Method for manufacturing lithium-ion battery modules and a corresponding lithium-ion battery module

[0001] The present invention relates to a method for manufacturing lithium-ion battery modules and a corresponding lithium-ion battery module.

[0002] FIG. 3 shows a schematic diagram of the design of an exemplary configuration of mechanically clamped cells.

[0003] In FIG. 3, reference numeral 10 denotes a cover plate of an electronics system, 20 denotes a control electronics system, 30 denotes a laser-welded connecting rail, 40 denotes a connecting cover, 50 denotes a pressure band, 60 denotes a pressure plate, 70 denotes a prismatic lithium-ion cell, and reference numeral 80 denotes a cooling element.

[0004] It is believed to be understood that mechanical pressure may, under certain circumstances, positively influence the service life of lithium-ion cells.

[0005] Furthermore, mechanical compression is believed to have been used for mechanical fixation. The cells may also be compressed for the thermal contact for cooling those cells. Cells which are mechanically compressed particularly may be found in cell constructions which are configured to be particularly thin and light, for example, in pouch cells or in the slightly more rigid prismatic metal case cells.

[0006] According to DE 10 2009 010 148 A1, the related art is, for example, a conductor of a galvanic cell or a contact element for its contacting, which, at least in part, has a surface structure, which, in a force-fit bond between the conductor and a contact element, increases the pressure which the conductor and the contact element apply on each other.

[0007] It is also believed to be understood that elastic elements, such as, for example, elastic films, are often used for the path-controlled application of the load pressure.

[0008] A novel, robust and economical concept for applying the pressing forces is thus desirable. Here it is particularly to be taken into account that the cells become thicker and more round over their service life. Furthermore, a concept is to be used which is robust against fluctuations during the production process, which may result in differences in the thickness of the cell.

[0009] The object defined above may be achieved with the present invention by providing a method for manufacturing lithium-ion battery modules, which includes the following steps: positioning an elastic plastic device between at least two cells of a battery module; path-controlled compression of the at least two cells of the battery module and of the elastic plastic device situated between the at least two cells.

[0010] The present invention also provides a corresponding lithium-ion battery module.

[0011] Further exemplary embodiments are the subject matter of the respective further descriptions herein.

[0012] According to an exemplary embodiment, the elastic plastic device is an elastic plastic film, which only has a certain amount of elastic recovery. Using a purely elastic plastic film and thus no viscoelastic film, which shows a time-dependent plastic behavior, results in the following advantages:

[0013] The plastic component of the film compensates for variations in thickness of the cell, which may occur after the manufacturing process. Breathing of the cell, the expanding and contraction of the cell thickness during charging and discharging of the cell, is compensated for by the elastic component and is thus largely independent of the total compression of the film. The plastic component compensates for the cell growing with age, so that the pressure applied to the cell increases only minimally. The plasticity compensates for irregularities on the surface of the cell, for example, the round shape, and the cell is subjected to uniform load.

[0014] According to an exemplary embodiment, where the elastic plastic film is expanded graphite, the advantage results that the expanded graphite has excellent thermal conductivity and thus positively influences the temperature control of the cell.

[0015] According to an exemplary embodiment, where the shape of the cells is round, this results in the advantage of a good thermal connection.

[0016] According to an exemplary embodiment, where a purely plastic film is used and the elastic properties are provided by at least one elastic element, this results in the advantage that a plurality of materials may be used for the method according to the present invention.

[0017] Further features and advantages of specific embodiments of the present invention result from the following description with reference to the appended drawings. Identical reference numerals denote identical or functionally identical elements.

[0022] FIG. 3 shows a schematic diagram of the design of an exemplary configuration of mechanically clamped cells.

[0023] In FIG. 3, reference numeral 10 denotes a cover plate of an electronics system, 20 denotes a control electronics system, 30 denotes a laser-welded connecting rail, 40 denotes a connecting cover, 50 denotes a pressure band, 60 denotes a pressure plate, 70 denotes a prismatic lithium-ion cell, and reference numeral 80 denotes a cooling element.

[0024] FIG. 1a shows a schematic diagram of a lithium-ion battery module, manufactured according to one specific embodiment of the method according to the present invention, and FIG. 1b) shows a schematic diagram of the housing of a lithium-ion battery module manufactured according to one specific embodiment of the method according to the present invention.

[0025] In FIGS. 1a and 1b, reference symbol Z denotes a cell of a battery module. Reference symbol F denotes an elastic plastic film, and L is the longitudinal expansion of the entire system of cells and films. B denotes the battery module. P denotes the direction in which the path-controlled compressing process is carried out.

[0026] According to one first specific embodiment of the method according to the present invention, an elastic plastic film F, for example made from expanded graphite, is placed between the, generally, prismatic cells Z of a battery module.

[0027] When compressing the stack, an increasing amount of pressure is applied to elastic plastic film F, which yields plastically when a pressure set by the material properties of film F is exceeded. The stack of cells Z and elastic plastic film F is compressed path-controlled.

[0028] ‘Path-controlled’ is to be understood as the compression process being carried out along a set path P up to a defined endpoint.

[0029] In another advantageous specific embodiment of the method according to the present invention, other elastic plastic films F may be used, which are not made from expanded graphite.

[0030] FIG. 2 is a schematic diagram of a lithium-ion battery module manufactured according to another specific embodiment of the method according to the present invention.

[0031] In FIG. 2, reference symbol Z denotes a cell of the battery module. Reference symbol F′ denotes a plastic film and reference symbol E denotes an elastic element, for example a spring.

[0032] In particular, the method according to the present invention may also be applied to round cells Z with a good thermal connection.

[0033] Although the present invention has been described with reference to exemplary embodiments, it is not limited thereto. The mentioned materials and topologies in particular are only exemplary and not limited to the above-explained examples.