Battery module
By using a plate spring and elastic insulating pad structure in the battery module, the problem of end plate deformation caused by lithium battery cell expansion is solved, thereby improving the cycle performance and safety of the battery module.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- TIANJIN ZHONGDIAN NEW ENERGY RES INST CO LTD
- Filing Date
- 2025-01-21
- Publication Date
- 2026-05-08
AI Technical Summary
During use, the expansion of lithium battery cells due to the thickening of the electrode sheets can cause excessive deformation of the module end plate, or even breakage, affecting the cycle life and safety of the cells.
The structure employs a plate spring and elastic insulating pad, combined with an end plate design. The central protrusion of the plate spring and the design of the pressure relief ear plate absorb the expansion displacement of the battery cell and balance the force on the end plate, avoiding excessive constraint or relaxation.
It effectively suppresses cell expansion and deformation, improves cell cycle performance and safety performance, avoids excessive deformation of end plates, and extends the service life of battery modules.
Smart Images
Figure CN224217594U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of electrochemical energy technology, and in particular to a battery module. Background Technology
[0002] Lithium-ion batteries are widely used in the new energy vehicle and energy storage industries. When using lithium-ion batteries, cells are typically stacked into modules, which are then placed in a battery case for charge-discharge cycles. Each lithium-ion battery cell contains an electrode assembly, which is formed by assembling electrode sheets. With repeated use of the battery case, the electrode sheets thicken, causing expansion in the thickness direction of the electrode assembly, resulting in cell expansion. This cell expansion exerts significant expansion pressure on the module endplate, with the largest bulge displacement occurring in the center of the cell's large surface area. This leads to the greatest outward deformation of the endplate's large surface area, causing dimensional deviations in the module and even endplate breakage. Excessively increasing the constraint force of the module frame (including the endplate) on the cells can affect the cell's cycle life and may even trigger internal short circuits, leading to cell fires and explosions.
[0003] Besides increasing the rigidity of the module frame and increasing the preload, other common practices in the industry are to reduce the rigidity of the middle part of the end plate or to add a U-shaped elastic gasket between the cells in the module to reserve expansion space in the middle of the large surface of the cell. However, all of the above methods will lead to increased deformation of the electrode plates inside the cell and reduce the cycle performance of the cell. Utility Model Content
[0004] The purpose of this invention is to provide a battery module to solve the problems mentioned above.
[0005] The technical solution adopted by this utility model is: a battery module, which includes a shell and a cell assembly. The shell includes at least an end plate disposed in the thickness direction of the cell assembly. A plate spring is disposed in the end plate, and the central protrusion of the plate spring faces the cell assembly.
[0006] Furthermore, the plate spring is composed of several arc-shaped spring sheets with different radii stacked together; the middle part of the arc-shaped spring sheet closest to the battery cell assembly protrudes and contacts the inner wall of one side of the end plate; the two ends of the arc-shaped spring sheet furthest from the battery cell assembly are provided with pressure relief plates, and the pressure relief plates contact the inner wall of the other side of the end plate.
[0007] Furthermore, the pressure relief ear plate is parallel to the inner wall of the end plate it abuts against, and the contact portion of the pressure relief ear plate with the inner wall of the end plate is close to the edge of the inner wall of the end plate.
[0008] Furthermore, a plurality of leaf springs are arranged along the height direction of the battery cell assembly, wherein the stiffness of the leaf spring located in the middle is greater than or equal to the stiffness of the leaf springs in other parts.
[0009] Furthermore, the end plate includes a first main board and a second main board arranged in parallel. The side ends of the first main board and the second main board are connected by different side connecting plates. The plate spring is located between the first main board and the second main board. The first main board contacts the end face of the cell assembly in the thickness direction.
[0010] Furthermore, the thickness of the first motherboard is less than the thickness of the second motherboard.
[0011] Furthermore, the housing includes side pull plates, which are positioned on both sides of the cell assembly in the width direction, with different end plates connected to each end to secure the end plates.
[0012] Furthermore, the battery cell assembly includes battery cells and elastic insulating pads arranged alternately along its thickness direction, wherein the large surface area of the elastic insulating pad is greater than or equal to the large surface area of the electrode assembly in the battery cell.
[0013] The beneficial effects of this utility model are as follows: Based on the configuration and selection of the plate spring, elastic insulating pad and end plate in this utility model, the expansion displacement of the battery cell can be reasonably absorbed, and the battery cell can be given a reasonable constraint force to resist its expansion trend and suppress the bulging of the middle of the battery cell. In addition, the pressure relief ear plate can release part of the pressure borne by the plate spring to the edge of the second main plate, adjust the stress of each part of the second main plate, and cooperate with the end plate to be pulled by the side pull plate, which can effectively avoid excessive pressure on the middle of the second main plate and deformation exceeding the tolerance. The above effects can effectively improve the cycle performance and safety performance of the battery cell. Attached Figure Description
[0014] Figure 1 This is an overall structural diagram of an embodiment of the present utility model;
[0015] Figure 2 This is an exploded view of the structure of an embodiment of this utility model;
[0016] Figure 3 This is a schematic diagram of the end plate and the plate spring in an embodiment of this utility model;
[0017] Figure 4 This is a projected view of the plate spring in an embodiment of this utility model.
[0018] In the picture:
[0019] 1. Outer shell; 11. End plate; 111. First main board; 112. Second main board; 113. Side connecting plate; 12. Side pull plate;
[0020] 2. Battery cell assembly; 21. Individual battery cell; 22. Elastic insulating pad;
[0021] 3. Leaf spring; 31. Curved spring sheet;
[0022] 4. Pressure relief ear plates. Detailed Implementation
[0023] The technical solutions of the embodiments of this utility model will be described in detail below with reference to the accompanying drawings.
[0024] In the description of the embodiments of this utility model, it should be understood that the terms "top," "bottom," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In the description of this utility model, it should be noted that unless otherwise expressly specified and limited, the terms "set" and "connected" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication of two elements. Those skilled in the art can understand the specific meaning of the above terms in this utility model through specific circumstances.
[0025] Reference Appendix Figure 1-4This embodiment provides a battery module, which includes a housing 1 and a cell assembly 2. The housing 1 includes an end plate 11 disposed in the thickness direction of the cell assembly 2 and side pull plates 12 disposed on both sides in the width direction of the cell assembly 2. The two ends of the side pull plates 12 are respectively connected to different end plates 11 to fix the end plates 11. The cell assembly 2 includes cell cells 21 and elastic insulating pads 22 alternately disposed along its own thickness direction. The large surface of the elastic insulating pad 22 is coated with adhesive on both sides. The large surface area S1 of the elastic insulating pad 22 is greater than or equal to the large surface area S2 of the electrode group in the cell cell 21. When the middle part of the large surface of the cell cell 21 (this is the part of the cell cell 21 where the expansion and deformation are most severe) is covered by the elastic insulating pad 22, its expansion and deformation will squeeze the elastic insulating pad 22. Within the thickness variation range of the elastic insulating pad 22, the elastic insulating pad 22 can provide a certain expansion space for the cell cell 21 and absorb the expansion displacement, but the large surface area of the elastic insulating pad 22 is not large enough to support the expansion of the cell cell 21. When the middle part of the surface is compressed, it will provide a certain reaction force to the cell 21, which will counteract the expansion and deformation tendency of the cell 21, but will not excessively constrain the cell 21, thus ensuring the flatness of the internal electrode group of the cell 21. In addition, a plate spring 3 is provided in the end plate 11, with the middle protrusion of the plate spring 3 facing the cell group 2. When the cell 21 in the cell group 2 expands, similar to the elastic insulating pad 22, the plate spring 3 provides the cell 21 with a certain expansion space and a certain reaction force, which can absorb the expansion displacement of the cell 21 and counteract the expansion and deformation tendency of the cell 21, but will not excessively constrain the cell 21, thus ensuring the flatness of the internal electrode group of the cell 21. This avoids problems such as module size deviation caused by excessive relaxation and the resulting decrease in cycle performance, and avoids problems such as decreased cycle life and safety performance of the cell 21 caused by excessive constraint.
[0026] It should be noted that the height, width and thickness of the elastic insulating pad 22 can be determined by those skilled in the art according to actual needs, and are not limited here, nor are they limited to the values that may be mentioned in this embodiment.
[0027] In this embodiment, the end plate 11 includes a first main plate 111 and a second main plate 112 arranged in parallel. The side ends of the first main plate 111 and the second main plate 112 are connected by different side connecting plates 113. The first main plate 111, the second main plate 112 and the two side connecting plates 113 surround the installation and deformation space of the plate spring 3. The plate spring 3 is arranged between the first main plate 111 and the second main plate 112. The first main plate 111 contacts the end face of the cell assembly 2 in the thickness direction. The middle protrusion of the plate spring 3 contacts the first main plate 111. The two ends of the plate spring 3 contact the second main plate 112.
[0028] The thickness of the first main board 111 is t1, the thickness of the second main board 112 is t2, and the thickness of the side plate 113 is t3. These thicknesses satisfy the following conditions: t1 < t2, t1 < t3. The first main board 111 is the structure that directly contacts the cell assembly 2, and it needs to provide a certain expansion space for the cells in the cell assembly 2 to absorb expansion displacement. The second main board 112, as the outermost encapsulation structure of the battery module, needs to have a certain resistance to deformation; therefore, its thickness should be greater than that of the first main board 111.
[0029] Reference Appendix Figure 4 The plate spring 3 is composed of several stacked arc-shaped spring plates 31 with different radii; the middle part of the arc-shaped spring plate 31 closest to the battery cell assembly 2 protrudes and contacts the inner wall of the first main board 111; the two ends of the arc-shaped spring plate 31 furthest from the battery cell assembly 2 are provided with pressure relief plates 4, which contact the inner wall of the second main board 112. In order to reduce the bulging deformation of the middle part of the end plate 11, in this embodiment, the pressure relief plates 4 are configured parallel to the inner wall of the second main board 112, and the contact part between the pressure relief plates 4 and the second main board 112 is close to the edge of the second main board 112. When the center of the large surface of the battery cell 21 expands, part of the energy accumulated by the compressed plate spring 3 is returned to the battery cell 21 to counteract its expansion trend. The other part is transferred to the edge area of the second main plate 112 through the pressure relief ear plate 4, balancing the stress on various parts of the large surface of the second main plate 112. It also works in conjunction with the end plate 11 under the tension of the side pull plate 12, effectively preventing excessive pressure on the center of the large surface of the second main plate 112 and thus avoiding deformation exceeding tolerance. The pressure relief ear plate 4 can be an integrally formed structure with the arc-shaped spring plate 31, or it can be a structure welded together later; no further specific limitations are made here.
[0030] Furthermore, based on the expansion and deformation pattern of the individual battery cell 21, i.e., the expansion is most pronounced in the center of the large surface area, in this embodiment, a number of leaf springs 3 are arranged along the height direction of the battery cell assembly 2. The stiffness of the leaf spring 3 located in the center is greater than or equal to the stiffness of the leaf springs 3 in other locations. The number of leaf springs 3 can be determined by those skilled in the art according to actual needs, and is not limited here, nor is it limited to the values that may be mentioned in this embodiment.
[0031] In some embodiments, three sets of leaf springs 3 are arranged along the height direction of the cell assembly 2. The stiffness of the leaf spring 3 at the top is K1, the stiffness of the leaf spring 3 in the middle is K2, and the stiffness of the leaf spring 3 at the bottom is K3. The above stiffnesses satisfy: K2≥K1, K2≥K3. The stiffness of the leaf springs 3 can be obtained through cell cycle experiments with pressure distribution sensors, combined with structural simulation analysis.
[0032] The number of arc-shaped spring plates 31 in the aforementioned plate spring 3 can be determined by those skilled in the art according to actual needs, and is not limited here, nor is it limited to the values that may be mentioned in this embodiment. Not only can the radius of the arc-shaped spring plates 31 be different, but the arc length of the arc-shaped spring plates 31 can also be configured differently according to the force conditions and the ease of stacking. As an example, in this embodiment, the arc length of the arc-shaped spring plates 31 closer to the battery cell group 2 is smaller. The multiple layers of arc-shaped spring plates 31 can be connected by a bundling method or by a welding method, which is not limited here. The pressure relief ear plates 4 at both ends of the arc-shaped spring plates 31 furthest from the battery cell group 2 can be connected to the second main board 112 by welding or by bolting, which is not limited here.
[0033] In this embodiment, both ends of the side pull plate 12 are fixedly connected to the end plate 11. The height of the end plate 11 is h1, and the height of the side pull plate 12 is h2, and h1 and h2 satisfy: h1 = h2. This configuration reduces the deformation difference of the module's outer contour in the height direction. It should be noted that the specific connection position between the side pull plate 12 and the end plate 11 is not limited. The connection can be made by bending the side pull plate 12 and connecting it to the outer side of the second main plate 112, or by not bending the side pull plate 12 and connecting it to the outer side of the side connecting plate 113; it is not limited to the above example.
[0034] Compared with the prior art, the beneficial effects of this utility model are as follows: Based on the configuration and selection of the plate spring 3, elastic insulating pad 22 and end plate 11 in this utility model, the expansion displacement of the battery cell 21 can be reasonably absorbed, and the battery cell 21 can be given a reasonable constraint force to resist its expansion trend and suppress the bulging of the middle part of the battery cell 21. In addition, the pressure relief ear plate 4 can release part of the pressure borne by the plate spring 3 to the edge of the large surface of the second main board 112, adjust the force on each part of the large surface of the second main board 112, and cooperate with the end plate 11 to be pulled by the side pull plate 12, which can effectively avoid excessive pressure on the middle part of the large surface of the second main board 112 and deformation exceeding the tolerance. The above effects can effectively improve the cycle performance and safety performance of the battery cell.
[0035] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.
[0036] The above are preferred embodiments of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.
Claims
1. A battery module, characterized in that, The device includes a housing and a battery cell assembly. The housing includes at least an end plate disposed in the thickness direction of the battery cell assembly. A leaf spring is disposed in the end plate, with a central protrusion of the leaf spring facing the battery cell assembly. The leaf spring is composed of a plurality of stacked arc-shaped spring plates with different radii. The central protrusion of the arc-shaped spring plate closest to the battery cell assembly contacts one side of the inner wall of the end plate. Pressure relief plates are provided at both ends of the arc-shaped spring plate furthest from the battery cell assembly, and the pressure relief plates contact the other side of the inner wall of the end plate.
2. The battery module according to claim 1, characterized in that, The pressure relief ear plate is parallel to the inner wall of the end plate it abuts against, and the contact portion of the pressure relief ear plate with the inner wall of the end plate is close to the edge of the inner wall of the end plate.
3. The battery module according to any one of claims 1-2, characterized in that, A plurality of leaf springs are arranged along the height direction of the battery cell assembly, wherein the stiffness of the leaf spring located in the middle is greater than or equal to the stiffness of the leaf springs in other parts.
4. The battery module according to claim 3, characterized in that, The end plate includes a first main plate and a second main plate arranged in parallel. The side ends of the first main plate and the second main plate are connected by different side plates. The plate spring is located between the first main plate and the second main plate. The first main plate contacts the end face of the cell assembly in the thickness direction.
5. The battery module according to claim 4, characterized in that, The thickness of the first motherboard is less than the thickness of the second motherboard.
6. The battery module according to any one of claims 1-2 and 4-5, characterized in that, The housing includes side pull plates that are positioned on both sides of the cell assembly in the width direction, with each end connected to a different end plate to secure the end plate.
7. The battery module according to claim 6, characterized in that, The battery cell assembly includes battery cells and elastic insulating pads arranged alternately along its thickness direction, wherein the large surface area of the elastic insulating pad is greater than or equal to the large surface area of the electrode assembly in the battery cell.