BATTERY MODULE FOR A TRACTION BATTERY OF AN ELECTRIC VEHICLE

Abstract

A battery module for a traction battery of an electric vehicle is described. The battery module has two side parts arranged on opposite sides of the battery module and aligned substantially parallel to an electrode surface of cells of the battery module. At least one of the side parts has an elastic region offset from a main extension plane of the side part. The elastic region is adapted to exert a pressing force perpendicular to the electrode surface on the cells.

Claims

1. A battery module for a traction battery of an electric vehicle, the battery module comprising: two side members arranged on opposite sides of the battery module and oriented substantially parallel to an electrode surface of cells of the battery module, and wherein at least one side member comprises a resilient portion configured to exert a pressing force perpendicular to the electrode surface on the cells.

2. The battery module according to claim 1, wherein the elastic portion is offset from a main extension plane of the side member.

3. A battery module according to claim 1, wherein the side member comprises a metal material.

4. The battery module according to claim 1, wherein the pressing force corresponds to a surface pressure between 1 kPa and 10 kPa.

5. The battery module according to claim 1, wherein the side member comprises at least one recess arranged between the elastic region and a support region disposed in the main extension plane.

6. The battery module according to claim 1, wherein at least one distribution plate is arranged between the elastic region and an outermost cell.

7. The battery module according to claim 6, wherein the manifold plate comprises a metal sheet.

8. The battery module according to claim 6, wherein the manifold plate comprises a layer of a compressible material having a higher compressibility than a material of a supporting structure of the manifold plate.

9. The battery module according to claim 1, wherein the elastic region comprises a plurality of separate subregions.

10. The battery module according to claim 9, wherein the subregions are of the same type.

11. The battery module according to claim 1, wherein the side member comprises flexurally rigid support portions arranged along at least two opposing edges.

12. The battery module according to claim 9, wherein the side member comprises a flexurally rigid support region arranged between each of the subregions.

13. The battery module according to claim 1, wherein the side portions are interconnected by at least one web.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0032] Further advantages, features, and details of the various embodiments of this disclosure will become apparent from the ensuing description of a preferred exemplary embodiment and with the aid of the drawings. The features and combinations of features recited below in the description, as well as the features and feature combination shown after that in the drawing description or in the drawings alone, may be used not only in the particular combination recited, but also in other combinations on their own, without departing from the scope of the disclosure.

[0033] An advantageous embodiment of the present invention is set out below with reference to the accompanying figures, wherein:

[0034] FIG. 1 depicts a representation of a battery module according to an embodiment example;

[0035] FIG. 2 depicts a sectional view of a battery module according to an embodiment; and

[0036] FIG. 3 depicts an illustration of a battery module according to an embodiment.

[0037] The figures are merely schematic representations and serve only to explain the invention. Identical or similarly acting elements are marked throughout with the same reference signs.

DETAILED DESCRIPTION OF THE INVENTION

[0038] As used throughout the present disclosure, unless specifically stated otherwise, the term “or” encompasses all possible combinations, except where infeasible. For example, the expression “A or B” shall mean A alone, B alone, or A and B together. If it is stated that a component includes “A, B, or C”, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C. Expressions such as “at least one of” do not necessarily modify an entirety of the following list and do not necessarily modify each member of the list, such that “at least one of” A, B, and C” should be understood as including only one of A, only one of B, only one of C, or any combination of A, B, and C.

[0039] FIG. 1 depicts an illustration of a battery module 100 according to an embodiment of the present invention. The battery module 100 may be interconnected with a plurality of other battery modules 100 to form a traction battery of an electric vehicle. The battery module 100 includes a housing 102 that encloses a plurality of flat side to flat side battery cells, or cells for short, of the battery module 100. The cells may be pouch cells or prismatic cells. Electrodes of the cells are arranged parallel to the flat sides. The cells are electrically connected within the housing between two terminals of the battery module 100. Here, the cells are arranged side by side in the housing 102.

[0040] The housing 102 is approximately cuboidal in shape. Two opposing side portions 104 of the housing 102 are oriented substantially parallel to the flat sides of the cells and electrode surfaces of the electrodes, respectively.

[0041] When the cells are charged or discharged, their volume may change. In particular, the volume change affects a thickness of the individual cell. The changes in the thickness of all cells of the battery module 100 may add up.

[0042] To compensate for this change in thickness, at least one of the side members 104 includes an elastic region 106. The elastic region 106 acts as a mechanical spring and compensates for the change in thickness of the cells. The elastic region 106 is arranged inwardly offset from a main extension plane 108 of the side member 104 to provide a defined spring travel. The elastic region 106 can be deformed to a maximum of the main extension plane 108. That is, an offset between the elastic region 106 and the main extension plane 108 defined, for example, by support regions 112 is preferably greater than or equal to the spring travel by which the elastic region 106 elastically displaces under normal operating conditions. For example, the displacement in a direction perpendicular to the main extension plane 108 may be more than 1 mm, such as for example several millimeters.

[0043] The elastic region 106 has a spring characteristic. A pressing force 110 of the elastic area 106 depends on the spring characteristic and a deformation of the elastic area 106. The spring characteristic depends on material properties of the side part 104 and a geometric design of the elastic area 106. For an advantageous spring characteristic, the side part 104 consists in particular of a metal material or metal sheet. The pressing force 110 acts perpendicularly on the flat side of the outermost cell. The pressing force 110 presses all cells of the battery module 100 together. The pressing force 110 is variable and becomes greater when the thickness of the cells increases, as the deformation of the elastic region 106 increases. When the thickness of the cells decreases, the pressing force 110 becomes smaller as the deformation decreases.

[0044] In one embodiment, the elastic region 106 is embossed or deep-drawn into the side part 104. During the embossing or deep-drawing process, the side part is permanently plastically deformed and the elastic region 106 is formed as a depression or pocket in the side part 104.

[0045] In one embodiment, the side member 104 includes at least one recess 114 between support regions 112 of the side member 104 and the elastic region 106. The recess 114 is a slot or opening in the side member 104. The recess 114 allows the spring characteristic of the elastic region 106 to be adjusted as required. In particular, the recess 114 makes the elastic region 106 less stiff. In other words, the elastic region 106 can be selectively weakened by the recess 114 to reduce the pressing force 110. For example, the pressing force 110 can be limited such that a surface pressure of the cells between 0.01 bar and 0.1 bar results.

[0046] In one embodiment, the elastic region 106 is divided into a plurality of subregions 116. A support region 112 is disposed between each two subregions 116. The support regions 112 are arranged substantially in the main extension plane 108. The support regions 112 are configured here in a ladder-like manner, wherein two outer support regions 112 extending along opposite longitudinal edges of the side portion 104 represent uprights of a ladder and support regions 112 extending transversely between the outer support regions 112 represent rungs of the ladder. The sub-regions 116 of the resilient region 106 are thus enclosed by the rungs and stiles. The sub-regions 116 may be substantially similar.

[0047] In one embodiment, the support portions 112 extending along the edges are stiffened by three-dimensional deformations of the side portion 104. In this regard, the deformations are folded regions of the side portion 104 substantially perpendicular to the main extension plane 108. The folded regions thus extend substantially parallel to a cover of the battery module 100.

[0048] FIG. 2 depicts a sectional view of a battery module 100 according to an embodiment. The battery module 100 corresponding substantially to the battery module in FIG. 1 is shown cut perpendicular to the main extension plane 108. The battery module 100 has 12 cells 200. Here, the cells 200 are pouch cells. In this embodiment example, both side portions 104 have elastic regions 106.

[0049] In one embodiment, distributor plates 202 are arranged between the outermost cells 200 and the elastic regions 106 for even distribution of the pressing force 110. The distribution plates 202 may be, for example, flat metal sheets that provide good heat dissipation due to their high thermal conductivity. The distributor plates 202 may also comprise a compressible material 204. In particular, the compressible material 204 may directly contact the outer cells 200 and compensate for flatness tolerances of the cells 200 and the manifold plates 202. The compressible material 204 may also be compressed or relieved by the change in thickness of the cells 200.

[0050] FIG. 3 depicts an illustration of a battery module 100 according to an embodiment. The battery module 100 is substantially similar to the battery modules shown previously. In addition, here the side portions 104 arranged on opposite sides of the battery module 100 are connected to each other by a web 300 loaded in tension. The web 300 transmits at least a portion of the counterforce to the pressing force 110 of one side part 104 to the respective other side part 104. The web 300 is connected to the respective side part 104 in the region of the support region 112 extending along the respective side part 104. The web 300 approximately prevents outward deformation of the support areas 112.

[0051] Here, the web 300 is arranged on a bottom side of the battery module 100. Similarly, at least one other web may be arranged on an upper side of the battery module 100. For example, the webs may each be arranged centrally on the side portions 104.

[0052] In an alternative embodiment, the side portions 104 are supported by at least one band extending around the entire battery module 100. The band extends in a closed annular manner over the top side, the bottom side and the side parts 104. For example, a bead for the band may be provided in the side parts.

[0053] In other words, a module housing with swelling compensation is presented.

[0054] Lithium pouch cells exhibit a reversible change in thickness perpendicular to the electrode surface during charging and discharging (cyclization). Furthermore, pouch cells require a minimum pressure of the electrodes so that the electrode stack can be reset during recurring cyclization and no delamination of the electrodes to each other takes place. If pouch cells are assembled to form a cell module, compensating elements can be provided to ensure a minimum pressing force over the electrode surface. For example, the module frame can conventionally be designed to be as rigid as possible and thickness compensation can be achieved using elastic insertion mats. However, this requires high pretensioning forces and uniform surface pressure is difficult to achieve.

[0055] In the approach presented here, the pressing sides of the module frame are designed in such a way that they are elastically prestressed to ensure uniform surface pressure over the operating time of the module.

[0056] The approach presented here can achieve weight savings in the module frame, reduced complexity by eliminating additional balancing elements, and simplification of the module design.

[0057] The cell module with lithium pouch cells for a vehicle battery presented here has preformed side parts which exert a homogeneous pressing force perpendicular to the electrode surfaces. The side parts have elastic areas that allow thickness changes of the cells and permanently ensure homogeneous surface pressure. The side parts consist of stamped or deep-drawn metal sheets. In conjunction with a minimum pressing force, the embossing exhibits a uniform bending curve which exerts uniform surface pressure. The bending stiffness of the side parts can be adjusted by recesses. For example, the initial pressing force on each cell area can be set between 0.01 bar and 0.1 bar.

[0058] The side parts can additionally be connected at least once along their length by an elastic web or other mechanical connection to reduce outward deflection of the support areas. The web or connection can be designed, for example, as a metal clip or encircling band. The connection can be arranged on an upper side and/or lower side of the battery module.

[0059] Since the devices and methods described in detail above are examples of embodiments, they can be modified to a wide extent by the skilled person in the usual manner without leaving the scope of the invention. In particular, the mechanical arrangements and the proportions of the individual elements with respect to each other are merely exemplary. Some preferred embodiments of apparatus according to the invention have been disclosed above. The invention is not limited to the solutions explained above, but the innovative solutions can be applied in different ways within the limits set by the claims.