Battery module

Abstract

The utility model relates to the technical field of batteries, and discloses a battery module which comprises a battery cell, a buffer structure and colloid, the plurality of battery cells are arranged side by side along a first direction, and each battery cell is provided with two first side surfaces which are oppositely arranged along the first direction; a buffer structure is arranged between two adjacent battery cells, a glue injection groove is formed in the buffer structure, a buffer groove is defined by the buffer structure, and the first side surfaces of the two adjacent battery cells are arranged at intervals through the buffer groove; the colloid is arranged in the glue injection groove, and the first side faces of the two adjacent battery cells are bonded through the colloid. According to the utility model, the buffer groove is arranged to provide a buffer space for the expansion of the battery cell in the circulation process, so that the expansion of the battery cell in the circulation process can be borne by the buffer groove, and the circulation attenuation caused by overlarge internal pressure due to overlarge expansion in the later period of the battery cell circulation is avoided; the glue injection groove is formed in the buffer structure, so that the pouring space of the glue is limited, the glue is prevented from occupying the buffer space, and the structural strength of the battery module is enhanced.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to battery modules. Background Technology

[0002] During charging and discharging, the volume of a battery cell undergoes a "breathing" change. With each charge-discharge cycle, the cell's volume gradually expands, and its thickness increases to some extent. This expansion of individual battery cells not only affects their cycle life but also significantly impacts the module's connection and dimensional design.

[0003] In existing technologies, buffer pads are used to maintain the external gaps and pressure of individual battery cells within an appropriate range. To further enhance the connection strength between cells in modules, structural adhesive is applied to the large surface of each cell to establish a rigid connection. However, the presence of structural adhesive deprives the cell of the external space reserved for cyclic expansion, resulting in excessive internal pressure in the later stages of cycling. Cyclic expansion still affects the cell's lifespan. Utility Model Content

[0004] In view of this, the present invention provides a battery module to solve the problem in the prior art where excessive internal pressure in the later stages of cell cycling and the impact of cycle expansion on cell lifespan are caused by the expansion.

[0005] This utility model provides a battery module, including: a battery cell, a buffer structure, and an adhesive; a plurality of battery cells are arranged side by side along a first direction, and each battery cell has two opposing first sides along the first direction; the buffer structure is provided between two adjacent battery cells, the buffer structure is connected to the first sides, the buffer structure has a glue injection groove, and the buffer structure encloses a buffer groove, the first sides of two adjacent battery cells are spaced apart through the buffer groove; the adhesive is disposed in the glue injection groove, and the first sides of two adjacent battery cells are bonded together by the adhesive.

[0006] Beneficial effects: By setting up buffer grooves, a buffer space is provided for the expansion of the battery cells during cycling, ensuring that the expansion of the cells during cycling can be supported by the buffer grooves, avoiding excessive internal pressure caused by excessive expansion of the cells in the later stages of cycling, which leads to cycle attenuation. By opening injection grooves in the buffer structure, the injection space of the adhesive is limited, preventing the adhesive from encroaching on the buffer space, and the adhesive is used to bond adjacent cells, thereby enhancing the structural strength of the battery module. Therefore, the battery module of this embodiment can both enhance the connection strength of the cells in the module and reduce the impact of cell cyclic expansion on its lifespan.

[0007] In one optional embodiment, the area of ​​the first side surface is A, the orthographic projection area of ​​the buffer structure along the first direction on the first side surface is A1, and the orthographic projection area of ​​the glue injection groove along the first direction on the first side surface is A2, satisfying 15% < (A1 + A2) × 100% / A < 50%; where A is in meters. 2 The unit of A1 is m. 2 The unit of A2 is m. 2 .

[0008] Beneficial effects: By limiting the projected area of ​​the buffer structure and the glue injection groove on the first side along the first direction, sufficient space is ensured in the buffer groove while guaranteeing the buffering effect of the buffer structure.

[0009] In one optional embodiment, the ratio of the orthographic projection area of ​​the glue injection groove on the first side along the first direction to the orthographic projection area of ​​the buffer structure on the first side along the first direction satisfies 30% < (A2 / A1) × 100% < 80%.

[0010] Beneficial effect: By controlling the ratio of the orthogonal projection area of ​​the glue injection groove on the first side along the first direction to the orthogonal projection area of ​​the buffer structure on the first side along the first direction, the buffering effect of the buffering result can be guaranteed while ensuring the structural strength of the buffer structure.

[0011] In one optional embodiment, the elastic modulus of the buffer structure is E, satisfying A1×E≥6×10. 4 N; where E is in N / m 2 .

[0012] Beneficial effects: By matching the elastic modulus of the buffer structure with the orthographic projection area of ​​the buffer structure on the first side along the first direction, the thickness change of the buffer structure caused by the expansion force in the later stage of the cycle is less than 40%, ensuring the stability of the buffer performance and extending the service life of the buffer structure.

[0013] In one optional embodiment, the battery module further includes end plates, two of which are spaced apart along a first direction, and a plurality of battery cells are disposed between the two end plates, with a buffer structure disposed between the end plates and the adjacent battery cells.

[0014] Beneficial effect: The end plate protects the battery cell in the first direction, preventing the battery cell from moving in that direction.

[0015] In one optional embodiment, the battery module further includes a clamping structure, which is sleeved on the outside of the end plate and a plurality of the battery cells to apply a preload force to the battery cells.

[0016] Beneficial effects: By applying pre-tightening force to the battery cells through the clamping structure, displacement of the battery cells during use and transportation is effectively prevented, and the overall structural strength of the battery module is improved, thereby enhancing the reliability of the battery module.

[0017] In one optional embodiment, the thickness of the buffer structure along the first direction is h, the preload force applied by the clamping structure to the battery cell is F, and the amount of adhesive injected into the injection groove is L, satisfying the following conditions: Where h is in meters (m) and F is in nanometers (N).

[0018] Beneficial effects: The amount of glue injected is calculated and selected based on the pre-tightening force applied to the battery cell by the clamping structure. The appropriate amount of glue injected can ensure that when the buffer structure is under pressure, it will not overflow from the glue injection groove due to excessive glue, thus affecting the buffering effect of the buffer structure; nor will it lead to low connection strength between adjacent battery cells due to insufficient glue.

[0019] In one optional embodiment, the battery cell includes a housing and an insulating film. The insulating film is adhered to the outside of the housing. A buffer structure is bonded to the insulating film, and an adhesive is bonded to the insulating film. The bonding strength between the buffer structure and the insulating film is σ1, the bonding strength between the adhesive and the insulating film is σ2, and the bonding strength between the housing and the insulating film is σ3, satisfying σ3 > σ1 and σ3 > σ2; wherein the unit of σ1 is MPa, the unit of σ2 is MPa, and the unit of σ3 is MPa.

[0020] Beneficial effects: By controlling the bonding strength between the insulating film and each structural component, it is ensured that the insulating film will not separate from the shell before the colloid and buffer structure peel off under stress.

[0021] In one alternative embodiment, the adhesion strength σ2 between the colloid and the insulating film is ≥6MPa.

[0022] Beneficial effects: By controlling the bonding strength between the colloid and the insulating film, the connection strength between the colloid and the insulating film is guaranteed.

[0023] In one optional embodiment, the dispensing groove includes a plurality of sub-grooves, which are spaced apart along the direction surrounding the buffer groove.

[0024] Beneficial effects: By opening several sub-grooves around the buffer groove, the adhesive is distributed more evenly around the buffer groove, avoiding the adhesive from concentrating in one place, ensuring that the sealant around the buffer groove is evenly distributed, and improving the overall connection strength of the structure. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the overall structure of the battery module according to an embodiment of the present utility model;

[0027] Figure 2 This is a schematic diagram of the battery cell, buffer structure, and colloid according to an embodiment of the present invention;

[0028] Figure 3 This is a frontal projection view of the battery cell, buffer structure, and colloid along a first direction on a first side surface according to an embodiment of the present invention.

[0029] Figure 4 This is a frontal projection view of the battery cell along the first direction on the first side surface according to an embodiment of the present invention;

[0030] Figure 5 This is a frontal projection view of the buffer structure of this utility model along the first direction on the first side surface according to an embodiment of the present utility model;

[0031] Figure 6 This is a frontal projection view of the colloid along the first direction on the first side surface according to an embodiment of the present invention;

[0032] Figure 7 This is a frontal projection view of the first side surface along the first direction in Comparative Example 1 of the battery module vibration and cyclic test.

[0033] Figure 8 This is a frontal projection view of Comparative Example 2 along the first direction on the first side surface during the vibration and cyclic test of the battery module.

[0034] Explanation of reference numerals in the attached figures:

[0035] 10. Battery cell; 11. First side; 20. Buffer structure; 21. Glue injection groove; 211. Dividing groove; 22. Buffer groove; 30. Glue; 40. End plate; 50. Clamping structure. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0037] The thickness of a battery cell undergoes a regular change during charging and discharging. During charging, Li ions are extracted from the positive electrode and embedded in the layered graphite negative electrode, increasing the interlayer spacing and causing the negative electrode to expand. During discharging, Li ions are extracted from the layered graphite, gradually reducing the interlayer spacing and causing the negative electrode to shrink. Macroscopically, this change manifests as a gradual increase in cell thickness during charging and a gradual decrease during discharging. Simultaneously, during continuous charge-discharge cycles, due to the combined effects of SEI film growth, gas generation, electrode material breakage, and lithium plating, the cell volume gradually expands with increasing cycle count, and the thickness increases to some extent. This expansion of a single battery cell not only affects its cycle life but also significantly impacts the module's connection and dimensional design.

[0038] In related technologies, after individual battery cells are assembled into a module, to ensure that the external pressure of the cells does not become excessively high or low due to thickness changes during continuous charge-discharge cycles, and to provide a certain gap for later cyclic expansion, buffer pads are used to maintain the external gaps and pressure of the individual cells within an appropriate range. To further strengthen the connection strength between cells in the module, structural adhesive is applied to the large surface of the individual cells to establish a rigid connection between adjacent cells. However, the presence of structural adhesive directly eliminates the reserved gaps between cells, depriving the cells of the external space reserved for cyclic expansion. This results in excessive internal pressure in the later stages of cycling, accelerating cell degradation. In other words, the battery modules in related technologies cannot reduce the impact of cell cyclic expansion on cell lifespan while increasing the connection strength of the cells within the module.

[0039] The following is combined with Figures 1 to 6 The following describes embodiments of the present invention.

[0040] According to an embodiment of the present invention, a battery module is provided, comprising: a battery cell 10, a buffer structure 20, and a gel 30; a plurality of battery cells 10 are provided, the plurality of battery cells 10 are arranged side by side along a first direction, and the battery cell 10 has two opposing first side surfaces 11 along the first direction; a buffer structure 20 is provided between two adjacent battery cells 10, the buffer structure 20 is connected to the first side surface 11, a glue injection groove 21 is provided on the buffer structure 20, and the buffer structure 20 encloses to form a buffer groove 22, the first side surfaces 11 of two adjacent battery cells 10 are spaced apart through the buffer groove 22; the gel 30 is provided in the glue injection groove 21, and the first side surfaces 11 of two adjacent battery cells 10 are bonded together by the gel 30.

[0041] The battery module of this embodiment, by setting a buffer groove 22, provides a buffer space for the expansion of the cell 10 during cycling, ensuring that the expansion of the cell 10 during cycling can be borne by the buffer groove 22, avoiding excessive internal pressure caused by excessive expansion of the cell 10 in the later stages of cycling, which leads to cycle attenuation. By opening a glue injection groove 21 on the buffer structure 20, the pouring space of the glue 30 is limited, preventing the glue 30 from encroaching on the buffer space, and the glue 30 is used to bond two adjacent cells 10, thereby enhancing the structural strength of the battery module. Therefore, the battery module of this embodiment can both enhance the connection strength of the cells 10 in the module and reduce the impact of the cyclic expansion of the cell 10 on its lifespan.

[0042] It is worth noting that in this embodiment, the first side 11 of the battery cell 10 is the large surface of the battery cell 10, and the first direction is the thickness direction of the battery cell 10.

[0043] It should be noted that the glue injection groove 21 is disposed through the buffer structure 20 along the first direction (that is, the thickness direction of the buffer structure 20). It can be understood that the glue injection groove 21 is a hollow part disposed on the buffer structure 20. When no glue is injected into the glue injection groove 21, the first side 11 of two adjacent battery cells 10 are connected through the glue injection groove 21. Therefore, the glue 30 in the glue injection groove 21 can bond the first side 11 of two adjacent battery cells 10 together.

[0044] Specifically, in this embodiment, the buffer structure 20 is a U-shaped buffer pad with a glue injection groove 21. The two sides of the buffer pad are coated with glue, and the buffer pad can be directly attached to the first side 11 of the battery cell 10.

[0045] Furthermore, the cushioning pad can be made of materials such as silicone rubber, silicone, or aerogel.

[0046] Further preferred material for the cushioning pad is silicone rubber.

[0047] Specifically, in this embodiment, colloid 30 is a structural adhesive.

[0048] Furthermore, the structural adhesive can be selected from epoxy resin adhesive, polyurethane adhesive, silicone adhesive, and polyimide adhesive, etc.

[0049] Further preferably, silicone adhesive is selected as the structural adhesive. Silicone adhesive has strong adhesion and low volume shrinkage after curing, ensuring good bonding effect. At the same time, silicone adhesive itself has a certain degree of elasticity, which can be compressed together with the buffer pad, providing a good buffering effect for expansion in the later stages of the cycle.

[0050] In one embodiment, such as Figure 4 As shown, the area of ​​the first side 11 is A, as... Figure 5 As shown, the area of ​​the buffer structure 20 projected onto the first side 11 along the first direction is A1, as... Figure 6 As shown, the projected area of ​​the glue injection groove 21 on the first side surface 11 along the first direction is A2, which satisfies 15% < (A1 + A2) × 100% / A < 50%. By limiting the projected areas of the buffer structure 20 and the glue injection groove 21 on the first side surface 11 along the first direction, sufficient space is ensured for the buffer groove 22 while guaranteeing the buffering effect of the buffer structure 20.

[0051] Specifically, the area A of the first side 11 is measured in meters. 2 The area A1 of the buffer structure 20 projected onto the first side 11 along the first direction is in m². 2 The area A2 of the injection groove 21 projected onto the first side surface 11 along the first direction is in m². 2 It is worth noting that, as Figure 4 As shown, the area A of the first side surface 11 is L0 × H0; the projected area of ​​the dispensing groove 21 on the first side surface 11 is the same as the projected area of ​​the colloid 30 on the first side surface 11. Therefore, as Figure 6 As shown, the orthographic projection area A2 of the glue injection groove 21 on the first side surface 11 along the first direction is A2 = (L3×H3 + L4×H4)×2; Figure 5 As shown, the orthogonal projection area of ​​the buffer structure 20 on the first side 11 along the first direction is A1 = L1×H1-L2×H2-A2.

[0052] It should be noted that when (A1+A2)×100% / A < 15%, the projected area of ​​the buffer structure 20 and the glue injection groove 21 on the first side 11 along the first direction is too small. A small projected area means that the contact area between the buffer structure 20 and the cell 10 is small. Under the same impact force, the buffer structure 20 with a small contact area bears a large pressure per unit area, resulting in poor buffering effect of the buffer structure 20. When (A1+A2)×100% / A > 50%, the projected area of ​​the buffer structure 20 and the glue injection groove 21 on the first side 11 along the first direction is too large, resulting in that the projected area of ​​the buffer groove 22 on the first side 11 along the first direction is too small, thereby reducing the load-bearing capacity of the buffer groove 22 for the expansion of the cell 10 during the cycle.

[0053] Preferably, the following condition is met: 20% < (A1 + A2) × 100% / A < 30%.

[0054] In one embodiment, the ratio of the orthographic projection area of ​​the glue injection groove 21 along the first direction on the first side surface 11 to the orthographic projection area of ​​the buffer structure 20 along the first direction on the first side surface 11 satisfies 30% < (A2 / A1) × 100% < 80%. By controlling the ratio of the orthographic projection area of ​​the glue injection groove 21 along the first direction on the first side surface 11 to the orthographic projection area of ​​the buffer structure 20 along the first direction on the first side surface 11, the buffering effect of the buffering result is guaranteed while ensuring the structural strength of the buffer structure 20.

[0055] It should be noted that when (A2 / A1)×100% < 30%, the injection area of ​​colloid 30 is small, resulting in insufficient overall structural strength of buffer structure 20 and colloid 30 after injection; when (A2 / A1)×100% > 80%, the effective buffer area of ​​buffer structure 20 is small, and the buffering effect of buffer structure 20 is not obvious.

[0056] Preferably, the following condition is met: 50% < (A2 / A1) × 100% < 60%.

[0057] In one embodiment, the elastic modulus of the buffer structure 20 is E, satisfying A1×E≥6×10. 4 N. By matching the elastic modulus of the buffer structure 20 with the orthographic projection area of ​​the buffer structure 20 on the first side 11 along the first direction, the thickness change of the buffer structure 20 caused by the expansion force in the later stage of the cycle is less than 40%, ensuring the stability of the buffer performance and extending the service life of the buffer structure 20.

[0058] Specifically, the unit of elastic modulus E is N / m. 2 .

[0059] It should be noted that, after determining the size of the orthographic projection area A1 of the buffer structure 20 along the first direction on the first side surface 11, the size of the elastic modulus E should be selected based on the size of the orthographic projection area A1; similarly, after determining the size of the elastic modulus E of the buffer structure 20, the size of the orthographic projection area A1 of the buffer structure 20 along the first direction on the first side surface 11 should be selected based on the size of the elastic modulus E. In other words, the values ​​of the orthographic projection area A1 of the buffer structure 20 along the first direction on the first side surface 11 and the elastic modulus E of the buffer structure 20 should satisfy the requirements of this embodiment.

[0060] Preferably, it meets the requirement of 7×10 4 N≤A1×E≤8×10 4 N.

[0061] It should be noted that when the thickness change of the buffer structure 20 due to the expansion force in the later stage of the cycle exceeds 40%, the buffering performance of the buffer structure 20 will be significantly affected. Excessive thickness change may cause the buffer structure 20 to fail to distribute the force evenly when subjected to pressure, resulting in uneven impact force on the cell 10 and increasing the risk of damage to the cell 10.

[0062] In one embodiment, such as Figure 1 As shown, the battery module also includes end plates 40, of which two end plates 40 are provided, spaced apart along a first direction. A plurality of battery cells 10 are disposed between the two end plates 40, and a buffer structure 20 is provided between the end plate 40 and the adjacent battery cell 10. The end plates 40 protect the battery cells 10 in the first direction, preventing the battery cells 10 from shifting in the first direction.

[0063] Specifically, a buffer structure 20 is provided between the end plate 40 and the adjacent battery cell 10, and the two sides of the buffer structure 20 are respectively bonded to the battery cell 10 and the end plate 40.

[0064] It should be noted that, since the buffer structure 20 between the end plate 40 and the adjacent cell 10 is only subjected to the pressure of the expansion of one cell 10, the thickness of the buffer structure 20 between the end plate 40 and the adjacent cell 10 can be appropriately reduced.

[0065] In one embodiment, such as Figure 1 As shown, the battery module also includes a clamping structure 50, which is sleeved on the outside of the end plate 40 and several battery cells 10 to apply a pre-tightening force to the battery cells 10. By applying a pre-tightening force to the battery cells 10 through the clamping structure 50, displacement of the battery cells 10 during use and transportation is effectively prevented, and the overall structural strength of the battery module is improved, thereby enhancing the reliability of the battery module.

[0066] Specifically, such as Figure 1As shown, there are two clamping structures 50, which are spaced apart along the height direction of the battery cell 10 to apply a more uniform preload to the end plate 40 and the battery cell 10.

[0067] Furthermore, in this embodiment, the clamping structure 50 is a steel hoop.

[0068] In one embodiment, such as Figure 2 As shown, along the first direction, the thickness of the buffer structure 20 is h, the preload force applied by the clamping structure 50 to the battery cell 10 is F, and the amount of glue injected into the glue injection groove 21 is L, satisfying the following conditions: The amount of glue injected is calculated and selected based on the pre-tightening force applied to the battery cell 10 by the clamping structure 50. A suitable amount of glue injected can ensure that when the buffer structure 20 is subjected to pressure, it will not overflow from the glue injection groove 21 due to excessive glue, thus affecting the buffering effect of the buffer structure 20; nor will it result in low connection strength between adjacent battery cells 10 due to insufficient glue.

[0069] Specifically, along the first direction, the thickness h of the buffer structure 20 is in meters (m), and the preload F applied by the clamping structure 50 to the battery cell 10 is in kilometres (N).

[0070] It should be noted that if the amount of glue injected is too much, the overall structural hardness of the buffer structure 20 and the glue 30 will be too high, the buffering effect will be poor, and the excess glue 30 will easily overflow from the glue injection tank 21 and seep into other parts of the battery module; if the amount of glue injected is too little, the connection strength between adjacent cells 10 will be low, which is not conducive to maintaining a stable connection state.

[0071] In one embodiment, the battery cell 10 includes a housing and an insulating film. The insulating film is adhered to the outside of the housing. A buffer structure 20 is bonded to the insulating film, and an adhesive 30 is bonded to the insulating film. The adhesion strength between the buffer structure 20 and the insulating film is σ1, the adhesion strength between the adhesive 30 and the insulating film is σ2, and the adhesion strength between the housing and the insulating film is σ3, satisfying σ3 > σ1 and σ3 > σ2. By controlling the adhesion strength between the insulating film and each structural component, it is ensured that the insulating film will not separate from the housing before the adhesive 30 and the buffer structure 20 peel off under stress.

[0072] Specifically, the unit of the bonding strength σ1 between the buffer structure 20 and the insulating film is MPa, the unit of the bonding strength σ2 between the colloid 30 and the insulating film is MPa, and the unit of the bonding strength σ3 between the shell and the insulating film is MPa.

[0073] It should be noted that if the bonding strength between the shell and the insulating film is less than the bonding strength between the buffer structure 20 and the insulating film, or if the bonding strength between the shell and the insulating film is less than the bonding strength between the colloid 30 and the insulating film, when it is necessary to separate the buffer structure 20 from the cell 10 in the battery module, the insulating film will detach from the shell of the cell 10 along with the buffer structure 20 or the colloid 30, causing damage to the insulation of the cell 10.

[0074] In one embodiment, the adhesion strength σ2 between the colloid 30 and the insulating film is ≥ 6 MPa. By controlling the adhesion strength between the colloid 30 and the insulating film, the connection strength between the colloid 30 and the insulating film is ensured.

[0075] It should be noted that when the bonding strength σ2 between the colloid 30 and the insulating film is less than 6 MPa, the connection strength between the colloid 30 and the insulating film is too low, which leads to a decrease in the connection strength between the cells 10 of the battery module and an unstable structure of the battery module.

[0076] In one embodiment, such as Figure 5 As shown, the glue injection groove 21 includes several sub-grooves 211, which are spaced apart along the direction surrounding the buffer groove 22. By opening several sub-grooves 211 around the buffer groove 22, several glue particles 30 are evenly distributed around the buffer groove 22, thereby providing a more uniform adhesive force between two adjacent cells 10 and improving the connection effect of the overall structure of the battery module.

[0077] It should be noted that the calculated amount of adhesive needs to be allocated to each sub-slot 211.

[0078] For example, please refer to Figure 3 There are four slots 211, and one slot 211 is provided on each side of the U-shaped buffer pad.

[0079] It should be noted that in other alternative embodiments, the number of slots 211 can be adjusted according to the actual situation.

[0080] Specifically, in this embodiment, the orthographic projection of the slot 211 on the first side 11 along the first direction is a rectangle.

[0081] In other alternative embodiments, the orthographic projection of the slot 211 along the first direction onto the first side 11 can also be a circle, an ellipse, or a polygon, etc.

[0082] When assembling the battery module of this embodiment, firstly, the buffer structure 20 is neatly attached to the first side 11 of the cell 10; then, the amount of glue is calculated according to the formula, and glue is injected into each sub-slot 211 of the glue injection groove 21; after the glue 30 is injected, the next cell 10 is flatly attached to the buffer structure 20; then, the same operation is repeated to attach the buffer structure 20 and the cell 10 until all the cells 10 in the battery module are assembled, and then the end plates 40 are assembled on both sides of the cell 10 assembly; finally, after all the cells 10 and the end plates 40 are assembled, a certain pre-tightening force is applied, the clamping structure 50 is put on and fixed, and the assembly is left to stand and wait for the glue 30 to cure.

[0083] Vibration and cyclic tests were conducted on battery modules using different buffer structures 20.

[0084] Specifically, three different battery modules are set up. The three different battery modules adopt a U-shaped buffer structure with four slots 211, a large surface buffer structure, and a U-shaped buffer structure without glue injection slots 21, respectively.

[0085] Specifically, such as Figure 3 and Figure 5 As shown, in Example 1, a buffer structure with a square frame shape and four slots 211 is attached to the first side 11 of the battery cell 10, and each of the four slots 211 is filled with 1.2 mL of silicone sealant; Figure 7 As shown, in Comparative Example 1, a large-area buffer structure is attached to the first side 11 of the battery cell 10, and no glue is injected between the battery cells; as Figure 8 As shown, in Comparative Example 2, a rectangular buffer structure without a glue injection groove 21 is attached to the first side 11 of the battery cell 10, and 4.8 mL of silicone sealant is applied to the hollow part in the middle of the rectangular buffer structure without a glue injection groove 21.

[0086] Specifically, the battery cells 10 used in the test were all 53.6mm×174mm×216mm·200Ah square-shell battery cells 10, and the buffer structure 20 was made of 1.2mm silicone rubber. Each battery module consisted of eight battery cells 10 connected in series, and the preload of each battery module was set to 300kgf.

[0087] After the battery modules are assembled, X, Y, and Z axis vibration tests are conducted on the three battery modules according to the test requirements in GB 38031-2020 "Safety Requirements for Power Batteries for Electric Vehicles". The specific test structure is shown in Table 1.

[0088] Table 1 Vibration test results

[0089] Example 1 Comparative Example 1 Comparative Example 2 X-axis vibration test pass pass pass Y-axis vibration test pass pass pass Z-axis vibration test pass Failure pass

[0090] According to the vibration test results in Table 1, the battery module of Comparative Example 1 failed after 6 hours of Z-axis vibration. The battery modules of Example 1 and Comparative Example 2 passed the vibration test.

[0091] After the vibration test was completed, the battery modules of Example 1 and Comparative Example 2 were subjected to cyclic tests respectively. The specific test steps are shown in Table 2.

[0092] Table 2. Cyclic Test Procedure

[0093]

[0094]

[0095] After the cycle test was completed, the results showed that the battery module of Comparative Example 2 experienced accelerated degradation after 3200 cycles, while the battery module of Example 1 only experienced a drop in performance after 4000 cycles.

[0096] In summary, based on the results of vibration and cyclic testing, the battery module of Example 1 meets the vibration requirements in GB38031-2020 "Safety Requirements for Power Batteries for Electric Vehicles", and its cyclic test results are better than those of the battery module of Comparative Example 2.

[0097] Therefore, the battery module of this embodiment not only satisfies the requirement of enhanced structural strength, but also ensures the ability to withstand the expansion of the cell 10 during cycling, and its performance is superior to that of battery modules in the prior art.

[0098] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the present invention.

Claims

1. A battery module, characterized in that, include: A plurality of battery cells (10) are provided, and the plurality of battery cells (10) are arranged side by side along a first direction. Each battery cell (10) has two opposing first side surfaces (11) along the first direction. A buffer structure (20) is provided between two adjacent battery cells (10). The buffer structure (20) is connected to the first side surface (11). A glue injection groove (21) is opened on the buffer structure (20). The buffer structure (20) encloses and forms a buffer groove (22). The first side surfaces (11) of two adjacent battery cells (10) are spaced apart by the buffer groove (22). The colloid (30) is disposed in the glue injection groove (21), and the first side (11) of two adjacent battery cells (10) are bonded together by the colloid (30).

2. The battery module according to claim 1, characterized in that, The area of ​​the first side surface (11) is A, the orthographic projection area of ​​the buffer structure (20) along the first direction on the first side surface (11) is A1, and the orthographic projection area of ​​the glue injection groove (21) along the first direction on the first side surface (11) is A2, satisfying 15% < (A1 + A2) × 100% / A < 50%; where A is in meters. 2 The unit of A1 is m. 2 The unit of A2 is m. 2 .

3. The battery module according to claim 2, characterized in that, The ratio of the orthographic projection area of ​​the glue injection groove (21) on the first side (11) along the first direction to the orthographic projection area of ​​the buffer structure (20) on the first side (11) along the first direction satisfies 30% < (A2 / A1) × 100% < 80%.

4. The battery module according to claim 2, characterized in that, The elastic modulus of the buffer structure (20) is E, which satisfies A1×E≥6×10 4 N; where E is in N / m 2 .

5. The battery module according to claim 4, characterized in that, The battery module also includes an end plate (40), two end plates (40) are provided, the two end plates (40) are spaced apart along a first direction, a plurality of battery cells (10) are provided between the two end plates (40), and a buffer structure (20) is provided between the end plate (40) and the adjacent battery cell (10).

6. The battery module according to claim 5, characterized in that, The battery module also includes a clamping structure (50), which is sleeved on the outside of the end plate (40) and a plurality of the battery cells (10) to apply a pre-tightening force to the battery cells (10).

7. The battery module according to claim 6, characterized in that, The thickness of the buffer structure (20) along the first direction is h, the preload force applied by the clamping structure (50) to the battery cell (10) is F, and the amount of glue injected into the glue injection groove (21) is L, satisfying the following conditions: Where h is in meters (m) and F is in nanometers (N).

8. The battery module according to any one of claims 1 to 7, characterized in that, The battery cell (10) includes a housing and an insulating film. The insulating film is adhered to the outside of the housing. The buffer structure (20) is bonded to the insulating film. The colloid (30) is bonded to the insulating film. The bonding strength between the buffer structure (20) and the insulating film is σ1. The bonding strength between the colloid (30) and the insulating film is σ2. The bonding strength between the housing and the insulating film is σ3, satisfying σ3 > σ1 and σ3 > σ2. Wherein, the unit of σ1 is MPa, the unit of σ2 is MPa, and the unit of σ3 is MPa.

9. The battery module according to claim 8, characterized in that, The adhesion strength σ2 between the colloid (30) and the insulating film is ≥6MPa.

10. The battery module according to any one of claims 1 to 7, characterized in that, The glue injection groove (21) includes a plurality of sub-grooves (211), which are spaced apart along the direction surrounding the buffer groove (22).

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