Battery cell, battery, and electric device

Abstract

The application provides a battery monomer, a battery and an electric device. The battery monomer comprises a shell, an end cover and an electrode assembly. The shell has an opening at at least one end along a first direction, the shell comprises a first wall, the end cover closes the opening, and the first wall is welded with the end cover to form a first connecting part. The electrode assembly is at least partially accommodated in the shell, and the electrode assembly comprises a positive electrode sheet and a negative electrode sheet. At least part of the positive electrode sheet and at least part of the negative electrode sheet are arranged in a stacking mode along a second direction, the second direction is parallel to the thickness direction of the first wall, and the first direction intersects the second direction. The first wall comprises a first area and a second area arranged along the first direction, the thickness of the first area is greater than the thickness of the second area, and the first area is located between the first connecting part and the second area. The risk of fatigue cracking of the area of the first wall near the first connecting part due to the expansion of the electrode assembly is reduced, and the service life of the battery monomer is improved.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to three international patent applications filed on April 22, 2024, entitled “A battery cell, a battery and an electrical device”, PCT / CN2024 / 089160; filed on November 30, 2023, entitled “A battery cell, a battery, an electrical device and an energy storage device”, PCT / CN2023 / 135607; and filed on November 24, 2023, entitled “A housing, a battery cell, a battery and an electrical device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, and more specifically, to a battery cell, a battery, and an electrical device. Background Technology

[0004] Energy conservation and emission reduction are key to the sustainable development of the automotive industry, and electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of this sustainable development. For electric vehicles, battery technology is a crucial factor in their development.

[0005] In battery technology, the lifespan of individual battery cells is a crucial issue. Therefore, improving the lifespan of individual battery cells is a pressing technical problem that needs to be solved. Utility Model Content

[0006] This application provides a battery cell, a battery, and an electrical device, which can effectively improve the service life of the battery cell.

[0007] In a first aspect, embodiments of this application provide a battery cell, the battery cell including a housing, an end cap, and an electrode assembly; the housing has an opening at at least one end along a first direction, and the housing includes a first wall; the end cap closes the opening, and the first wall is welded to the end cap to form a first connection portion; the electrode assembly is at least partially housed within the housing, the electrode assembly including a positive electrode sheet and a negative electrode sheet, at least a portion of the positive electrode sheet and at least a portion of the negative electrode sheet are stacked along a second direction, the second direction being parallel to the thickness direction of the first wall, and the first direction intersecting the second direction; the first wall includes a first region and a second region arranged along the first direction, the thickness of the first region being greater than the thickness of the second region, and the first region being located between the first connection portion and the second region.

[0008] In the above technical solution, the thickness of the first region is greater than that of the second region, and the first region is located between the first connecting part and the second region. This makes the thicker first region closer to the first connecting part than the second region. The first region strengthens the area of ​​the first wall near the first connecting part, reducing the risk of fatigue cracking of the area of ​​the first wall near the first connecting part due to the expansion of the electrode assembly, thereby improving the service life of the battery cell.

[0009] In some embodiments, the electrode assembly has a flat region, and portions of the positive electrode and negative electrode located in the flat region are stacked along a second direction. The second direction is the stacking direction of the portions of the positive and negative electrode located in the flat region. During cycling, the electrode assembly expands more along the second direction, and the first wall is more significantly affected by this expansion. However, because the first region reinforces the area of ​​the first wall near the first connection, the risk of fatigue cracking of the first wall near the first connection due to electrode assembly expansion is reduced.

[0010] In some embodiments, the electrode assembly includes adjacent first and second surfaces, the first surface being perpendicular to a second direction, the area of ​​the first surface being larger than the area of ​​the second surface, and the first surface and the first wall being disposed opposite each other along the second direction. The larger area of ​​the first surface compared to the second surface results in a greater expansion force on the first wall disposed opposite to the first surface within the housing. Because the first region reinforces the area of ​​the first wall near the first connection, the risk of fatigue cracking of the first wall near the first connection due to the expansion of the electrode assembly is reduced.

[0011] In some embodiments, the first surface is the surface with the largest area among the outer surfaces of the electrode assembly. This maximizes the expansion force experienced by the first wall in the housing, which is disposed opposite to the first surface. Since the first region reinforces the area of ​​the first wall near the first connection, the risk of fatigue cracking of the first wall near the first connection due to the expansion of the electrode assembly is reduced.

[0012] In some embodiments, the electrode assembly is a wound structure, and the electrode assembly further includes a corner region. The corner region is located at at least one end of the straight region along a third direction. The first direction, the second direction, and the third direction are not coplanar and intersect each other. The outer surface of the straight region includes a first surface, and the outer surface of the corner region includes a second surface, at least a portion of which is an arc surface. For the wound electrode assembly, the expansion amount of the straight region in the second direction is greater. Since the first region reinforces the area of ​​the first wall near the first connection, the risk of fatigue cracking of the first wall near the first connection due to the expansion of the electrode assembly can be effectively reduced.

[0013] In some embodiments, the electrode assembly is a stacked structure, with the flat region including multiple positive electrode sheets and multiple negative electrode sheets. These multiple positive and negative electrode sheets are stacked along a second direction, and the first surface is perpendicular to the second surface. For stacked electrode assemblies, the expansion amount in the stacking direction of the positive and negative electrode sheets is greater. Since the first region reinforces the area of ​​the first wall near the first connection portion, the risk of fatigue cracking of the first wall near the first connection portion due to the expansion of the electrode assembly can be effectively reduced.

[0014] In some embodiments, the first wall is the wall with the largest outer surface area in the housing. The wall with the largest outer surface area in the housing is more prone to deformation under the expansion force of the electrode assembly. Since the first wall is the wall with the largest outer surface area in the housing, the risk of fatigue cracking of the wall with the largest outer surface area in the housing near the first connection due to the expansion of the electrode assembly is reduced.

[0015] In some embodiments, the housing includes two first walls disposed opposite each other along a second direction, with the electrode assembly located between the two first walls. This reduces the risk of fatigue cracking of the two first walls near the first connection due to the expansion of the electrode assembly.

[0016] In some embodiments, the first region includes a first portion and a second portion arranged along a first direction, the second portion connecting the first portion and the second region, and the thickness of the first portion being greater than the thickness of the second portion. The area of ​​the first region near the first connection is more prone to forming a heat-affected zone, which is more susceptible to fatigue cracking. However, because the second portion connects the first portion and the second region, and the thickness of the first portion is greater than the thickness of the second portion, the thicker first portion in the first region is closer to the first connection, effectively weakening the impact of the heat-affected zone on the first region and reducing the risk of fatigue cracking in the area of ​​the first wall near the first connection. Furthermore, because the thickness of the second portion is less than the thickness of the first portion, the material used in the first region can be reduced, lowering production costs.

[0017] In some embodiments, the thickness of the second portion decreases along the direction from the end cap to the electrode assembly. On the one hand, this reduces the impact of the second portion on the electrode assembly and lowers the risk of interference between the second portion and the electrode assembly; on the other hand, it increases the reinforcing effect of the second portion along the direction from the electrode assembly to the end cap, ensuring that the area of ​​the second portion near the first portion has a good reinforcing effect even when affected by the first connection, thus reducing the risk of fatigue cracking of the first wall in the second portion; furthermore, the second portion facilitates the transition between the first portion and the second region, reducing stress concentration.

[0018] In some embodiments, the dimension of the first region along the third direction is larger than the dimension of the first region along the first direction, and the first direction, the second direction, and the third direction are not coplanar and intersect each other. This makes the dimension of the first region along the third direction larger, thereby increasing the strength of the first wall in a larger area along the third direction and further reducing the risk of fatigue cracking in the area of ​​the first wall near the first connection.

[0019] In some embodiments, the first region includes a first connecting segment that passes through the mid-section of the first wall. The mid-section is perpendicular to a third direction, and the distances from the mid-section to both ends of the first wall along the third direction are equal. When the first wall is subjected to the expansion force of the battery cell electrode assembly, the deformation of the middle region of the first wall along the third direction is greater, and the middle region of the first wall along the third direction is more prone to fatigue cracking. Because the first connecting segment of the first region passes through the mid-section of the first wall, the strength of at least the middle region of the first wall along the third direction is strengthened, reducing the risk of fatigue cracking of the middle region of the first wall along the third direction near the first connecting portion.

[0020] In some embodiments, the first region further includes a second connecting segment and a third connecting segment. The second connecting segment, the first connecting segment, and the third connecting segment are arranged along a third direction. The first connecting segment connects the second connecting segment and the third connecting segment, and the thickness of the first connecting segment is greater than the thickness of the second connecting segment and the thickness of the third connecting segment. When the first wall is subjected to the expansion force of the electrode assembly, the deformation of the first wall gradually decreases from the middle to both ends along the third direction. By dividing the first region into multiple segments, and setting the thickness of the first connecting segment located in the middle region to be larger, and setting the thickness of the second connecting segment and the third connecting segment located at both ends of the first connecting segment to be smaller, the first region is designed specifically according to the different deformation amounts of different regions of the first wall along the third direction. This specifically improves the strength of different regions of the first wall along the third direction, ensuring sufficient strength in the region of the first wall near the first connecting portion while reducing the material used in the first region and lowering production costs.

[0021] In some embodiments, the first region further includes a first transition section, a first connecting section, a first transition section, and a second connecting section arranged along a third direction, the first transition section connecting the second connecting section and the first connecting section, and the thickness of the first transition section increasing along the direction from the second connecting section to the first connecting section; and / or, the first region further includes a second transition section, a first connecting section, a second transition section, and a third connecting section arranged along a third direction, the second transition section connecting the third connecting section and the first connecting section, and the thickness of the second transition section increasing along the direction from the third connecting section to the first connecting section. If the second connecting section and the first connecting section are connected by the first transition section, and the thickness of the first transition section increasing along the direction from the second connecting section to the first connecting section, the first transition section can achieve a transition between the second connecting section and the first connecting section, reducing stress concentration. If the third connecting section and the first connecting section are connected by the second transition section, and the thickness of the second transition section increasing along the direction from the third connecting section to the first connecting section, the second transition section can achieve a transition between the third connecting section and the first connecting section, reducing stress concentration.

[0022] In some embodiments, the dimension of the first connecting segment along the third direction is L1, and the dimension of the first wall along the third direction is L, where 0.2 ≤ L1 / L ≤ 0.6. L1 / L ≥ 0.2 increases the proportion of the first connecting segment's dimension along the third direction in the first wall, thus increasing the reinforcement area of ​​the middle region of the first wall along the third direction and improving its strength. L1 / L ≤ 0.6 decreases the proportion of the first connecting segment's dimension along the third direction in the first wall, reducing material usage and lowering production costs. Therefore, setting the ratio of the first connecting segment's dimension along the third direction to the first wall's dimension along the third direction to 0.2–0.6 ensures sufficient reinforcement capacity for the first connecting segment while reducing material usage, thus balancing the reinforcement requirements and economic considerations.

[0023] In some embodiments, the first connecting segment has a first end and a second end opposite each other along a third direction, and the first wall has a third end and a fourth end opposite each other along a third direction, with the first end closer to the third end and the second end closer to the fourth end. The dimension of the first wall along the third direction is L, the minimum distance between the first end and the third end along the third direction is L2, and the minimum distance between the second end and the fourth end along the third direction is L3; L2 / L≤0.3; and / or, L3 / L≤0.3. If L2 / L≤0.3, the proportion of the minimum distance between the first end and the third end along the third direction in the dimension of the first wall along the third direction is reduced, thereby strengthening the strength of a larger area of ​​the first wall along the third direction and further reducing the risk of fatigue cracking in the area of ​​the first wall near the first connecting portion. If L3 / L≤0.3, the proportion of the minimum distance between the second end and the fourth end along the third direction in the dimension of the first wall along the third direction is reduced, thereby strengthening the strength of a larger area of ​​the first wall along the third direction and further reducing the risk of fatigue cracking in the area of ​​the first wall near the first connecting portion.

[0024] In some embodiments, 100mm ≤ L ≤ 450mm.

[0025] In some embodiments, the housing includes corner walls, with corner walls connecting both ends of the first wall along a third direction; at least one end of the first region along the third direction does not contact the corner walls; or, both ends of the first region along the third direction extend to the two corner walls respectively. If at least one end of the first region along the third direction does not contact the corner walls, the material used in the first region can be reduced, thus lowering production costs. If both ends of the first region along the third direction extend to the two corner walls respectively, the length of the first region is increased, improving the reinforcement capacity of the first region, thereby strengthening more areas of the first wall along the third direction, further reducing the risk of fatigue cracking in the area of ​​the first wall near the first connection.

[0026] In some embodiments, the electrode assembly further includes a spacer disposed between the positive electrode and the negative electrode. The positive electrode includes a positive electrode body region and a positive electrode tab protruding from the positive electrode body region, the positive electrode body region having a positive active material layer. The negative electrode includes a negative electrode body region and a negative electrode tab protruding from the negative electrode body region, the negative electrode body region having a negative active material layer. Along a first direction, the positive electrode body region has a fifth end facing the end cap, the negative electrode body region has a sixth end facing the end cap, and the spacer has a seventh end facing the end cap, the seventh end being closer to the end cap than the fifth and sixth ends. This allows the spacer to extend beyond the fifth and sixth ends, enhancing the insulation effect of the spacer between the positive and negative electrode, and reducing the risk of overlap between the positive and negative electrode.

[0027] In some embodiments, the separator includes an extension region extending beyond the fifth and sixth ends along a first direction, wherein the orthographic projection of the extension region partially overlaps with the orthographic projection of the first region in a projection plane perpendicular to the second direction. This structure increases the size of the first region along the first direction, improves the reinforcement capacity of the first region, strengthens more areas of the first wall along the first direction, and further reduces the risk of fatigue cracking in the area of ​​the first wall near the first connection.

[0028] In some embodiments, the second region has a first inner surface facing the internal space of the housing, and the first region includes a first protrusion protruding from the first inner surface; in a projection plane perpendicular to the second direction, the orthographic projection of the positive electrode main region does not overlap with the orthographic projection of the first protrusion; and / or, in a projection plane perpendicular to the second direction, the orthographic projection of the negative electrode main region does not overlap with the orthographic projection of the first protrusion. If the orthographic projection of the positive electrode main region does not overlap with the orthographic projection of the first protrusion in a projection plane perpendicular to the second direction, the housing can provide a larger expansion space for the electrode assembly, reducing the risk that the expansion of the electrode assembly directly applies an expansion force to the first protrusion, reducing the deformation of the first wall, and further reducing the risk of fatigue cracking in the area of ​​the first wall near the first connection portion. Similarly, if the orthographic projection of the negative electrode main region does not overlap with the orthographic projection of the first protrusion in a projection plane perpendicular to the second direction, the housing can provide a larger expansion space for the electrode assembly, reducing the risk that the expansion of the electrode assembly directly applies an expansion force to the first protrusion, reducing the deformation of the first wall, and further reducing the risk of fatigue cracking in the area of ​​the first wall near the first connection portion.

[0029] In some embodiments, the negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one side of the negative current collector, the negative active material layer including a negative active material.

[0030] In some embodiments, the negative electrode active material layer includes a negative electrode body portion and a negative electrode thinning portion, which are arranged along a first direction. Along the first direction, the negative electrode body portion is provided at one end near the end cap. The electrode assembly has a larger expansion gap in the region corresponding to the negative electrode thinning portion. After expansion, the region of the electrode assembly corresponding to the negative electrode thinning portion exerts less force on the first wall, thereby reducing the risk of fatigue cracking in the region of the first wall near the first connection portion.

[0031] In some embodiments, in a projection plane perpendicular to the second direction, the orthographic projection of the negative electrode thinning portion and the orthographic projection of the first region are spaced apart along the first direction. This can reduce the impact of the negative electrode thinning portion on the first region, reduce the risk of the electrode assembly expansion directly applying expansion force to the first region, and further reduce the risk of fatigue cracking in the area of ​​the first wall near the first connection portion.

[0032] In some embodiments, in a projection plane perpendicular to the second direction, the distance between the orthographic projection of the negative electrode thinning portion and the orthographic projection of the first region along the first direction is greater than or equal to 1 mm. This makes the orthographic projection of the negative electrode thinning portion and the orthographic projection of the first region further apart along the first direction in the projection plane perpendicular to the second direction, thereby further reducing the influence of the negative electrode thinning portion on the first region.

[0033] In some embodiments, the single-sided coating weight of the negative electrode active material layer is 90 mg / 1540 mm. 2 ~170mg / 1540mm 2 The single-sided coating weight of the negative electrode active material layer is related to the expansion of the negative electrode active material layer. Therefore, the single-sided coating weight of the negative electrode active material layer is set at 90 mg / 1540 mm². 2 ~170mg / 1540mm 2 It can, to a certain extent, balance the high energy density requirements of individual battery cells and the low expansion requirements of negative electrode sheets, thereby reducing the impact of negative electrode sheet expansion on the first wall and reducing the risk of fatigue cracking in the area of ​​the first wall near the first connection part.

[0034] In some embodiments, the single-sided coating weight of the negative electrode active material layer is 110 mg / 1540 mm. 2 ~150mg / 1540mm 2 This can further improve the energy density requirements of individual battery cells and further reduce the expansion of the negative electrode.

[0035] In some embodiments, the porosity of the negative electrode sheet is 27% to 40%. This provides space for impurities generated by side reactions in the negative electrode sheet, slows down the expansion of the negative electrode sheet, and reduces the impact of the expansion of the negative electrode sheet on the first wall.

[0036] In some embodiments, the negative electrode active material includes a silicon-based material, wherein the mass content of silicon element in the negative electrode active material is 0.3% to 10%, optionally 1% to 6%.

[0037] In some embodiments, the silicon-based material includes at least one of silicon oxides and silicon-carbon composites.

[0038] In some embodiments, the positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one side of the positive current collector, the positive active material layer including a positive active material.

[0039] In some embodiments, the positive electrode active material layer includes a positive electrode body portion and a positive electrode thinning portion, which are arranged along a first direction. Along the first direction, the positive electrode body portion is provided at one end near the end cap. The electrode assembly has a larger expansion gap in the region corresponding to the positive electrode thinning portion. After expansion, the region of the electrode assembly corresponding to the positive electrode thinning portion exerts less force on the first wall, thereby reducing the risk of fatigue cracking in the region of the first wall near the first connection portion.

[0040] In some embodiments, in a projection plane perpendicular to the second direction, the orthographic projection of the positive electrode thinning portion and the orthographic projection of the first region are spaced apart along the first direction. This can reduce the impact of the positive electrode thinning portion on the first region, reduce the risk of the electrode assembly expansion directly applying expansion force to the first region, and further reduce the risk of fatigue cracking in the area of ​​the first wall near the first connection portion.

[0041] In some embodiments, in a projection plane perpendicular to the second direction, the distance between the orthographic projection of the positive electrode thinning portion and the orthographic projection of the first region along the first direction is greater than or equal to 1 mm. This makes the orthographic projection of the positive electrode thinning portion and the orthographic projection of the first region further apart along the first direction in the projection plane perpendicular to the second direction, thereby further reducing the influence of the positive electrode thinning portion on the first region.

[0042] In some embodiments, the single-sided coating weight of the positive electrode active material layer is 200 mg / 1540 mm. 2 ~370mg / 1540 / mm 2 The single-sided coating weight of the positive electrode active material layer is related to the expansion of the positive electrode active material layer. Therefore, the single-sided coating weight of the positive electrode active material layer is set at 200 mg / 1540 mm². 2 ~370mg / 1540 / mm 2 It can, to a certain extent, balance the high energy density requirements of individual battery cells and the low expansion requirements of the positive electrode sheet, thereby reducing the impact of positive electrode sheet expansion on the first wall and reducing the risk of fatigue cracking in the area of ​​the first wall near the first connection part.

[0043] In some embodiments, the single-sided coating weight of the positive electrode active material layer is 240 mg / 1540 mm. 2 ~330mg / 1540mm 2 This can further improve the energy density requirements of individual battery cells and further reduce the expansion of the positive electrode.

[0044] In some embodiments, the positive electrode active material is a lithium phosphate.

[0045] In some embodiments, the shell material includes steel; the maximum thickness of the second region is D1, and the dimension of the shell along the second direction is D, where 0.001 ≤ D1 / D ≤ 0.012. For a steel shell, D1 / D ≥ 0.001 increases the thickness proportion of the second region in the shell, ensuring sufficient strength for the second region to meet the shell's strength requirements; D1 / D ≤ 0.012 decreases the thickness proportion of the second region in the shell, allowing for increased internal space within a fixed shell volume, thus providing more space for the electrode assembly to meet the volumetric energy density requirements of the battery cell.

[0046] In some embodiments, the casing material includes steel; the maximum thickness of the second region is D1, 0.08mm ≤ D1 ≤ 0.35mm; and / or, the maximum thickness of the first region is D2, 0.1mm ≤ D2 ≤ 0.6mm. For a steel casing, setting the maximum thickness of the second region to 0.08mm to 0.35mm satisfies both the strength requirements of the second region and the volumetric energy density requirements of the battery cell. Setting the maximum thickness of the first region to 0.1mm to 0.6mm provides sufficient strength to enhance the strength of the area of ​​the first wall near the first connection.

[0047] In some embodiments, the housing is made of aluminum alloy; the maximum thickness of the second region is D1, and the dimension of the housing along the second direction is D, where 0.005 ≤ D1 / D ≤ 0.065. For a housing made of aluminum alloy, D1 / D ≥ 0.005 increases the thickness proportion of the second region in the housing, ensuring sufficient strength for the second region to meet the strength requirements of the housing; D1 / D ≤ 0.065 reduces the thickness proportion of the second region in the housing, allowing for a larger internal space within a fixed housing volume, thus providing more space for the electrode assembly to meet the volumetric energy density requirements of the battery cell.

[0048] In some embodiments, the casing material includes aluminum alloy; the maximum thickness of the second region is D1, 0.4mm ≤ D1 ≤ 0.8mm; and / or, the maximum thickness of the first region is D2, 0.5mm ≤ D2 ≤ 1.5mm. For a casing made of aluminum alloy, setting the maximum thickness of the second region to 0.4mm to 0.8mm satisfies both the strength requirements of the second region and the volumetric energy density requirements of the battery cell. Setting the maximum thickness of the first region to 0.5mm to 1.5mm provides sufficient strength to enhance the strength of the area of ​​the first wall near the first connection portion.

[0049] In some embodiments, the aluminum alloy comprises the following components by weight percentage: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other individual elements ≤ 0.03%. This aluminum alloy has good processing and forming properties, facilitating shell forming.

[0050] In some embodiments, the first region is directly connected to the first connection portion. This brings the first region and the first connection portion closer together along the first direction, placing the first region near the first connection portion and further reducing the risk of fatigue cracking of the area of ​​the first wall near the first connection portion due to the expansion of the electrode assembly.

[0051] In some embodiments, the first wall further includes a first transition region connected to the end of the first region away from the second region along a first direction. The first transition region is connected to a first connecting portion, and the connection position between the first transition region and the first connecting portion forms a first connection interface. The first connection interface has a first position closest to the first region along the first direction, and the first position is located at the end of the first region away from the second region along the first direction. The connection between the first transition region and the first connecting portion to form the first connection interface provides a sufficiently large contact area between the first transition region and the first connecting portion, improving the robustness of the first wall after welding to the end cap.

[0052] In some embodiments, at least a portion of the first connection interface extends obliquely relative to the second direction. After the end cap and the first wall are welded, the first connection portion shrinks as it solidifies, generating tensile stress in the first transition region. When the first wall is subjected to the expansion force of the electrode assembly, the first wall deforms, and the first transition region generates tensile stress in the first connection portion. Because at least a portion of the first connection interface extends obliquely relative to the second direction, the tensile stress generated by the first connection portion due to shrinkage in the first transition region near the portion of the first connection interface that extends obliquely relative to the second direction is not on the same straight line as the tensile stress generated by the first transition region due to deformation of the first wall in the first connection portion, reducing the risk of fatigue cracking in the area of ​​the first transition region near the first connection interface.

[0053] In some embodiments, the first connection interface includes a first interface that extends obliquely from a first position toward the end cap. Along a second direction, at least a portion of the first transition region is located between the first interface and the end cap. The first connection portion protects the first transition region. When the first wall is subjected to the expansion force of the electrode assembly, the deformation of the first transition region during the stress process is blocked by the first connection portion, reducing the risk of fatigue cracking in the area of ​​the first transition region near the first interface.

[0054] In some embodiments, the first interface is connected to the outer surface of the first region at a first location. This allows the first region and the first connection to be in a direct connection state, bringing the first region and the first connection closer together along a first direction, further reducing the risk of fatigue cracking of the area of ​​the first wall near the first connection due to the expansion of the electrode assembly.

[0055] In some embodiments, the first connection interface includes a second interface that extends obliquely from the first position toward the end cap. Along a second direction, at least a portion of the first transition region is located on the side of the second interface opposite to the end cap. This allows the first transition region to restrict the first connection portion, reducing the risk of the first connection portion detaching.

[0056] In some embodiments, the second interface is connected to the inner surface of the first region at a first location. This allows the first region and the first connection to be in a direct connection state, bringing the first region and the first connection closer together along a first direction, further reducing the risk of fatigue cracking of the area of ​​the first wall near the first connection due to the expansion of the electrode assembly.

[0057] In some embodiments, the Vickers hardness of the first transition zone is less than that of the second zone; and / or, the Vickers hardness of the first transition zone is less than that of the first connecting portion. If the Vickers hardness of the first transition zone is less than that of the second zone, connecting the lower Vickers hardness first transition zone to the first connecting portion can alleviate the rigid tension between the first wall and the first connecting portion when the first wall deforms, reducing the risk of separation between the first wall and the first connecting portion. If the Vickers hardness of the first transition zone is less than that of the first connecting portion, the first transition zone is more prone to deformation than the first connecting portion, which can alleviate the rigid tension between the first wall and the first connecting portion when the first wall deforms, reducing the risk of separation between the first wall and the first connecting portion.

[0058] In some embodiments, along the first direction, the first connection interface is closer to the second region than the outer surface of the end cap. This allows the first connection portion to sink deeper into the first wall, effectively improving the connection strength between the first wall and the end cap.

[0059] In some embodiments, the housing further includes a second wall and a corner wall, with the first wall, corner wall, and second wall arranged circumferentially along the opening, and the corner wall connecting the first wall and the second wall. This allows the first wall to transition to the second wall via the corner wall, effectively reducing the risk of stress concentration at corner locations in the housing.

[0060] In some embodiments, the corner wall is welded to the end cap to form a second connection. The corner wall includes a third region and a fourth region arranged along a first direction, the thickness of the third region being greater than the thickness of the fourth region, and the third region being located between the fourth region and the second connection. The greater thickness of the third region compared to the fourth region, and the location of the third region between the second connection and the fourth region, makes the thicker third region closer to the second connection than the fourth region. The third region strengthens the area of ​​the corner wall near the second connection, reducing the risk of fatigue cracking in the area of ​​the corner wall near the second connection, thereby improving the service life of the battery cell.

[0061] In some embodiments, the third zone is directly connected to the first zone. Directly connecting the third zone to the first zone makes them a unified whole, with the third zone and the first zone mutually reinforcing each other, enhancing the strengthening effect of the first zone on the first wall and the strengthening effect of the second zone on the corner wall.

[0062] In some embodiments, along the circumference of the opening, the corner wall has a first connecting end and a second connecting end, the first wall being connected to the first connecting end and the second wall being connected to the second connecting end. The thickness of the third region decreases along the direction from the first connecting end to the second connecting end. When the first wall is subjected to the expansion force of the electrode assembly in the second direction, the deformation of the first wall may cause the corner wall to deform. Along the circumference of the opening, the corner wall is more affected by the first wall the closer it is to the first wall, and the deformation of the area of ​​the corner wall closer to the first wall is greater. The thickness of the third region decreases along the direction from the first connecting end to the second connecting end, making the area of ​​the third region closer to the first wall along the circumference of the opening stronger, thereby reducing the impact of the deformation of the first wall on the corner wall. While ensuring sufficient strength in the area of ​​the corner wall near the second connecting part, the material used in the third region is reduced, thus lowering production costs.

[0063] In some embodiments, the third region is directly connected to the second connection portion. This brings the third region closer to the second connection portion along the first direction, placing the third region near the second connection portion and further reducing the risk of fatigue cracking in the area of ​​the corner wall near the second connection portion.

[0064] In some embodiments, the corner wall further includes a second transition region connected to the end of the third region away from the fourth region along a first direction. The second transition region is connected to a second connecting portion, and the connection point between the second transition region and the second connecting portion forms a second connecting interface. The second connecting interface has a second position closest to the third region along the first direction, located at the end of the third region away from the fourth region along the first direction. The connection between the second transition region and the second connecting portion to form the second connecting interface provides a sufficiently large contact area, improving the robustness of the corner wall after welding to the end cap.

[0065] In some embodiments, at least a portion of the second connection interface extends obliquely relative to the thickness direction of the corner wall. Near the portion of the second connection interface that extends obliquely relative to the thickness direction of the corner wall, the tensile stress generated by the contraction of the second connection portion on the second transition zone is not on the same straight line as the tensile stress generated by the deformation of the corner wall on the second connection portion in the second transition zone, thus reducing the risk of fatigue cracking in the area of ​​the second transition zone near the second connection interface.

[0066] In some embodiments, the second connection interface includes a third interface that extends obliquely from the second position toward the end cap. Along the thickness direction of the corner wall, at least a portion of the second transition zone is located between the third interface and the end cap. The second connection portion protects the second transition zone, preventing outward deformation of the second transition zone and reducing the risk of fatigue cracking in the area of ​​the second transition zone near the third interface.

[0067] In some embodiments, the third interface is connected to the outer surface of the third region at a second location. This allows the third region and the second connection to be in a direct connection state, bringing the third region and the second connection closer together along the first direction, further reducing the risk of fatigue cracking in the area of ​​the corner wall near the second connection.

[0068] In some embodiments, the second connection interface includes a fourth interface that extends obliquely from the second position toward the end cap. Along the thickness direction of the corner wall, at least a portion of the second transition region is located on the side of the fourth interface opposite to the end cap. This allows the second transition region to restrict the second connection portion, reducing the risk of the second connection portion detaching.

[0069] In some embodiments, the fourth interface is connected to the inner surface of the third region at a second location. This allows the third region and the second connection to be in a direct connection state, bringing the third region and the second connection closer together along the first direction, further reducing the risk of fatigue cracking in the area of ​​the corner wall near the second connection.

[0070] In some embodiments, the Vickers hardness of the second transition zone is less than that of the fourth zone; and / or, the Vickers hardness of the second transition zone is less than that of the second connecting portion. If the Vickers hardness of the second transition zone is less than that of the fourth zone, connecting the lower-hardness second transition zone to the second connecting portion can alleviate the rigid tension between the corner wall and the second connecting portion when the corner wall deforms, reducing the risk of separation between the corner wall and the second connecting portion. If the Vickers hardness of the second transition zone is less than that of the second connecting portion, the second transition zone is more prone to deformation than the second connecting portion, which can alleviate the rigid tension between the corner wall and the second connecting portion when the corner wall deforms, reducing the risk of separation between the corner wall and the second connecting portion.

[0071] In some embodiments, along the first direction, the second connection interface is closer to the fourth region than the outer surface of the end cap. This allows the second connection portion to sink deeper into the corner wall, effectively improving the connection strength between the corner wall and the end cap.

[0072] In some embodiments, the housing includes two first walls and two second walls, the two first walls being disposed opposite each other along a second direction, and the two second walls being disposed opposite each other along a third direction, with the first, second, and third directions being perpendicular to each other. This makes the housing generally rectangular, allowing for a larger housing size, which is beneficial for meeting the large capacity requirements of individual battery cells.

[0073] In some embodiments, at least a portion of the Vickers hardness of the first region is less than that of the second region. When the second region deforms under the expansion force of the electrode assembly, the region in the first region with a lower Vickers hardness than the second region can reduce the impact of the deformation of the second region on the region of the first wall near the first connection, thereby reducing the risk of fatigue cracking of the region of the first wall near the first connection due to the expansion of the electrode assembly.

[0074] In some embodiments, along a first direction, the first wall has a limiting surface facing the end cap, which abuts against the end cap to restrict movement of the end cap toward the electrode assembly. The limiting surface restricts the end cap, reducing the risk of the end cap moving toward the electrode assembly during welding to the housing, effectively improving the welding quality between the end cap and the housing, and reducing the welding difficulty between the end cap and the housing.

[0075] In some embodiments, the first wall further includes a limiting region disposed on the limiting surface. The limiting region and the end cap are disposed opposite to each other along the second direction, and the limiting region and the end cap are welded to form a first connection portion. The limiting region can also limit the end cap, reducing the risk of movement along the thickness direction of the first wall when the end cap is welded to the housing, further improving the welding quality of the end cap and the housing, and reducing the welding difficulty of the end cap and the housing.

[0076] In some embodiments, the electrode assembly has a stacked structure, comprising multiple positive electrode sheets and multiple negative electrode sheets, which are stacked along a second direction. The stacked electrode assembly has a more compact structure and stronger resistance to compression.

[0077] In some embodiments, the number of negative electrode plates is greater than the number of positive electrode plates, and a positive electrode plate is disposed between two adjacent negative electrode plates.

[0078] In some embodiments, each negative electrode is provided with a negative electrode tab; and / or, each positive electrode is provided with a positive electrode tab.

[0079] In some embodiments, along the third direction, the size of the first region is larger than the size of the positive electrode and / or the negative electrode, and the first direction, the second direction, and the third direction are perpendicular to each other. This makes the size of the first region larger along the third direction, thereby strengthening the first wall by increasing the area along the third direction and further reducing the risk of fatigue cracking in the area of ​​the first wall near the first connection.

[0080] In some embodiments, the battery cell further includes two electrode terminals disposed on an end cap. The two electrode terminals have opposite polarities and are both electrically connected to the electrode assembly. The end cap has a lead-out hole. Each electrode terminal includes a terminal body, a first limiting portion, and a second limiting portion. The terminal body connects to the first and second limiting portions and passes through the lead-out hole. Along a first direction, the first limiting portion is located on the side of the end cap away from the electrode assembly, and the second limiting portion is located on the side of the end cap facing the electrode assembly. This type of electrode terminal can be riveted to the end cap, which is easy to install and more economical.

[0081] Secondly, embodiments of this application provide a battery, including the battery cell provided in any one of the embodiments of the first aspect.

[0082] Thirdly, embodiments of this application provide an electrical device, including a battery cell provided in any one of the embodiments of the first aspect, wherein the battery cell is used to provide electrical energy to the electrical device. Attached Figure Description

[0083] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0084] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0085] Figure 2 Exploded views of batteries provided for some embodiments of this application;

[0086] Figure 3 Exploded views of a single battery cell provided in some embodiments of this application;

[0087] Figure 4 for Figure 3 The image shows an isometric view of a single battery cell.

[0088] Figure 5 for Figure 4 A cross-sectional view of the battery cell shown in Figure AA;

[0089] Figure 6 for Figure 5 A magnified view of a section at point B in the middle;

[0090] Figure 7 for Figure 5 The isometric view of the shell shown;

[0091] Figure 8 Axonometric views of electrode assemblies provided in some embodiments of this application;

[0092] Figure 9 for Figure 8 The diagram shows the structure of the electrode assembly.

[0093] Figure 10 Axonometric views of electrode assemblies provided for other embodiments of this application;

[0094] Figure 11 for Figure 10 The diagram shows the structure of the electrode assembly.

[0095] Figure 12 for Figure 6 A partial view of the first wall shown;

[0096] Figure 13 Axonometric views of the housing provided for some embodiments of this application;

[0097] Figure 14 for Figure 13 The top view of the casing shown;

[0098] Figure 15 Axonometric views of the housing provided for other embodiments of this application;

[0099] Figure 16 for Figure 15 The top view of the casing shown;

[0100] Figure 17 Axonometric views of the housing provided for some embodiments of this application;

[0101] Figure 18 for Figure 17 The top view of the casing shown;

[0102] Figure 19 Partial view of a battery cell provided for some embodiments of this application (showing the positive electrode, negative electrode, and separator of the electrode assembly);

[0103] Figure 20 This application provides a diagram showing the positional relationship between the positive electrode, negative electrode, and insulating element in some embodiments.

[0104] Figure 21This is a diagram showing the positional relationship between the positive electrode, negative electrode, and separator provided in other embodiments of this application;

[0105] Figure 22 A partial view of a battery cell (showing the first wall) provided for some embodiments of this application;

[0106] Figure 23 for Figure 22 A partial view of the first wall shown;

[0107] Figure 24 for Figure 22 The isometric view of the shell shown;

[0108] Figure 25 A partial view of a battery cell (showing the first wall) provided for other embodiments of this application;

[0109] Figure 26 for Figure 25 A magnified view of a section at point C;

[0110] Figure 27 A partial view of a battery cell (showing the first wall) provided for some embodiments of this application;

[0111] Figure 28 for Figure 27 A magnified view of a section at point D;

[0112] Figure 29 A partial view of a battery cell (showing the first wall) provided for some embodiments of this application;

[0113] Figure 30 for Figure 29 A magnified view of a section at point E in the middle;

[0114] Figure 31 Axonometric views of the housing are provided for further embodiments of this application;

[0115] Figure 32 for Figure 31 A magnified view of a section at point F in the middle;

[0116] Figure 33 A partial view of a battery cell provided for some embodiments of this application (showing a corner wall);

[0117] Figure 34 This is a schematic diagram of the corner wall structure provided in some embodiments of this application;

[0118] Figure 35 Schematic diagrams of the corner wall provided for other embodiments of this application;

[0119] Figure 36Partial view of a battery cell provided for other embodiments of this application (showing a corner wall);

[0120] Figure 37 for Figure 36 A magnified view of a section at point G in the middle;

[0121] Figure 38 A partial view of a battery cell provided for some embodiments of this application (showing a corner wall);

[0122] Figure 39 for Figure 38 A magnified view of a section at point H in the middle;

[0123] Figure 40 A partial view of a battery cell provided for some embodiments of this application (showing a corner wall);

[0124] Figure 41 for Figure 40 A magnified view of a section at point I;

[0125] Figure 42 This is a diagram showing the positional relationship between the end cap and the side wall before welding in some embodiments of this application;

[0126] Figure 43 This is a schematic diagram showing the connection between the end cap and the electrode terminal provided in some embodiments of this application.

[0127] Icons: 1-Outer shell; 11-Shell; 111-First wall; 1111-First region; 11111-First part; 11112-Second part; 11113-First connecting section; 11113a-First end; 11113b-Second end; 11114-Second connecting section; 11115-Third connecting section; 11116-First transition section; 11117-Second transition section; 11118-First protrusion; 1112-Second region; 11121-First inner surface; 11122-First outer surface; 1113-Third end; 1114-Fourth end; 1115-Limiting surface; 1116-Limiting area; 117-First transition zone; 112-Second wall; 113-Corner wall; 1131-Third zone; 1132-Fourth zone; 11321-Second inner surface; 11322-Second outer surface; 1133-First connecting end; 1134-Second connecting end; 1135-Second transition zone; 12-End cap; 121-Outer surface of end cap; 2-Electrode assembly; 21-Taper; 21a-Positive electrode tab; 21b-Negative electrode tab; 22-Positive electrode sheet; 221-Positive electrode body region; 2211-Fifth end; 222-Positive electrode current collector; 223-Positive electrode active material layer; 2231-Positive electrode body portion; 2232-Positive electrode thinning Part; 224-Insulating layer; 23-Negative electrode sheet; 231-Negative electrode body region; 2311-Sixth terminal; 232-Negative electrode current collector; 233-Negative electrode active material layer; 2331-Negative electrode body part; 2332-Negative electrode thinning part; 24-Isolator; 241-Seventh terminal; 242-Excess area; 25-Straight area; 26-Corner area; 27-First surface; 28-Second surface; 3-Electrode terminal; 31-Terminal body; 32-First limiting part; 33-Second limiting part; 4-Pressure relief mechanism; 5-Connecting part; 51-First connecting part; 511-First connecting interface; 5111-First position; 5112-First Interface; 5113 - Second interface; 5114 - Third position; 5115 - Fourth position; 52 - Second connecting part; 521 - Second connecting interface; 5211 - Second position; 5212 - Third interface; 5213 - Fourth interface; 5214 - Fifth position; 5215 - Sixth position; 6 - First insulating component; 7 - Second insulating component; 10 - Battery cell; 20 - Housing; 201 - First housing; 202 - Second housing; 100 - Battery; 200 - Controller; 300 - Motor; 1000 - Vehicle; Z - First direction; Y - Second direction; X - Third direction; U - First sub-interface; V - Second sub-interface. Detailed Implementation

[0128] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0129] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0130] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0131] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0132] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0133] In this application, "multiple" means two or more (including two).

[0134] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0135] Battery cells include, but are not limited to, lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0136] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, reduces the risk of short circuits while allowing active ions to pass through.

[0137] In some embodiments, the positive electrode can be a positive electrode sheet, which may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector.

[0138] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0139] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0140] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0141] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0142] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative current collector.

[0143] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Foamed metal can be nickel foam, copper foam, aluminum foam, foam alloy, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0144] As an example, the negative electrode sheet may include a negative current collector and a negative active material disposed on at least one surface of the negative current collector.

[0145] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0146] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0147] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0148] In some embodiments, the separator is a separator membrane. The separator membrane can be any known porous structure separator membrane with good chemical and mechanical stability.

[0149] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0150] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0151] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include electrolyte salts and solvents.

[0152] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0153] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0154] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0155] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0156] As an example, polymer solid electrolytes can be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0157] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0158] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0159] In some embodiments, the electrode assembly is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0160] In some implementations, the electrode assembly is a stacked structure.

[0161] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0162] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0163] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0164] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0165] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0166] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0167] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0168] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0169] As an example, a battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic battery cells, such as hexagonal prismatic battery cells.

[0170] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity.

[0171] In some embodiments, the battery can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0172] In some embodiments, the battery can be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0173] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0174] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0175] In related technologies, a battery cell generally includes a casing and an electrode assembly. The casing may include a housing and an end cap. The housing has an opening. After the electrode assembly is installed inside the housing, the opening of the housing can be closed by the end cap to form a sealed space inside the housing to accommodate the electrode assembly.

[0176] To achieve a stable connection between the end cap and the housing, the end cap and the housing can be welded. After welding, a connection part will be formed at the welding point. The area of ​​the housing wall near the connection part will form a heat-affected zone due to the high temperature of welding, and the strength of the portion of the housing wall in the heat-affected zone will be reduced.

[0177] During the charge and discharge cycle of a battery cell, the electrode assembly expands. The wall of the casing is deformed by the expansion force of the electrode assembly. Over time, this can easily lead to fatigue cracking in the area of ​​the casing wall near the connection (heat-affected zone), affecting the service life of the battery cell.

[0178] Based on the above considerations, to alleviate the problem of fatigue cracking in the area of ​​the casing wall near the connection portion, this application provides a battery cell, which includes a casing, an end cap, and an electrode assembly. The casing has an opening at at least one end along a first direction, and includes a first wall. The end cap closes the opening, and the first wall and end cap are welded to form a first connection portion. The electrode assembly is at least partially housed within the casing. The electrode assembly includes a positive electrode and a negative electrode, and at least portions of the positive and negative electrode are stacked along a second direction parallel to the thickness direction of the first wall. The first and second directions intersect. The first wall includes a first region and a second region arranged along the first direction. The thickness of the first region is greater than the thickness of the second region, and the first region is located between the first connection portion and the second region.

[0179] In such a battery cell, the thickness of the first region is greater than that of the second region, and the first region is located between the first connection and the second region. This makes the thicker first region closer to the first connection than the second region. The first region strengthens the area of ​​the first wall near the first connection, reducing the risk of fatigue cracking of the area of ​​the first wall near the first connection due to the expansion of the electrode assembly, thereby improving the service life of the battery cell.

[0180] The battery cells described in the embodiments of this application are applicable to batteries and electrical devices that use battery cells.

[0181] Electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical equipment.

[0182] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0183] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. A battery 100 is disposed inside the vehicle 1000, and the battery 100 may be located at the bottom, front, or rear of the vehicle 1000. The battery 100 can be used to power the vehicle 1000; for example, the battery 100 can serve as the operating power source for the vehicle 1000.

[0184] The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, for the power needs of the vehicle 1000 during startup, navigation and driving.

[0185] In some embodiments of this application, the battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0186] Please refer to Figure 2 , Figure 2 This is an exploded view of a battery 100 provided in some embodiments of this application. The battery 100 may include a battery cell 10 and a housing 20, wherein the battery cell 10 is housed within the housing 20.

[0187] The housing 20 is a component that houses the battery cell 10, providing a space for the battery cell 10. The housing 20 can adopt various structures. In some embodiments, the housing 20 may include a first housing 201 and a second housing 202, which overlap each other to define a space for accommodating the battery cell 10. The first housing 201 and the second housing 202 can have various shapes, such as cuboid or cylindrical. The first housing 201 can be a hollow structure with an opening on one side, and the second housing 202 can also be a hollow structure with an opening on one side. The opening side of the second housing 202 overlaps the opening side of the first housing 201, thus forming a housing 20 with a accommodating space. Alternatively, the first housing 201 can be a hollow structure with an opening on one side, and the second housing 202 can be a plate-like structure, overlapping the opening side of the first housing 201, thus forming a housing 20 with a accommodating space. The first housing 201 and the second housing 202 can be sealed by a sealing element, such as a sealing ring or sealant.

[0188] In battery 100, there can be one or more battery cells 10. If there are multiple battery cells 10, they can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 10 are connected in both series and parallel. Alternatively, multiple battery cells 10 can be first connected in series, parallel, or in a mixed manner to form a battery module, and then multiple battery modules can be connected in series, parallel, or in a mixed manner to form a whole, which is then housed within the housing 20. Another option is that all battery cells 10 can be directly connected in series, parallel, or in a mixed manner, and then the whole consisting of all battery cells 10 is housed within the housing 20.

[0189] Please refer to Figure 3 and Figure 4 , Figure 3 Exploded views of a battery cell 10 provided in some embodiments of this application; Figure 4 for Figure 3 The image shows an isometric view of a battery cell 10. The battery cell 10 may include a housing 1 and an electrode assembly 2, which is housed within the housing 1.

[0190] In some embodiments, the housing 1 may include a housing 11 and an end cap 12, the housing 11 having an opening and the end cap 12 closing the opening of the housing 11.

[0191] The housing 11 is a component used to house the electrode assembly 2. The housing 11 can be a hollow structure with an opening at one end, or it can be a hollow structure with openings at both opposite ends. The housing 11 can have various shapes, such as cylindrical or cuboid. The housing 11 can be made of various materials, such as copper, iron, aluminum, steel, or aluminum alloy. The electrode assembly 2 can be partially or completely housed within the housing 11.

[0192] End cap 12 is a component that closes the opening of housing 11 to isolate the internal environment of battery cell 10 from the external environment. End cap 12 and housing 11 together define a storage space for accommodating electrode assembly 2, electrolyte, and other components. End cap 12 can be connected to housing 11 by welding or roll sealing to close the opening of housing 11. The shape of end cap 12 can be adapted to the shape of housing 11. For example, if housing 11 is a cuboid structure, end cap 12 can be a rectangular plate structure adapted to housing 11; or if housing 11 is a cylindrical structure, end cap 12 can be a circular plate structure adapted to housing 11. The material of end cap 12 can also be various, such as copper, iron, aluminum, steel, aluminum alloy, etc. The materials of end cap 12 and housing 11 can be the same or different.

[0193] In an embodiment where the housing 11 has an opening at one end, one end cap 12 may be provided accordingly. In an embodiment where the housing 11 has openings at both opposite ends, two end caps 12 may be provided accordingly. The two end caps 12 respectively close the two openings of the housing 11, and the two end caps 12 and the housing 11 together define the receiving space.

[0194] In some embodiments, the battery cell 10 may further include electrode terminals 3, which are disposed on the housing 1 and are used for electrical connection with the tabs 21 of the electrode assembly 2 to input or output electrical energy of the battery cell 10. The electrode terminals 3 may be disposed on the housing 11 of the housing 1 or on the end cap 12 of the housing 1. The electrode terminals 3 and the tabs 21 may be directly connected, for example, by welding. Alternatively, the electrode terminals 3 and the tabs 21 may be indirectly connected, for example, through a current collector. The current collector may be a metallic conductor, such as copper, iron, aluminum, steel, or aluminum alloy.

[0195] In some embodiments, the battery cell 10 may further include a pressure relief mechanism 4, which may be disposed on the end cap 12 or the housing 11. The pressure relief mechanism 4 may be a pressure relief component installed on the housing 11 or the end cap 12, such as an explosion-proof plate or a safety valve. The pressure relief mechanism 4 may also be integrally formed with the end cap 12 or the housing 11. The pressure relief mechanism 4 may be provided with a pressure relief groove to split along the pressure relief groove when the battery cell 10 is depressurized. The pressure relief groove may be a groove extending along a closed trajectory, which may be a circular trajectory, a rectangular trajectory, etc.; the pressure relief groove may also be a groove extending along a non-closed trajectory, which may be an H-shaped trajectory, a Y-shaped trajectory, a V-shaped trajectory, a U-shaped trajectory, etc.

[0196] As an example, such as Figure 3 and Figure 4As shown, one end of the housing 11 forms an opening, and there is one end cap 12 in the housing 1, which closes one opening of the housing 11. The end cap 12 is provided with a pressure relief mechanism 4, and two electrode terminals 3 are provided on the end cap 12. The two electrode terminals 3 are a positive electrode terminal and a negative electrode terminal, respectively. The end of the electrode assembly 2 facing the end cap 12 has a positive electrode tab 21a and a negative electrode tab 21b. The positive electrode terminal is electrically connected to the positive electrode tab 21a, and the negative electrode terminal is electrically connected to the negative electrode tab 21b.

[0197] Please refer to Figures 5-7 , Figure 5 for Figure 4 A cross-sectional view of the battery cell 10 shown in Figure AA; Figure 6 for Figure 5 A magnified view of a section at point B in the middle; Figure 7 for Figure 5 The image shows an isometric view of the housing 11. This application provides a battery cell 10, which includes a housing 11, an end cap 12, and an electrode assembly 2. The housing 11 has an opening at at least one end along a first direction Z. The housing 11 includes a first wall 111, and the end cap 12 closes the opening. The first wall 111 and the end cap 12 are welded together to form a first connection portion 51. The electrode assembly 2 is at least partially housed within the housing 11. The electrode assembly 2 includes a positive electrode 22 and a negative electrode 23. At least portions of the positive electrode 22 and the negative electrode 23 are stacked along a second direction Y, which is parallel to the thickness direction of the first wall 111. The first direction Z intersects the second direction Y. The first wall 111 includes a first region 1111 and a second region 1112 arranged along the first direction Z. The thickness of the first region 1111 is greater than the thickness of the second region 1112. The first region 1111 is located between the first connection portion 51 and the second region 1112.

[0198] The shell 11 may have an opening at only one end along the first direction Z, with one end cap 12 correspondingly provided; alternatively, the shell 11 may have openings at both opposite ends along the first direction Z, with two end caps 12 correspondingly provided. The shell 11 can be of various shapes, such as cylindrical, prismatic, etc. The prism can be a triangular prism, square prism, pentagonal prism, hexagonal prism, etc., and the square prism can be a cuboid, cube, etc. The first direction Z is parallel to the orientation of the opening of the shell 11. In the embodiment where the shell 11 is cylindrical, the first direction Z can be parallel to the axial direction of the shell 11; in the embodiment where the shell 11 is prismatic, the first direction Z can be parallel to the extension direction of the side edge of the shell 11. The second direction Y is parallel to the thickness direction of the first wall 111. In the embodiment where the shell 11 is cylindrical, the first wall 111 is cylindrical, the radial direction of the shell 11 is the thickness direction of the first wall 111, and the second direction Y is parallel to the radial direction of the shell 11. In embodiments where the housing 11 is prismatic, the first wall 111 can be a rectangular plate structure. The first direction Z and the second direction Y can be set at an acute angle, a right angle, or an obtuse angle.

[0199] The end cap 12 can be welded to the housing 11, and the welding of the end cap 12 and the housing 11 forms a connecting part 5, which can extend circumferentially along the opening of the housing 11. The end cap 12 and the housing 11 are connected and fixed through the connecting part 5 to achieve a seal between the end cap 12 and the housing 11. The connecting part 5 is the part with weld marks formed after the end cap 12 and the housing 11 are welded together; the connecting part 5 can be the part where the end cap 12 and the housing 11 are welded together.

[0200] The first wall 111 in the housing 11 can be one or more. The first connecting portion 51 can correspond one-to-one with the first wall 111. The first connecting portion 51 is the part with weld marks formed after the end cap 12 is welded to the first wall 111; it can be the part where the end cap 12 and the first wall 111 are welded together. A portion of the first connecting portion 51 is formed on the end cap 12, and another portion is formed on the first wall 111. The first wall 111 and the end cap 12 can form the first connecting portion 51 by seam welding or by through welding. The first connecting portion 51 can be a part of the connecting portion 5 or the entire connecting portion 5. In an embodiment where the housing 11 is cylindrical, there is only one first wall 111 in the housing 11, and the first wall 111 is cylindrical. The first connecting part 51 is the connecting part 5. In an embodiment where the housing 11 is prismatic, the housing 11 may include multiple side walls, which are arranged along the opening of the housing 11. At least one of the two side walls arranged opposite each other in the second direction Y may be the first wall 111, and the first connecting part 51 is a part of the connecting part 5.

[0201] The first wall 111 can be the wall with the largest outer surface area in the shell 11, or it can be other than the wall with the largest outer surface area in the shell 11. Taking the shell 11 as a cuboid as an example, the shell 11 can include two first walls 111 and two second walls 112. The two first walls 111 are arranged opposite each other along the second direction Y, and the two second walls 112 are arranged opposite each other along the third direction X. The first direction Z, the second direction Y, and the third direction X are all perpendicular to each other. The first wall 111 can be the wall with the largest outer surface area in the shell 11, such that the outer surface area of ​​the first wall 111 is greater than the outer surface area of ​​the second wall 112, or the second wall 112 can be the wall with the largest outer surface area in the shell 11, such that the outer surface area of ​​the second wall 112 is greater than the outer surface area of ​​the first wall 111.

[0202] The first region 1111 can be a region where the thickness of the first wall 111 is increased, and the first region 1111 is thicker than the second region 1112. The second region 1112 can be the portion of the first wall 111 located along the first direction Z on the side of the first region 1111 opposite to the first connecting portion 51. The first region 1111 and the first connecting portion 51 can be directly connected or indirectly connected; the first region 1111 and the second region 1112 can be directly connected or indirectly connected. The first region 1111 can be a structure of equal thickness or a structure of unequal thickness; the second region 1112 can be a structure of equal thickness or a structure of unequal thickness. If at least one of the first region 1111 and the second region 1112 is a structure of unequal thickness, the maximum thickness of the second region 1112 can be less than or equal to the minimum thickness of the first region 1111, so that the thickness of the first region 1111 is greater than the thickness of the second region 1112.

[0203] The second region 1112 has a first inner surface 11121 facing the interior space of the housing 11 and a first outer surface 11122 facing away from the interior space of the housing 11. The first region 1111 may partially protrude from the first inner surface 11121 and / or the first outer surface 11122. As an example, in Figure 6 In the illustrated embodiment, a portion of the first region 1111 protrudes from the first inner surface 11121, and the outer surface of the first region 1111 is coplanar with the first outer surface 11122.

[0204] The electrode assembly 2 is located within the receiving space defined by the housing 11 and the end cap 12. The electrode assembly 2 can be a stacked structure or a wound structure. There can be one or more electrode assemblies 2 in the housing 11. If there are multiple electrode assemblies 2, they can be stacked, for example, multiple electrode assemblies 2 can be stacked along the second direction Y.

[0205] At least a portion of the positive electrode 22 and at least a portion of the negative electrode 23 are stacked along the second direction Y. During cycling, the electrode assembly 2 expands along the second direction Y. The first wall 111 deforms under the expansion force of the electrode assembly 2, which can easily cause fatigue cracking in the area of ​​the first wall 111 near the first connection portion 51. In this application, the thickness of the first region 1111 is set to be greater than the thickness of the second region 1112, and the first region 1111 is located between the first connection portion 51 and the second region 1112. This makes the thicker first region 1111 closer to the first connection portion 51 than the second region 1112. The first region 1111 provides a certain degree of reinforcement to the area of ​​the first wall 111 near the first connection portion 51, reducing the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection portion 51 due to the expansion of the electrode assembly 2, thereby improving the service life of the battery cell 10.

[0206] In some embodiments, please refer to Figures 8-11 , Figure 8 Axonometric view of electrode assembly 2 provided in some embodiments of this application; Figure 9 for Figure 8 The diagram shows the structure of electrode assembly 2. Figure 10 Axonometric view of electrode assembly 2 provided in other embodiments of this application; Figure 11 for Figure 10 The diagram shows the structure of electrode assembly 2. Electrode assembly 2 has a flat region 25, and the positive electrode 22 located in the flat region 25 and the negative electrode 23 located in the flat region 25 are stacked along the second direction Y.

[0207] The flat region 25 is the flat portion of electrode assembly 2. The portion of positive electrode 22 located in the flat region 25 is approximately flat, and the portion of negative electrode 23 located in the flat region 25 is also approximately flat. As an example, both the portions of positive electrode 22 and negative electrode 23 located in the flat region 25 are planar structures. If electrode assembly 2 is a wound structure, it is a wound electrode assembly, and a portion of electrode assembly 2 may be the flat region 25; if electrode assembly 2 is a stacked structure, it is a stacked electrode assembly, and the entire electrode assembly 2 may be the flat region 25. The second direction Y is the stacking direction of the portions of positive electrode 22 and negative electrode 23 located in the flat region 25.

[0208] As an example, the electrode assembly 2 may also include a separator 24, which is disposed between the positive electrode 22 and the negative electrode 23, and serves to separate the positive electrode 22 and the negative electrode 23. The portion of the positive electrode 22 located in the flat region 25, the portion of the negative electrode 23 located in the flat region 25, and the portion of the separator 24 located in the flat region 25 are stacked along the second direction Y.

[0209] The second direction Y is the stacking direction of the portion of the positive electrode 22 located in the flat region 25 and the portion of the negative electrode 23 located in the flat region 25. During cycling, the electrode assembly 2 expands more along the second direction Y, and the first wall 111 is more affected by the expansion of the electrode assembly 2. However, since the first region 1111 strengthens the area of ​​the first wall 111 near the first connection portion 51, the risk of fatigue cracking of the first wall 111 near the first connection portion 51 due to the expansion of the electrode assembly 2 is reduced.

[0210] In some embodiments, please continue to refer to Figures 8-11 The electrode assembly 2 includes an adjacent first surface 27 and a second surface 28. The first surface 27 is perpendicular to the second direction Y, and the area of ​​the first surface 27 is larger than the area of ​​the second surface 28. The first surface 27 and the first wall 111 are disposed opposite each other along the second direction Y.

[0211] The first surface 27 is the outer surface of the electrode assembly 2 perpendicular to the second direction Y, and the second surface 28 is the outer surface of the electrode assembly 2 adjacent to the first surface 27. The first surface 27 is disposed along the second direction Y towards the first wall 111. The first surface 27 can be a plane, and it can be the surface with the largest area on the outer surface of the electrode assembly 2, or it can be a surface that is not the surface with the largest area on the outer surface of the electrode assembly 2. The second surface 28 can be a plane, or it can be at least partially an arc surface. It should be noted that the first surface 27 is approximately perpendicular to the second direction Y, which should also be understood as the first surface 27 being perpendicular to the second direction Y.

[0212] As an example, there are two first surfaces 27 and two second surfaces 28. The two first surfaces 27 are arranged opposite each other along the second direction Y, and the two second surfaces 28 are arranged opposite each other along the third direction X. The positive electrode tab 21a and the negative electrode tab 21b protrude from the surface of the electrode assembly 2 along the first direction Z. The outermost part of the electrode assembly 2 along the second direction Y is the separator 24. The first surface 27 is formed on the separator 24. The first direction Z, the second direction Y and the third direction X are perpendicular to each other.

[0213] In this embodiment, the area of ​​the first surface 27 is larger than that of the second surface 28, resulting in a greater expansion force on the first wall 111, which is disposed opposite to the first surface 27 in the housing 11. Since the first region 1111 reinforces the area of ​​the first wall 111 near the first connection portion 51, the risk of fatigue cracking of the first wall 111 near the first connection portion 51 due to the expansion of the electrode assembly 2 is reduced.

[0214] In some embodiments, the first surface 27 is the surface with the largest area among the outer surfaces of the electrode assembly 2.

[0215] It should be noted that the first surface 27 is the largest surface among the outer surfaces of the electrode assembly 2, but this does not limit the first surface 27 in the electrode assembly 2 to only one. It can be understood that the first surface 27 of the electrode assembly 2 can be one or two.

[0216] As an example, in Figure 8 In the illustrated embodiment, the electrode assembly 2 has a wound structure and is flat. The electrode assembly 2 includes six surfaces, of which two surfaces arranged opposite each other along the second direction Y have the largest area; these two surfaces are both first surfaces 27. Figure 10 In the illustrated embodiment, the electrode assembly 2 is a stacked structure, and the electrode assembly 2 is generally cuboid in shape. The electrode assembly 2 includes six surfaces, among which the two surfaces arranged opposite each other along the second direction Y have the largest areas. These two surfaces are both first surfaces 27.

[0217] In this embodiment, the first surface 27 is the surface with the largest area among the outer surfaces of the electrode assembly 2, so that the first wall 111, which is disposed opposite to the first surface 27 in the housing 11, is subjected to the greatest expansion force. Since the first region 1111 strengthens the area of ​​the first wall 111 near the first connection portion 51, the risk of fatigue cracking of the first wall 111 near the first connection portion 51 due to the expansion of the electrode assembly 2 is reduced.

[0218] In some embodiments, please continue to refer to Figure 8 and Figure 9 The electrode assembly 2 has a wound structure and also has a corner region 26. The straight region 25 has a corner region 26 at at least one end along the third direction X. The first direction Z, the second direction Y, and the third direction X are not coplanar and intersect each other. The outer surface of the straight region 25 includes a first surface 27, and the outer surface of the corner region 26 includes a second surface 28. At least a portion of the second surface 28 is an arc surface.

[0219] The straight section 25 may have a corner section 26 at only one end along the third direction X, or it may have corner sections 26 at both opposite ends along the third direction X. The first direction Z, the second direction Y, and the third direction X are not coplanar, and any two of the first direction Z, the second direction Y, and the third direction X may be set at acute, right, or obtuse angles. The first surface 27 may be part of the outer surface of the straight section 25, and the second surface 28 may be part of the outer surface of the corner section 26. The second surface 28 may be entirely an arc surface, or only part of it may be an arc surface.

[0220] As an example, the positive electrode 22, the separator 24, and the negative electrode 23 are stacked and wound to form a wound structure. The first direction Z, the second direction Y, and the third direction X are perpendicular to each other, and the straight region 25 has corner regions 26 at both ends along the third direction X. The portions of the positive electrode 22, the negative electrode 23, and the separator 24 located in the corner regions 26 are in a bent state. The portion of the positive electrode 22 located in the corner region 26 can be at least partially arc-shaped, the portion of the negative electrode 23 located in the corner region 26 can be at least partially arc-shaped, and the portion of the separator 24 located in the corner region 26 can be at least partially arc-shaped. Along the winding direction of the electrode assembly 2, the outermost ring of the electrode assembly 2 is the separator 24. The first surface 27 and the second surface 28 are both part of the outer surface of the outermost ring of the electrode assembly 2. The first surface 27 is a plane, and the second surface 28 is an arc surface with the axis of the arc surface extending along the first direction Z. Along the second direction Y, the surfaces on both sides of the straight area 25 are both first surfaces 27; along the third direction X, the surface of one corner area 26 facing away from the other corner area 26 is a second surface 28, and the surface of the other corner area 26 facing away from one corner area 26 is another second surface 28.

[0221] For the wound electrode assembly, the flat region 25 expands more in the second direction Y. Since the first region 1111 reinforces the area of ​​the first wall 111 near the first connection 51, it can effectively reduce the risk of fatigue cracking of the first wall 111 near the first connection 51 due to the expansion of the electrode assembly 2.

[0222] In some embodiments, please continue to refer to Figure 10 and Figure 11 The electrode assembly 2 has a stacked structure. The flat region 25 includes multiple positive electrode plates 22 and multiple negative electrode plates 23. The multiple positive electrode plates 22 and multiple negative electrode plates 23 are stacked along the second direction Y. The first surface 27 is perpendicular to the second surface 28.

[0223] As an example, multiple positive electrode plates 22, multiple negative electrode plates 23, and multiple separators 24 are stacked along the second direction Y to form a laminated structure. The positive electrode plates 22 and negative electrode plates 23 are completely located in the flat region 25. Separators 24 are disposed between adjacent positive electrode plates 22 and negative electrode plates 23. The separators 24 extend beyond the two ends of the positive electrode plates 22 and the two ends of the negative electrode plates 23 along the third direction X. The extended portions of multiple separators 24 are connected to form a whole portion, and a second surface 28 is formed in this whole portion. Along the second direction Y, all positive electrode plates 22 and all negative electrode plates 23 are between the two outermost separators 24, and the outer surfaces of the two separators 24 are both first surfaces 27.

[0224] It should be noted that the fact that the first surface 27 is approximately perpendicular to the second surface 28 should also be understood as the first surface 27 being perpendicular to the second surface 28. For example, if the angle between the first surface 27 and the second surface 28 is in the range of 85° to 95°, it can be understood that the first surface 27 is perpendicular to the second surface 28.

[0225] For the wound electrode assembly, the expansion of electrode assembly 2 is greater in the stacking direction of positive electrode 22 and negative electrode 23. Since the first region 1111 strengthens the area of ​​the first wall 111 near the first connection portion 51, the risk of fatigue cracking of the first wall 111 near the first connection portion 51 due to the expansion of electrode assembly 2 can be effectively reduced.

[0226] In some embodiments, please continue to refer to Figure 7 The first wall 111 is the wall with the largest outer surface area in the shell 11.

[0227] It should be noted that the first wall 111 is the wall with the largest outer surface area in the shell 11, but this does not limit the first wall 111 in the shell 11 to only one. It can be understood that there can be one or two walls with the largest outer surface area in the shell 11.

[0228] The wall with the largest outer surface area in the housing 11 is more prone to deformation after being subjected to the expansion force of the electrode assembly 2. Since the first wall 111 is the wall with the largest outer surface area in the housing 11, the risk of fatigue cracking of the wall with the largest outer surface area in the housing 11 near the first connection 51 due to the expansion of the electrode assembly 2 is reduced.

[0229] In some embodiments, the housing 11 includes two first walls 111 arranged opposite to each other along a second direction Y, and the electrode assembly 2 ( Figure 5 (As shown in the image) It is located between the two first walls 111.

[0230] As an example, in Figure 7 In the illustrated embodiment, the housing 11 is cuboid in shape and may include two first walls 111 and two second walls 112. The two first walls 111 are arranged opposite each other along a second direction Y, and the two second walls 112 are arranged opposite each other along a third direction X. The outer surface area of ​​the first walls 111 is larger than the outer surface area of ​​the second walls 112. The first direction Z is parallel to the height direction of the housing 11, the second direction Y is parallel to the width direction of the housing 11, and the third direction X is parallel to the length direction of the housing 11.

[0231] In this embodiment, the housing 11 includes two first walls 111, which reduces the risk of fatigue cracking of the two first walls 111 near the first connection portion 51 due to the expansion of the electrode assembly 2.

[0232] In some embodiments, please refer to Figure 12 , Figure 12 for Figure 6 A partial view of the first wall 111 shown. The first region 1111 includes a first part 11111 and a second part 11112 arranged along a first direction Z. The second part 11112 connects the first part 11111 and the second region 1112. The thickness of the first part 11111 is greater than the thickness of the second part 11112.

[0233] The first part 11111, the second part 11112, and the second region 1112 are arranged sequentially along the first direction Z, with the first part 11111 transitioning to the second region 1112 via the second part 11112. The first part 11111 can be a structure of equal thickness or a structure of non-equal thickness; the second part 11112 can also be a structure of equal thickness or a structure of non-equal thickness. If at least one of the first part 11111 and the second part 11112 is a structure of non-equal thickness, the maximum thickness of the second part 11112 can be less than or equal to the minimum thickness of the first part 11111, so that the thickness of the first part 11111 is greater than the thickness of the second part 11112.

[0234] The first part 11111 may protrude from the first inner surface 11121 and / or the first outer surface 11122, and the second part 11112 may also protrude from the first inner surface 11121 and / or the first outer surface 11122.

[0235] The area of ​​the first region 1111 near the first connecting portion 51 is more prone to heat-affected zone formation, which is more susceptible to fatigue cracking. However, since the second portion 11112 connects the first portion 11111 and the second region 1112, and the thickness of the first portion 11111 is greater than the thickness of the second portion 11112, the thicker first portion 11111 in the first region 1111 is closer to the first connecting portion 51. This effectively weakens the impact of the heat-affected zone on the first region 1111, reducing the risk of fatigue cracking in the area of ​​the first wall 111 near the first connecting portion 51. Furthermore, since the thickness of the second portion 11112 is less than the thickness of the first portion 11111, the material used in the first region 1111 can be reduced, lowering production costs.

[0236] In some embodiments, the thickness of the second portion 11112 extends along the end cap 12 ( Figure 12 Pointing electrode assembly 2 (not shown) Figure 12 (Not shown) The direction shows a decreasing trend.

[0237] The direction in which the end cap 12 points to the electrode assembly 2 is consistent with the direction in which the first part 11111 points to the second region 1112 along the first direction Z.

[0238] It is understood that the second part 11112 is a non-uniform thickness structure. As an example, the thickness of the second part 11112 gradually decreases along the direction from the end cap 12 toward the electrode assembly 2. At least one of the inner and outer surfaces of the second part 11112 may be a slope to achieve the gradual decrease in thickness of the second part 11112 along the direction from the end cap 12 toward the electrode assembly 2.

[0239] As an example, in Figure 12 In the illustrated embodiment, both the first portion 11111 and the second region 1112 are of equal thickness. The inner and outer surfaces of the first portion 11111 are parallel, and the first inner surface 11121 and the first outer surface 11122 of the second region 1112 are parallel. The outer surface of the second portion 11112, the outer surface of the first portion 11111, and the first outer surface 11122 are coplanar. A portion of the first portion 11111 and a portion of the second portion 11112 both protrude from the first inner surface 11121. The inner surface of the second portion 11112 connects the first inner surface 11121 and the inner surface of the first portion 11111.

[0240] In this embodiment, the thickness of the second part 11112 decreases along the direction from the end cap 12 toward the electrode assembly 2. On the one hand, this reduces the impact of the second part 11112 on the electrode assembly 2 and lowers the risk of interference between the second part 11112 and the electrode assembly 2. On the other hand, it increases the reinforcing effect of the second part 11112 along the direction from the electrode assembly 2 toward the end cap 12, so that the area of ​​the second part 11112 near the first part 11111 has a good reinforcing effect even if it is affected by the first connecting part 51, reducing the risk of fatigue cracking of the first wall 111 in the second part 11112. Furthermore, the second part 11112 can realize the transition between the first part 11111 and the second region 1112, reducing stress concentration.

[0241] In some embodiments, please refer to Figure 13 and Figure 14 , Figure 13 Axonometric view of housing 11 provided for some embodiments of this application; Figure 14 for Figure 13 The top view of the housing 11 shown. The dimension of the first region 1111 along the third direction X is greater than the dimension of the first region 1111 along the first direction Z. The first direction Z, the second direction Y and the third direction X are not coplanar and intersect each other.

[0242] The dimension of the first region 1111 along the third direction X is the length of the first region 1111, and the dimension of the first region 1111 along the first direction Z is the width of the first region 1111. The length of the first region 1111 is greater than the width of the first region 1111, making the first region 1111 a long strip structure extending along the third direction X.

[0243] As an example, the housing 11 is cuboid in shape and includes two first walls 111 and two second walls 112. The two first walls 111 are arranged opposite each other along the second direction Y, and the two second walls 112 are arranged opposite each other along the third direction X. The first direction Z, the second direction Y and the third direction X are perpendicular to each other. The first direction Z is parallel to the height direction of the housing 11, the second direction Y is parallel to the width direction of the housing 11, and the third direction X is parallel to the length direction of the housing 11.

[0244] In this embodiment, the size of the first region 1111 along the third direction X is larger than the size of the first region 1111 along the first direction Z, making the size of the first region 1111 along the third direction X larger. This strengthens the first wall 111 by having more areas along the third direction X, further reducing the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection portion 51.

[0245] In some embodiments, the first region 1111 includes a first connecting segment 11113, which passes through the middle section of the first wall 111. The middle section is perpendicular to the third direction X, and the distance from the middle section to both ends of the first wall 111 along the third direction X is equal.

[0246] The first connecting segment 11113 can be a part of the first region 1111, or the first connecting segment 11113 can be the same as the first region 1111. The first connecting segment 11113 can be a structure of uniform thickness or a structure of non-uniform thickness. The first connecting segment 11113 has two opposite ends along the third direction X. The first connecting segment 11113 passes through the mid-section of the first wall 111, such that the mid-section of the first wall 111 is located between the two opposite ends of the first connecting segment 11113 along the third direction X. The distances from the two opposite ends of the first connecting segment 11113 along the third direction X to the mid-section can be equal or unequal. If the distances from the two opposite ends of the first connecting segment 11113 along the third direction X to the mid-section of the first wall 111 are equal, the first connecting segment 11113 can be a symmetrical structure symmetrically arranged about the mid-section of the first wall 111. It should be noted that the mid-section of the first wall 111 is a virtual plane and is not shown in the figure.

[0247] As an example, in Figure 13 and Figure 14 In the illustrated embodiment, the first connecting segment 11113 is the first region 1111. The first connecting segment 11113 has a uniform thickness structure. The distances from the two opposite ends of the first connecting segment 11113 along the third direction X to the mid-section of the first wall 111 are equal.

[0248] Taking the shell 11 as a cuboid as an example, the distance from the mid-section of the first wall 111 to both ends of the first wall 111 along the third direction X is equal, that is, the distance from the mid-section of the first wall 111 to the two second walls 112 that are arranged opposite each other along the third direction X of the shell 11 is equal.

[0249] It should be noted that, along the third direction X, the distance from the mid-section of the first wall 111 to both ends of the first wall 111 is approximately equal, which should also be understood as the distance from the mid-section to both ends of the first wall 111 being equal.

[0250] When the first wall 111 is subjected to the expansion force of the electrode assembly 2 of the battery cell 10, the deformation of the middle region of the first wall 111 along the third direction X is greater, and the middle region of the first wall 111 along the third direction X is more prone to fatigue cracking. Since the first connecting segment 11113 of the first region 1111 passes through the middle section of the first wall 111, the strength of the first wall 111 is strengthened at least in the middle region along the third direction X, reducing the risk of fatigue cracking of the middle region of the first wall 111 along the third direction X near the first connecting part 51.

[0251] In some embodiments, Figure 15 Axonometric view of housing 11 provided for other embodiments of this application; Figure 16 for Figure 15 The top view of the housing 11 is shown. The first region 1111 also includes a second connecting segment 11114 and a third connecting segment 11115. The second connecting segment 11114, the first connecting segment 11113, and the third connecting segment 11115 are arranged along a third direction X. The first connecting segment 11113 connects the second connecting segment 11114 and the third connecting segment 11115. The thickness of the first connecting segment 11113 is greater than the thickness of the second connecting segment 11114 and the thickness of the third connecting segment 11115.

[0252] The first connecting segment 11113 is a section passing through the mid-section of the first wall 111 in the first region 1111. The second connecting segment 11114 and the third connecting segment 11115 are two segments of the first region 1111 located at two ends along the third direction X, respectively. The second connecting segment 11114 can be directly connected to the first connecting segment 11113 or indirectly connected to it. The third connecting segment 11115 can also be directly connected to the first connecting segment 11113 or indirectly connected to it.

[0253] The first connecting segment 11113 can be of uniform thickness or non-uniform thickness; the second connecting segment 11114 can be of uniform thickness or non-uniform thickness; the third connecting segment 11115 can be of uniform thickness or non-uniform thickness. If at least one of the first connecting segment 11113 and the second connecting segment 11114 is of non-uniform thickness, the maximum thickness of the second connecting segment 11114 can be less than or equal to the minimum thickness of the first connecting segment 11113, so that the thickness of the first connecting segment 11113 is greater than the thickness of the second connecting segment 11114. If at least one of the third connecting segment 11115 and the first connecting segment 11113 is of non-uniform thickness, the maximum thickness of the third connecting segment 11115 can be less than or equal to the minimum thickness of the first connecting segment 11113, so that the thickness of the first connecting segment 11113 is greater than the thickness of the third connecting segment 11115.

[0254] The dimensions of the second connecting segment 11114 along the third direction X and the dimensions of the third connecting segment 11115 along the third direction X can be equal or unequal. If the dimensions of the second connecting segment 11114 along the third direction X and the dimensions of the third connecting segment 11115 along the third direction X are equal, the second connecting segment 11114 and the third connecting segment 11115 can be symmetrically arranged about the midsection of the first wall 111.

[0255] It is understood that in embodiments where the first region 1111 includes a first part 11111 and a second part 11112, at least one of the first connecting segment 11113, the second connecting segment 11114, and the third connecting segment 11115 may include the first part 11111 and the second part 11112 arranged along the first direction Z.

[0256] The second connecting segment 11114 may partially protrude from the first inner surface 11121. Figure 15 and Figure 16 (not shown) and / or the first outer surface 11122 ( Figure 15 and Figure 16 (Not shown), the first connecting segment 11113 may partially protrude from the first inner surface 11121 and / or the first outer surface 11122, and the third connecting segment 11115 may partially protrude from the first inner surface 11121 and / or the first outer surface 11122.

[0257] As an example, in Figure 16In the illustrated embodiment, both the second connecting segment 11114 and the third connecting segment 11115 are directly connected to the first connecting segment 11113. The thickness of the second connecting segment 11114 gradually decreases along the direction from the third connecting segment 11115 to the second connecting segment 11114, and the thickness of the third connecting segment 11115 gradually decreases along the direction from the second connecting segment 11114 to the third connecting segment 11115. A portion of the second connecting segment 11114, a portion of the first connecting segment 11113, and a portion of the third connecting segment 11115 all protrude from the first inner surface 11121 of the second region 1112. The inner surface of the second connecting segment 11114 is connected to the inner surface of the first connecting segment 11113 and the first inner surface 11121, and the inner surface of the third connecting segment 11115 is connected to the inner surface of the first connecting segment 11113 and the first inner surface 11121. The outer surfaces of the second connecting segment 11114, the first connecting segment 11113, and the third connecting segment 11115 are coplanar.

[0258] When the first wall 111 is subjected to the expansion force of the electrode assembly 2, the deformation of the first wall 111 gradually decreases from the middle to both ends along the third direction X. By dividing the first region 1111 into multiple segments, and setting the thickness of the first connecting segment 11113 located in the middle region to be larger, and setting the thickness of the second connecting segment 11114 and the third connecting segment 11115 located at both ends of the first connecting segment 11113 to be smaller, the first region 1111 is designed specifically according to the different deformation amounts of the first wall 111 in different regions along the third direction X. This specifically improves the strength of the first wall 111 in different regions along the third direction X, ensuring sufficient strength in the region of the first wall 111 near the first connecting part 51 while reducing the material used in the first region 1111 and lowering production costs.

[0259] In some embodiments, please refer to Figure 17 and Figure 18 , Figure 17 Axonometric view of housing 11 provided for some embodiments of this application; Figure 18 for Figure 17The diagram shows a top view of the housing 11. The first region 1111 further includes a first transition segment 11116, a first connecting segment 11113, a first transition segment 11116, and a second connecting segment 11114 arranged along a third direction X. The first transition segment 11116 connects the second connecting segment 11114 and the first connecting segment 11113. The thickness of the first transition segment 11116 increases in the direction from the second connecting segment 11114 to the first connecting segment 11113. And / or, the first region 1111 further includes a second transition segment 11117, a first connecting segment 11113, a second transition segment 11117, and a third connecting segment 11115 arranged along a third direction X. The second transition segment 11117 connects the third connecting segment 11115 and the first connecting segment 11113. The thickness of the second transition segment 11117 increases in the direction from the third connecting segment 11115 to the first connecting segment 11113.

[0260] The first transition segment 11116 has a non-uniform thickness structure. As an example, the thickness of the first transition segment 11116 gradually increases along the direction from the second connecting segment 11114 to the first connecting segment 11113. The second transition segment 11117 also has a non-uniform thickness structure. As an example, the thickness of the second transition segment 11117 gradually increases along the direction from the third connecting segment 11115 to the first connecting segment 11113.

[0261] If a first transition section 11116 is provided between the second connecting section 11114 and the first connecting section 11113, and a second transition section 11117 is provided between the third connecting section 11115 and the first connecting section 11113, the dimensions of the first transition section 11116 along the third direction X and the dimensions of the second transition section 11117 along the third direction X can be equal or unequal. If the dimensions of the first transition section 11116 along the third direction X and the dimensions of the second transition section 11117 along the third direction X are equal, the first transition section 11116 and the second transition section 11117 can be symmetrically arranged about the midsection of the first wall 111.

[0262] It is understandable that if a first transition section 11116 is provided between the second connecting section 11114 and the first connecting section 11113, the first transition section 11116 may partially protrude from the first inner surface 11121 of the second region 1112. Figure 17 and Figure 18 (not shown) and / or the first outer surface 11122 ( Figure 17 and Figure 18 (Not shown); If a second transition section 11117 is provided between the third connecting section 11115 and the first connecting section 11113, the second transition section 11117 may partially protrude from the first inner surface 11121 and / or the first outer surface 11122 of the second region 1112.

[0263] As an example, in Figure 18 In the illustrated embodiment, the second connecting segment 11114 is indirectly connected to the first connecting segment 11113 via a first transition segment 11116, and the third connecting segment 11115 is indirectly connected to the first connecting segment 11113 via a second transition segment 11117. The thickness of the first transition segment 11116 gradually increases along the direction from the second connecting segment 11114 to the first connecting segment 11113, and the thickness of the second transition segment 11117 gradually increases along the direction from the third connecting segment 11115 to the first connecting segment 11113. A portion of the second connecting segment 11114, a portion of the first connecting segment 11113, a portion of the third connecting segment 11115, a portion of the first transition segment 11116, and a portion of the second transition segment 11117 all protrude from the first inner surface 11121. The inner surface of the first transition segment 11116 is connected to the inner surface of the first connecting segment 11113 and the inner surface of the second connecting segment 11114. The inner surface of the second transition segment 11117 is connected to the inner surface of the first connecting segment 11113 and the inner surface of the third connecting segment 11115. The outer surfaces of the second connecting segment 11114, the first connecting segment 11113, the third connecting segment 11115, the first transition segment 11116, and the second transition segment 11117 are coplanar.

[0264] In this embodiment, if the second connecting segment 11114 and the first connecting segment 11113 are connected by a first transition segment 11116, and the thickness of the first transition segment 11116 increases along the direction from the second connecting segment 11114 to the first connecting segment 11113, the first transition segment 11116 can achieve a transition between the second connecting segment 11114 and the first connecting segment 11113, reducing stress concentration. If the third connecting segment 11115 and the first connecting segment 11113 are connected by a second transition segment 11117, and the thickness of the second transition segment 11117 increases along the direction from the third connecting segment 11115 to the first connecting segment 11113, the second transition segment 11117 can achieve a transition between the third connecting segment 11115 and the first connecting segment 11113, reducing stress concentration.

[0265] In some embodiments, please continue to refer to Figure 14 , Figure 16 and Figure 18 The dimension of the first connecting segment 11113 along the third direction X is L1, and the dimension of the first wall 111 along the third direction X is L, 0.2≤L1 / L≤0.6.

[0266] The dimension of the first connecting segment 11113 along the third direction X is the length of the first connecting segment 11113, the dimension of the first wall 111 along the third direction X is the length of the first wall 111, the dimension of the first wall 111 along the second direction Y is the thickness of the first wall 111, and the dimension of the first wall 111 along the first direction Z is the width of the first wall 111.

[0267] L1 / L can take any one of the following point values ​​or a range between any two: 0.2, 0.22, 0.25, 0.28, 0.3, 0.32, 0.35, 0.38, 0.4, 0.42, 0.45, 0.48, 0.5, 0.52, 0.55, 0.58, 0.6.

[0268] A ratio of L1 / L ≥ 0.2 increases the proportion of the first connecting segment 11113 in the third-direction X of the first wall 111, thus strengthening the central region of the first wall 111 in the third-direction X and increasing its strength. A ratio of L1 / L ≤ 0.6 decreases the proportion of the first connecting segment 11113 in the third-direction X of the first wall 111, reducing material usage and production costs. Therefore, setting the ratio of the dimension of the first connecting segment 11113 in the third-direction X to the dimension of the first wall 111 in the third-direction X to 0.2–0.6 ensures sufficient reinforcement while reducing material usage, balancing both reinforcement requirements and economic efficiency.

[0269] In some embodiments, please continue to refer to Figure 14 , Figure 16 and Figure 18 The first connecting segment 11113 has a first end 11113a and a second end 11113b along the third direction X. The first wall 111 has a third end 1113 and a fourth end 1114 along the third direction X. The first end 11113a is close to the third end 1113, and the second end 11113b is close to the fourth end 1114. The dimension of the first wall 111 along the third direction X is L. The minimum distance between the first end 11113a and the third end 1113 along the third direction X is L2, and the minimum distance between the second end 11113b and the fourth end 1114 along the third direction X is L3. L2 / L≤0.3; and / or, L3 / L≤0.3.

[0270] It is understandable that, along the third direction X, the first end 11113a is closer to the third end 1113 than the second end 11113b, and the second end 11113b is closer to the fourth end 1114 than the first end 11113a.

[0271] It can be L2 = L3; or it can be L2 > L3 or L2 < L3.

[0272] L2 / L can take any one of the following values ​​or a range between any two: 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3.

[0273] L3 / L can take any one of the following values ​​or a range between any two: 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3.

[0274] If L2 / L≤0.3, the proportion of the minimum distance between the first end 11113a and the third end 1113 along the third direction X in the dimension of the first wall 111 along the third direction X is reduced, thus strengthening more areas of the first wall 111 along the third direction X, further reducing the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection 51. If L3 / L≤0.3, the proportion of the minimum distance between the second end 11113b and the fourth end 1114 along the third direction X in the dimension of the first wall 111 along the third direction X is reduced, thus strengthening more areas of the first wall 111 along the third direction X, further reducing the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection 51.

[0275] In some embodiments, 100mm ≤ L ≤ 450mm.

[0276] L can be any one of the following values ​​or a range between any two: 100mm, 120mm, 150mm, 180mm, 200mm, 220mm, 250mm, 260mm, 280mm, 300mm, 310mm, 320mm, 350mm, 390mm, 400mm, 410mm, 420mm, 430mm, 440mm, 450mm.

[0277] In some embodiments, please continue to refer to Figures 13-18The housing 11 includes corner walls 113, and the first wall 111 is connected to the corner walls 113 at both ends along the third direction X; at least one end of the first region 1111 along the third direction X does not contact the corner walls 113; or, the first region 1111 extends to the two corner walls 113 at both ends along the third direction X.

[0278] Along the third direction X, the first region 1111 has two opposite ends. One end of the first region 1111 may extend to a corner wall 113 while the other end does not extend to another corner wall 113. Alternatively, neither end of the first region 1111 may extend to a corner wall 113, so that at least one end of the first region 1111 along the third direction X does not contact the corner wall 113.

[0279] As an example, in Figures 13-18 In the illustrated embodiment, along the third direction X, one end of the first region 1111 does not contact the corner wall 113 at one end of the first wall 111, and the other end of the first region 1111 does not contact the corner wall 113 at the other end of the first wall 111.

[0280] If at least one end of the first zone 1111 along the third direction X does not contact the corner wall 113, the material used in the first zone 1111 can be reduced, thus lowering production costs. If the first zone 1111 extends to both corner walls 113 along the third direction X, the length of the first zone 1111 is increased, improving its reinforcing capacity. This allows more areas of the first wall 111 along the third direction X to be reinforced, further reducing the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection portion 51.

[0281] In some embodiments, please refer to Figures 19-21 , Figure 19 A partial view of a battery cell 10 provided for some embodiments of this application (showing the positive electrode 22, negative electrode 23, and separator 24 of the electrode assembly 2); Figure 20The figure shows the positional relationship of the positive electrode 22, negative electrode 23, and separator 24 provided in some embodiments of this application; the figure also shows the positional relationship of the positive electrode 22, negative electrode 23, and separator 24 provided in other embodiments of this application. The electrode assembly 2 further includes a separator 24, which is disposed between the positive electrode 22 and the negative electrode 23. The positive electrode 22 includes a positive electrode body region 221 and a positive electrode tab 21a protruding from the positive electrode body region 221, and the positive electrode body region 221 has a positive electrode active material layer 223. The negative electrode 23 includes a negative electrode body region 231 and a negative electrode tab 21b protruding from the negative electrode body region 231, and the negative electrode body region 231 has a negative electrode active material layer 233. Along the first direction Z, the positive electrode main body region 221 has a fifth end 2211 facing the end cap 12, the negative electrode main body region 231 has a sixth end 2311 facing the end cap 12, and the separator 24 has a seventh end 241 facing the end cap 12. The seventh end 241 is closer to the end cap 12 than the fifth end 2211 and the sixth end 2311.

[0282] In this embodiment, the electrode assembly 2 can be a wound structure or a stacked structure.

[0283] The positive electrode 22 may include a positive current collector 222 and a positive active material layer 223, wherein the positive current collector 222 has the positive active material layer 223 disposed on one or both surfaces in its thickness direction. Figure 20 In the illustrated embodiment, the positive electrode 22 further includes an insulating layer 224. The positive current collector 222 has insulating layers 224 on both opposite surfaces in the thickness direction. The insulating layer 224 and the positive active material layer 223 are arranged along the first direction Z. The insulating layer 224 is located at the end of the positive active material layer 223. The portion of the positive electrode 22 that corresponds to the positive active material layer 223 and the insulating layer 224 as a whole is the positive electrode body region 221. The end of the insulating layer 224 near the end cap 12 forms the fifth end 2211 of the positive electrode body region 221. The portion of the positive current collector 222 extending beyond the insulating layer 224 forms a positive electrode tab 21a. Figure 21 In the illustrated embodiment, the positive electrode 22 does not have an insulating layer 224. The portion of the positive electrode 22 corresponding to the positive active material layer 223 is the positive electrode body region 221. The end of the positive active material layer 223 near the end cap 12 forms the fifth end 2211 of the positive electrode body region 221. The portion of the positive current collector 222 that extends beyond the positive active material layer 223 forms the positive electrode tab 21a.

[0284] The negative electrode sheet 23 may include a negative electrode current collector 232 and a negative electrode active material layer 233. The negative electrode current collector 232 has the negative electrode active material layer 233 disposed on one or both surfaces in its thickness direction. The portion of the negative electrode sheet 23 corresponding to the negative electrode active material layer 233 is the negative electrode main body region 231. The end of the negative electrode active material layer 233 near the end cap 12 forms the sixth end 2311 of the negative electrode main body region 231. The portion of the negative electrode current collector 232 that extends beyond the negative electrode active material layer 233 forms the negative electrode tab 21b.

[0285] The fifth end 2211 and the sixth end 2311 can be flush; for example Figure 20 As shown, the fifth end 2211 can also be closer to the end cap 12 than the sixth end 2311. Figure 19 (as shown in the image); Figure 21 As shown, the sixth end 2311 can also be closer to the end cap 12 than the fifth end 2211. Figure 19 (as shown in the image).

[0286] In this embodiment, the seventh end 241 of the isolator 24 is closer to the end cap 12 than the fifth end 2211 of the positive electrode main body region 221 and the sixth end 2311 of the negative electrode main body region 231, so that the isolator 24 has a portion that extends beyond the fifth end 2211 and the sixth end 2311, which enhances the insulation effect of the isolator 24 between the positive electrode plate 22 and the negative electrode plate 23 and reduces the risk of overlap between the positive electrode plate 22 and the negative electrode plate 23.

[0287] In some embodiments, please continue to refer to Figures 19-21 The isolation member 24 includes an extension region 242 extending beyond the fifth end 2211 and the sixth end 2311 along the first direction Z. In a projection plane perpendicular to the second direction Y, the orthographic projection of the extension region 242 partially overlaps with the orthographic projection of the first region 1111.

[0288] The portion extending beyond region 242 is the part of the isolation element 24 that extends beyond both the fifth end 2211 of the positive electrode main body region 221 and the sixth end 2311 of the negative electrode main body region 231. It is understandable that, as... Figure 20 As shown, in the embodiment where the fifth end 2211 is closer to the end cap 12 than the sixth end 2311, the portion of the spacer 24 extending beyond the fifth end 2211 is the extended area 242; as Figure 21 As shown, in an embodiment where the sixth end 2311 is closer to the end cap 12 than the fifth end 2211, the portion of the spacer 24 that extends beyond the sixth end 2311 is the extended area 242.

[0289] As an example, in Figures 19-21 In the electrode assembly 2, the positive electrode 22, the negative electrode 23, and the separator 24 are located in the flat region 25. Figures 19-21 (Not shown) portions are stacked along the second direction Y.

[0290] In this embodiment, in the projection plane perpendicular to the second direction Y, the orthographic projection of the region 242 overlaps with the orthographic projection of the first region 1111. This structure can increase the size of the first region 1111 along the first direction Z, improve the reinforcement capability of the first region 1111, and strengthen more areas of the first wall 111 along the first direction Z, further reducing the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection 51.

[0291] In some embodiments, please continue to refer to Figures 19-21 The second region 1112 has a first inner surface 11121 facing the interior space of the housing 11, and the first region 1111 includes a first protrusion 11118 protruding from the first inner surface 11121. In a projection plane perpendicular to the second direction Y, the orthographic projection of the positive electrode main body region 221 does not overlap with the orthographic projection of the first protrusion 11118; and / or, in a projection plane perpendicular to the second direction Y, the orthographic projection of the negative electrode main body region 231 does not overlap with the orthographic projection of the first protrusion 11118.

[0292] The first protrusion 11118 is the portion of the first region 1111 that protrudes from the first inner surface 11121 of the second region 1112. The first protrusion 11118 can be a structure of uniform thickness or a structure of non-uniform thickness. Along the first direction Z, the first protrusion 11118 can extend to the first connecting portion 51, so that the first protrusion 11118 is directly connected to the first connecting portion 51.

[0293] It is understood that in embodiments where the first region 1111 includes a first portion 11111 and a second portion 11112 arranged along a first direction Z, a portion of the first protrusion 11118 may be located in the first portion 11111, and another portion may be located in the second portion 11112. In embodiments where the first region 1111 includes a first connecting segment 11113, a second connecting segment 11114, and a third connecting segment 11115 arranged along a third direction X, a portion of the first protrusion 11118 may be located in the first connecting segment 11113, another portion of the first protrusion 11118 may be located in the second connecting segment 11114, and yet another portion of the first protrusion 11118 may be located in the third connecting segment 11115.

[0294] As an example, in Figures 19-21 In the embodiment, in the projection plane perpendicular to the second direction Y, the positive electrode main body region 221 and the orthogonal projection of the first protrusion 11118 do not overlap, and the negative electrode main body region 231 and the orthogonal projection of the first protrusion 11118 do not overlap.

[0295] If the orthographic projection of the positive electrode main body region 221 and the orthographic projection of the first protrusion 11118 do not overlap in the projection plane perpendicular to the second direction Y, the housing 11 can provide a larger expansion space for the electrode assembly 2, reducing the risk that the expansion of the electrode assembly 2 will directly exert an expansion force on the first protrusion 11118, reducing the deformation of the first wall 111, and further reducing the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection 51. Similarly, if the orthographic projection of the negative electrode main body region 231 and the orthographic projection of the first protrusion 11118 do not overlap in the projection plane perpendicular to the second direction Y, the housing 11 can provide a larger expansion space for the electrode assembly 2, reducing the risk that the expansion of the electrode assembly 2 will directly exert an expansion force on the first protrusion 11118, reducing the deformation of the first wall 111, and further reducing the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection 51.

[0296] In some embodiments, please continue to refer to Figures 19-21 The negative electrode 23 includes a negative current collector 232 and a negative active material layer 233 disposed on at least one side of the negative current collector 232, the negative active material layer 233 including a negative active material.

[0297] The negative electrode current collector 232 may have a negative electrode active material layer 233 on only one side, that is, the negative electrode current collector 232 may have a negative electrode active material layer 233 on only one surface along the thickness direction; or the negative electrode current collector 232 may have a negative electrode active material layer 233 on both opposite sides, that is, the negative electrode current collector 232 may have a negative electrode active material layer 233 on both opposite surfaces along the thickness direction.

[0298] The negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc.

[0299] In some embodiments, the negative electrode active material layer 233 includes a negative electrode main body 2331 and a negative electrode thinning part 2332. The negative electrode main body 2331 and the negative electrode thinning part 2332 are arranged along a first direction Z. Along the first direction Z, the negative electrode main body 2331 is provided with a negative electrode thinning part 2332 at one end near the end cap 12.

[0300] The thickness of the negative electrode main body 2331 is greater than the thickness of the negative electrode thinning portion 2332. The negative electrode thinning portion 2332 may be provided only at one end of the negative electrode main body 2331 along the first direction Z, near the end cap 12, or it may be provided at both ends of the negative electrode main body 2331 along the first direction Z. The negative electrode main body 2331 may be of uniform thickness or non-uniform thickness, and the negative electrode thinning portion 2332 may also be of uniform thickness or non-uniform thickness. If at least one of the negative electrode main body 2331 and the negative electrode thinning portion 2332 is of non-uniform thickness, the maximum thickness of the negative electrode thinning portion 2332 may be less than or equal to the minimum thickness of the negative electrode main body 2331, thereby achieving a thickness greater than that of the negative electrode main body 2331.

[0301] As an example, the negative electrode main body 2331 has a uniform thickness structure, and the thickness of the negative electrode thinning part 2332 decreases along the direction from the negative electrode main body 2331 to the negative electrode thinning part 2332.

[0302] In this embodiment, a negative electrode thinning portion 2332 is provided at one end of the negative electrode main body 2331 near the end cap 12. The electrode assembly 2 has a larger expansion gap in the area corresponding to the negative electrode thinning portion 2332. After expansion, the area of ​​the electrode assembly 2 corresponding to the negative electrode thinning portion 2332 exerts less force on the first wall 111, which can reduce the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection portion 51.

[0303] In some embodiments, in a projection plane perpendicular to the second direction Y, the orthographic projection of the negative electrode thinning portion 2332 located at one end of the negative electrode main body portion 2331 near the end cap 12 and the orthographic projection of the first region 1111 are spaced apart along the first direction Z.

[0304] It is understandable that, in the projection plane perpendicular to the second direction Y, the orthographic projection of the negative electrode thinning portion 2332 located at the end of the negative electrode main body portion 2331 near the end cap 12 does not overlap with the orthographic projection of the first region 1111.

[0305] In this embodiment, in the projection plane perpendicular to the second direction Y, the orthographic projection of the negative electrode thinning portion 2332 located at the end of the negative electrode main body 2331 near the end cap 12 and the orthographic projection of the first region 1111 are spaced apart along the first direction Z. This can reduce the influence of the negative electrode thinning portion 2332 on the first region 1111, reduce the risk that the expansion of the electrode assembly 2 will directly apply expansion force to the first region 1111, and further reduce the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection portion 51.

[0306] In some embodiments, in a projection plane perpendicular to the second direction Y, the orthographic projection of the negative electrode thinning portion 2332 located at one end of the negative electrode main body portion 2331 near the end cap 12 and the orthographic projection of the first region 1111 are spaced apart along the first direction Z by a dimension greater than or equal to 1 mm.

[0307] In a projection plane perpendicular to the second direction Y, the distance between the orthographic projection of the negative electrode thinning portion 2332 located at the end of the negative electrode main body 2331 near the end cap 12 and the orthographic projection of the first region 1111 along the first direction Z is W1, where W1 ≥ 1 mm. This distance is the minimum distance between the orthographic projections of the negative electrode thinning portion 2332 and the first region 1111 along the first direction Z in a projection plane perpendicular to the second direction Y. W1 can be any point value or a range between any two of the following: 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm.

[0308] In this embodiment, W1≥1mm makes the orthographic projection of the negative electrode thinning portion 2332 and the orthographic projection of the first region 1111 further apart along the first direction Z in the projection plane perpendicular to the second direction Y, thereby further reducing the influence of the negative electrode thinning portion 2332 on the first region 1111.

[0309] In some embodiments, the single-sided coating weight of the negative electrode active material layer 233 is 90 mg / 1540 mm. 2 ~170mg / 1540mm 2 .

[0310] The single-sided coating weight of the negative electrode active material layer 233 can be 90 mg / 1540 mm. 2 100mg / 1540mm 2 110mg / 1540mm 2 120mg / 1540mm 2 130mg / 1540mm 2 140mg / 1540mm 2 150mg / 1540mm 2 160mg / 1540mm 2 170mg / 1540mm 2 The value of any one of them or the range between any two.

[0311] When measuring the single-sided coating weight of the negative electrode active material layer 233, a single-sided coated negative electrode sheet 23 (if it is a double-sided coated negative electrode sheet 23, the negative electrode active material layer 233 on one side can be wiped off first), is cut into a small circular piece with an area of ​​S1, and its weight is recorded as M1. Then, the negative electrode active material layer 233 of the weighed negative electrode sheet 23 is wiped off, and the weight of the negative electrode current collector 232 is measured and recorded as M2. The single-sided coating weight of the negative electrode active material layer 233 = (M1-M2) / S1.

[0312] The single-sided coating weight of the negative electrode active material layer 233 is related to the expansion of the negative electrode active material layer 233. The single-sided coating weight of the negative electrode active material layer 233 is set at 90 mg / 1540 mm². 2 ~170mg / 1540mm 2 It can, to a certain extent, balance the high energy density requirements of the battery cell 10 and the low expansion requirements of the negative electrode 23, so as to reduce the impact of the expansion of the negative electrode 23 on the first wall 111 and reduce the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection 51.

[0313] In some embodiments, the single-sided coating weight of the negative electrode active material layer 233 is 110 mg / 1540 mm. 2 ~150mg / 1540mm 2 .

[0314] In this embodiment, the single-sided coating weight of the negative electrode active material layer 233 can be 110 mg / 1540 mm. 2 115mg / 1540mm 2 120mg / 1540mm 2 125mg / 1540mm 2 130mg / 1540mm 2 135mg / 1540mm 2 140mg / 1540mm 2 145mg / 1540mm 2 150mg / 1540mm 2 The value of any one of them or the range between any two.

[0315] In this embodiment, the single-sided coating weight of the negative electrode active material layer 233 is 110 mg / 1540 mm. 2 ~150mg / 1540mm 2 This can further improve the energy density requirements of the battery cell 10 and further reduce the expansion of the negative electrode 23.

[0316] In some embodiments, the porosity of the negative electrode 23 is 27% to 40%.

[0317] The porosity of the negative electrode 23 can be any one of the following values ​​or a range between any two: 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%.

[0318] The porosity of the negative electrode 23 can be defined as the percentage of the pore volume within the negative electrode 23 to the total volume of the negative electrode 23. As an example, when the battery cell 10 is at 0% state of charge, a negative electrode 23 with double-sided coating is taken; the porosity of the negative electrode 23 is measured using a true density meter AccuPyc II 1340 according to the national standard GB / T 24586-2009.

[0319] In this embodiment, the porosity of the negative electrode 23 is 27% to 40%, which provides space for impurities generated by side reactions in the negative electrode 23, slows down the expansion of the negative electrode 23, and reduces the impact of the expansion of the negative electrode 23 on the first wall 111.

[0320] In some embodiments, the negative electrode active material includes a silicon-based material, wherein the mass content of silicon element in the negative electrode active material is 0.3% to 10%, optionally 1% to 6%.

[0321] In silicon-based materials, the mass content of silicon in the negative electrode active material can be any one of the following values ​​or any range between two: 0.3%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%.

[0322] In some embodiments, the silicon-based material includes at least one of silicon oxides and silicon-carbon composites.

[0323] In some embodiments, please continue to refer to Figures 19-21 The positive electrode 22 includes a positive current collector 222 and a positive active material layer 223 disposed on at least one side of the positive current collector 222, the positive active material layer 223 including a positive active material.

[0324] The positive electrode current collector 222 may have a positive electrode active material layer 223 on only one side, that is, the positive electrode current collector 222 may have a positive electrode active material layer 223 on only one surface along the thickness direction; or the positive electrode current collector 222 may have a positive electrode active material layer 223 on both opposite sides, that is, the positive electrode current collector 222 may have a positive electrode active material layer 223 on both opposite surfaces along the thickness direction.

[0325] The positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide and their respective modified compounds.

[0326] In some embodiments, the positive electrode active material layer 223 includes a positive electrode main body 2231 and a positive electrode thinning portion 2232. The positive electrode main body 2231 and the positive electrode thinning portion 2232 are arranged along a first direction Z. Along the first direction Z, the positive electrode main body 2231 is provided with a positive electrode thinning portion 2232 at one end near the end cap 12.

[0327] The thickness of the positive electrode main body 2231 is greater than the thickness of the positive electrode thinning portion 2232. The positive electrode thinning portion 2232 may be provided only at one end of the positive electrode main body 2231 near the end cap 12 along the first direction Z, or it may be provided at both ends of the positive electrode main body 2231 along the first direction Z. The positive electrode main body 2231 may be of uniform thickness or non-uniform thickness, and the positive electrode thinning portion 2232 may also be of uniform thickness or non-uniform thickness. If at least one of the positive electrode main body 2231 and the positive electrode thinning portion 2232 is of non-uniform thickness, the maximum thickness of the positive electrode thinning portion 2232 may be less than or equal to the minimum thickness of the positive electrode main body 2231, thereby achieving a thickness greater than that of the positive electrode thinning portion 2232.

[0328] As an example, the positive electrode main body 2231 has a uniform thickness structure, and the thickness of the positive electrode thinning part 2232 decreases along the direction from the positive electrode main body 2231 to the positive electrode thinning part 2232.

[0329] In this embodiment, a positive electrode thinning portion 2232 is provided at one end of the positive electrode main body 2231 near the end cap 12. The electrode assembly 2 has a larger expansion gap in the area corresponding to the positive electrode thinning portion 2232. After expansion, the area of ​​the electrode assembly 2 corresponding to the positive electrode thinning portion 2232 exerts less force on the first wall 111, which can reduce the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection portion 51.

[0330] In some embodiments, in a projection plane perpendicular to the second direction Y, the orthographic projection of the positive electrode thinning portion 2232 located at one end of the positive electrode main body portion 2231 near the end cap 12 and the orthographic projection of the first region 1111 are spaced apart along the first direction Z.

[0331] It is understandable that, in the projection plane perpendicular to the second direction Y, the orthographic projection of the positive electrode thinning portion 2232 located at the end of the positive electrode main body portion 2231 near the end cap 12 does not overlap with the orthographic projection of the first region 1111.

[0332] In the projection plane perpendicular to the second direction Y, the orthographic projection of the positive electrode thinning portion 2232 located at the end of the positive electrode main body 2231 near the end cap 12 and the orthographic projection of the first region 1111 are spaced apart along the first direction Z. This can reduce the influence of the positive electrode thinning portion 2232 on the first region 1111, reduce the risk that the expansion of the electrode assembly 2 will directly exert an expansion force on the first region 1111, and further reduce the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection portion 51.

[0333] In some embodiments, in a projection plane perpendicular to the second direction Y, the orthographic projection of the positive electrode thinning portion 2232 located at one end of the positive electrode main body portion 2231 near the end cap 12 and the orthographic projection of the first region 1111 are spaced apart along the first direction Z by a dimension greater than or equal to 1 mm.

[0334] In a projection plane perpendicular to the second direction Y, the distance between the orthographic projection of the positive electrode thinning portion 2232 located at the end of the positive electrode main body 2231 near the end cap 12 and the orthographic projection of the first region 1111 along the first direction Z is W2, where W2 ≥ 1 mm. This distance is the minimum distance between the orthographic projections of the positive electrode thinning portion 2232 and the first region 1111 along the first direction Z in a projection plane perpendicular to the second direction Y. W2 can be any value among 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, and 20 mm, or any value between two of these values.

[0335] In this embodiment, W2≥1mm, so that in the projection plane perpendicular to the second direction Y, the orthographic projection of the positive electrode thinning portion 2232 and the orthographic projection of the first region 1111 are further apart along the first direction Z, thereby further reducing the influence of the positive electrode thinning portion 2232 on the first region 1111.

[0336] In some embodiments, the single-sided coating weight of the positive electrode active material layer 223 is 200 mg / 1540 mm. 2 ~370mg / 1540 / mm 2 .

[0337] The single-sided coating weight of the positive electrode active material layer 223 can be 200 mg / 1540 mm. 2 210mg / 1540mm 2 220mg / 1540mm 2 230mg / 1540mm 2 240mg / 1540mm 2250mg / 1540mm 2 260mg / 1540mm 2 270mg / 1540mm 2 280mg / 1540mm 2 290mg / 1540mm 2 300mg / 1540mm 2 310mg / 1540mm 2 320mg / 1540mm 2 330mg / 1540mm 2 340mg / 1540mm 2 350mg / 1540mm 2 360mg / 1540mm 2 370mg / 1540mm 2 The value of any one of them or the range between any two.

[0338] When measuring the weight of a single-sided coating of the positive electrode active material layer 223, a single-sided coated positive electrode sheet 22 (if it is a double-sided coated positive electrode sheet 22, the positive electrode active material layer 223 on one side can be wiped off first) can be cut into a small circular piece with an area of ​​S2, and its weight recorded as M3. Then, the positive electrode active material layer 223 of the weighed positive electrode sheet 22 can be wiped off, and the weight of the positive electrode current collector 222 can be measured and recorded as M4. The weight of a single-sided coating of the positive electrode active material layer 223 = (M3-M4) / S2.

[0339] The single-sided coating weight of the positive electrode active material layer 223 is related to the expansion of the positive electrode active material layer 223. The single-sided coating weight of the positive electrode active material layer 223 is set at 200 mg / 1540 mm². 2 ~370mg / 1540 / mm 2 It can, to a certain extent, balance the high energy density requirements of the battery cell 10 and the low expansion requirements of the positive electrode 22, so as to reduce the impact of the expansion of the positive electrode 22 on the first wall 111 and reduce the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection 51.

[0340] In some embodiments, the single-sided coating weight of the positive electrode active material layer 223 is 240 mg / 1540 mm. 2 ~330mg / 1540mm 2 .

[0341] The single-sided coating weight of the positive electrode active material layer 223 can be 240 mg / 1540 mm. 2 245mg / 1540mm 2 250mg / 1540mm2 255mg / 1540mm 2 260mg / 1540mm 2 265mg / 1540mm 2 270mg / 1540mm 2 275mg / 1540mm 2 280mg / 1540mm 2 285mg / 1540mm 2 290mg / 1540mm 2 295mg / 1540mm 2 300mg / 1540mm 2 305mg / 1540mm 2 310mg / 1540mm 2 315mg / 1540mm 2 320mg / 1540mm 2 325mg / 1540mm 2 330mg / 1540mm 2 The value of any one of them or the range between any two.

[0342] In this embodiment, the single-sided coating weight of the positive electrode active material layer 223 is 240 mg / 1540 mm. 2 ~330mg / 1540mm 2 This can further improve the energy density requirements of the battery cell 10 and further reduce the expansion of the positive electrode 22.

[0343] In some embodiments, the positive electrode active material is a lithium phosphate.

[0344] In some embodiments, please refer to Figures 22-24 , Figure 22 A partial view of a battery cell 10 provided for some embodiments of this application (showing the first wall 111); Figure 23 for Figure 22 A partial view of the first wall 111 shown; Figure 24 for Figure 22 The diagram shows an isometric view of the housing 11. The housing 11 is made of steel. The maximum thickness of the second region 1112 is D1, and the dimension of the housing 11 along the second direction Y is D, where 0.001≤D1 / D≤0.012.

[0345] The thickness at the thickest point of the second zone 1112 is the maximum thickness of the second zone 1112. As an example, the second zone 1112 is a structure of uniform thickness, and the thickness at any point of the second zone 1112 can be regarded as the maximum thickness of the second zone 1112.

[0346] In this embodiment, the first region 1111 may partially protrude from the first inner surface 11121 and / or the first outer surface 11122. As an example, in... Figures 22-24 In the illustrated embodiment, a portion of the first region 1111 protrudes from the first outer surface 11122, and the inner surface of the first region 1111 is coplanar with the first inner surface 11121.

[0347] The maximum distance between the first outer surfaces 11122 of the second regions 1112 of the two opposing first walls 111 of the housing 11 is the dimension of the housing 11 along the second direction Y. It is understood that when measuring the dimension of the housing 11 along the second direction Y, the measurement reference is the first outer surface 11122 of the second region 1112. As an example, the first outer surfaces 11122 of the second regions 1112 of the two opposing first walls 111 are arranged parallel to each other.

[0348] For the steel shell 11, D1 / D can take any one of the following point values ​​or any range between two values: 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.011, 0.012.

[0349] For the steel casing 11, D1 / D≥0.001 increases the thickness ratio of the second region 1112 in the casing 11, giving the second region 1112 sufficient strength to meet the strength requirements of the casing 11; D1 / D≤0.012 decreases the thickness ratio of the second region 1112 in the casing 11. With a fixed volume of the casing 11, the internal space of the casing 11 can be increased, thereby freeing up more space for the electrode assembly 2 to meet the volumetric energy density requirements of the battery cell 10.

[0350] For the steel casing 11, in order to meet the volumetric energy density requirements of the battery cell 10, the D1 / D ratio needs to be controlled below 0.012. If the overall thickness of the first wall 111 is the same as that of the second region 1112, the first wall 111 is prone to deformation when subjected to the expansion force of the electrode assembly 2. Over time, this will lead to fatigue cracking in the area of ​​the first wall 111 near the first connection portion 51. Therefore, a thicker first region 1111 is provided in the first wall 111 to enhance the strength of the area of ​​the first wall 111 near the first connection portion 51 and reduce the risk of fatigue cracking.

[0351] In some embodiments, the material of the housing 11 includes steel. The maximum thickness of the second region 1112 is D1, 0.08mm≤D1≤0.35mm; and / or, the maximum thickness of the first region 1111 is D2, 0.1mm≤D2≤0.6mm.

[0352] The thickness at the thickest point in zone 1112 is the maximum thickness of zone 1112. The thickness at the thickest point in zone 1111 is the maximum thickness of zone 1111. It can be understood that the maximum thickness of zone 1112 is less than the maximum thickness of zone 1111, i.e., D1 < D2.

[0353] For the steel shell 11, D1 can be any one of the following values ​​or a range between any two: 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, 0.32mm, 0.35mm; D2 can be any one of the following values ​​or a range between any two: 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm.

[0354] For the steel casing 11, setting the maximum thickness of the second region 1112 to 0.08mm to 0.35mm satisfies both the strength requirements of the second region 1112 and the volumetric energy density requirements of the battery cell 10. Setting the maximum thickness of the first region 1111 to 0.1mm to 0.6mm ensures that the first region 1111 has sufficient strength to enhance the strength of the area of ​​the first wall 111 near the first connection portion 51.

[0355] In some embodiments, the material of the housing 11 includes aluminum alloy. The maximum thickness of the second region 1112 is D1, and the dimension of the housing 11 along the second direction Y is D, where 0.005≤D1 / D≤0.065.

[0356] For the aluminum alloy housing 11, D1 / D can be any one of the following values ​​or a range between any two: 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.055, 0.06, 0.65.

[0357] For the aluminum alloy casing 11, D1 / D≥0.005 increases the thickness ratio of the second region 1112 in the casing 11, giving the second region 1112 sufficient strength to meet the strength requirements of the casing 11; D1 / D≤0.065 decreases the thickness ratio of the second region 1112 in the casing 11, which, with a fixed volume of the casing 11, can increase the internal space of the casing 11, thereby freeing up more space for the electrode assembly 2 to meet the volumetric energy density requirements of the battery cell 10.

[0358] For the aluminum alloy casing 11, in order to meet the volumetric energy density requirements of the battery cell 10, the D1 / D ratio needs to be controlled below 0.065. If the overall thickness of the first wall 111 is the same as that of the second region 1112, the first wall 111 is prone to deformation when subjected to the expansion force of the electrode assembly 2. Over time, this will lead to fatigue cracking in the area of ​​the first wall 111 near the first connection portion 51. Therefore, a thicker first region 1111 is provided in the first wall 111 to enhance the strength of the area of ​​the first wall 111 near the first connection portion 51 and reduce the risk of fatigue cracking.

[0359] In some embodiments, the housing 11 is made of aluminum alloy. The maximum thickness of the second region 1112 is D1, 0.4mm≤D1≤0.8mm; and / or, the maximum thickness of the first region 1111 is D2, 0.5mm≤D2≤1.5mm.

[0360] For the aluminum alloy shell 11, D1 can be any one of the following values ​​or a range between any two: 0.4mm, 0.42mm, 0.45mm, 0.48mm, 0.5mm, 0.52mm, 0.55mm, 0.58mm, 0.6mm, 0.62mm, 0.65mm, 0.68mm, 0.7mm, 0.72mm, 0.75mm, 0.78mm, 0.8mm; D2 can be any one of the following values ​​or a range between any two: 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm.

[0361] For the aluminum alloy casing 11, setting the maximum thickness of the second region 1112 to 0.4mm to 0.8mm satisfies both the strength requirements of the second region 1112 and the volumetric energy density requirements of the battery cell 10. Setting the maximum thickness of the first region 1111 to 0.5mm to 1.5mm ensures that the first region 1111 has sufficient strength to enhance the strength of the area of ​​the first wall 111 near the first connection portion 51.

[0362] In some embodiments, the aluminum alloy comprises the following components by weight percentage: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other individual elements ≤ 0.03%. This aluminum alloy has good processing and forming properties, facilitating the forming of the shell 11.

[0363] In some embodiments, the aluminum alloy comprises the following components by mass percentage: aluminum ≥ 96.7%, copper ≤ 0.05% ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other individual element components ≤ 0.05%, and other element total components ≤ 0.15%. This aluminum alloy exhibits good processing and forming properties and corrosion resistance.

[0364] In some embodiments, please refer to Figure 25 and Figure 26 , Figure 25 A partial view of a battery cell 10 provided for other embodiments of this application (showing the first wall 111), Figure 26 for Figure 25 A magnified view of a portion at point C. The first region 1111 is directly connected to the first connecting part 51.

[0365] The first zone 1111 and the first connecting part 51 can be in point contact, line contact or surface contact to achieve direct connection between the two.

[0366] In this embodiment, the first region 1111 is directly connected to the first connecting part 51, making the first region 1111 and the first connecting part 51 closer along the first direction Z, so that the first region 1111 is located near the first connecting part 51, further reducing the risk of fatigue cracking of the area of ​​the first wall 111 located near the first connecting part 51 due to the expansion of the electrode assembly 2.

[0367] In some embodiments, the first wall 111 further includes a first transition region 1117, which is connected to the end of the first region 1111 that is away from the second region 1112 along the first direction Z. The first transition region 1117 is connected to the first connecting portion 51, and the connection position of the first transition region 1117 and the first connecting portion 51 forms a first connecting interface 511. The first connecting interface 511 has a first position 5111 that is closest to the first region 1111 along the first direction Z. The first position 5111 is located at the end of the first region 1111 that is away from the second region 1112 along the first direction Z.

[0368] The first transition zone 1117 may be the portion of the first wall 111 connecting the first connecting portion 51 and the first zone 1111. The first transition zone 1117 may be a structure of uniform thickness or a structure of non-uniform thickness. The thickness of the first transition zone 1117 may be less than the thickness of the first zone 1111. As an example, in Figure 25 and Figure 26 In the illustrated embodiment, the thickness of the first transition region 1117 gradually decreases along the direction from the second region 1112 to the first region 1111.

[0369] The first connection interface 511 is formed at the connection position between the first transition region 1117 and the first connection part 51, and the first transition region 1117 and the first connection part 51 are separated by the first connection interface 511. The first connection interface 511 can be a plane or a curved surface.

[0370] The first zone 1111 and the first transition zone 1117 are separated by the first interface U, which is a virtual plane. The first interface U passes through the first position 5111 and is perpendicular to the first direction Z. The first transition zone 1117 and the first connecting part 51 are located above the first interface U, and the first zone 1111 is located below the first interface U.

[0371] In this embodiment, the first transition region 1117 is connected to the first connecting part 51 to form a first connecting interface 511, so that the first transition region 1117 and the first connecting part 51 have a sufficiently large contact area, which improves the firmness of the first wall 111 and the end cap 12 after welding.

[0372] In some embodiments, at least a portion of the first connection interface 511 extends at an angle relative to the second direction Y.

[0373] The first connection interface 511 can extend at an overall angle relative to the second direction Y, or the first connection interface 511 can extend at a partial angle relative to the second direction Y.

[0374] It is understandable that the extension direction of the portion of the first connecting interface 511 that extends at an angle relative to the second direction Y is not parallel to the second direction Y.

[0375] After the end cap 12 and the first wall 111 are welded, the first connecting portion 51 will shrink as it solidifies, generating tensile stress on the first transition region 1117. When the first wall 111 is subjected to the expansion force of the electrode assembly 2, the first wall 111 will deform, and the first transition region 1117 will generate tensile stress on the first connecting portion 51. Since the first connecting interface 511 extends at least partially at an angle relative to the second direction Y, the tensile stress generated by the first connecting portion 51 due to shrinkage on the first transition region 1117 near the portion of the first connecting interface 511 that extends at an angle relative to the second direction Y is not on the same straight line as the tensile stress generated by the first transition region 1117 due to deformation of the first wall 111 on the first connecting portion 51, thus reducing the risk of fatigue cracking in the area of ​​the first transition region 1117 near the first connecting interface 511.

[0376] In some embodiments, please continue to refer to Figure 26The first connection interface 511 includes a first interface 5112, which extends obliquely from the first position 5111 toward the end cap 12 along the second direction Y. At least a portion of the first transition area 1117 is located between the first interface 5112 and the end cap 12.

[0377] It is understandable that the first interface 5112 extends at an angle relative to the second direction Y. The first interface 5112 can be a plane or a curved surface.

[0378] The first position 5111 is the lowest position of the first interface 5112 (the position closest to the first area 1111). The first interface 5112 extends obliquely from the first position 5111 towards the end cover 12, that is, the first interface 5112 extends obliquely upward from the first position 5111 towards the end cover 12.

[0379] Along the second direction Y, the first transition region 1117 can be entirely located between the first interface 5112 and the end cap 12, or only a portion of the first transition region 1117 can be located between the first interface 5112 and the end cap 12.

[0380] In this embodiment, at least a portion of the first transition region 1117 is located between the first interface 5112 and the end cap 12 along the second direction Y. In this way, the first connecting portion 51 protects the first transition region 1117. When the first wall 111 is subjected to the expansion force of the electrode assembly 2, the deformation of the first transition region 1117 during the stress process is blocked by the first connecting portion 51, thereby reducing the risk of fatigue cracking in the area of ​​the first transition region 1117 near the first interface 5112.

[0381] In some embodiments, please continue to refer to Figure 26 The first interface 5112 is connected to the outer surface of the first area 1111 at the first position 5111.

[0382] As an example, the first interface 5112 intersects the outer surface of the first region 1111 at a first straight line, which extends along a third direction X, and the location of the first straight line is the first position 5111. The first interface 5112 is connected to the inner surface of the first transition region 1117 at a third position 5114 along a first direction Z. The third position 5114 is farther away from the first region 1111 than the first position 5111. The first transition region 1117 is approximately triangular in shape.

[0383] In this embodiment, the first interface 5112 is connected to the outer surface of the first region 1111 at the first position 5111, so that the first region 1111 and the first connection part 51 are in a direct connection state, making the first region 1111 and the first connection part 51 closer along the first direction Z, further reducing the risk of fatigue cracking of the area of ​​the first wall 111 near the first connection part 51 due to the expansion of the electrode assembly 2.

[0384] In some embodiments, please refer to Figure 27 and Figure 28 , Figure 27 A partial view of a battery cell 10 provided for some embodiments of this application (showing the first wall 111); Figure 28 for Figure 27 A partial enlarged view at point D. The first connection interface 511 includes a second interface 5113, which extends obliquely from the first position 5111 in a direction away from the end cap 12 along the second direction Y. At least a portion of the first transition region 1117 is located on the side of the second interface 5113 away from the end cap 12.

[0385] Understandably, the second interface 5113 extends at an angle relative to the second direction Y. The second interface 5113 can be planar or curved. Along the second direction Y, at least a portion of the first connecting portion 51 is located between the second interface 5113 and the end cap 12.

[0386] The first position 5111 is the lowest position of the second interface 5113 (the position closest to the first area 1111). The second interface 5113 extends obliquely from the first position 5111 in a direction away from the end cover 12, that is, the second interface 5113 extends obliquely upward from the first position 5111 in a direction away from the end cover 12.

[0387] Along the second direction Y, the first transition region 1117 can be entirely located on the side of the second interface 5113 away from the end cover 12, or the first transition region 1117 can be only partially located on the side of the second interface 5113 away from the end cover 12.

[0388] In this embodiment, at least a portion of the first transition region 1117 is located on the side of the second interface 5113 away from the end cap 12 along the second direction Y, so that the first transition region 1117 restricts the first connecting part 51 and reduces the risk of the first connecting part 51 falling off.

[0389] In some embodiments, please continue to refer to Figure 28 The second interface 5113 is connected to the inner surface of the first region 1111 at the first position 5111.

[0390] As an example, the second interface 5113 intersects the inner surface of the first region 1111 at a first straight line, which extends along a third direction X, and the location of the first straight line is the first position 5111. The second interface 5113 is connected to the outer surface of the first transition region 1117 at a fourth position 5115 along a first direction Z. The fourth position 5115 is farther away from the first region 1111 than the first position 5111. The first transition region 1117 is approximately triangular in shape.

[0391] In this embodiment, the second interface 5113 is connected to the inner surface of the first region 1111 at the first position 5111, so that the first region 1111 and the first connecting part 51 are in a direct connection state, making the first region 1111 and the first connecting part 51 closer along the first direction Z, further reducing the risk of fatigue cracking of the area of ​​the first wall 111 near the first connecting part 51 due to the expansion of the electrode assembly 2.

[0392] In some embodiments, please refer to Figure 29 and Figure 30 , Figure 29 A partial view of a battery cell 10 provided for some embodiments of this application (showing the first wall 111); Figure 30 for Figure 29 A partial enlarged view at point E. The first connection interface 511 includes a first interface 5112 and a second interface 5113. The first interface 5112 extends obliquely from the first position 5111 toward the end cap 12, and the second interface 5113 extends obliquely from the first position 5111 toward the end cap 12. Along the second direction Y, a portion of the first transition region 1117 is located between the first interface 5112 and the end cap 12, and another portion of the first transition region 1117 is located on the side of the second interface 5113 away from the end cap 12.

[0393] As an example, the first interface 5112 is connected to the inner surface of the first transition zone 1117 at the third position 5114, and the second interface 5113 is connected to the outer surface of the first transition zone 1117 at the fourth position 5115.

[0394] In some embodiments, the Vickers hardness of the first transition region 1117 is less than the Vickers hardness of the second region 1112; and / or, the Vickers hardness of the first transition region 1117 is less than the Vickers hardness of the first connecting portion 51.

[0395] As an example, the Vickers hardness of the second zone 1112 is less than that of the first connecting part 51.

[0396] If the Vickers hardness of the first transition zone 1117 is less than that of the second zone 1112, the first transition zone 1117, with its lower Vickers hardness, connects to the first connecting portion 51. This alleviates the rigid tension between the first wall 111 and the first connecting portion 51 when the first wall 111 deforms, reducing the risk of separation between the first wall 111 and the first connecting portion 51. Conversely, if the Vickers hardness of the first transition zone 1117 is less than that of the first connecting portion 51, the first transition zone 1117 is more prone to deformation than the first connecting portion 51. This also alleviates the rigid tension between the first wall 111 and the first connecting portion 51 when the first wall 111 deforms, reducing the risk of separation between the first wall 111 and the first connecting portion 51.

[0397] In some embodiments, please continue to refer to Figures 25-30 Along the first direction Z, the first connection interface 511 is closer to the second region 1112 than the outer surface 121 of the end cap.

[0398] Along the first direction Z, the surface of the end cap 12 that is away from the electrode assembly 2 is the outer surface 121 of the end cap.

[0399] exist Figure 25 and Figure 26 In the illustrated embodiment, along the first direction Z, both the third position 5114 and the first position 5111 are closer to the second region 1112 than the outer surface 121 of the end cap.

[0400] exist Figure 27 and Figure 28 In the illustrated embodiment, along the first direction Z, both the fourth position 5115 and the first position 5111 are closer to the second region 1112 than the outer surface 121 of the end cap.

[0401] exist Figure 29 and Figure 30 In the illustrated embodiment, along the first direction Z, the third position 5114, the fourth position 5115 and the first position 5111 are all closer to the second region 1112 than the outer surface 121 of the end cap.

[0402] In this embodiment, the first connection interface 511 is closer to the second region 1112 along the first direction Z than the outer surface 121 of the end cap, so that the first connection part 51 can sink to a deeper position in the first wall 111, which can effectively improve the connection strength between the first wall 111 and the end cap 12.

[0403] In some embodiments, please refer to Figure 31 and Figure 32 , Figure 31 Axonometric views of housing 11 are provided for further embodiments of this application; Figure 32 for Figure 31 A partial enlarged view at point F. The shell 11 also includes a second wall 112 and a corner wall 113. The first wall 111, the corner wall 113 and the second wall 112 are arranged circumferentially along the opening, and the corner wall 113 connects the first wall 111 and the second wall 112.

[0404] The second wall 112 and the end cap 12 can be welded to form a third connecting part, and both the first connecting part 51 and the third connecting part are part of the connecting part 5. The second wall 112 can be a structure of equal thickness or a structure of non-equal thickness.

[0405] exist Figure 31 and Figure 32In one embodiment, the second wall 112 has a uniform thickness. In other embodiments, the second wall 112 may also have a non-uniform thickness structure. The structure of the second wall 112 may be the same as that of the first wall 111. For example, the second wall 112 may include a fifth region and a sixth region arranged along the first direction Z, with the thickness of the fifth region being greater than that of the sixth region. The fifth region is located between the third connection portion and the sixth region, which can reduce the risk of fatigue cracking in the area of ​​the second wall 112 near the third connection portion. The structure of the fifth region may be the same as that of the first region 1111, and the structure of the sixth region may be the same as that of the second region 1112.

[0406] The first wall 111 and the second wall 112 in the shell 11 are indirectly connected by a corner wall 113, and the sum of the number of the first wall 111 and the second wall 112 is equal to the number of corner walls 113.

[0407] As an example, the first wall 111, the second wall 112, and the corner wall 113 are integrally formed. The cross-section of the outer surface and / or the inner surface of the corner wall 113 may be arc-shaped, and the cross-section is perpendicular to the first direction Z.

[0408] In this embodiment, the first wall 111 and the second wall 112 are connected by a corner wall 113, which allows the first wall 111 to transition to the second wall 112 through the corner wall 113, effectively reducing the risk of stress concentration in the shell 11 at the corner position.

[0409] In some embodiments, please refer to Figures 33-35 , Figure 33 A partial view of a battery cell 10 provided for some embodiments of this application (showing corner wall 113); Figure 34 This is a structural schematic diagram of the corner wall 113 provided in some embodiments of this application; Figure 35 This is a schematic diagram of the corner wall 113 provided in some other embodiments of this application. The corner wall 113 is welded to the end cap 12 to form a second connecting portion 52. The corner wall 113 includes a third region 1131 and a fourth region 1132 arranged along a first direction Z. The thickness of the third region 1131 is greater than the thickness of the fourth region 1132. The third region 1131 is located between the fourth region 1132 and the second connecting portion 52.

[0410] The third region 1131 can be a region where the corner wall 113 is thickened, and the third region 1131 is thicker than the fourth region 1132. The fourth region 1132 can be the portion of the corner wall 113 located along the first direction Z on the side of the third region 1131 opposite to the second connecting portion 52. The third region 1131 and the second connecting portion 52 can be directly connected or indirectly connected; the third region 1131 and the fourth region 1132 can be directly connected or indirectly connected. The third region 1131 can be a structure of equal thickness or a structure of unequal thickness; the fourth region 1132 can be a structure of equal thickness or a structure of unequal thickness. If at least one of the third region 1131 and the fourth region 1132 is a structure of unequal thickness, the maximum thickness of the fourth region 1132 can be less than or equal to the minimum thickness of the third region 1131, so that the thickness of the third region 1131 is greater than the thickness of the fourth region 1132.

[0411] The fourth region 1132 has a second inner surface 11321 facing the interior space of the housing 11 and a second outer surface 11322 facing away from the interior space of the housing 11. The third region 1131 may partially protrude from the second inner surface 11321 and / or the second outer surface 11322. As an example, in Figure 33 and Figure 34 In the illustrated embodiment, a portion of the third region 1131 protrudes from the second inner surface 11321, and the outer surface of the third region 1131 is coplanar with the second outer surface 11322; Figure 35 In the illustrated embodiment, a portion of the third region 1131 protrudes from the second outer surface 11322, and the inner surface of the third region 1131 is coplanar with the second inner surface 11321.

[0412] The second connecting portion 52 can correspond one-to-one with the corner wall 113. The second connecting portion 52 is the part with weld marks formed after the end cap 12 and the corner wall 113 are welded together. The part where the end cap 12 and the corner wall 113 are welded together can be the second connecting portion 52. A part of the second connecting portion 52 is formed on the end cap 12, and another part of the second connecting portion 52 is formed on the corner wall 113. The corner wall 113 and the end cap 12 can form the second connecting portion 52 by seam welding or by through welding. The second connecting portion 52 and the first connecting portion 51 are both part of the connecting portion 5.

[0413] The thickness of the third region 1131 is greater than that of the fourth region 1132, and the third region 1131 is located between the second connecting part 52 and the fourth region 1132. This makes the thicker third region 1131 closer to the second connecting part 52 than the fourth region 1132. The third region 1131 strengthens the area of ​​the corner wall 113 near the second connecting part 52, reduces the risk of fatigue cracking in the area of ​​the corner wall 113 near the second connecting part 52, and thus improves the service life of the battery cell 10.

[0414] In some embodiments, please continue to refer to Figure 32 Zone 3 1131 is directly connected to Zone 1 1111.

[0415] As an example, the third zone 1131 is integrally formed with the first zone 1111, and the first zone 1111 is connected to the third zone 1131 at both ends along the third direction X.

[0416] In an embodiment where the second wall 112 includes a fifth zone and a sixth zone, the third zone 1131 can connect the first zone 1111 and the fifth zone, and the fourth zone 1132 can connect the second zone 1112 and the sixth zone.

[0417] The third zone 1131 is directly connected to the first zone 1111, so that the first zone 1111 and the third zone 1131 are connected into a whole. The third zone 1131 and the first zone 1111 have a promoting effect on each other, which enhances the strengthening effect of the first zone 1111 on the first wall 111 and the strengthening effect of the second zone 1112 on the corner wall 113.

[0418] In some embodiments, please continue to refer to Figure 32 Along the circumference of the opening, the corner wall 113 has a first connecting end 1133 and a second connecting end 1134. The first wall 111 is connected to the first connecting end 1133, and the second wall 112 is connected to the second connecting end 1134. The thickness of the third region 1131 decreases along the direction from the first connecting end 1133 to the second connecting end 1134.

[0419] As an example, the thickness of the third region 1131 gradually decreases along the direction from the first connecting end 1133 to the second connecting end 1134, the second wall 112 has a uniform thickness structure, the inner surface of the third region 1131 is connected to the inner surface of the first region 1111 and the inner surface of the second wall 112, and the outer surface of the third region 1131 is connected to the outer surface of the first region 1111 and the outer surface of the second wall 112.

[0420] When the first wall 111 is subjected to the expansion force of the electrode assembly 2 in the second direction Y, the deformation of the first wall 111 may cause the corner wall 113 to deform. Along the circumference of the opening, the corner wall 113 is more affected by the first wall 111 the closer it is to the first wall 111, and the deformation of the area of ​​the corner wall 113 closer to the first wall 111 is greater. The thickness of the third region 1131 decreases along the direction from the first connecting end 1133 to the second connecting end 1134, making the area of ​​the third region 1131 closer to the first wall 111 along the circumference of the opening stronger. This reduces the impact of the deformation of the first wall 111 on the corner wall 113. While ensuring that the area of ​​the corner wall 113 near the second connecting part 52 has sufficient strength, the material used in the third region 1131 is reduced, thus lowering the production cost.

[0421] In some embodiments, please refer to Figure 36 and Figure 37 , Figure 36 A partial view of a battery cell 10 provided for other embodiments of this application (showing corner wall 113); Figure 37 for Figure 36 A magnified view of a section at point G. The third region 1131 is directly connected to the second connecting part 52.

[0422] The third zone 1131 and the second connecting part 52 can be in point contact, line contact, or surface contact to achieve direct connection between the two.

[0423] In this embodiment, the third region 1131 is directly connected to the second connecting part 52, making the third region 1131 and the second connecting part 52 closer along the first direction Z, so that the third region 1131 is located near the second connecting part 52, further reducing the risk of fatigue cracking in the area of ​​the corner wall 113 near the second connecting part 52.

[0424] In some embodiments, the corner wall 113 further includes a second transition region 1135, which is connected to the end of the third region 1131 that is away from the fourth region 1132 along the first direction Z. The second transition region 1135 is connected to the second connecting portion 52, and the connection position of the second transition region 1135 and the second connecting portion 52 forms a second connecting interface 521. The second connecting interface 521 has a second position 5211 that is closest to the third region 1131 along the first direction Z. The second position 5211 is located at the end of the third region 1131 that is away from the fourth region 1132 along the first direction Z.

[0425] The second transition zone 1135 may be the portion of the corner wall 113 connecting the second connecting portion 52 and the third zone 1131. The second transition zone 1135 may be a structure of uniform thickness or a structure of non-uniform thickness. The thickness of the second transition zone 1135 may be less than the thickness of the third zone 1131. As an example, in... Figure 36and Figure 37 In the illustrated embodiment, the thickness of the second transition region 1135 gradually decreases along the direction from the fourth region 1132 to the third region 1131.

[0426] The second connection interface 521 is formed at the connection position between the second transition region 1135 and the second connection portion 52, and the second transition region 1135 and the second connection portion 52 are separated by the second connection interface 521. The second connection interface 521 can be a plane or a curved surface.

[0427] The third zone 1131 and the second transition zone 1135 are separated by the second interface V, which is a virtual plane. The second interface V passes through the second position 5211 and is perpendicular to the first direction Z. The second transition zone 1135 and the second connecting part 52 are located above the second interface V, and the third zone 1131 is located below the second interface V.

[0428] In this embodiment, the second transition area 1135 is connected to the second connecting part 52 to form a second connecting interface 521, so that the second transition area 1135 and the second connecting part 52 have a sufficiently large contact area, which improves the firmness of the corner wall 113 and the end cap 12 after welding.

[0429] In some embodiments, at least a portion of the second connection interface 521 extends obliquely relative to the thickness direction of the corner wall 113.

[0430] The second connection interface 521 can extend at an angle relative to the thickness direction of the corner wall 113 as a whole, or it can extend at an angle relative to the thickness direction of the corner wall 113 locally.

[0431] Near the portion of the second connection interface 521 that extends obliquely relative to the thickness direction of the corner wall 113, the tensile stress generated by the second connection portion 52 on the second transition zone 1135 due to contraction is not on the same straight line as the tensile stress generated by the second transition zone 1135 on the second connection portion 52 due to the deformation of the corner wall 113. This reduces the risk of fatigue cracking in the area of ​​the second transition zone 1135 near the second connection interface 521.

[0432] In some embodiments, please continue to refer to Figure 37 The second connection interface 521 includes a third interface 5212, which extends obliquely from the second position 5211 toward the end cap 12. Along the thickness direction of the corner wall 113, at least a portion of the second transition area 1135 is located between the third interface 5212 and the end cap 12.

[0433] It is understandable that the third interface 5212 extends at an angle relative to the thickness direction of the corner wall 113. The third interface 5212 can be a plane or a curved surface.

[0434] The second position 5211 is the lowest position of the third interface 5212 (the position closest to the third area 1131). The third interface 5212 extends obliquely from the second position 5211 toward the end cover 12, that is, the third interface 5212 extends obliquely upward from the second position 5211 toward the end cover 12.

[0435] Along the thickness direction of the corner wall 113, the second transition zone 1135 can be entirely located between the third interface 5212 and the end cap 12, or only a portion of the second transition zone 1135 can be located between the third interface 5212 and the end cap 12.

[0436] In this embodiment, at least a portion of the second transition region 1135 is located between the third interface 5212 and the end cap 12 along the thickness direction of the corner wall 113. The second connecting portion 52 protects the second transition region 1135. When the second transition region 1135 deforms outward, it will be blocked by the second connecting portion 52, reducing the risk of fatigue cracking in the area of ​​the second transition region 1135 near the third interface 5212.

[0437] In some embodiments, please continue to refer to Figure 37 The third interface 5212 is connected to the outer surface of the third region 1131 at the second position 5211.

[0438] As an example, the third interface 5212 intersects the outer surface of the third region 1131 at a second straight line, which extends along the third direction X, and the location of the second straight line is the second position 5211. The third interface 5212 is connected to the inner surface of the second transition region 1135 at a fifth position 5214 along the first direction Z. The fifth position 5214 is farther away from the third region 1131 than the second position 5211. The second transition region 1135 is approximately triangular.

[0439] In this embodiment, the third interface 5212 is connected to the outer surface of the third region 1131 at the second position 5211, so that the third region 1131 and the second connecting part 52 are in a direct connection state, making the third region 1131 and the second connecting part 52 closer along the first direction Z, further reducing the risk of fatigue cracking in the area of ​​the corner wall 113 near the second connecting part 52.

[0440] In some embodiments, please refer to Figure 38 and Figure 39 , Figure 38 A partial view of a battery cell 10 provided for some embodiments of this application (showing corner wall 113); Figure 39 for Figure 38A partial enlarged view at point H. The second connection interface 521 includes a fourth interface 5213, which extends obliquely from the second position 5211 in a direction away from the end cap 12. Along the thickness direction of the corner wall 113, at least a portion of the second transition region 1135 is located on the side of the fourth interface 5213 away from the end cap 12.

[0441] Understandably, the fourth interface 5213 extends at an angle relative to the second direction Y. The fourth interface 5213 can be planar or curved. Along the thickness direction of the corner wall 113, at least a portion of the second connection portion 52 is located between the fourth interface 5213 and the end cap 12.

[0442] The second position 5211 is the lowest position of the fourth interface 5213 (the position closest to the first area 1111). The fourth interface 5213 extends obliquely from the second position 5211 in a direction away from the end cover 12, that is, the fourth interface 5213 extends obliquely upward from the second position 5211 in a direction away from the end cover 12.

[0443] Along the thickness direction of the corner wall 113, the second transition zone 1135 can be entirely located on the side of the fourth interface 5213 away from the end cap 12, or the second transition zone 1135 can be only partially located on the side of the fourth interface 5213 away from the end cap 12.

[0444] In this embodiment, at least a portion of the second transition region 1135 is located on the side of the fourth interface 5213 away from the end cap 12 along the thickness direction of the corner wall 113, so that the second transition region 1135 restricts the second connection portion 52 and reduces the risk of the second connection portion 52 falling off.

[0445] In some embodiments, the fourth interface 5213 is connected to the inner surface of the third region 1131 at the second position 5211.

[0446] As an example, the fourth interface 5213 intersects the inner surface of the third region 1131 at a second straight line, which extends along the third direction X, and the location of the second straight line is the second position 5211. The fourth interface 5213 is connected to the outer surface of the second transition region 1135 at a sixth position 5215 along the first direction Z. The sixth position 5215 is farther away from the third region 1131 than the second position 5211. The second transition region 1135 is approximately triangular in shape.

[0447] In this embodiment, the fourth interface 5213 is connected to the inner surface of the third region 1131 at the second position 5211, so that the third region 1131 and the second connecting part 52 are in a direct connection state, making the third region 1131 and the second connecting part 52 closer along the first direction Z, further reducing the risk of fatigue cracking in the area of ​​the corner wall 113 near the second connecting part 52.

[0448] In some embodiments, please refer to Figure 40 and Figure 41 , Figure 40 A partial view of a battery cell 10 provided for some embodiments of this application (showing corner wall 113); Figure 41 for Figure 40 A partial enlarged view at point I. The second connection interface 521 includes a third interface 5212 and a fourth interface 5213. The third interface 5212 extends obliquely from the second position 5211 toward the end cap 12, and the fourth interface 5213 extends obliquely from the second position 5211 toward the end cap 12. Along the thickness direction of the corner wall 113, a portion of the second transition region 1135 is located between the third interface 5212 and the end cap 12, and another portion of the second transition region 1135 is located on the side of the fourth interface 5213 away from the end cap 12.

[0449] As an example, the third interface 5212 is connected to the inner surface of the second transition region 1135 at the fifth position 5214, and the fourth interface 5213 is connected to the outer surface of the second transition region 1135 at the sixth position 5215.

[0450] In some embodiments, the Vickers hardness of the second transition region 1135 is less than the Vickers hardness of the fourth region 1132; and / or, the Vickers hardness of the second transition region 1135 is less than the Vickers hardness of the second connecting portion 52.

[0451] As an example, the Vickers hardness of the fourth zone 1132 is less than that of the second connecting part 52.

[0452] If the Vickers hardness of the second transition zone 1135 is less than that of the fourth zone 1132, the second transition zone 1135, with its lower Vickers hardness, connects with the second connecting portion 52. This alleviates the rigid tension between the corner wall 113 and the second connecting portion 52 when the corner wall 113 deforms, reducing the risk of separation between the corner wall 113 and the second connecting portion 52. Conversely, if the Vickers hardness of the second transition zone 1135 is less than that of the second connecting portion 52, the second transition zone 1135 is more prone to deformation than the second connecting portion 52. This also alleviates the rigid tension between the corner wall 113 and the second connecting portion 52 when the corner wall 113 deforms, reducing the risk of separation between the corner wall 113 and the second connecting portion 52.

[0453] In some embodiments, please refer to Figures 36-41 Along the first direction Z, the second connection interface 521 is closer to the fourth region 1132 than the outer surface 121 of the end cap.

[0454] exist Figure 36 and Figure 37In the illustrated embodiment, along the first direction Z, both the fifth position 5214 and the second position 5211 are closer to the fourth region 1132 than the outer surface 121 of the end cap.

[0455] exist Figure 38 and Figure 39 In the illustrated embodiment, along the first direction Z, the sixth position 5215 and the second position 5211 are both closer to the fourth region 1132 than the outer surface 121 of the end cap.

[0456] exist Figure 40 and Figure 41 In the illustrated embodiment, along the first direction Z, the fifth position 5214, the sixth position 5215, and the second position 5211 are all closer to the fourth region 1132 than the outer surface 121 of the end cap.

[0457] In this embodiment, the second connection interface 521 is closer to the fourth region 1132 along the first direction Z than the outer surface 121 of the end cap, so that the second connection part 52 can sink to a deeper position in the corner wall 113, which can effectively improve the connection strength between the corner wall 113 and the end cap 12.

[0458] In some embodiments, please continue to refer to Figure 31 The housing 11 includes two first walls 111 and two second walls 112. The two first walls 111 are arranged opposite each other along the second direction Y, and the two second walls 112 are arranged opposite each other along the third direction X. The first direction Z, the second direction Y and the third direction X are perpendicular to each other.

[0459] The first wall 111 has corner walls 113 at both ends along the third direction X, and the second wall 112 has corner walls 113 at both ends along the second direction Y. It can be understood that there are four corner walls 113 in the shell 11.

[0460] In this embodiment, the housing 11 is generally rectangular, and the size of the housing 11 can be made larger, which is beneficial to meet the large capacity requirements of the battery cell 10.

[0461] In some embodiments, at least a portion of the Vickers hardness of the first region 1111 is less than the Vickers hardness of the second region 1112.

[0462] It can be that the Vickers hardness of the entire first zone 1111 is less than the Vickers hardness of the second zone 1112, or it can be that only a part of the first zone 1111 has a Vickers hardness less than the Vickers hardness of the second zone 1112.

[0463] As an example, the Vickers hardness of a portion of the first zone 1111 is less than that of the second zone 1112, the Vickers hardness of another portion of the first zone 1111 is equal to that of the second zone 1112, and the portion of the first zone 1111 with the same Vickers hardness as the second zone 1112 is directly connected to the second zone 1112.

[0464] When the second region 1112 deforms under the expansion force of the electrode assembly 2, the area in the first region 1111 with a smaller Vickers hardness than the second region 1112 can reduce the impact of the deformation of the second region 1112 on the area of ​​the first wall 111 near the first connection 51, thereby reducing the risk of fatigue cracking of the area of ​​the first wall 111 near the first connection 51 due to the expansion of the electrode assembly 2.

[0465] In some embodiments, please refer to Figure 42 , Figure 42 This is a diagram showing the positional relationship between the end cap 12 and the sidewall before welding in some embodiments of this application. Along the first direction Z, the first wall 111 has a limiting surface 1115 facing the end cap 12, and the limiting surface 1115 abuts against the end cap 12 to restrict the end cap 12 from moving towards the electrode assembly 2.

[0466] The limiting surface 1115 can be perpendicular to the first direction Z. The limiting surface 1115 can be the end face of the first wall 111 located at the opening of the housing 11. The limiting surface 1115 can also be a step surface on the first wall 111. The step surface is a certain distance away from the end face of the first wall 111 located at the opening of the housing 11.

[0467] The limiting surface 1115 limits the end cap 12, reducing the risk of the end cap 12 moving towards the electrode assembly 2 when it is welded to the housing 11. This can effectively improve the welding quality of the end cap 12 and the housing 11 and reduce the welding difficulty of the end cap 12 and the housing 11.

[0468] In some embodiments, the first wall 111 further includes a limiting region 1116 disposed on the limiting surface 1115. The limiting region 1116 and the end cap 12 are disposed opposite to each other along the second direction Y. The limiting region 1116 and the end cap 12 are welded to form a first connecting portion 51.

[0469] As an example, the end cap 12 is at least partially housed within the housing 11, such that the limiting region 1116 is disposed opposite to the end cap 12 along the second direction Y.

[0470] After the limiting region 1116 is welded to the end cap 12, a portion of the limiting region 1116 and a portion of the end cap 12 can be fused together to form the first connecting portion 51, and the remaining portion of the limiting region 1116 can form the first transition region 1117. Figure 42 At least a portion of (not shown).

[0471] The limiting area 1116 can also limit the end cover 12, reducing the risk of the end cover 12 moving along the thickness direction of the first wall 111 when welding the end cover 12 and the shell 11, further improving the welding quality of the end cover 12 and the shell 11, and reducing the welding difficulty of the end cover 12 and the shell 11.

[0472] In some embodiments, the electrode assembly 2 is a stacked structure, and the electrode assembly 2 includes a plurality of positive electrode plates 22 and a plurality of negative electrode plates 23, which are stacked along the second direction Y.

[0473] As an example, the positive electrode 22 and the negative electrode tab 21b in the electrode assembly 2 are arranged alternately along the second direction Y, and an isolation member 24 is provided between the positive electrode 22 and the negative electrode 23.

[0474] In this embodiment, electrode assembly 2 is a wound electrode assembly, which has a more compact structure and stronger resistance to compression.

[0475] In some embodiments, the number of negative electrode plates 23 is greater than the number of positive electrode plates 22, and a positive electrode plate 22 is disposed between two adjacent negative electrode plates 23.

[0476] As an example, the negative electrode 23 has one more electrode than the positive electrode 22.

[0477] In some embodiments, each negative electrode 23 is provided with a negative electrode tab 21b; and / or, each positive electrode 22 is provided with a positive electrode tab 21a.

[0478] In some embodiments, along the third direction X, the size of the first region 1111 is larger than the size of the positive electrode 22 and / or the size of the negative electrode 23, and the first direction Z, the second direction Y and the third direction X are perpendicular to each other.

[0479] If along the third direction X, the size of the first region 1111 is larger than the size of the positive electrode 22, and the first region 1111 extends beyond at least one end of the positive electrode 22 along the third direction X; if along the third direction X, the size of the first region 1111 is larger than the size of the negative electrode 23, and the first region 1111 extends beyond at least one end of the negative electrode 23 along the third direction X.

[0480] In this embodiment, along the third direction X, the size of the first region 1111 is larger than the size of the positive electrode 22 and / or the size of the negative electrode 23, making the size of the first region 1111 larger along the third direction X. This strengthens the first wall 111 by having more areas along the third direction X, further reducing the risk of fatigue cracking in the area of ​​the first wall 111 near the first connection portion 51.

[0481] In some embodiments, please refer to Figure 43 , Figure 43 This is a schematic diagram showing the connection between the end cap 12 and the electrode terminals 3 according to some embodiments of this application. The battery cell 10 also includes two electrode terminals 3, which are disposed on the end cap 12. The two electrode terminals 3 have opposite polarities and are both electrically connected to the electrode assembly 2. The end cap 12 is provided with a lead-out hole. The electrode terminal 3 includes a terminal body 31, a first limiting part 32 and a second limiting part 33. The terminal body 31 is connected to the first limiting part 32 and the second limiting part 33. The terminal body 31 passes through the lead-out hole. Along the first direction Z, the first limiting part 32 is located on the side of the end cap 12 away from the electrode assembly 2, and the second limiting part 33 is located on the side of the end cap 12 facing the electrode assembly 2.

[0482] The first limiting part 32 and the second limiting part 33 have a limiting function. The first limiting part 32 and the second limiting part 33 are respectively connected to both ends of the terminal body 31. The first limiting part 32 and the second limiting part 33 cooperate to prevent the terminal body 31 from disengaging from the lead-out hole. Along the first direction Z, the projected area of ​​the first limiting part 32 and the projected area of ​​the second limiting part 33 are both larger than the projected area of ​​the terminal body 31. Alternatively, the projected area of ​​the first limiting part 32 can be larger than the projected area of ​​the second limiting part 33, or the projected area of ​​the second limiting part 33 can be larger than the projected area of ​​the first limiting part 32. The first limiting part 32, the second limiting part 33 and the terminal body 31 can be integrally formed, or one of the first limiting part 32 and the second limiting part 33 can be integrally formed with the terminal body 31, while the other is separately provided and connected to the terminal body 31.

[0483] As an example, the battery cell 10 may also include a first insulating member 6 and a second insulating member 7. The first insulating member 6 is at least partially disposed between the electrode terminal 3 and the end cap 12 to insulate and isolate the electrode terminal 3 and the end cap 12. The second insulating member 7 is disposed on the side of the end cap 12 facing the electrode assembly 2 to insulate and isolate the electrode assembly 2 and the end cap 12.

[0484] In this embodiment, the electrode terminal 3 can be installed on the end cap 12 by riveting, which is easy to install and more economical.

[0485] This application provides a battery 100, including the battery cell 10 provided in any of the above embodiments.

[0486] This application provides an electrical device, including a battery cell 10 provided in any of the above embodiments, the battery cell 10 being used to provide electrical energy to the electrical device.

[0487] This application embodiment also provides a battery cell 10, which includes a housing 11, an end cap 12, and an electrode assembly 2. The housing 11 has an opening at one end along a first direction Z. The end cap 12 is welded to the housing 11 and closes the opening of the housing 11. The electrode assembly 2 is at least partially housed within the housing 11. The housing 11 is cuboid in shape and includes two first walls 111, two second walls 112, and four corner walls 113. The first walls 111 are the walls with the largest outer surface area in the housing 11. Adjacent first walls 111 and second walls 112 are connected by a corner wall 113. The two first walls 111 are arranged opposite each other along a second direction Y, and the two second walls 112 are arranged opposite each other along a third direction X. The first direction Z, the second direction Y, and the third direction X are perpendicular to each other. Electrode assembly 2 includes a positive electrode 22, a negative electrode 23, and a separator 24. The separator 24 is disposed between the positive electrode 22 and the negative electrode 23. Electrode assembly 2 has a flat region 25. The portions of the positive electrode 22, the negative electrode 23, and the separator 24 located in the flat region 25 are stacked along the second direction Y. Electrode assembly 2 includes a first surface 27 perpendicular to the second direction Y. The first surface 27 is the surface with the largest area among the outer surfaces of electrode assembly 2. A first wall 111 is disposed opposite to the first surface 27 along the second direction Y.

[0488] The first wall 111 is welded to the end cap 12 to form a first connecting portion 51. The first wall 111 includes a first region 1111 and a second region 1112 arranged along the first direction Z. The thickness of the first region 1111 is greater than the thickness of the second region 1112. The first region 1111 is located between the first connecting portion 51 and the second region 1112. The material of the shell 11 includes aluminum alloy. The maximum thickness of the second region 1112 is D1, the maximum thickness of the first region 1111 is D2, and the dimension of the shell 11 along the second direction Y is D, where 0.005≤D1 / D≤0.065, 0.4mm≤D1≤0.8mm, and 0.5mm≤D2≤1.5mm. The corner wall 113 is welded to the end cap 12 to form a second connecting portion 52. The corner wall 113 includes a third region 1131 and a fourth region 1132 arranged along the first direction Z. The thickness of the third region 1131 is greater than the thickness of the fourth region 1132, and the third region 1131 is located between the fourth region 1132 and the second connecting portion 52. The dimension of the first region 1111 along the third direction X is greater than the dimension of the second region 1112 along the first direction Z. The two ends of the first region 1111 along the third direction X are directly connected to the third regions 1131 of the two corner walls 113 respectively. Along the circumference of the opening, the corner wall 113 has a first connecting end 1133 and a second connecting end 1134. The first wall 111 is connected to the first connecting end 1133, and the second wall 112 is connected to the second connecting end 1134. The thickness of the third region 1131 decreases from the first connecting end 1133 to the second connecting end 1134. The first region 1111 includes a first part 11111 and a second part 11112 arranged along the first direction Z. The second part 11112 connects the first part 11111 and the second region 1112. The thickness of the first part 11111 is greater than the thickness of the second part 11112. The thickness of the second part 11112 decreases along the direction from the end cap 12 toward the electrode assembly 2.

[0489] The positive electrode 22 includes a positive electrode body region 221 protruding from the positive electrode body region 221 and a positive electrode tab 21a. The negative electrode 23 includes a negative electrode body region 231 and a negative electrode tab 21b protruding from the negative electrode body region 231. Along the first direction Z, the positive electrode body region 221 has a fifth end 2211 facing the end cap 12, and the negative electrode body region 231 has a sixth end 2311 facing the end cap 12. The isolator 24 has a seventh end 241 facing the end cap 12, and the seventh end 241 is closer to the end cap 12 than the fifth end 2211 and the sixth end 2311. The isolator 24 includes an extension region 242 extending beyond the fifth end 2211 and the sixth end 2311 along the first direction Z. In a projection plane perpendicular to the second direction Y, the extension region 242 overlaps with the orthographic projection portion of the first region 1111. The first region 1111 includes a first protrusion 11118 protruding from the first inner surface 11121; in the projection plane perpendicular to the second direction Y, the orthographic projection of the positive electrode main body region 221 and the first protrusion 11118 does not overlap; in the projection plane perpendicular to the second direction Y, the orthographic projection of the negative electrode main body region 231 and the first protrusion 11118 does not overlap.

[0490] The first wall 111 also includes a first transition region 1117, which is connected to the end of the first region 1111 away from the second region 1112 along the first direction Z. The first transition region 1117 is connected to the first connecting portion 51, and the connection position of the first transition region 1117 and the first connecting portion 51 forms a first connecting interface 511. The first connecting interface 511 has a first position 5111 closest to the first region 1111 along the first direction Z. The first position 5111 is located at the end of the first region 1111 away from the second region 1112 along the first direction Z. The first connecting interface 511 includes a second interface 5113, which extends obliquely from the first position 5111 away from the end cap 12 along the second direction Y. A portion of the first connecting portion 51 is located between the second interface 5113 and the end cap 12. The second interface 5113 is connected to the inner surface of the first region 1111 at the first position 5111.

[0491] The corner wall 113 also includes a second transition region 1135, which is connected to the end of the third region 1131 away from the fourth region 1132 along the first direction Z. The second transition region 1135 is connected to the second connecting portion 52, and the connection position of the second transition region 1135 and the second connecting portion 52 forms a second connecting interface 521. The second connecting interface 521 has a second position 5211 that is closest to the third region 1131 along the first direction Z. The second position 5211 is located at the end of the third region 1131 away from the fourth region 1132 along the first direction Z. The second connecting interface 521 includes a fourth interface 5213, which extends obliquely from the second position 5211 in a direction away from the end cap 12. Along the thickness direction of the corner wall 113, a portion of the second connecting portion 52 is located between the fourth interface 5213 and the end cap 12. The fourth interface 5213 is connected to the inner surface of the third region 1131 at the second position 5211.

[0492] This application embodiment also provides a battery cell 10, which includes a housing 11, an end cap 12, and an electrode assembly 2. The housing 11 has an opening at one end along a first direction Z. The end cap 12 is welded to the housing 11 and closes the opening of the housing 11. The electrode assembly 2 is at least partially housed within the housing 11. The housing 11 is cuboid in shape and includes two first walls 111, two second walls 112, and four corner walls 113. The first walls 111 are the walls with the largest outer surface area in the housing 11. Adjacent first walls 111 and second walls 112 are connected by a corner wall 113. The two first walls 111 are arranged opposite each other along a second direction Y, and the two second walls 112 are arranged opposite each other along a third direction X. The first direction Z, the second direction Y, and the third direction X are perpendicular to each other. Electrode assembly 2 includes a positive electrode 22, a negative electrode 23, and a separator 24. The separator 24 is disposed between the positive electrode 22 and the negative electrode 23. Electrode assembly 2 has a flat region 25. The portions of the positive electrode 22, the negative electrode 23, and the separator 24 located in the flat region 25 are stacked along the second direction Y. Electrode assembly 2 includes a first surface 27 perpendicular to the second direction Y. The first surface 27 is the surface with the largest area among the outer surfaces of electrode assembly 2. A first wall 111 is disposed opposite to the first surface 27 along the second direction Y.

[0493] The first wall 111 is welded to the end cap 12 to form a first connecting portion 51. The first wall 111 includes a first region 1111 and a second region 1112 arranged along the first direction Z. The thickness of the first region 1111 is greater than the thickness of the second region 1112. The first region 1111 is located between the first connecting portion 51 and the second region 1112. The material of the shell 11 includes aluminum alloy. The maximum thickness of the second region 1112 is D1, the maximum thickness of the first region 1111 is D2, and the dimension of the shell 11 along the second direction Y is D, where 0.005≤D1 / D≤0.065, 0.4mm≤D1≤0.8mm, and 0.5mm≤D2≤1.5mm.

[0494] The dimension of the first region 1111 along the third direction X is greater than the dimension of the first region 1111 along the first direction Z. The first region 1111 includes a first part 11111 and a second part 11112 arranged along the first direction Z. The second part 11112 connects the first part 11111 and the second region 1112. The thickness of the first part 11111 is greater than the thickness of the second part 11112. The thickness of the second part 11112 decreases along the direction from the end cap 12 toward the electrode assembly 2.

[0495] The first zone 1111 does not contact the corner wall 113 at either end along the third direction X. The first zone 1111 includes a second connecting segment 11114, a first connecting segment 11113, and a third connecting segment 11115 arranged along the third direction X. The first connecting segment 11113 passes through the mid-section, and the thickness of the first connecting segment 11113 is greater than the thickness of the second connecting segment 11114 and the third connecting segment 11115. The first connecting segment 11113 has a dimension L1 along the third direction X, and the first wall 111 has a dimension L along the third direction X, where 0.2 ≤ L1 / L ≤ 0.6. The first connecting segment 11113 has a first end 11113a and a second end 11113b along the third direction X. The first wall 111 has a third end 1113 and a fourth end 1114 along the third direction X. The first end 11113a is close to the third end 1113, and the second end 11113b is close to the fourth end 1114. The dimension of the first wall 111 along the third direction X is L. The minimum distance between the first end 11113a and the third end 1113 along the third direction X is L2, and the minimum distance between the second end 11113b and the fourth end 1114 along the third direction X is L3. L2 / L≤0.3, L3 / L≤0.3, and 100mm≤L≤450mm.

[0496] The positive electrode 22 includes a positive electrode body region 221 protruding from the positive electrode body region 221 and a positive electrode tab 21a. The negative electrode 23 includes a negative electrode body region 231 and a negative electrode tab 21b protruding from the negative electrode body region 231. Along the first direction Z, the positive electrode body region 221 has a fifth end 2211 facing the end cap 12, and the negative electrode body region 231 has a sixth end 2311 facing the end cap 12. The isolator 24 has a seventh end 241 facing the end cap 12, and the seventh end 241 is closer to the end cap 12 than the fifth end 2211 and the sixth end 2311. The isolator 24 includes an extension region 242 extending beyond the fifth end 2211 and the sixth end 2311 along the first direction Z. In a projection plane perpendicular to the second direction Y, the extension region 242 overlaps with the orthographic projection portion of the first region 1111. The first region 1111 includes a first protrusion 11118 protruding from the first inner surface 11121; in the projection plane perpendicular to the second direction Y, the orthographic projection of the positive electrode main body region 221 and the first protrusion 11118 does not overlap; in the projection plane perpendicular to the second direction Y, the orthographic projection of the negative electrode main body region 231 and the first protrusion 11118 does not overlap.

[0497] The first wall 111 also includes a first transition region 1117, which is connected to the end of the first region 1111 away from the second region 1112 along the first direction Z. The first transition region 1117 is connected to the first connecting portion 51, and the connection position of the first transition region 1117 and the first connecting portion 51 forms a first connecting interface 511. The first connecting interface 511 has a first position 5111 closest to the first region 1111 along the first direction Z. The first position 5111 is located at the end of the first region 1111 away from the second region 1112 along the first direction Z. The first connecting interface 511 includes a second interface 5113, which extends obliquely from the first position 5111 away from the end cap 12 along the second direction Y. A portion of the first connecting portion 51 is located between the second interface 5113 and the end cap 12. The second interface 5113 is connected to the inner surface of the first region 1111 at the first position 5111.

[0498] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0499] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit this application. For those skilled in the art, this application can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized by, include: A housing having an opening at at least one end along a first direction, the housing including a first wall; An end cap is provided to close the opening, and the first wall is welded to the end cap to form a first connection portion. An electrode assembly, at least partially housed within the housing, includes a positive electrode and a negative electrode, at least portions of the positive electrode and the negative electrode being stacked along a second direction parallel to the thickness direction of the first wall, and the first direction intersecting the second direction. The first wall includes a first region and a second region arranged along the first direction, the thickness of the first region is greater than the thickness of the second region, and the first region is located between the first connecting portion and the second region.

2. The battery cell of claim 1, wherein, The electrode assembly has a flat region, and the portion of the positive electrode plate located in the flat region and the portion of the negative electrode plate located in the flat region are stacked along the second direction.

3. The battery cell of claim 2, wherein, The electrode assembly includes an adjacent first surface and a second surface, the first surface being perpendicular to the second direction, the area of ​​the first surface being larger than the area of ​​the second surface, and the first surface and the first wall being disposed opposite each other along the second direction.

4. The battery cell of claim 3, wherein, The first surface is the surface with the largest area among the outer surfaces of the electrode assembly.

5. The battery cell of claim 3, wherein the cathode comprises a lithium metal oxide. The electrode assembly is a wound structure, and the electrode assembly also has a corner area. The corner area is provided at least one end of the straight area along a third direction. The first direction, the second direction and the third direction are not coplanar and intersect each other. The outer surface of the straight area includes the first surface, and the outer surface of the corner area includes the second surface, at least a portion of which is an arc surface.

6. The battery cell of claim 3, wherein, The electrode assembly is a stacked structure, and the flat region includes a plurality of positive electrode plates and a plurality of negative electrode plates. The plurality of positive electrode plates and the plurality of negative electrode plates are stacked along the second direction, and the first surface is perpendicular to the second surface.

7. The battery cell as described in claim 1, characterized in that, The first wall is the wall with the largest outer surface area in the shell.

8. The battery cell of claim 1, wherein, The housing includes two first walls disposed opposite each other along the second direction, and the electrode assembly is located between the two first walls.

9. The battery cell of claim 1, wherein, The first region includes a first part and a second part arranged along the first direction, the second part connecting the first part and the second region, and the thickness of the first part being greater than the thickness of the second part.

10. The battery cell of claim 9, wherein the cathode comprises a lithium metal oxide. The thickness of the second part decreases along the direction from the end cap toward the electrode assembly.

11. The battery cell as described in claim 1, characterized in that, The dimension of the first region along the third direction is greater than the dimension of the first region along the first direction, and the first direction, the second direction, and the third direction are not coplanar and intersect each other.

12. The battery cell of claim 11, wherein, The first region includes a first connecting segment that passes through the mid-section of the first wall. The mid-section is perpendicular to the third direction, and the mid-section is equidistant from both ends of the first wall along the third direction.

13. The battery cell as described in claim 12, characterized in that, The first area further includes a second connecting segment and a third connecting segment. The second connecting segment, the first connecting segment, and the third connecting segment are arranged along the third direction. The first connecting segment connects the second connecting segment and the third connecting segment. The thickness of the first connecting segment is greater than the thickness of the second connecting segment and the thickness of the third connecting segment.

14. The battery cell as described in claim 13, characterized in that, The first region further includes a first transition segment, the first connecting segment, the first transition segment, and the second connecting segment are arranged along the third direction, the first transition segment connects the second connecting segment and the first connecting segment, and the thickness of the first transition segment increases along the direction from the second connecting segment to the first connecting segment; and / or, the first region further includes a second transition segment, the first connecting segment, the second transition segment, and the third connecting segment are arranged along the third direction, the second transition segment connects the third connecting segment and the first connecting segment, and the thickness of the second transition segment increases along the direction from the third connecting segment to the first connecting segment.

15. The battery cell as described in claim 12, characterized in that, The dimension of the first connecting segment along the third direction is L1, and the dimension of the first wall along the third direction is L, where 0.2≤L1 / L≤0.

6.

16. The battery cell as described in claim 12, characterized in that, The first connecting segment has a first end and a second end opposite to each other along the third direction, the first wall has a third end and a fourth end opposite to each other along the third direction, the first end is close to the third end, the second end is close to the fourth end, the dimension of the first wall along the third direction is L, the minimum distance between the first end and the third end along the third direction is L2, the minimum distance between the second end and the fourth end along the third direction is L3; L2 / L≤0.3; and / or, L3 / L≤0.

3.

17. The battery cell as described in claim 16, characterized in that, 100mm≤L≤450mm.

18. The battery cell as described in claim 11, characterized in that, The housing includes corner walls, and the first wall is connected to both ends of the corner walls in the third direction; The first region does not contact the corner wall at at least one end along the third direction; or, the first region extends to the two corner walls at both ends along the third direction.

19. The battery cell of any one of claims 1-18, wherein, The electrode assembly further includes an insulating element, which is disposed between the positive electrode and the negative electrode. The positive electrode includes a positive electrode body region and a positive electrode tab protruding from the positive electrode body region. The positive electrode body region has a positive electrode active material layer. The negative electrode includes a negative electrode body region and a negative electrode tab protruding from the negative electrode body region. The negative electrode body region has a negative electrode active material layer. Along the first direction, the positive electrode body region has a fifth end facing the end cap, the negative electrode body region has a sixth end facing the end cap, and the separator has a seventh end facing the end cap. The seventh end is closer to the end cap than the fifth end and the sixth end.

20. The battery cell of claim 19, wherein, The isolation member includes an extension area extending beyond the fifth end and the sixth end along a first direction, and in a projection plane perpendicular to the second direction, the orthographic projection of the extension area partially overlaps with the orthographic projection of the first area.

21. The battery cell as described in claim 19, characterized in that, The second region has a first inner surface facing the interior space of the housing, and the first region includes a first protrusion protruding from the first inner surface; In a projection plane perpendicular to the second direction, the orthographic projection of the positive electrode main body area does not overlap with the orthographic projection of the first protrusion; and / or, in a projection plane perpendicular to the second direction, the orthographic projection of the negative electrode main body area does not overlap with the orthographic projection of the first protrusion.

22. The battery cell of any one of claims 1-18, wherein, The negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one side of the negative current collector, wherein the negative active material layer includes a negative active material.

23. The battery cell as described in claim 22, characterized in that, The negative electrode active material layer includes a negative electrode main body and a negative electrode thinning part. The negative electrode main body and the negative electrode thinning part are arranged along the first direction. Along the first direction, the negative electrode thinning part is provided at one end of the negative electrode main body near the end cap.

24. The battery cell as described in claim 23, characterized in that, In a projection plane perpendicular to the second direction, the orthographic projection of the negative electrode thinning portion and the orthographic projection of the first region are spaced apart along the first direction.

25. The battery cell as described in claim 24, characterized in that, In the projection plane perpendicular to the second direction, the distance between the orthographic projection of the negative electrode thinning portion and the orthographic projection of the first region along the first direction is greater than or equal to 1 mm.

26. The battery cell as described in claim 22, characterized in that, The single-sided coating weight of the negative electrode active material layer is 90 mg / 1540 mm. 2 ~170mg / 1540mm 2 110mg / 1540mm is available as an option. 2 ~150mg / 1540mm 2 .

27. The battery cell as described in claim 22, characterized in that, The porosity of the negative electrode sheet is 27% to 40%.

28. The battery cell as described in claim 22, characterized in that, The negative electrode active material includes a silicon-based material, wherein the silicon element in the silicon-based material has a mass content of 0.3% to 10%, optionally 1% to 6%.

29. The battery cell as described in claim 28, characterized in that, The silicon-based material includes at least one of silicon oxides and silicon-carbon composites.

30. The battery cell of any one of claims 1-18, wherein, The positive electrode includes a positive current collector and a positive active material layer disposed on at least one side of the positive current collector, wherein the positive active material layer includes a positive active material.

31. The battery cell of claim 30, wherein the cathode comprises a lithium metal oxide. The positive electrode active material layer includes a positive electrode body portion and a positive electrode thinning portion. The positive electrode body portion and the positive electrode thinning portion are arranged along the first direction. Along the first direction, the positive electrode thinning portion is provided at one end of the positive electrode body portion near the end cap.

32. The battery cell of claim 31, wherein the cathode comprises a lithium metal oxide. In a projection plane perpendicular to the second direction, the orthographic projection of the positive electrode thinning portion and the orthographic projection of the first region are spaced apart along the first direction.

33. The battery cell as described in claim 32, characterized in that, In a projection plane perpendicular to the second direction, the distance between the orthographic projection of the positive electrode thinning portion and the orthographic projection of the first region along the first direction is greater than or equal to 1 mm.

34. The battery cell as described in claim 30, characterized in that, The single-sided coating weight of the positive electrode active material layer is 200 mg / 1540 mm. 2 ~370mg / 1540 / mm 2 ; 240mg / 1540mg is optional 2 ~330mg / 1540mm 2 .

35. The battery cell as described in claim 30, characterized in that, The positive electrode active material is a lithium phosphate.

36. The battery cell of any one of claims 1-18, wherein, The shell is made of steel; The maximum thickness of the second region is D1, and the dimension of the shell along the second direction is D, where 0.001≤D1 / D≤0.

012.

37. The battery cell of any one of claims 1-18, wherein, The shell is made of steel; The maximum thickness of the second region is D1, 0.08mm≤D1≤0.35mm; and / or, the maximum thickness of the first region is D2, 0.1mm≤D2≤0.6mm.

38. The battery cell of any one of claims 1-18, wherein, The housing is made of aluminum alloy; The maximum thickness of the second region is D1, and the dimension of the shell along the second direction is D, where 0.005≤D1 / D≤0.

065.

39. The battery cell of any one of claims 1-18, wherein, The housing is made of aluminum alloy; The maximum thickness of the second region is D1, 0.4mm≤D1≤0.8mm; and / or, the maximum thickness of the first region is D2, 0.5mm≤D2≤1.5mm.

40. The battery cell of claim 39, wherein the cathode comprises a lithium metal oxide. The aluminum alloy comprises the following components by mass percentage: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other individual elements ≤ 0.03%.

41. The battery cell of any one of claims 1-18, wherein, The first area is directly connected to the first connecting part.

42. The battery cell of any one of claims 1-18, wherein, The first wall further includes a first transition zone, which is connected to the end of the first zone away from the second zone along the first direction. The first transition zone is connected to the first connecting portion, and the connection position of the first transition zone and the first connecting portion forms a first connecting interface. The first connecting interface has a first position closest to the first zone along the first direction, and the first position is located at the end of the first zone away from the second zone along the first direction.

43. The battery cell as described in claim 42, characterized in that, At least a portion of the first connection interface extends at an angle relative to the second direction.

44. The battery cell of claim 43, wherein the lithium metal anode comprises a lithium metal anode having a surface area of at least 1000 cm2. The first connection interface includes a first interface that extends obliquely from the first position toward the end cap. Along the second direction, at least a portion of the first transition area is located between the first interface and the end cap.

45. The battery cell of claim 44, wherein the lithium metal anode comprises a lithium metal anode having a surface area of at least 1000 cm2. The first interface is connected to the outer surface of the first area at the first position.

46. The battery cell of any one of claims 43-45, wherein, The first connection interface includes a second interface that extends obliquely from the first position toward the end cap. Along the second direction, at least a portion of the first transition area is located on the side of the second interface opposite to the end cap.

47. The battery cell of claim 46, wherein the cathode comprises a lithium metal oxide. The second interface is connected to the inner surface of the first area at the first position.

48. The battery cell as described in claim 42, characterized in that, The Vickers hardness of the first transition zone is less than that of the second zone; and / or, the Vickers hardness of the first transition zone is less than that of the first connecting portion.

49. The battery cell as described in claim 42, characterized in that, Along the first direction, the first connection interface is closer to the second region than the outer surface of the end cap.

50. The battery cell of any one of claims 1-18, wherein, The housing also includes a second wall and a corner wall, the first wall, the corner wall and the second wall are arranged circumferentially along the opening, and the corner wall connects the first wall and the second wall.

51. The battery cell of claim 50, wherein the lithium metal anode comprises a lithium metal anode having a surface area of at least 1000 cm2. The corner wall is welded to the end cap to form a second connection part; The corner wall includes a third zone and a fourth zone arranged along the first direction. The thickness of the third zone is greater than the thickness of the fourth zone. The third zone is located between the fourth zone and the second connecting portion.

52. The battery cell of claim 51, wherein the lithium metal anode comprises a lithium metal anode having a surface area of at least 1000 cm2. The third zone is directly connected to the first zone.

53. The battery cell as described in claim 52, characterized in that, Along the circumference of the opening, the corner wall has a first connecting end and a second connecting end, the first wall being connected to the first connecting end and the second wall being connected to the second connecting end, and the thickness of the third region decreasing along the direction from the first connecting end to the second connecting end.

54. The battery cell of any one of claims 51-53, wherein, The third zone is directly connected to the second connecting part.

55. The battery cell of any one of claims 51-53, wherein, The corner wall further includes a second transition zone, which is connected to the end of the third zone away from the fourth zone along the first direction. The second transition zone is connected to the second connecting part, and the connection position of the second transition zone and the second connecting part forms a second connecting interface. The second connecting interface has a second position that is closest to the third zone along the first direction. The second position is located at the end of the third zone away from the fourth zone along the first direction.

56. The battery cell of claim 55, wherein the lithium metal anode comprises a lithium metal anode having a surface area of at least 1000 cm2. At least a portion of the second connection interface extends obliquely relative to the thickness direction of the corner wall.

57. The battery cell of claim 56, wherein the lithium metal anode comprises a lithium metal anode having a surface area of at least 1000 cm2. The second connection interface includes a third interface that extends obliquely from the second position toward the end cap along the thickness direction of the corner wall, and at least a portion of the second transition area is located between the third interface and the end cap.

58. The battery cell as described in claim 57, characterized in that, The third interface is connected to the outer surface of the third region at the second position.

59. The battery cell of any one of claims 56-58, wherein, The second connection interface includes a fourth interface that extends obliquely from the second position toward the end cap along the thickness direction of the corner wall, and at least a portion of the second transition area is located on the side of the fourth interface away from the end cap.

60. The battery cell of claim 59, wherein the lithium metal anode comprises a lithium metal anode having a surface area of at least 1000 cm2. The fourth interface is connected to the inner surface of the third region at the second position.

61. The battery cell as described in claim 55, characterized in that, The Vickers hardness of the second transition zone is less than that of the fourth zone; and / or, the Vickers hardness of the second transition zone is less than that of the second connecting portion.

62. The battery cell as described in claim 55, characterized in that, Along the first direction, the second connection interface is closer to the fourth region than the outer surface of the end cap.

63. The battery cell as described in claim 50, characterized in that, The housing includes two first walls and two second walls. The two first walls are arranged opposite each other along the second direction, and the two second walls are arranged opposite each other along the third direction. The first direction, the second direction, and the third direction are perpendicular to each other.

64. The battery cell of any one of claims 1-18, wherein, At least a portion of the Vickers hardness in the first region is less than that in the second region.

65. The battery cell of any one of claims 1-18, wherein, Along the first direction, the first wall has a limiting surface facing the end cap, the limiting surface abutting against the end cap to restrict the end cap from moving toward the electrode assembly.

66. The battery cell of claim 65, wherein the lithium metal anode comprises a lithium metal anode having a surface area of at least 1000 cm2. The first wall further includes a limiting area disposed on the limiting surface, the limiting area and the end cap being disposed opposite to each other along the second direction, and the limiting area and the end cap being welded to form the first connecting part.

67. The battery cell according to any one of claims 1-18, characterized in that, The electrode assembly is a stacked structure, comprising a plurality of positive electrode plates and a plurality of negative electrode plates, which are stacked along the second direction.

68. The battery cell of claim 67, wherein the lithium metal anode comprises a lithium metal anode having a surface area of at least 1000 cm2. The number of negative electrode plates is greater than the number of positive electrode plates, and a positive electrode plate is disposed between two adjacent negative electrode plates.

69. The battery cell of claim 67, wherein the lithium metal anode comprises a lithium metal anode having a surface area of at least 1000 cm2. Each of the negative electrode plates is provided with a negative electrode tab; and / or, each of the positive electrode plates is provided with a positive electrode tab.

70. The battery cell as described in claim 67, characterized in that, Along the third direction, the size of the first region is larger than the size of the positive electrode and / or the size of the negative electrode, and the first direction, the second direction and the third direction are perpendicular to each other.

71. The battery cell of any one of claims 1-18, wherein, The battery cell also includes two electrode terminals, which are disposed on the end cap. The two electrode terminals have opposite polarities and are both electrically connected to the electrode assembly. The end cap is provided with an outlet hole. The electrode terminal includes a terminal body, a first limiting part and a second limiting part. The terminal body is connected to the first limiting part and the second limiting part. The terminal body passes through the outlet hole. Along the first direction, the first limiting part is located on the side of the end cap away from the electrode assembly, and the second limiting part is located on the side of the end cap facing the electrode assembly.

72. A battery, comprising: Includes the battery cell as described in any one of claims 1-71.

73. An electrical device, comprising: Includes a battery cell as described in any one of claims 1-71, the battery cell being used to provide electrical energy to the electrical equipment.

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