Battery cell and battery module

Abstract

The invention belongs to the technical field of batteries, and discloses a battery monomer and a battery module, the battery module comprises a shell, a cover plate, a first pole assembly and a pole group arranged in the shell, an opening is formed in one side, facing a first direction, of the shell, the cover plate covers the opening and comprises a first plate body and a second plate body, the first plate body is perpendicular to the first direction, and the second plate body is perpendicular to the second direction. The second plate body comprises a first side and a second side which are opposite to each other, the first side is connected with the first plate body and points to the direction of the second side from the first side, the second plate body inclines towards a second direction opposite to the first direction, the first pole assembly penetrates through and is fixed to the second plate body, and the first plate body protrudes out of the first pole assembly in the first direction; a first end wall and a second end wall which are connected with each other are arranged on one side, facing the first direction, of the pole group, the first end wall is parallel to and attached to the first plate body, the second end wall directly faces the second plate body, the first tab extending out of the second end wall is connected with the first pole column assembly, and the safety, the product yield and the energy density of the single battery are relatively high.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a battery cell and a battery module. Background Technology

[0002] A battery cell includes an electrode assembly, a housing, a cover plate, and a terminal assembly. The electrode assembly is disposed inside the housing, and the cover plate covers the opening of the housing. The terminal assembly passes through the cover plate. The side of the terminal assembly located inside the housing is connected to the tab extending from the electrode assembly, and the side of the terminal assembly located outside the housing is connected to a connecting piece, so that the two battery cells can be electrically connected through the connecting piece.

[0003] Currently, the most common cover plates are flat, with the electrode assembly protruding from the side of the cover plate away from the casing. During transportation and assembly, the protruding electrode assembly is easily bumped, reducing the safety performance and appearance yield of the battery cell. Furthermore, the flat cover plate has a gap between itself and the electrode assembly to accommodate the tabs. When the electrode assembly is installed in the casing and during charging and discharging, the cover plate cannot provide support, leading to electrode damage and excessive electrode movement, thus reducing the safety performance of the battery cell. Additionally, the gap between the cover plate and the electrode assembly reduces the utilization of internal space in the casing, which is detrimental to improving the energy density of the battery cell.

[0004] Therefore, there is an urgent need to provide a battery cell and a battery module to solve the above-mentioned technical problems. Summary of the Invention

[0005] The first objective of this invention is to provide a battery cell in which the first plate can protect the first terminal assembly, reducing the probability of the first terminal assembly being bumped or knocked; the first plate can also support the electrode assembly, reducing the probability of electrode damage and electrode assembly displacement; the gap between the electrode assembly and the cover plate of this battery cell is small, which is beneficial to improving the energy density of the battery cell.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] Battery cells, including:

[0008] The housing has an opening on the side facing the first direction;

[0009] A cover plate is placed over the opening. The cover plate includes a first plate and a second plate. The first plate is perpendicular to a first direction. The second plate includes a first side and a second side that are disposed opposite to each other. The first side is connected to the first plate and points from the first side to the second side. The second plate is inclined in the second direction, which is opposite to the first direction.

[0010] The first pole assembly is inserted into and fixed to the second plate, and the first plate protrudes from the first pole assembly in a first direction.

[0011] The electrode assembly is disposed inside the housing. On the side of the electrode assembly facing the first direction, there is a first end wall and a second end wall connected to each other. The first end wall is parallel to the first plate and fits against the first plate. The second end wall is directly opposite the second plate. A first electrode tab extends from the second end wall and is connected to the first electrode post assembly.

[0012] Optionally, a groove is provided on the first end wall.

[0013] Optionally, the groove can be a through groove.

[0014] Optionally, the battery cell also includes an explosion-proof valve, which is disposed on the first plate and positioned directly opposite the groove.

[0015] Optionally, the electrode assembly also includes a third end wall and a fourth end wall disposed opposite to each other. The third end wall and the fourth end wall are both perpendicular to the first end wall. The third end wall is connected to the side of the second end wall away from the first end wall. The direction in which the third end wall and the fourth end wall point to each other is the width direction. The dimension of the groove along the width direction is A, and the dimension of the first end wall along the width direction is W2, where 0.24≤A / W2≤0.51.

[0016] Optionally, the electrode assembly also includes a third end wall and a fourth end wall disposed opposite to each other. The third end wall and the fourth end wall are both perpendicular to the first end wall. The third end wall is connected to the side of the second end wall away from the first end wall. The direction in which the third end wall and the fourth end wall point to each other is the width direction. The dimension of the electrode assembly along the width direction is W1, and the dimension of the first end wall along the width direction is W2. 39mm≤W1-W2≤93mm;

[0017] And / or, the distance between the side of the second end wall facing the first end wall and the side facing away from the first end wall is L1, and the distance between the side of the first electrode ear facing the first end wall and the side facing away from the first end wall is L2, 5.2mm≤L1-L2≤17mm.

[0018] Optionally, the second end wall is parallel to the second plate.

[0019] Optionally, the number of the second plate, the first pole post assembly, the second end wall, and the first pole tab are all two and correspond one-to-one, and the two second end walls and the two first pole tabs are symmetrically arranged about the first end wall.

[0020] The second objective of this invention is to provide a battery module that has high safety, high product yield, and high energy density.

[0021] To achieve this objective, the present invention adopts the following technical solution:

[0022] The battery module includes a connecting piece and the aforementioned battery cell, with the connecting piece connected to the first terminal assembly.

[0023] Optionally, the connecting piece is connected to the side of the first pole assembly opposite to the second plate, and the first plate protrudes from the connecting piece in a first direction.

[0024] The beneficial effects of this invention are:

[0025] The battery cell provided by the present invention has a cover plate comprising a first plate and a second plate. The first plate is perpendicular to a first direction, and a first side of the second plate is connected to the first plate. The second plate is inclined in a direction from the first side to the second side, which is opposite to the first direction. A first terminal assembly is inserted through and fixed on the second plate, and the first plate protrudes from the first terminal assembly in the first direction. Therefore, the first plate protects the first terminal assembly, reducing the probability of the first terminal assembly being bumped during transportation and assembly processes, which is beneficial to improving the safety and product yield of the battery cell.

[0026] On the other hand, the electrode assembly has a first end wall and a second end wall connected to each other on the side facing the first direction. The second end wall is directly opposite the second plate. A first tab extending from the second end wall is connected to the first terminal post assembly. The first end wall is parallel to and fits against the first plate. Thus, while achieving the connection between the first tab and the first terminal post assembly, the first plate can provide support for the electrode assembly, reducing the probability of electrode damage and electrode assembly movement, which is beneficial to improving the safety performance of the battery cell. In addition, this structure eliminates the gap between the first end wall and the first plate, which not only improves the utilization rate of the internal space of the casing but also increases the volume of the electrode assembly, which is beneficial to improving the energy density of the battery cell. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a battery cell provided by the present invention;

[0028] Figure 2 This is a first structural schematic diagram of the cover plate provided by the present invention;

[0029] Figure 3 This is a schematic diagram of the first structure of the pole assembly provided by the present invention;

[0030] Figure 4 This is a partial cross-sectional structural diagram of a battery cell provided by the present invention;

[0031] Figure 5 This is a schematic diagram of the second structure of the pole group provided by the present invention;

[0032] Figure 6 This is a schematic diagram of the second structure of the cover plate provided by the present invention;

[0033] Figure 7 This is a schematic diagram of the third structure of the pole assembly provided by the present invention;

[0034] Figure 8 yes Figure 4 Enlarged view of a section at point E in the middle.

[0035] In the picture:

[0036] D1, First Direction; D2, Second Direction;

[0037] 1. Housing; 2. Cover plate; 21. First plate; 211. Explosion-proof hole; 22. Second plate; 221. First side; 222. Second side; 31. First pole post assembly; 311. Plastic part; 312. Riveting block; 313. Base; 314. Column; 32. Second pole post assembly; 4. Pole group; 41. First end wall; 411. Groove; 42. Second end wall; 43. First pole lug; 44. Third end wall; 45. Fourth end wall; 5. Insulating part. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0039] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0041] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, 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. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0042] This embodiment provides a battery cell. The first plate of the battery cell can protect the first terminal assembly and reduce the probability of the first terminal assembly being bumped or knocked. The first plate can also support the electrode assembly, reducing the probability of electrode damage and electrode assembly displacement. The gap between the electrode assembly and the cover plate of the battery cell is small, which is beneficial to improving the energy density of the battery cell.

[0043] Specifically, such as Figures 1 to 4 As shown, the battery module includes a housing 1, a cover plate 2, a first terminal assembly 31, and a terminal group 4. The housing 1 has an opening on the side facing the first direction D1, and the cover plate 2 covers the opening. The cover plate 2 includes a first plate 21 and a second plate 22. The first plate 21 is perpendicular to the first direction D1, and the second plate 22 includes a first side 221 and a second side 222 oppositely disposed. The first side 221 is connected to the first plate 21, pointing from the first side 221 to the second side 222. The second plate 22 is inclined towards the second direction D2. D2 is opposite to the first direction D1. The first pole post assembly 31 passes through and is fixed to the second plate 22. The first plate 21 protrudes from the first pole post assembly 31 in the first direction D1. The pole group 4 is disposed in the housing 1. The pole group 4 has a first end wall 41 and a second end wall 42 connected to each other on the side facing the first direction D1. The first end wall 41 is parallel to the first plate 21 and fits against the first plate 21. The second end wall 42 is directly opposite the second plate 22. A first pole tab 43 extends from the second end wall 42 and is connected to the first pole post assembly 31.

[0044] Based on the above design, the cover plate 2 includes a first plate 21 and a second plate 22. The first plate 21 is perpendicular to the first direction D1. The first side 221 of the second plate 22 is connected to the first plate 21 and points from the first side 221 to the second side 222. The second plate 22 is inclined in the second direction D2, which is opposite to the first direction D1. The first terminal assembly 31 passes through and is fixed on the second plate 22. The first plate 21 protrudes from the first terminal assembly 31 in the first direction D1. Therefore, the first plate 21 plays a protective role for the first terminal assembly 31, reducing the probability of the first terminal assembly 31 being bumped during transportation and assembly processes, which is beneficial to improving the safety of the battery cell and the product yield.

[0045] On the other hand, the electrode assembly 4 has a first end wall 41 and a second end wall 42 connected to each other on the side facing the first direction D1. The second end wall 42 is directly opposite the second plate 22. The first tab 43 extending from the second end wall 42 is connected to the first terminal assembly 31. The first end wall 41 is parallel to and fits against the first plate 21. Thus, while achieving the connection between the first tab 43 and the first terminal assembly 31, the first plate 21 can provide support for the electrode assembly 4, reducing the probability of electrode damage and electrode assembly 4 shifting, which is beneficial to improving the safety performance of the battery cell. In addition, this structure also eliminates the gap between the first end wall 41 and the first plate 21, which not only improves the internal space utilization of the housing 1, but also increases the volume of the electrode assembly 4, which is beneficial to improving the energy density of the battery cell.

[0046] It should be noted that in this embodiment, the electrode group 4 includes an electrode group body and an insulating film (not shown in the figure). The entire outer surface of the electrode group body is covered with an insulating film. When the first end wall 41 is attached to the first plate 21, an insulating film is sandwiched between the electrode group body and the first plate 21 to achieve insulation between the electrode group body and the cover plate 2.

[0047] Furthermore, the second end wall 42 is parallel to the second plate 22 to minimize the gap between the second end wall 42 and the second plate 22, thereby further improving the utilization rate of the internal space of the casing 1 and further increasing the volume of the electrode assembly 4, providing further assurance for improving the energy density of the battery cell. In addition, the structure in which the second end wall 42 is parallel to the second plate 22 makes the shape of the electrode assembly 4 facing the first direction D1 match the shape of the cover plate 2, which helps to reduce the risk of collision between the electrode assembly 4 and the cover plate 2.

[0048] Optionally, the second plate 22, the first electrode assembly 31, the second end wall 42, and the first tab 43 are all in pairs and correspond one-to-one. The two second end walls 42 and the two first tabs 43 are symmetrically arranged about the first end wall 41. Compared with the structure in which the two first tabs 43 are arranged on the same end wall, the technical solution provided in this embodiment is advantageous in increasing the size of each first tab 43, especially the distance L2 between the side of the first tab 43 facing the first end wall 41 and the side facing away from the first end wall 41, thereby improving the current carrying capacity of the first tab 43. In addition, since the two first tabs 43 are symmetrically distributed on both sides of the first end wall 41, the heat generated by the electrode group 4 during charging and discharging can be dispersed to the two first tabs 43, making the heat distribution of the first electrode group 4 more uniform. This is beneficial for the rapid dissipation of heat inside the electrode group 4 and improves the safety of the battery cell.

[0049] Furthermore, the two second plates 22 and the two first pole post assemblies 31 are symmetrically arranged about the first plate 21, so that the cover plate 2 and the pole group 4 are both symmetrical structures, which helps to reduce the assembly difficulty and positioning difficulty of the cover plate 2 and the pole group 4, and has the effect of reducing production costs.

[0050] Furthermore, the housing 1 at the opening is provided with a protruding structure that matches the shape of the cover plate 2, so that the cover plate 2 can be placed over the opening.

[0051] Optionally, the two first tabs 43 have the same polarity. For example, in this embodiment, both first tabs 43 are negative tabs, and correspondingly, the two first terminal assembly 31 are negative terminal assembly. This structure can improve the negative overcurrent capability of the electrode group 4, which is beneficial to realize fast charging and high-rate discharge of the battery cell.

[0052] Furthermore, the battery cell also includes a second terminal assembly 32, which is disposed on the side of the housing 1 facing the second direction D2. The polarity of the second terminal assembly 32 is opposite to that of the first terminal assembly 31, i.e., the second terminal assembly 32 is the positive terminal assembly. A second tab (not shown in the figure) extends from the side of the electrode group 4 facing the second direction D2. The polarity of the second tab is opposite to that of the first tab 43, i.e., the second tab is the positive tab, and the second tab is connected to the second terminal assembly 32. Of course, in other embodiments, the first terminal assembly 31 and the first tab 43 can also be the positive terminal assembly, the second terminal assembly 32 can be the negative terminal assembly, and the second tab can be the negative tab.

[0053] Optionally, a groove 411 is provided on the first end wall 41 to improve the wetting effect of the electrolyte on the electrode assembly 4, especially to improve the wetting effect of the electrode assembly 4 on the side facing the first direction D1.

[0054] Furthermore, the groove 411 is a through groove, so that the electrolyte on both sides of the electrode group 4 can flow through the through groove, which can not only improve the wetting effect of the electrolyte on the electrode group 4, but also improve the uniformity of electrolyte distribution inside the shell 1.

[0055] In this embodiment, along the thickness direction of the pole group 4 (i.e. Figure 3 In the z-direction of the electrode assembly 4, the groove 411 is a through groove, allowing the electrolyte to flow through the groove 411 in the thickness direction of the electrode assembly 4. Of course, in other embodiments, the groove 411 can also be a through groove in other directions; for example, the groove 411 can be in the width direction of the electrode assembly 4. Figure 3 The groove 411 is a through groove in the y direction of the electrode group 4, which allows the electrolyte to flow through the groove 411 in the width direction of the electrode group 4; the groove 411 can also be a through groove in the diagonal direction of the electrode group 4, which allows the electrolyte to flow through the groove 411 in the diagonal direction of the electrode group 4.

[0056] Furthermore, the battery cell also includes an explosion-proof valve (not shown in the figure). The first plate 21 is provided with an explosion-proof hole 211, which is set directly opposite the groove 411. The explosion-proof valve is sealed in the explosion-proof hole 211, that is, the explosion-proof valve is set directly opposite the groove 411. Thus, an exhaust gap is formed between the first end wall 41 and the explosion-proof valve at the groove 411. When the battery cell is abnormal, the high-temperature and high-pressure material in the housing 1 can quickly reach the explosion-proof valve through the exhaust gap, shortening the explosion-proof valve's bursting time. In addition, after the explosion-proof valve bursts, when the high-temperature and high-pressure material in the housing 1 flows to the exhaust gap, the flow cross-section increases, allowing the high-temperature and high-pressure material in the housing 1 to be quickly discharged from the housing 1. It can be seen that the design of setting the explosion-proof valve directly opposite the groove 411 achieves the effect of rapid explosion-proof valve bursting and rapid exhaust, improving the safety of the battery cell.

[0057] Optionally, such as Figure 5 As shown, the pole group 4 also includes a third end wall 44 and a fourth end wall 45 disposed opposite to each other. The third end wall 44 and the fourth end wall 45 are both perpendicular to the first end wall 41. The third end wall 44 is connected to the side of the second end wall 42 away from the first end wall 41. The direction in which the third end wall 44 and the fourth end wall 45 point to each other is the width direction (i.e., the y direction). The dimension of the groove 411 along the width direction is A, and the dimension of the first end wall 41 along the width direction is W2. 0.24≤A / W2≤0.51. For example, A / W2 can be 0.24, 0.25, 0.3, 0.43, 0.5 or 0.51, etc., among which 0.25≤A / W2≤0.5 is preferred. If A / W2 < 0.24, the size of the groove 411 is too small. This increases the flow resistance of the electrolyte at the groove 411, which can easily lead to insufficient electrolyte wetting in the area of ​​the electrode assembly 4 near the first end wall 41, thus affecting the electrical performance of the battery cell. In addition, a small groove 411 will prolong the bursting time of the explosion-proof valve, and after the explosion-proof valve bursts, it will be difficult for the high-temperature and high-pressure substances inside the casing 1 to be quickly discharged, which is not conducive to improving the safety of the battery cell. If A / W2 > 0.51, the size of the groove 411 is too large, which reduces the volume of the electrode assembly 4, thereby reducing the capacity of the electrode assembly 4 and the electrical performance of the battery cell. Secondly, a large groove 411 will reduce the support area of ​​the first plate 21 on the first end wall 41, and will also reduce the structural strength of the area of ​​the electrode assembly 4 near the first end wall 41, which can easily lead to deformation and damage in the area of ​​the electrode assembly 4 near the first end wall 41.

[0058] Optionally, the dimension of the electrode assembly 4 along the width direction is W1, and the dimension of the first end wall 41 along the width direction is W2, where 39mm ≤ W1 - W2 ≤ 93mm. For example, W1-W2 can be 39mm, 40mm, 55mm, 62mm, 81mm, 92mm, or 93mm, with 40mm ≤ W1-W2 ≤ 92mm being preferred. If W1-W2 > 93mm, the dimension of the first end wall 41 along the width direction is too small, which reduces the volume of the electrode assembly 4 facing the first direction D1, thereby reducing the capacity of the electrode assembly 4 and the electrical performance of the battery cell. Figures 4 to 6 As shown, since the first end wall 41 is positioned directly opposite the first plate 21 and is parallel to and attached to the first plate 21, and the second end wall 42 is parallel to and directly opposite the second plate 22, and the two second plates 22 are symmetrically arranged about the first plate 21, and the two second end walls 42 are symmetrically arranged about the first end wall 41, the shape of the electrode assembly 4 facing the first direction D1 is adapted to the shape of the cover plate 2. Therefore, the dimension W1 of the electrode assembly 4 along the width direction is related to the dimension W3 of the cover plate 2 along the width direction. The first end wall 41 along... The dimension W2 in the width direction is related to the dimension W4 of the first plate 21 in the width direction. If W1-W2 < 39mm, then W3-W4 is too small, which makes the dimension W5 of the second plate 22 in the width direction too small. This will reduce the size of the first plate 21 protruding from the first terminal assembly 31 in the first direction D1, or even make the first terminal assembly 31 protrude from the first plate 21 in the first direction D1, increasing the risk of the first terminal assembly 31 being bumped during the manufacturing process, which is not conducive to improving the safety of the battery cell and the product yield.

[0059] It should be noted that in this embodiment, there are two second end walls 42, which are symmetrically arranged about the first end wall 41. The third end wall 44 and the fourth end wall 45 are arranged opposite each other. Therefore, the third end wall 44 and the fourth end wall 45 correspond to one second end wall 42. That is, the side of one of the two second end walls 42 away from the first end wall 41 is connected to the third end wall 44, and the side of the other of the two second end walls 42 away from the first end wall 41 is connected to the fourth end wall 45. The distance between the side of the third end wall 44 away from the fourth end wall 45 and the side of the fourth end wall 45 away from the third end wall 44 is the dimension of the pole group 4 along the width direction, i.e., W1.

[0060] It should also be noted that, such as Figure 3 As shown, in this embodiment, the first direction D1 and the second direction D2 are both length directions, i.e., the x direction, the width direction is the y direction, and the thickness direction is the z direction. The x, y, and z directions are perpendicular to each other.

[0061] Optionally, such as Figure 5As shown, the distance between the side of the second end wall 42 facing the first end wall 41 and the side facing away from the first end wall 41 is L1, and the distance between the side of the first tab 43 facing the first end wall 41 and the side facing away from the first end wall 41 is L2, where 5.2mm ≤ L1-L2 ≤ 17mm. For example, L1-L2 can be 5.2mm, 6mm, 8mm, 11.5mm, 16mm, or 17mm, etc., with 6mm ≤ L1-L2 ≤ 16mm being preferred. If L1-L2 < 5.2mm, the first tab 43 is too long, which reduces the distance between the side of the first tab 43 facing away from the first end wall 41 and the side of the second end wall 42 facing away from the first end wall 41. When the insulating film is wrapped on the electrode assembly body, problems such as instantaneous heat deformation and tearing are likely to occur, which is not conducive to improving the product yield of the battery cell. It should be noted that this problem is particularly pronounced in the stacked electrode assembly 4 structure. Specifically, when the positive and negative electrode sheets are stacked to form the electrode assembly body through a stacking process, process errors can lead to an insufficient gap between the side of the first tab 43 facing away from the first end wall 41 and the side of the second end wall 42 facing away from the first end wall 41. This increases the likelihood of the aforementioned thermal deformation and tearing problems. If L1-L2 > 17mm, the first tab 43 is too short. On the one hand, this reduces the overcurrent capacity of the first tab 43, making it impossible for the battery cell to meet the overcurrent requirements of high rate and high capacity. On the other hand, it reduces the heat dissipation capacity of the first tab 43, reducing the heat dissipation efficiency of the electrode assembly 4, and thus reducing the safety of the battery cell.

[0062] Optionally, the groove depth of the groove 411 is B, where 1.2mm ≤ B ≤ 4mm. For example, B can be 1.2mm, 2mm, or 4mm. If B < 1.2mm, the flow resistance of the electrolyte in the groove 411 will increase, which may lead to insufficient electrolyte wetting in the area of ​​the electrode assembly 4 near the first end wall 41, thereby affecting the electrical performance of the battery cell. In addition, if the size of the groove 411 is too small, it will prolong the bursting time of the explosion-proof valve. After the explosion-proof valve bursts, it will not be conducive to the rapid discharge of high-temperature and high-pressure substances from the housing 1, which is not conducive to improving the safety of the battery cell. If B > 4mm, the volume of the electrode assembly 4 will be reduced, thereby reducing the capacity of the electrode assembly 4 and the electrical performance of the battery cell. It will also reduce the structural strength of the area of ​​the electrode assembly 4 near the first end wall 41, which may lead to deformation and damage in the area of ​​the electrode assembly 4 near the first end wall 41.

[0063] Optionally, the acute angle between the first end wall 41 and the second end wall 42 is N, where 35°≤N≤60°. For example, N can be 35°, 50°, or 60°. If N<35°, the size of the first plate 21 protruding from the first pole post assembly 31 in the first direction D1 will be reduced, thereby reducing the protective capability of the first plate 21 for the first pole post assembly 31 and increasing the probability of the first pole post assembly 31 being bumped during the manufacturing process. If N>60°, the side of the pole group 4 facing the first direction D1 will be relatively narrow and long. On the one hand, this will reduce the structural strength of the side of the pole group 4 facing the first direction D1, making it prone to deformation. On the other hand, it will reduce the volume of the pole group 4, which is not conducive to increasing the capacity of the pole group 4.

[0064] Optionally, such as Figure 7 As shown, the dimension of the electrode group 4 in the thickness direction (i.e., the z-direction) is T, 12mm≤T≤115mm. For example, T can be 12mm, 50mm or 115mm, etc.

[0065] like Figure 8 As shown, in this embodiment, the first pole assembly 31 includes a plastic part 311, a riveting block 312, and a pole. Both the plastic part 311 and the riveting block 312 are located on the side of the second plate 22 facing away from the housing 1, with the plastic part 311 sandwiched between the second plate 22 and the riveting block 312. The pole includes a base 313 and a column 314. The base 313 is located on the side of the second plate 22 facing the housing 1. One end of the column 314 is connected to the base 313, and the other end of the column 314 passes through the second plate 22, the plastic part 311, and the riveting block 312, and is riveted to and fixed to the riveting block 312. The first plate 21 protrudes from the riveting block 312 in the first direction D1 to reduce the probability of the riveting block 312 being bumped during the manufacturing process.

[0066] Furthermore, the side of the rivet block 312 facing away from the second plate 22 is parallel to the surface of the second plate 22, so as to further reduce the probability of the rivet block 312 being bumped during the manufacturing process.

[0067] The cover plate 2, housing 1 and first pole post assembly 31 provided in this embodiment have simple structures. The cover plate 2 and housing 1 can be made of common materials such as aluminum or stainless steel. The cover plate 2 and housing 1 can be made by stamping process, the plastic part 311 can be formed on the cover plate 2 by injection molding process, and the pole group 4 can be formed by stacking process and die cutting process. The above-mentioned stamping process, injection molding process, stacking process and die cutting process are all common production processes in the field, which are conducive to realizing mass automated production.

[0068] Table 1 below provides six sets of embodiments and six sets of comparative examples. In all six sets of embodiments and six sets of comparative examples, the shell 1 is made of 0.35mm thick ternary aluminum plate, the insulating film is polypropylene (PP) film, the plastic parts 311 are all made of polyphenylene sulfide (PPS) material, and the insulating parts 5 sandwiched between the base 313 and the second plate 22 are all made of PP material.

[0069]

[0070] In Example 1, B is 1.2mm, T is 12mm, N is 35°, W1 is 70mm, W1-W2 is 40mm, A / W2 is 0.25, L2-L1 is 6mm, and the yield rate of the battery cell is >98%. No displacement or movement of the electrode group 4 was observed. No damage to the insulating film or electrode body occurred during the assembly of the casing 1 and the electrode group 4. The overcurrent capacity and temperature rise of the first electrode tab 43 both meet the requirements of the battery cell.

[0071] In Example 2, B is 1.5mm, T is 38mm, N is 38°, W1 is 120mm, W1-W2 is 48mm, A / W2 is 0.32, L2-L1 is 10mm, and the yield rate of the battery cell is >98%. No displacement or movement of the electrode group 4 was observed. No damage to the insulating film or electrode body occurred during the assembly of the casing 1 and the electrode group 4. The overcurrent capacity and temperature rise of the first electrode tab 43 both meet the requirements of the battery cell.

[0072] In Example 3, B is 2mm, T is 63mm, N is 45°, W1 is 150mm, W1-W2 is 52mm, A / W2 is 0.36, L2-L1 is 11.5mm, and the yield rate of the battery cell is >98%. No displacement or movement of the electrode group 4 was observed. No damage to the insulating film or electrode body occurred during the assembly of the casing 1 and the electrode group 4. The overcurrent capacity and temperature rise of the first electrode tab 43 both meet the requirements of the battery cell.

[0073] In Example 4, B is 2.8mm, T is 80mm, N is 50°, W1 is 190mm, W1-W2 is 66mm, A / W2 is 0.4, L2-L1 is 13.2mm, and the yield rate of the battery cell is >98%. No displacement or movement of the electrode group 4 was observed. No damage to the insulating film or electrode body occurred during the assembly of the casing 1 and the electrode group 4. The overcurrent capacity and temperature rise of the first electrode tab 43 both meet the requirements of the battery cell.

[0074] In Example 5, B is 3.5mm, T is 100mm, N is 55°, W1 is 240mm, W1-W2 is 80mm, A / W2 is 0.44, L2-L1 is 15mm, and the yield rate of the battery cell is >98%. No displacement or movement of the electrode group 4 was observed. No damage to the insulating film or electrode body occurred during the assembly of the casing 1 and the electrode group 4. The overcurrent capacity and temperature rise of the first electrode tab 43 both meet the requirements of the battery cell.

[0075] In Example 6, B is 4mm, T is 115mm, N is 60°, W1 is 290mm, W1-W2 is 92mm, A / W2 is 0.5, L2-L1 is 16mm, and the yield rate of the battery cell is >98%. No displacement or movement of the electrode group 4 was observed. No damage to the insulating film or electrode body occurred during the assembly of the casing 1 and the electrode group 4. The overcurrent capacity and temperature rise of the first electrode tab 43 both meet the requirements of the battery cell.

[0076] In Comparative Example 1, B is 2mm, T is 63mm, N is 35°, W1 is 150mm, W1-W2 is 38mm, A / W2 is 0.25, L2-L1 is 8mm, and the yield rate of the battery cell is <98%. The size of the first plate 21 protruding from the first terminal assembly 31 in the first direction D1 is too small, and there may even be a problem that the first terminal assembly 31 protrudes from the first plate 21 in the first direction D1, which increases the risk of the first terminal assembly 31 being bumped during the manufacturing process.

[0077] In Comparative Example 2, B is 2mm, T is 63mm, N is 60°, W1 is 150mm, W1-W2 is 94mm, A / W2 is 0.5, L2-L1 is 10mm, and the yield of the battery cell is <98%. This is because the volume of the electrode group 4 facing the first direction D1 was reduced, which in turn reduced the capacity of the electrode group 4 and reduced the electrical performance of the battery cell.

[0078] In Comparative Example 3, B is 2mm, T is 63mm, N is 45°, W1 is 150mm, W1-W2 is 52mm, A / W2 is 0.23, L2-L1 is 10mm, and the yield of the single battery cell is <98%. The size of the groove 411 is too small, which increases the flow resistance of the electrolyte in the groove 411, resulting in insufficient electrolyte wetting in the area of ​​the electrode group 4 near the first end wall 41. It prolongs the bursting time of the explosion-proof valve, and after the explosion-proof valve bursts, the flow cross section of the high-temperature and high-pressure substances in the shell 1 is small, which is not conducive to the rapid discharge of high-temperature and high-pressure substances from the shell 1.

[0079] In Comparative Example 4, B is 2mm, T is 63mm, N is 45°, W1 is 150mm, W1-W2 is 52mm, A / W2 is 0.52, L2-L1 is 10mm, and the yield rate of the battery cell is <98%. The size of the groove 411 is too large, which reduces the volume of the electrode group 4 and the capacity of the electrode group 4. It also reduces the support area of ​​the first plate 21 on the first end wall 41 and reduces the structural strength of the area of ​​the electrode group 4 near the first end wall 41, which makes it easy for the area of ​​the electrode group 4 near the first end wall 41 to deform and be damaged.

[0080] In Comparative Example 5, B is 2mm, T is 63mm, N is 45°, W1 is 150mm, W1-W2 is 52mm, A / W2 is 0.4, L2-L1 is 5mm, and the yield of qualified battery cells is <98%. The gap between the side of the first tab 43 facing away from the first end wall 41 and the side of the second end wall 42 facing away from the first end wall 41 is too small. When the insulating film is wrapped on the electrode assembly body, problems such as heat deformation and tearing are likely to occur.

[0081] In Comparative Example 6, B is 2mm, T is 63mm, N is 45°, W1 is 150mm, W1-W2 is 52mm, A / W2 is 0.4, L2-L1 is 18mm, and the yield of the battery cell is <98%. The first tab 43 is too short, which reduces the overcurrent capacity of the first tab 43, making the battery cell unable to meet the overcurrent requirements of high rate and high capacity; it also reduces the heat dissipation capacity of the first tab 43, thereby reducing the heat dissipation efficiency of the electrode group 4.

[0082] In summary, when the above parameters satisfy 39mm≤W1-W2≤93mm, 1.2mm≤B≤4mm, 0.24≤A / W2≤0.51, 35°≤N≤60°, 5.2mm≤L1-L2≤17mm, and 12mm≤T≤115mm, the probability of damage and cross-flow of electrode group 4 can be reduced, the probability of damage to the insulating film and electrode group body can be reduced, and the first electrode tab 43 can be ensured to have a large current carrying capacity and heat dissipation capacity.

[0083] This embodiment also provides a battery module, which includes a connecting piece and at least two of the above-mentioned battery cells. For example, the number of battery cells can be two, three or more. The connecting piece is usually made of a metal material with conductive properties, such as copper or aluminum. The first terminal assembly 31 of each pair of battery cells is welded and fixed to the same connecting piece to achieve conductive connection (series or parallel connection) between the two battery cells. The battery module uses the above-mentioned battery cells and has high safety, product yield and energy density.

[0084] Furthermore, the connecting piece is connected to the side of the first terminal assembly 31 opposite to the second plate 22, and the first plate 21 protrudes from the connecting piece in the first direction D1, so that the first plate 21 protects the connecting piece and reduces the probability of the connecting piece being bumped during the manufacturing process. In addition, compared with the flat cover plate 2, with the same length, width and thickness of the battery cell, this structure can save assembly space of the battery module, which is conducive to improving the assembly rate of the battery module, thereby improving the energy density and performance of the battery module, and reducing the cost of the battery module.

[0085] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A single battery cell, characterized in that, include: The housing (1) has an opening on the side facing the first direction (D1); A cover plate (2) is provided over the opening. The cover plate (2) includes a first plate body (21) and a second plate body (22). The first plate body (21) is perpendicular to the first direction (D1). The second plate body (22) includes a first side (221) and a second side (222) arranged opposite to each other. The first side (221) is connected to the first plate body (21) and points from the first side (221) to the second side (222). The second plate body (22) is inclined to the second direction (D2), which is opposite to the first direction (D1). The first pole post assembly (31) passes through and is fixed to the second plate (22), and the first plate (21) protrudes from the first pole post assembly (31) in the first direction (D1). The electrode assembly (4) is disposed inside the housing (1). The electrode assembly (4) has a first end wall (41) and a second end wall (42) connected to each other on the side facing the first direction (D1). The first end wall (41) is parallel to the first plate (21) and fits against the first plate (21). The second end wall (42) is directly opposite the second plate (22). A first electrode tab (43) extends from the second end wall (42) and is connected to the first electrode post assembly (31).

2. The battery cell according to claim 1, characterized in that, The first end wall (41) is provided with a groove (411).

3. The battery cell according to claim 2, characterized in that, The groove (411) is a through groove.

4. The battery cell according to claim 2, characterized in that, The battery cell also includes an explosion-proof valve, which is disposed on the first plate (21) and is positioned opposite the groove (411).

5. The battery cell according to claim 2, characterized in that, The pole group (4) further includes a third end wall (44) and a fourth end wall (45) disposed opposite to each other. The third end wall (44) and the fourth end wall (45) are both perpendicular to the first end wall (41). The third end wall (44) is connected to the side of the second end wall (42) away from the first end wall (41). The direction in which the third end wall (44) and the fourth end wall (45) point to each other is the width direction. The dimension of the groove (411) along the width direction is A, and the dimension of the first end wall (41) along the width direction is W2, 0.24≤A / W2≤0.

51.

6. The battery cell according to any one of claims 1-5, characterized in that, The pole group (4) further includes a third end wall (44) and a fourth end wall (45) disposed opposite to each other. The third end wall (44) and the fourth end wall (45) are both perpendicular to the first end wall (41). The third end wall (44) is connected to the side of the second end wall (42) away from the first end wall (41). The direction in which the third end wall (44) and the fourth end wall (45) point to each other is the width direction. The dimension of the pole group (4) along the width direction is W1, and the dimension of the first end wall (41) along the width direction is W2. 39mm≤W1-W2≤93mm; And / or, the distance between the side of the second end wall (42) facing the first end wall (41) and the side away from the first end wall (41) is L1, and the distance between the side of the first tab (43) facing the first end wall (41) and the side away from the first end wall (41) is L2, 5.2mm≤L1-L2≤17mm.

7. The battery cell according to any one of claims 1-5, characterized in that, The second end wall (42) is parallel to the second plate (22).

8. The battery cell according to any one of claims 1-5, characterized in that, The number of the second plate (22), the first pole post assembly (31), the second end wall (42) and the first pole tab (43) are all two and correspond one-to-one. The two second end walls (42) and the two first pole tabs (43) are symmetrically arranged about the first end wall (41).

9. A battery module, characterized in that, It includes a connecting piece and a battery cell as described in any one of claims 1-8, wherein the connecting piece is connected to the first terminal assembly (31).

10. The battery module according to claim 9, characterized in that, The connecting piece is connected to the side of the first pole post assembly (31) away from the second plate (22), and the first plate (21) protrudes from the connecting piece in the first direction (D1).

Images