode active materials including the complex oxide ZnAl₂O₄ coating on Li(Co_0.97Mn_0.03)O₂ compared with uncoated Li(Co_0.97Mn_0.03)O₂ and Al₂O₃ coating on Li(Co_0.97Mn_0.03)O₂, according to an illustrative embodiment. As shown in FIG. 15, the complex oxide ZnAl₂O₄ coating provides a boost to the discharge energy to about 755 Wh/kg after 4 cycles, which is higher than about 735 Wh/kg for the Al₂O₃ coating. Also, the complex oxide ZnAl₂O₄ coating provides a boost to the discharge energy to about 725 Wh/kg after 30 cycles, which is higher than about 695 Wh/kg for the Al₂O₃ coating. The cathode with the complex oxide ZnAl₂O₄ coating maintains higher discharge energy up to 30 cycles, as shown in FIG. 15.

[0176] FIG. 16 is a plot of energy retention versus cycle count for cathode active materials including the complex oxide ZnAl₂O₄ coating on Li(Co_0.97Mn_0.03)O₂ compared with uncoated Li(Co_0.97Mn_0.03)O₂ and Al₂O₃ coating on Li(Co_0.97Mn_0.03)O₂, according to an illustrative embodiment. The complex oxide ZnAl₂O₄ coating also enhances the energy retention, as shown in FIG. 16 by a less steeper slope than the Al₂O₃ coating. For example, after 30 cycles, the energy retention becomes about 0.97 for the complex oxide ZnAl₂O₄ coating, which is higher than an energy retention of about 0.95 for the Al₂O₃ coating. The cathode with the complex oxide ZnAl₂O₄ coating maintains higher energy retention up to 30 cycles as shown in FIG. 16.

[0177] Lower calcination temperature (e.g., 400° C.) was also used to form the complex oxide coating. However, no improvement was observed in the electrochemical performance, which may be attributed to the too low calcination temperature to promote the complex oxide formation on the cathode active compound particles.

[0178] FIG. 17 is a phase diagram of binary oxides Al₂O₃ and ZnO. (Bur. Standards J. Research, 8(2) 280 1932; R.P.413). Even though the phase diagram of binary oxides exhibits formation of the spinel phase (ZnAl₂O₄) occurs at high temperatures, more recent studies (see Electrochimica Acta 115 (2014) 326-331) show that the spinel phase can form at much lower temperatures. The phase formation also depends on the synthesis procedure and condition. e.g., the spinel phase was formed at 900° C. by using a sol-gel synthetic method.

[0179] The coatings, powder, and cathode active materials can be used in batteries as described herein. The materials can be used in electronic devices. An electronic device herein can refer to any electronic device known in the art, including a portable electronic device. For example, the electronic device can be a telephone, such as a cell phone, and a land-line phone, or any communication device, such as a smart phone, including, for example an iPhone®, an electronic email sending/receiving device. The electronic device can also be an entertainment device, including a portable DVD player, conventional DVD player, Blue-Ray disk player, video game console, music player, such as a portable music player (e.g., iPod®), etc. The electronic device can be a part of a display, such as a digital display, a TV monitor, an electronic-book reader, a portable web-browser (e.g., iPad®), watch (e.g., AppleWatch), or a computer monitor. The electronic device can also be a part of a device that provides control, such as controlling the streaming of images, videos, sounds (e.g., Apple TV®), or it can be a remote control for an electronic device. Moreover, the electronic device can be a part of a computer or its accessories, such as the hard drive tower housing or casing, laptop housing, laptop keyboard, laptop track pad, desktop keyboard, mouse, and speaker. The battery and battery packs can also be applied to a device such as a watch or a clock. The components powered by a battery or battery pack can include, but are not limited to, microprocessors, computer readable storage media, in-put and/or out-put devices such as a keyboard, track pad, touch-screen, mouse, speaker, and the like.

[0180] The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.