Battery monomer, battery and electric equipment

Abstract

The embodiment of the invention provides a battery monomer, a battery and electric equipment. The battery cell includes a case, an end cap, and an electrode assembly. At least one end of the shell in the first direction is provided with an opening, the shell comprises a first wall, the end cover seals the opening, and the first wall and the end cover are welded to form a first connecting part. The electrode assembly is at least partially contained in the shell and comprises a positive pole piece and a negative pole piece, at least part of the positive pole piece and at least part of the negative pole piece are stacked in the second direction, the second direction is parallel to the thickness direction of the first wall, and the first direction intersects with the second direction. The first wall comprises a first area and a second area which are arranged in the first direction, the thickness of the first area is larger than that of the second area, and the first area is located between the first connecting part and the second area. And the risk of fatigue cracking of the area, near the first connecting part, of the first wall due to expansion of the electrode assembly is reduced, so that the service life of the battery monomer is prolonged.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of International Patent Application PCT / CN2024 / 089160 entitled "A Battery Cell, Battery and Electrical Appliance" filed on April 22, 2024, International Patent Application PCT / CN2023 / 135607 entitled "Battery Cell, Battery, Electrical Equipment and Energy Storage Device" filed on November 30, 2023, and International Patent Application PCT / CN2023 / 134129 entitled "Housing, Battery Cell, Battery and Electrical Appliance" filed on November 24, 2023. The entire contents of these three applications are incorporated herein by reference. Technical field

[0003] This application relates to the technical field of batteries. Specifically, it relates to a battery cell, a battery and an electrical equipment. Background art

[0004] Energy conservation and emission reduction are the keys to the sustainable development of the automotive industry. Electric vehicles have become an important part of the sustainable development of the automotive industry due to their energy - saving and environmental - protection advantages. For electric vehicles, battery technology is an important factor related to their development.

[0005] In battery technology, the service life of a battery cell is an issue that cannot be ignored. Therefore, how to improve the service life of a battery cell is an urgent technical problem in battery technology. Summary of the invention

[0006] The embodiments of this application provide a battery cell, a battery and an electrical equipment, which can effectively improve the service life of the battery cell.

[0007] In a first aspect, the embodiments of this application provide a battery cell. The battery cell includes a housing, an end - cover and an electrode assembly; at least one end of the housing in a first direction has an opening, and the housing includes a first wall; the end - cover closes the opening, and the first wall is welded to the end - cover to form a first connection part; the electrode assembly is at least partially accommodated in the housing, the electrode assembly includes a positive electrode tab and a negative electrode tab, at least a part of the positive electrode tab and at least a part of the negative electrode tab are stacked in a second direction, the second direction is parallel to the thickness direction of the first wall, and the first direction intersects with the second direction; the first wall includes a first region and a second region arranged in the first direction, the thickness of the first region is greater than that of the second region, and the first region is located between the first connection part 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 connection portion and the second region, such that the first region with a greater thickness is closer to the first connection portion than the second region. The first region strengthens the region of the first wall near the first connection portion, reducing the risk of fatigue cracking of the region of the first wall near the first connection portion 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 the portion of the positive electrode tab located in the flat region and the portion of the negative electrode tab located in the flat region are stacked along the second direction. The second direction is the stacking direction of the portion of the positive electrode tab located in the flat region and the portion of the negative electrode tab located in the flat region. During cycling, the electrode assembly expands more along the second direction, and the first wall is more affected by the expansion of the electrode assembly. However, since the first region strengthens the region 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 is reduced.

[0010] In some embodiments, the electrode assembly includes an adjacent first surface and a second surface. The first surface is perpendicular to the second direction, and the area of the first surface is greater than the area of the second surface. The first surface is disposed opposite to the first wall along the second direction. The larger area of the first surface compared to the area of the second surface causes the first wall disposed opposite to the first surface in the housing to be subjected to a greater expansion force. Since the first region strengthens the region 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 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 causes the first wall disposed opposite to the first surface in the housing to be subjected to the greatest expansion force. Since the first region strengthens the region 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 is reduced.

[0012] In some embodiments, the electrode assembly is a wound structure, and the electrode assembly further has a corner region. The corner region is provided at at least one end of the flat region along the third direction. The first direction, the second direction, and the third direction are non-coplanar and intersect pairwise; the outer surface of the flat region includes the first surface, and the outer surface of the corner region includes the second surface, and at least a part of the second surface is an arc surface. For a wound electrode assembly, the flat region expands more in the second direction. Since the first region strengthens the region 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.

[0013] In some embodiments, the electrode assembly has a laminated structure. 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. For a laminated electrode assembly, the expansion amount of the electrode assembly in the stacking direction of the positive electrode plate and the negative electrode plate is larger. Since the first region reinforces the region 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 likely to deform after being subjected to 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 portion due to the expansion of the electrode assembly is reduced.

[0015] In some embodiments, the housing includes two first walls. Along the second direction, the two first walls are arranged opposite to each other, and the electrode assembly is located between the two first walls. In this way, the risk of fatigue cracking of the two first walls near the first connection portion due to the expansion of the electrode assembly is reduced.

[0016] In some embodiments, the first region includes a first portion and a second portion arranged along the first direction. 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 region of the first region near the first connection portion is more likely to form a heat-affected zone, and this region is more likely to suffer from fatigue cracking. However, since 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 portion, which can effectively weaken the influence of the heat-affected zone on the first region and reduce the risk of fatigue cracking of the region of the first wall near the first connection portion. In addition, since 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, and the production cost is lowered.

[0017] In some embodiments, the thickness of the second portion shows a decreasing trend in the direction from the end cover to the electrode assembly. On the one hand, it can reduce the influence of the second portion on the electrode assembly and lower the risk of interference between the second portion and the electrode assembly; on the other hand, it makes the strengthening effect of the second portion show an increasing trend in the direction from the electrode assembly to the end cover, so that the region of the second portion close to the first portion has a good strengthening effect even under the influence of the first connection portion, reducing the risk of fatigue cracking of the first wall in the second portion; on the other hand, through the second portion, the transition between the first portion and the second region can be realized, reducing stress concentration.

[0018] In some embodiments, 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 non-coplanar and intersect pairwise. Making the dimension of the first region along the third direction larger, so that the strength of more regions of the first wall along the third direction is enhanced, and further reducing the risk of fatigue cracking in the region of the first wall near the first connection portion.

[0019] In some embodiments, the first region includes a first connection segment that passes through the mid-section of the first wall. The mid-section is perpendicular to the third direction, and the distances from the mid-section to the two 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 amount of the middle region of the first wall along the third direction is larger, and the middle region of the first wall along the third direction is more prone to fatigue cracking. Since the first connection 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 enhanced, reducing the risk of fatigue cracking in the middle region of the first wall along the third direction near the first connection portion.

[0020] In some embodiments, the first region further includes a second connection segment and a third connection segment. The second connection segment, the first connection segment, and the third connection segment are arranged along the third direction. The first connection segment connects the second connection segment and the third connection segment, and the thickness of the first connection segment is greater than the thicknesses of the second connection segment and the third connection segment. When the first wall is subjected to the expansion force of the electrode assembly, the deformation amount of the first wall along the third direction gradually decreases from the middle to the two ends. By dividing the first region into a multi-segment structure, and setting the thickness of the first connection segment located in the middle region to be larger, and setting the thicknesses of the second connection segment and the third connection segment respectively located at the two ends of the first connection segment to be smaller, in this way, according to the different deformation amounts of different regions of the first wall along the third direction, the first region is designed specifically, thereby specifically improving the strength of different regions of the first wall along the third direction. While making the region of the first wall near the first connection portion have sufficient strength, the material consumption of the first region is reduced, and the production cost is lowered.

[0021] In some embodiments, the first region further includes a first transition section. The first connection section, the first transition section, and the second connection section are arranged along a third direction. The first transition section connects the second connection section and the first connection section, and the thickness of the first transition section increases in a direction from the second connection section towards the first connection section; and / or, the first region further includes a second transition section. The first connection section, the second transition section, and the third connection section are arranged along the third direction. The second transition section connects the third connection section and the first connection section, and the thickness of the second transition section increases in a direction from the third connection section towards the first connection section. If the second connection section and the first connection section are connected through the first transition section, and the thickness of the first transition section increases in a direction from the second connection section towards the first connection section, the first transition section can achieve the transition between the second connection section and the first connection section, reducing stress concentration. If the third connection section and the first connection section are connected through the second transition section, and the thickness of the second transition section increases in a direction from the third connection section towards the first connection section, the second transition section can achieve the transition between the third connection section and the first connection section, reducing stress concentration.

[0022] In some embodiments, the dimension of the first connection section along the third direction is L 1 , the dimension of the first wall along the third direction is L, and 0.2 ≤ L 1 / L ≤ 0.6. L 1 / L ≥ 0.2 increases the proportion of the dimension of the first connection section in the first wall along the third direction, so that the range of the middle region of the first wall along the third direction is strengthened more, improving the strength of the middle region of the first wall along the third direction; L 1 / L ≤ 0.6 reduces the proportion of the dimension of the first connection section in the first wall along the third direction, reduces the material used for the first connection section, and reduces the production cost. Therefore, setting the ratio of the dimension of the first connection section along the third direction to the dimension of the first wall along the third direction to be 0.2 to 0.6 can, while enabling the first connection section to have sufficient strengthening ability, reduce the material used for the first connection section, taking into account both the strengthening ability requirements and the economic requirements of the first connection section.

[0023] In some embodiments, the first connection section has opposite first and second ends along the third direction, the first wall has opposite third and fourth ends 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 L 2 , and the minimum distance between the second end and the fourth end along the third direction is L 3 ; L 2 / L ≤ 0.3; and / or, L 3 / L ≤ 0.3. If L 2 / L ≤ 0.3 reduces the proportion of the minimum distance between the first end and the third end in the dimension of the first wall along the third direction, enabling more regions of the first wall along the third direction to have enhanced strength, and further reducing the risk of fatigue cracking in the region of the first wall near the first connection portion. If L 3 / L ≤ 0.3 reduces the proportion of the minimum distance between the second end and the fourth end in the dimension of the first wall along the third direction, enabling more regions of the first wall along the third direction to have enhanced strength, and further reducing the risk of fatigue cracking in the region of the first wall near the first connection portion.

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

[0025] In some embodiments, the housing includes corner walls, and both ends of the first wall along the third direction are connected to corner walls; at least one end of the first region along the third direction is not in contact with the corner wall; or, both ends of the first region along the third direction extend to two corner walls respectively. If at least one end of the first region along the third direction is not in contact with the corner wall, the material used in the first region can be reduced, and the production cost can be lowered. If both ends of the first region along the third direction extend to two corner walls respectively, the length of the first region is increased, the strengthening ability of the first region is improved, more regions of the first wall along the third direction are strengthened, and the risk of fatigue cracking in the region of the first wall near the first connection portion is further reduced.

[0026] In some embodiments, the electrode assembly further includes a separator, and a separator is disposed between the positive electrode plate and the negative electrode plate; the positive electrode plate includes a positive electrode main region and a positive electrode tab protruding from the positive electrode main region, the positive electrode main region has a positive electrode active material layer, the negative electrode plate includes a negative electrode main region and a negative electrode tab protruding from the negative electrode main region, the negative electrode main region has a negative electrode active material layer, along the first direction, the positive electrode main region has a fifth end facing the end cover, the negative electrode main region has a sixth end facing the end cover, and the separator has a seventh end facing the end cover, and the seventh end is closer to the end cover than the fifth end and the sixth end. This makes the separator have a portion that extends beyond the fifth end and the sixth end, enhancing the insulation effect of the separator between the positive electrode plate and the negative electrode plate, and reducing the risk of overlap between the positive electrode plate and the negative electrode plate.

[0027] In some embodiments, the separator includes an extending region that extends beyond the fifth end and the sixth end along the first direction, and in the projection plane perpendicular to the second direction, the positive projection of the extending region partially overlaps with the positive projection of the first region. This structure can increase the dimension of the first region along the first direction, improve the strengthening ability of the first region, strengthen more regions of the first wall along the first direction, and further reduce the risk of fatigue cracking in the region of the first wall near the first connection portion.

[0028] In some embodiments, the second region has a first inner surface facing the inner space of the housing, and the first region includes a first protruding portion protruding from the first inner surface; in a projection plane perpendicular to the second direction, the orthographic projection of the positive electrode main body region does not overlap with the orthographic projection of the first protruding portion; and / or, in a projection plane perpendicular to the second direction, the orthographic projection of the negative electrode main body region does not overlap with the orthographic projection of the first protruding portion. If in a projection plane perpendicular to the second direction, the orthographic projection of the positive electrode main body region does not overlap with the orthographic projection of the first protruding portion, 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 protruding portion, reducing the deformation amount of the first wall, and further reducing the risk of fatigue cracking in the region of the first wall near the first connection portion. If in a projection plane perpendicular to the second direction, the orthographic projection of the negative electrode main body region does not overlap with the orthographic projection of the first protruding portion, 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 protruding portion, reducing the deformation amount of the first wall, and further reducing the risk of fatigue cracking in the region of the first wall near the first connection portion.

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

[0030] In some embodiments, the negative electrode active material layer includes a negative electrode main body portion and a negative electrode thinning portion, and the negative electrode main body portion and the negative electrode thinning portion are arranged along the first direction. Along the first direction, a negative electrode thinning portion is provided at one end of the negative electrode main body portion close to the end cap. The electrode assembly has a larger expansion gap in the region corresponding to the negative electrode thinning portion, and the force exerted on the first wall by the region of the electrode assembly corresponding to the negative electrode thinning portion after expansion is smaller, which can reduce 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 influence of the negative electrode thinning portion on the first region, reduce the risk that the expansion of the electrode assembly directly applies an expansion force to the first region, and further reduce the risk of fatigue cracking in the region of the first wall near the first connection portion.

[0032] In some embodiments, in a projection plane perpendicular to the second direction, the spacing dimension 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 farther apart along the first direction in the projection plane perpendicular to the second direction, 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 mm2 ~170 mg / 1540 mm 2 。The single-sided coating weight of the negative electrode active material layer is related to the swelling of the negative electrode active material layer. Setting the single-sided coating weight of the negative electrode active material layer at 90 mg / 1540 mm 2 ~170 mg / 1540 mm 2 , can balance the requirements of high energy density of the battery cell and low swelling of the negative electrode sheet to a certain extent, so as to reduce the influence of the swelling of the negative electrode sheet on the first wall, and can reduce 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 ~150 mg / 1540 mm 2 . It can further improve the energy density requirements of the battery cell and further slow down the swelling of the negative electrode sheet.

[0035] In some embodiments, the porosity of the negative electrode sheet is 27% - 40%. This can provide space for impurities generated by side reactions in the negative electrode sheet, slow down the swelling of the negative electrode sheet, and reduce the influence of the swelling of the negative electrode sheet on the first wall.

[0036] In some embodiments, the negative electrode active material includes a silicon-based material, and the mass content of silicon element in the silicon-based material in the negative electrode active material is 0.3% - 10%, and can be selected as 1% - 6%.

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

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

[0039] In some embodiments, the positive electrode active material layer includes a positive electrode main body part and a positive electrode thinning part. The positive electrode main body part and the positive electrode thinning part are arranged along the first direction. Along the first direction, a positive electrode thinning part is provided at one end of the positive electrode main body part close to the end cover. The electrode assembly has a larger expansion gap in the area corresponding to the positive electrode thinning part, and the force exerted on the first wall by the area of the electrode assembly corresponding to the positive electrode thinning part after expansion is smaller, which can reduce the risk of fatigue cracking in the area of the first wall near the first connection part.

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

[0041] In some embodiments, in a projection plane perpendicular to the second direction, the spacing dimension between the positive projection of the positive electrode thinning portion and the positive projection of the first region along the first direction is greater than or equal to 1 mm. This makes the positive projection of the positive electrode thinning portion and the positive projection of the first region farther apart along the first direction in the projection plane perpendicular to the second direction, 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 ~370 mg / 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. By setting the single-sided coating weight of the positive electrode active material layer at 200 mg / 1540 mm 2 ~370 mg / 1540 / mm 2 it is possible to balance the requirements for high energy density of the battery cell and low expansion of the positive electrode sheet to a certain extent, reduce the influence of the expansion of the positive electrode sheet on the first wall, and reduce the risk of fatigue cracking in the region of the first wall near the first connection portion.

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

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

[0045] In some embodiments, the material of the housing includes steel; the maximum thickness of the second region is D 1 , the dimension of the housing along the second direction is D, 0.001 ≤ D 1 / D ≤ 0.012. For a housing made of steel, D 1 / D ≥ 0.001, which increases the thickness ratio of the second region in the housing, enabling the second region to have sufficient strength to meet the strength requirements of the housing; D 1 / D ≤ 0.012, reducing the thickness ratio of the second region in the housing. When the volume of the housing is fixed, the internal space of the housing can be increased, thereby creating more space for the electrode assembly to meet the requirements of the battery cell for volumetric energy density.

[0046] In some embodiments, the material of the housing includes steel; the maximum thickness of the second region is D 1 , 0.08 mm ≤ D 1 ≤ 0.35 mm; and / or, the maximum thickness of the first region is D 2 , 0.1 mm ≤ D 2 ≤ 0.6 mm. For a housing made of steel, if the maximum thickness of the second region is set to 0.08 mm to 0.35 mm, it can not only meet the strength requirements of the second region but also meet the requirements of the battery cell for volumetric energy density. If the maximum thickness of the first region is set to 0.1 mm to 0.6 mm, the first region has sufficient strength to enhance the strength of the region of the first wall near the first connection portion.

[0047] In some embodiments, the material of the housing includes aluminum alloy; the maximum thickness of the second region is D 1 , the dimension of the housing in the second direction is D, 0.005 ≤ D 1 / D ≤ 0.065. For a housing made of aluminum alloy, D 1 / D ≥ 0.005, increasing the thickness ratio of the second region in the housing, so that the second region has sufficient strength to meet the strength requirements of the housing; D 1 / D ≤ 0.065, reducing the thickness ratio of the second region in the housing. When the volume of the housing is fixed, the internal space of the housing can be increased, thereby creating more space for the electrode assembly to meet the requirements of the battery cell for volumetric energy density.

[0048] In some embodiments, the material of the housing includes aluminum alloy; the maximum thickness of the second region is D 1 , 0.4 mm ≤ D 1 ≤ 0.8 mm; and / or, the maximum thickness of the first region is D 2 , 0.5 mm ≤ D 2 ≤ 1.5 mm. For a housing made of aluminum alloy, if the maximum thickness of the second region is set to 0.4 mm to 0.8 mm, it can not only meet the strength requirements of the second region but also meet the requirements of the battery cell for volumetric energy density. If the maximum thickness of the first region is set to 0.5 mm to 1.5 mm, the first region has sufficient strength to enhance the strength of the region of the first wall near the first connection portion.

[0049] In some embodiments, the aluminum alloy comprises components with the following mass percentages: 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 single elements ≤ 0.03%. This aluminum alloy has good processing and forming properties, facilitating the forming of the housing.

[0050] In some embodiments, the first region is directly connected to the first connecting portion. This makes the first region and the first connecting portion closer in the first direction, such that the first region is located near the first connecting portion, further reducing the risk of fatigue cracking in the region of the first wall near the first connecting portion due to the expansion of the electrode assembly.

[0051] In some embodiments, the first wall further includes a first transition region. The first transition region is connected to one end of the first region away from the second region in the first direction. The first transition region is connected to the 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 in the first direction, and the first position is located at one end of the first region away from the second region in the first direction. The connection between the first transition region and the first connecting portion forms the first connection interface, such that the first transition region and the first connecting portion have a sufficiently large contact area, improving the firmness after welding the first wall and the end cover.

[0052] In some embodiments, at least a portion of the first connection interface extends obliquely with respect to the second direction. After the end cover and the first wall are welded, the first connecting portion will shrink as it solidifies, and the first connecting portion will generate tensile stress on the first transition region. When the first wall is subjected to the expansion force of the electrode assembly, the first wall will deform, and the first transition region will generate tensile stress on the first connecting portion. Since at least a portion of the first connection interface extends obliquely with respect to the second direction, near the portion where the first connection interface extends obliquely with respect to the second direction, the tensile stress generated by the contraction of the first connecting portion on the first transition region and the tensile stress generated by the deformation of the first wall on the first connecting portion by the first transition region are not on the same straight line, reducing the risk of fatigue cracking in the region of the first transition region near the first connection interface.

[0053] In some embodiments, the first connection interface includes a first interface. The first interface extends obliquely in the direction towards the end cover from the first position. Along the second direction, at least a portion of the first transition region is located between the first interface and the end cover. The first connecting portion plays a protective role for 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 force application process is blocked by the first connecting portion, reducing the risk of fatigue cracking in the region 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 position, so that the first region and the first connecting portion are in direct connection, so that the first region and the first connecting portion are closer in the first direction, and the risk of fatigue cracking of the area of ​​the first wall near the first connecting portion due to expansion of the electrode assembly is further reduced.

[0055] In some embodiments, the first connection interface includes a second interface, the second interface extends obliquely from the first position in a direction away from the end cap, and along the second direction, at least part of the first transition zone is located on a side of the second interface away from the end cap, so that the first transition zone has a limiting effect on the first connection portion, reducing the risk of the first connection portion falling off.

[0056] In some embodiments, the second interface is connected to the inner surface of the first region at a first position, so that the first region is directly connected to the first connecting portion, so that the first region is closer to the first connecting portion along the first direction, and the risk of fatigue cracking of the area of ​​the first wall near the first connecting portion due to expansion of the electrode assembly is further reduced.

[0057] In some embodiments, the Vickers hardness of the first transition zone is less than the Vickers hardness of the second zone; and / or, the Vickers hardness of the first transition zone is less than the Vickers hardness of the first connection portion. If the Vickers hardness of the first transition zone is less than the Vickers hardness of the second zone, the first transition zone with a lower Vickers hardness is connected to the first connection portion, which can alleviate the rigid pull between the first wall and the first connection portion when the first wall is deformed, and reduce the risk of separation of the first wall from the first connection portion. If the Vickers hardness of the first transition zone is less than the Vickers hardness of the first connection portion, the first transition zone is more likely to deform than the first connection portion, which can alleviate the rigid pull between the first wall and the first connection portion when the first wall is deformed, and reduce the risk of separation of the first wall from the first connection 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, so that the first connection portion can sink deeper into the first wall, which can effectively improve 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, the first wall, the corner wall and the second wall are arranged along the circumference of the opening, and the corner wall connects the first wall and the second wall. In this way, the first wall can transition to the second wall through the corner wall, which can effectively reduce the risk of stress concentration at the corner of the housing.

[0060] In some embodiments, the corner wall is welded to the end cap to form a second connection portion; the corner wall includes a third region and a fourth region arranged in a first direction, the thickness of the third region is greater than that of the fourth region, and the third region is located between the fourth region and the second connection portion. The thickness of the third region is greater than that of the fourth region, and the third region is located between the second connection portion and the fourth region, so that the third region with a greater thickness is closer to the second connection portion than the fourth region. The third region strengthens the region of the corner wall near the second connection portion, reduces the risk of fatigue cracking in the region of the corner wall near the second connection portion, and thus improves the service life of the battery cell.

[0061] In some embodiments, the third region is directly connected to the first region. Connecting the third region directly to the first region makes the first region and the third region form an integral body. The third region and the first region have a promoting effect on each other, enhancing the strengthening effect of the first region on the first wall and the strengthening effect of the second region on the corner wall.

[0062] In some embodiments, along the circumferential direction of the opening, the corner wall has a first connection end and a second connection end. The first wall is connected to the first connection end, and the second wall is connected to the second connection end. The thickness of the third region shows a decreasing trend along the direction from the first connection end to the second connection 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 drive the deformation of the corner wall. Along the circumferential direction of the opening, the closer the corner wall is to the first wall, the greater the influence of the first wall on it, and the greater the deformation amount of the region of the corner wall closer to the first wall. The thickness of the third region shows a decreasing trend along the direction from the first connection end to the second connection end, making the strength of the region of the third region closer to the first wall along the circumferential direction of the opening greater. Thus, the influence of the deformation of the first wall on the corner wall is reduced. While ensuring that the region of the corner wall near the second connection portion has sufficient strength, the material used in the third region is reduced, and the production cost is lowered.

[0063] In some embodiments, the third region is directly connected to the second connection portion. This makes the third region and the second connection portion closer in the first direction, so that the third region is located near the second connection portion, further reducing the risk of fatigue cracking in the region of the corner wall near the second connection portion.

[0064] In some embodiments, the corner wall further includes a second transition region. The second transition region is connected to one end of the third region away from the fourth region in the first direction. The second transition region is connected to the second connection portion, and the connection position between the second transition region and the second connection portion forms a second connection interface. The second connection interface has a second position closest to the third region in the first direction, and the second position is located at one end of the third region away from the fourth region in the first direction. The connection between the second transition region and the second connection portion forms a second connection interface, enabling the second transition region and the second connection portion to have a sufficiently large contact area, improving the firmness after the corner wall is welded to the end cap.

[0065] In some embodiments, at least a portion of the second connection interface extends obliquely in a direction perpendicular to the thickness direction of the corner wall. Near the portion where the second connection interface extends obliquely in the direction perpendicular to the thickness direction of the corner wall, the tensile stress generated by the shrinkage of the second connection portion on the second transition region and the tensile stress generated by the deformation of the corner wall on the second connection portion in the second transition region are not in the same straight line, reducing the risk of fatigue cracking in the region of the second transition region near the second connection interface.

[0066] In some embodiments, the second connection interface includes a third interface that extends obliquely from the second position towards the end cap. Along the thickness direction of the corner wall, at least a portion of the second transition region is located between the third interface and the end cap. The second connection portion protects the second transition region, and when the second transition region deforms outwards, it will be blocked by the second connection portion, reducing the risk of fatigue cracking in the region of the second transition region near the third interface.

[0067] In some embodiments, the third interface is connected to the outer surface of the third region at the second position. This enables the third region and the second connection portion to be in a directly connected state, making the third region and the second connection portion closer in the first direction, further reducing the risk of fatigue cracking in the region of the corner wall near the second connection portion.

[0068] In some embodiments, the second connection interface includes a fourth interface that extends obliquely from the second position away from 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 facing away from the end cap. This enables the second transition region to restrict the second connection portion, reducing the risk of the second connection portion falling off.

[0069] In some embodiments, the fourth interface is connected to the inner surface of the third region at the second position. This enables the third region and the second connection portion to be in a directly connected state, making the third region and the second connection portion closer in the first direction, further reducing the risk of fatigue cracking in the region of the corner wall near the second connection portion.

[0070] In some embodiments, the Vickers hardness of the second transition region is less than the Vickers hardness of the fourth region; and / or, the Vickers hardness of the second transition region is less than the Vickers hardness of the second connection portion. If the Vickers hardness of the second transition region is less than the Vickers hardness of the fourth region, connecting the second transition region with a lower Vickers hardness to the second connection portion can relieve the rigid pulling between the corner wall and the second connection portion when the corner wall deforms, reducing the risk of separation between the corner wall and the second connection portion. If the Vickers hardness of the second transition region is less than the Vickers hardness of the second connection portion, making the second transition region more likely to deform compared to the second connection portion can relieve the rigid pulling between the corner wall and the second connection portion when the corner wall deforms, reducing the risk of separation between the corner wall and the second connection 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, so that the second connection portion can sink deeper into the corner wall, which can effectively improve 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 are arranged opposite to each other along the second direction, the two second walls are arranged opposite to each other along the third direction, and the first direction, the second direction and the third direction are perpendicular to each other, so that the housing is roughly in the shape of a rectangular parallelepiped, and the size of the housing can be made larger, which is conducive to meeting the large capacity requirements of the battery cell.

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

[0074] In some embodiments, along the first direction, the first wall has a limiting surface facing the end cap, and the limiting surface abuts against the end cap to limit the end cap from moving in a direction close to the electrode assembly. The limiting surface limits the end cap, reduces the risk of the end cap moving in a direction close to the electrode assembly when welding with the shell, can effectively improve the welding quality of the end cap and the shell, and reduce the difficulty of welding the end cap and the shell.

[0075] In some embodiments, the first wall further includes a limiting area arranged on the limiting surface, the limiting area and the end cover are arranged opposite to each other along the second direction, and the limiting area and the end cover are welded to form a first connection portion. The limiting area can also limit the end cover, reducing the risk of the end cover moving along the thickness direction of the first wall when welding with the shell, further improving the welding quality of the end cover and the shell, and reducing the welding difficulty of the end cover and the shell.

[0076] In some embodiments, the electrode assembly is a laminated structure, the electrode assembly includes a plurality of positive electrode sheets and a plurality of negative electrode sheets, and the plurality of positive electrode sheets and the plurality of negative electrode sheets are stacked along the second direction. The laminated electrode assembly has a more compact structure and a stronger anti-extrusion capability.

[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 plate is provided with a negative electrode tab; and / or each positive electrode plate is provided with a positive electrode tab.

[0079] In some embodiments, along the third direction, the size of the first region is greater than the size of the positive electrode plate and / or the size of the negative electrode plate, and the first direction, the second direction, and the third direction are perpendicular to each other. Making the size of the first region larger along the third direction strengthens the strength of more regions of the first wall along the third direction, further reducing the risk of fatigue cracking in the region of the first wall near the first connection portion.

[0080] In some embodiments, the battery cell further includes two electrode terminals. The two electrode terminals 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 a lead-out hole. The electrode terminal includes a terminal body, a first limiting portion, and a second limiting portion. The terminal body connects the first limiting portion and the second limiting portion. The terminal body passes through the lead-out hole. Along the first direction, the first limiting portion is located on the side of the end cap facing away from the electrode assembly, and the second limiting portion is located on the side of the end cap facing the electrode assembly. The electrode terminal with this structure can be installed on the end cap by riveting, with low installation difficulty and better economy.

[0081] In a second aspect, an embodiment of the present application provides a battery, including the battery cell provided in any one of the first aspects.

[0082] In a third aspect, an embodiment of the present application provides an electrical device, including the battery cell provided in any one of the first aspects, and the battery cell is used to supply electrical energy to the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0084] Figure 1 Schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0085] Figure 2 Explosion view of a battery provided in some embodiments of the present application;

[0086] Figure 3 Explosion view of a battery cell provided in some embodiments of the present application;

[0087] Figure 4 For Figure 3 Isometric view of the battery cell shown;

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

[0089] Figure 6 is Figure 5 the partial enlarged view at position B in

[0090] Figure 7 is Figure 5 the axonometric view of the housing shown in

[0091] Figure 8 the axonometric view of the electrode assembly provided by some embodiments of the present application;

[0092] Figure 9 is Figure 8 the structural schematic diagram of the electrode assembly shown in

[0093] Figure 10 the axonometric view of the electrode assembly provided by some other embodiments of the present application;

[0094] Figure 11 is Figure 10 the structural schematic diagram of the electrode assembly shown in

[0095] Figure 12 is Figure 6 the partial view of the first wall shown in

[0096] Figure 13 the axonometric view of the housing provided by some embodiments of the present application;

[0097] Figure 14 is Figure 13 the top view of the housing shown in

[0098] Figure 15 the axonometric view of the housing provided by some other embodiments of the present application;

[0099] Figure 16 is Figure 15 the top view of the housing shown in

[0100] Figure 17 the axonometric view of the housing provided by some other embodiments of the present application;

[0101] Figure 18 is Figure 17 the top view of the housing shown in

[0102] Figure 19 the partial view of the battery cell provided by some embodiments of the present application (showing the positive electrode tab, negative electrode tab and separator of the electrode assembly);

[0103] Figure 20 the positional relationship diagram of the positive electrode tab, negative electrode tab and separator provided by some embodiments of the present application;

[0104] Figure 21Position relationship diagram of the positive electrode sheet, negative electrode sheet and separator provided for other embodiments of the present application;

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

[0106] Figure 23 For Figure 22 Partial view of the first wall shown;

[0107] Figure 24 For Figure 22 Axonometric view of the housing shown;

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

[0109] Figure 26 For Figure 25 Partial enlarged view at C in;

[0110] Figure 27 Partial view of a battery cell provided for still other embodiments of the present application (showing the first wall);

[0111] Figure 28 For Figure 27 Partial enlarged view at D in;

[0112] Figure 29 Partial view of a battery cell provided for still other embodiments of the present application (showing the first wall);

[0113] Figure 30 For Figure 29 Partial enlarged view at E in;

[0114] Figure 31 Axonometric view of the housing provided for still other embodiments of the present application;

[0115] Figure 32 For Figure 31 Partial enlarged view at F in;

[0116] Figure 33 Partial view of a battery cell provided for some embodiments of the present application (showing the corner wall);

[0117] Figure 34 Structural schematic diagram of the corner wall provided for some embodiments of the present application;

[0118] Figure 35 Structural schematic diagram of the corner wall provided for other embodiments of the present application;

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

[0120] Figure 37 For Figure 36 Partial enlarged view at position G in

[0121] Figure 38 Partial view of a battery cell provided for some other embodiments of the present application (showing the corner wall);

[0122] Figure 39 For Figure 38 Partial enlarged view at position H in

[0123] Figure 40 Partial view of a battery cell provided for some other embodiments of the present application (showing the corner wall);

[0124] Figure 41 For Figure 40 Partial enlarged view at position I in

[0125] Figure 42 Schematic diagram of the positional relationship between the end cap and the side wall before welding in some embodiments of the present application;

[0126] Figure 43 Schematic diagram of the connection between the end cap and the electrode terminal provided for some embodiments of the present application.

[0127] Icon: 1 - housing; 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 region; 1117 - first transition region; 112 - second wall; 113 - corner wall; 1131 - third region; 1132 - fourth region; 11321 - second inner surface; 11322 - second outer surface; 1133 - first connection end; 1134 - second connection end; 1135 - second transition region; 12 - end cap; 121 - outer surface of the end cap; 2 - electrode assembly; 21 - tab; 21a - positive tab; 21b - negative tab; 22 - positive electrode plate; 221 - positive electrode main body region; 2211 - fifth end; 222 - positive electrode current collector; 223 - positive electrode active material layer; 2231 - positive electrode main body part; 2232 - positive electrode thinning part; 224 - insulating layer; 23 - negative electrode plate; 231 - negative electrode main body region; 2311 - sixth end; 232 - negative electrode current collector; 233 - negative electrode active material layer; 2331 - negative electrode main body part; 2332 - negative electrode thinning part; 24 - separator; 241 - seventh end; 242 - extended region; 25 - flat region; 26 - corner region; 27 - first surface; 28 - second surface; 3 - electrode terminal; 31 - terminal main 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 part; 7 - second insulating part; 10 - battery cell; 20 - box body; 201 - first box body; 202 - second box body; 100 - battery; 200 - controller; 300 - motor; 1000 - vehicle; Z - first direction; Y - second direction; X - third direction; U - first interface; V - second interface. Detailed implementation

[0128] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall 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 those of ordinary skill in the technical field to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of this application or the above drawings are used to distinguish different objects and not to describe a specific order or primary-secondary relationship.

[0130] Reference to "embodiment" in this application means that a specific feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase may not necessarily refer to the same embodiment when it appears in various positions in the specification, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0131] The term "and / or" in this application is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally represents an "or" relationship between the associated objects before and after.

[0132] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the thickness, length, width, etc. of various components shown in the drawings of the embodiments of this application, as well as the overall thickness, length, width, etc. of the integrated device, are only for illustrative purposes and should not constitute any limitation to this application.

[0133] The term "plurality" as used in this application refers to two or more (including two).

[0134] In the embodiments of this application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging to continue use.

[0135] The battery cell includes, but is 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] The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are inserted and extracted back and forth between the positive electrode and the negative electrode. The separator is disposed between the positive electrode and the negative electrode, which can reduce the risk of short circuit between the positive and negative electrodes and at the same time allow the active ions to pass through.

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

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

[0139] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, 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. can be used. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as 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 can include at least one of the following materials: lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium-containing phosphate can include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (which can also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, etc. Examples of lithium transition metal oxides can include, but are not limited to, lithium cobalt oxide (such as LiCoO 2 ), lithium nickel oxide (such as LiNiO 2 ), lithium manganese oxide (such as LiMnO 2 , LiMn2O 4) Lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (which can also be abbreviated as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O 2 (which can also be abbreviated as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O 2 (which can also be abbreviated as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O 2 (which can also be abbreviated as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O 2 (which can also be abbreviated as NCM 811 )、Lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O 2 ) and at least one of its modified compounds, etc.

[0141] In some embodiments, the positive electrode can be made of foam metal. The foam metal can be nickel foam, copper foam, aluminum foam, foam alloy, etc. When the foam metal is used as the positive electrode, the positive electrode active material may not be provided on the surface of the foam metal, and of course, the positive electrode active material can also be provided. As an example, a lithium source material, potassium metal or sodium metal can also be filled and / or deposited in the foam metal, and the lithium source material is lithium metal and / or lithium-rich material.

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

[0143] As an example, the negative electrode current collector can be a metal foil, a foam metal, or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium can be used. The foam metal can be foam nickel, foam copper, foam aluminum, foam alloy, etc. The composite current collector can include a polymer material substrate and a metal layer. The composite current collector can be formed by forming a metal material (such as 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 plate can include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

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

[0146] As an example, the negative electrode active material can be a negative electrode active material for a battery cell known in the art. As an example, the negative electrode active material can 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. The silicon-based materials can be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials can be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0147] In some embodiments, the material of the positive electrode current collector can be aluminum, and the material of the negative electrode current collector can be 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 stability and mechanical stability.

[0149] As an example, the material of the separator membrane can include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator membrane can be a single-layer film or a multi-layer composite film. When the separator membrane is a multi-layer composite film, the materials of each layer can be the same or different. The separator can be a single component located between the positive and negative electrodes, or can 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 electrode and the negative electrode, and functions to transport ions and isolate the positive and negative electrodes simultaneously.

[0151] In some embodiments, the battery cell further includes an electrolyte, which functions to conduct ions between the positive and negative electrodes. The electrolyte can be liquid, gel or solid. Among them, the liquid electrolyte includes an electrolyte salt and a solvent.

[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 difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluoro bis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0153] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene 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. The ether solvent may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether, and crown ether.

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

[0155] Among them, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0156] As an example, the polymer solid electrolyte can be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, single-ion polymer, poly(ionic liquid)-lithium salt, cellulose, etc.

[0157] As an example, the inorganic solid electrolyte may include an oxide solid electrolyte (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superionic conductor (lithium germanium phosphorus sulfur, argyrodite), amorphous sulfide), and one or more of a halide solid electrolyte, a nitride solid electrolyte, and a hydride solid electrolyte.

[0158] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

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

[0160] In some embodiments, the electrode assembly has a stacked structure.

[0161] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets are alternately stacked.

[0162] As an example, multiple positive electrode sheets can be provided, and the negative electrode sheet is folded to form multiple stacked folding segments, and a positive electrode sheet is clamped between adjacent folding segments.

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

[0164] As an example, multiple separators can be provided and are respectively arranged between any adjacent positive electrode sheets or negative electrode sheets.

[0165] As an example, the separators can be continuously arranged and are arranged between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0166] In some embodiments, the shape of the electrode assembly can be cylindrical, flat or multi-prismatic, etc.

[0167] In some embodiments, the electrode assembly is provided with tabs, and the tabs can conduct current out of the electrode assembly. The tabs include positive tabs and negative tabs.

[0168] In some embodiments, the battery cell can include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell) or an aluminum-plastic film, etc.

[0169] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a multi-prismatic battery cell, and the multi-prismatic battery cell is, for example, a hexagonal-prismatic battery cell, etc.

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

[0171] In some embodiments, the battery can be a battery module. 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 may be a battery pack, which includes a box body and battery cells. The battery cells or battery modules are accommodated in the box body.

[0173] In some embodiments, the box body may be part of the chassis structure of a vehicle. For example, part of the box body may form at least part of the floor of the vehicle, or part of the box body may form at least part of the cross beams and longitudinal beams of the vehicle.

[0174] In some embodiments, the battery may be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

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

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

[0177] During the charge and discharge cycle of the battery cell, the electrode assembly will expand. After the wall of the shell is subjected to the expansion force of the electrode assembly, it will deform. Over time, it is easy to cause fatigue cracking in the area of the wall of the shell near the connection part (heat affected zone), affecting the service life of the battery cell.

[0178] Based on the above considerations, to alleviate the problem that the area of the wall of the shell near the connection part is prone to fatigue cracking, an embodiment of the present application provides a battery cell, which includes a shell, an end cap and an electrode assembly. At least one end of the shell in the first direction has an opening. The shell includes a first wall. The end cap closes the opening. The first wall and the end cap are welded to form a first connection part. The electrode assembly is at least partially accommodated in the shell. The electrode assembly includes a positive electrode tab and a negative electrode tab. At least part of the positive electrode tab and at least part of the negative electrode tab are stacked in the second direction. The second direction is parallel to the thickness direction of the first wall. The first direction intersects the second direction. The first wall includes a first area and a second area arranged in the first direction. The thickness of the first area is greater than that of the second area. The first area is located between the first connection part and the second area.

[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 portion and the second region, such that the first region with a greater thickness is closer to the first connection portion than the second region. The first region strengthens the region of the first wall near the first connection portion, reducing the risk of fatigue cracking of the region of the first wall near the first connection portion due to the expansion of the electrode assembly, thereby improving the service life of the battery cell.

[0180] The battery cell described in the embodiments of the present application is applicable to batteries and electrical equipment using the battery cell.

[0181] The electrical equipment can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or an extended-range electric vehicle, etc.; the spacecraft includes an airplane, a rocket, a space shuttle, a spaceship, etc.; the electric toy includes a fixed or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and a railway electric tool, for example, an electric drill, an electric grinding wheel, an electric wrench, an electric screwdriver, a hammer drill, an impact electric drill, a concrete vibrator and a planer, etc. The embodiments of the present application do not impose special restrictions on the above electrical equipment.

[0182] For the convenience of description, the following embodiments take the electrical equipment as a vehicle as an example for illustration.

[0183] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a vehicle 1000 provided by some embodiments of the present application. A battery 100 is disposed inside the vehicle 1000. The battery 100 can be disposed at the bottom, the head or the tail of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000. For example, the battery 100 can be used as an operating power source of the vehicle 1000.

[0184] The vehicle 1000 may further 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 working power requirements during the start, navigation and driving of the vehicle 1000.

[0185] In some embodiments of the present application, the battery 100 can not only be used as an operating power source of the vehicle 1000, but also be used as a driving power source of 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 2Exploded view of the battery 100 provided by some embodiments of the present application. The battery 100 may include battery cells 10 and a housing 20, and the battery cells 10 are accommodated in the housing 20.

[0187] Among them, the housing 20 is a component for accommodating the battery cells 10, the housing 20 provides an accommodation space for the battery cells 10, and the housing 20 can adopt various structures. In some embodiments, the housing 20 may include a first housing 201 and a second housing 202, and the first housing 201 and the second housing 202 are covered with each other to define an accommodation space for accommodating the battery cells 10. The first housing 201 and the second housing 202 can be various shapes, for example, rectangular parallelepiped shape, cylindrical shape, etc. The first housing 201 may be a hollow structure with an opening on one side, and the second housing 202 may also be a hollow structure with an opening on one side. The opening side of the second housing 202 is covered with the opening side of the first housing 201, then the housing 20 with an accommodation space is formed. It may also be that the first housing 201 is a hollow structure with an opening on one side, the second housing 202 is a plate-like structure, and the second housing 202 is covered with the opening side of the first housing 201, then the housing 20 with an accommodation space is formed. The first housing 201 and the second housing 202 can be sealed by a sealing element, and the sealing element can be a sealing ring, sealant, etc.

[0188] In the battery 100, the battery cells 10 can be one or multiple. If there are multiple battery cells 10, the multiple battery cells 10 can be connected in series, parallel or in a mixed connection. A mixed connection means that there are both series and parallel connections among the multiple battery cells 10. It can be that multiple battery cells 10 are first connected in series, parallel or in a mixed connection to form a battery module, and then multiple battery modules are connected in series, parallel or in a mixed connection to form a whole and are accommodated in the housing 20. It can also be that all the battery cells 10 are directly connected in series, parallel or in a mixed connection together, and then the whole formed by all the battery cells 10 is accommodated in the housing 20.

[0189] Please refer to Figure 3 and Figure 4 , Figure 3 Exploded view of the battery cell 10 provided by some embodiments of the present application; Figure 4 is Figure 3 Axonometric view of the battery cell 10 shown in. The battery cell 10 may include a housing 1 and an electrode assembly 2, and the electrode assembly 2 is accommodated in the housing 1.

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

[0191] The housing 11 is a component for accommodating the electrode assembly 2. The housing 11 can be a hollow structure with an opening formed at one end, or a hollow structure with openings formed at opposite ends. The housing 11 can be of various shapes, such as cylindrical, cuboid, etc. The material of the housing 11 can be various, such as copper, iron, aluminum, steel, aluminum alloy, etc. The electrode assembly 2 can be partially located inside the housing 11 or entirely located inside the housing 11.

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

[0193] In an embodiment where the housing 11 has an opening formed at one end, one end cap 12 can be correspondingly provided. In an embodiment where the housing 11 has openings formed at opposite ends, two end caps 12 can be correspondingly provided. 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 a receiving space.

[0194] In some embodiments, the battery cell 10 may further include electrode terminals 3. The electrode terminals 3 are provided on the outer casing 1 and are used to electrically connect to the tabs 21 of the electrode assembly 2 to input or output the electrical energy of the battery cell 10. The electrode terminals 3 can be provided on the housing 11 of the outer casing 1 or on the end cap 12 of the outer casing 1. The electrode terminals 3 and the tabs 21 can be directly connected, for example, the electrode terminals 3 and the tabs 21 are welded. The electrode terminals 3 and the tabs 21 can also be indirectly connected, for example, the electrode terminals 3 and the tabs 21 are indirectly connected through a current collector member. The current collector member can be a metal conductor, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0195] In some embodiments, the battery cell 10 may further include a pressure relief mechanism 4. The pressure relief mechanism 4 may be disposed on the end cap 12, or the pressure relief mechanism 4 may also be disposed on 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, for example, an explosion-proof film, a safety valve, etc. 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 so as to crack along the pressure relief groove when the battery cell 10 relieves pressure. The pressure relief groove may be a groove extending along a closed trajectory, and the closed trajectory may be a circular trajectory, a rectangular trajectory, etc.; the pressure relief groove may also be a groove extending along a non-closed trajectory, and the non-closed trajectory may be an H-shaped trajectory, a Y-shaped trajectory, a V-shaped trajectory, a U-shaped trajectory, etc.

[0196] As an example, as Figure 3 and Figure 4 shown, one end of the housing 11 forms an opening, there is one end cap 12 in the outer shell 1, and one end cap 12 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 respectively a positive electrode terminal and a negative electrode terminal. One end of the electrode assembly 2 facing the end cap 12 is formed with 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 the A-A cross-sectional view of the battery cell 10 shown in Figure 6 and Figure 5 the partial enlarged view at B in Figure 7 and Figure 5 the axonometric view of the housing 11 shown in . An embodiment of the present application provides a battery cell 10, which includes a housing 11, an end cap 12, and an electrode assembly 2. At least one end of the housing 11 has an opening along the 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 to form a first connection portion 51. The electrode assembly 2 is at least partially accommodated in the housing 11. The electrode assembly 2 includes a positive electrode plate 22 and a negative electrode plate 23. At least a part of the positive electrode plate 22 and at least a part of the negative electrode plate 23 are stacked along the second direction Y. The second direction Y is parallel to the thickness direction of the first wall 111, and 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, and the first region 1111 is located between the first connection portion 51 and the second region 1112.

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

[0199] The end cap 12 may be welded to the housing 11. The welding of the end cap 12 and the housing 11 may form a connecting portion 5, and the connecting portion 5 may extend along the circumference of the opening of the housing 11. The end cap 12 and the housing 11 are fixedly connected through the connecting portion 5 to achieve the sealing between the end cap 12 and the housing 11. The connecting portion 5 is the part where there is a weld mark after the end cap 12 and the housing 11 are welded, and the part where the end cap 12 and the housing 11 are welded and fused together may be the connecting portion 5.

[0200] There may be one or more first walls 111 in the housing 11. The first connecting portions 51 may correspond to the first walls 111 one by one. The first connecting portion 51 is the part where there is a weld mark after the end cap 12 and the first wall 111 are welded, and the part where the end cap 12 and the first wall 111 are welded and fused together may be the first connecting portion 51. A part of the first connecting portion 51 is formed on the end cap 12, and another part of the first connecting portion 51 is formed on the first wall 111. The first wall 111 and the end cap 12 may form the first connecting portion 51 by means of stitch welding or penetration welding. The first connecting portion 51 may be a part of the connecting portion 5 or the whole of the connecting portion 5. In an embodiment where the housing 11 is cylindrical, there is only one first wall 111 in the housing 11, the first wall 111 is cylindrical, and the first connecting portion 51 is the connecting portion 5; in an embodiment where the housing 11 is prismatic, the housing 11 may include a plurality of side walls arranged along the opening of the housing 11. At least one of the two side walls arranged opposite to each other in the second direction Y may be the first wall 111, and the first connecting portion 51 is a part of the connecting portion 5.

[0201] The first wall 111 may be the wall with the largest outer surface area in the shell 11, or the first wall 111 may not be the wall with the largest outer surface area in the shell 11. Taking the shell 11 as a rectangular parallelepiped as an example, the shell 11 may include two first walls 111 and two second walls 112, the two first walls 111 are arranged opposite to each other along the second direction Y, the two second walls 112 are arranged opposite to 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 wall 111 may be the wall with the largest outer surface area in the shell 11, so 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 may be the wall with the largest outer surface area in the shell 11, so 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 area 1111 may be an area where the thickness of the first wall 111 is thickened. The first area 1111 is thicker than the second area 1112. The second area 1112 may be a portion of the first wall 111 located along the first direction Z on the side of the first area 1111 away from the first connection portion 51. The first area 1111 may be directly connected to the first connection portion 51 or indirectly connected; the first area 1111 may be directly connected to the second area 1112 or indirectly connected. The first area 1111 may be an equal thickness structure or a non-equal thickness structure; the second area 1112 may be an equal thickness structure or a non-equal thickness structure. If at least one of the first area 1111 and the second area 1112 is a non-equal thickness structure, the maximum thickness of the second area 1112 may be less than or equal to the minimum thickness of the first area 1111, so that the thickness of the first area 1111 is greater than the thickness of the second area 1112.

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

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

[0205] At least a part of the positive electrode tab 22 and at least a part of the negative electrode tab 23 are stacked along the second direction Y. During cycling, the electrode assembly 2 will expand along the second direction Y. After the first wall 111 is subjected to the expansion force of the electrode assembly 2, it will deform, which easily causes fatigue cracking in the area of the first wall 111 near the first connection part 51. In the present 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 arranged between the first connection part 51 and the second region 1112, so that the first region 1111 with a greater thickness is closer to the first connection part 51 than the second region 1112. The first region 1111 plays a certain strengthening role in the area of the first wall 111 near the first connection part 51, reducing the risk of fatigue cracking in the area of the first wall 111 near the first connection part 51 due to the expansion of the electrode assembly 2, and thus improving the service life of the battery cell 10.

[0206] In some embodiments, please refer to Figures 8 - 11 , Figure 8 which is an isometric view of the electrode assembly 2 provided in some embodiments of the present application; Figure 9 is Figure 8 a schematic structural view of the electrode assembly 2 shown in Figure 10 which is an isometric view of the electrode assembly 2 provided in some other embodiments of the present application; Figure 11 is Figure 10 a schematic structural view of the electrode assembly 2 shown in

[0207] The flat area 25 is the flat part of the electrode assembly 2. The part of the positive electrode tab 22 located in the flat area 25 is substantially flat, and the part of the negative electrode tab 23 located in the flat area 25 is substantially flat. As an example, the part of the positive electrode tab 22 located in the flat area 25 and the part of the negative electrode tab 23 located in the flat area 25 are both flat plate structures. If the electrode assembly 2 is a wound structure, the electrode assembly 2 is a wound electrode assembly, and a part of the electrode assembly 2 can be the flat area 25; if the electrode assembly 2 is a stacked structure, the electrode assembly 2 is a wound electrode assembly, and the whole electrode assembly 2 can be the flat area 25. The second direction Y is the stacking direction of the part of the positive electrode tab 22 located in the flat area 25 and the part of the negative electrode tab 23 located in the flat area 25.

[0208] As an example, the electrode assembly 2 may further include a separator 24. A separator 24 is provided between the positive electrode tab 22 and the negative electrode tab 23. The separator 24 is used to separate the positive electrode tab 22 and the negative electrode tab 23. The part of the positive electrode tab 22 located in the flat area 25, the part of the negative electrode tab 23 located in the flat area 25, and the part of the separator 24 located in the flat area 25 are stacked along the second direction Y.

[0209] The second direction Y is the stacking direction of the portion of the positive electrode tab 22 located in the flat region 25 and the portion of the negative electrode tab 23 located in the flat region 25. The electrode assembly 2 has a greater amount of expansion in the second direction Y during cycling, and the first wall 111 is more affected by the expansion of the electrode assembly 2. However, since the first region 1111 strengthens the region 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, with continued reference to Figures 8 - 11 , the electrode assembly 2 includes adjacent first surface 27 and second surface 28. The first surface 27 is perpendicular to the second direction Y, the area of the first surface 27 is larger than the area of the second surface 28, and the first surface 27 and the first wall 111 are disposed opposite to each other along the second direction Y.

[0211] The first surface 27 is the surface of the outer surface of the electrode assembly 2 that is perpendicular to the second direction Y, and the second surface 28 is the surface of the outer surface of the electrode assembly 2 that is adjacent to the first surface 27. The first surface 27 faces the first wall 111 along the second direction Y. The first surface 27 may be a plane. The first surface 27 may be the surface with the largest area among the outer surfaces of the electrode assembly 2, or may not be the surface with the largest area among the outer surfaces of the electrode assembly 2. The second surface 28 may be a plane or at least partially an arc surface. It should be noted that the first surface 27 being substantially perpendicular to the second direction Y 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 disposed opposite to each other along the second direction Y, and the two second surfaces 28 are disposed opposite to 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 portion of the electrode assembly 2 along the second direction Y is the separator 24, and 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 pairwise.

[0213] In this embodiment, the area of the first surface 27 is larger than the area of the second surface 28, such that the first wall 111 disposed opposite to the first surface 27 in the housing 11 receives a greater expansion force. Since the first region 1111 strengthens the region 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, which does not limit the first surface 27 in the electrode assembly 2 to be 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 the illustrated embodiment, the electrode assembly 2 is a wound structure, the electrode assembly 2 is flat, the electrode assembly 2 includes six surfaces, and the two surfaces oppositely arranged along the second direction Y among the six surfaces have the largest areas, and both of these two surfaces are the first surfaces 27. In Figure 10 the illustrated embodiment, the electrode assembly 2 is a laminated structure, the electrode assembly 2 is generally in a cuboid shape, the electrode assembly 2 includes six surfaces, and the two surfaces oppositely arranged along the second direction Y among the six surfaces have the largest areas, and both of these two surfaces are the 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 oppositely arranged to the first surface 27 in the housing 11 receives the largest expansion force. Since the first region 1111 strengthens the region of the first wall 111 near the first connecting portion 51, the risk of fatigue cracking of the first wall 111 near the first connecting 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 is a wound structure, the electrode assembly 2 further has a corner region 26, the corner region 26 is provided at at least one end of the flat region 25 along the third direction X, and the first direction Z, the second direction Y, and the third direction X are not coplanar and intersect pairwise. The outer surface of the flat region 25 includes the first surface 27, the outer surface of the corner region 26 includes the second surface 28, and at least a part of the second surface 28 is an arc surface.

[0219] The corner region 26 can be provided at only one end of the flat region 25 along the third direction X, or can be provided at both opposite ends of the flat region 25 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 can be arranged at an acute angle, a right angle, or an obtuse angle. The first surface 27 can be a part of the outer surface of the flat region 25, the second surface 28 can be a part of the outer surface of the corner region 26, the second surface 28 can be an integral arc surface, or only a part of it can be an arc surface.

[0220] As an example, the positive electrode sheet 22, the separator 24, and the negative electrode sheet 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 in pairs. Both ends of the flat region 25 along the third direction X are provided with corner regions 26. The portions of the positive electrode sheet 22, the negative electrode sheet 23, and the separator 24 located in the corner region 26 are in a bent state. The portion of the positive electrode sheet 22 located in the corner region 26 can be at least partially arc-shaped, the portion of the negative electrode sheet 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 layer 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 layer of the electrode assembly 2. The first surface 27 is a flat surface, and the second surface 28 is an arc surface. The axis of the arc surface extends along the first direction Z. Along the second direction Y, the surfaces on both sides of the flat region 25 are both the first surface 27; along the third direction X, the surface on one side of one corner region 26 facing away from the other corner region 26 is one second surface 28, and the surface on one side of the other corner region 26 facing away from one corner region 26 is the other second surface 28.

[0221] For a wound electrode assembly, the flat region 25 has a greater expansion amount in the second direction Y. Since the first region 1111 strengthens the region 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 can be effectively reduced.

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

[0223] As an example, a plurality of positive electrode sheets 22, a plurality of negative electrode sheets 23, and a plurality of separators 24 are stacked along the second direction Y to form a stacked structure. The positive electrode sheets 22 and the negative electrode sheets 23 are completely located in the flat region 25. A separator 24 is provided between adjacent positive electrode sheets 22 and negative electrode sheets 23. The separator 24 extends beyond both ends of the positive electrode sheet 22 and both ends of the negative electrode sheet 23 along the third direction X. The extended portions of the plurality of separators 24 are connected to form an integral portion, and the second surface 28 is formed on this integral portion. Along the second direction Y, all the positive electrode sheets 22 and all the negative electrode sheets 23 are between the two outermost separators 24, and the outer surfaces of these two separators 24 are both the first surface 27.

[0224] It should be noted that the first surface 27 is substantially perpendicular to the second surface 28, which should also be understood as the first surface 27 being perpendicular to the second surface 28. For example, the angle formed by the first surface 27 and the second surface 28 within the range of 85° to 95° can be understood as the first surface 27 being perpendicular to the second surface 28.

[0225] For the wound electrode assembly, the electrode assembly 2 has a greater amount of expansion in the stacking direction of the positive electrode sheet 22 and the negative electrode sheet 23. Since the first region 1111 strengthens the region of the first wall 111 near the first connection portion 51, it can effectively reduce 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.

[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 housing 11.

[0227] It should be noted that the first wall 111 being the wall with the largest outer surface area in the housing 11 does not limit the first wall 111 in the housing 11 to only one. It can be understood that the wall with the largest outer surface area in the housing 11 can be one or two.

[0228] The wall with the largest outer surface area in the housing 11 is more likely to deform 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, it reduces the risk of fatigue cracking of the wall with the largest outer surface area in the housing 11 near the first connection portion 51 due to the expansion of the electrode assembly 2.

[0229] In some embodiments, the housing 11 includes two first walls 111. Along the second direction Y, the two first walls 111 are arranged oppositely, and the electrode assembly 2 ( Figure 5 shown in) is located between the two first walls 111.

[0230] As an example, in the Figure 7 embodiment shown, the housing 11 is in the shape of a cuboid. The housing 11 may include two first walls 111 and two second walls 112. The two first walls 111 are arranged oppositely along the second direction Y, and the two second walls 112 are arranged oppositely along the third direction X. The outer surface area of the first wall 111 is larger than the outer surface area of the second wall 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 toFigure 12 , Figure 12 is Figure 6 a partial view of the first wall 111 shown in the figure. 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.

[0233] The first part 11111, the second part 11112, and the second region 1112 are arranged in sequence along the first direction Z. The first part 11111 transitions to the second region 1112 through the second part 11112. The first part 11111 can be a structure with uniform thickness or a non-uniform thickness structure; the second part 11112 can be a structure with uniform thickness or a non-uniform thickness structure. If at least one of the first part 11111 and the second part 11112 is a non-uniform thickness structure, it can be that the maximum thickness of the second part 11112 is less than or equal to the minimum thickness of the first part 11111, so as to make the thickness of the first part 11111 greater than the thickness of the second part 11112.

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

[0235] The area of the first region 1111 close to the first connection part 51 is more likely to form a heat affected zone, and this area is more likely to fatigue crack. However, since the second part 11112 connects the first part 11111 and the second region 1112, and the thickness of the first part 11111 is greater than the thickness of the second part 11112, the thicker first part 11111 in the first region 1111 is closer to the first connection part 51, which can effectively weaken the influence of the heat affected zone on the first region 1111 and reduce the risk of fatigue cracking in the area of the first wall 111 near the first connection part 51. In addition, since the thickness of the second part 11112 is less than the thickness of the first part 11111, the material used in the first region 1111 can be reduced, and the production cost can be lowered.

[0236] In some embodiments, the thickness of the second part 11112 shows a decreasing trend along the direction from the end cap 12 ( Figure 12 not shown) to the electrode assembly 2 ( Figure 12 not shown).

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

[0238] It can be understood that the second part 11112 has a non-uniform thickness structure. As an example, the thickness of the second part 11112 gradually decreases in the direction from the end cover 12 towards the electrode assembly 2. At least one of the inner surface and the outer surface of the second part 11112 can be an inclined surface to achieve the gradual decrease of the thickness of the second part 11112 in the direction from the end cover 12 towards the electrode assembly 2.

[0239] As an example, in Figure 12 the illustrated embodiment, both the first part 11111 and the second region 1112 have a uniform thickness structure. The inner surface and the outer surface of the first part 11111 are parallel to each other, and the first inner surface 11121 and the first outer surface 11122 of the second region 1112 are parallel to each other. The outer surface of the second part 11112, the outer surface of the first part 11111, and the first outer surface 11122 are coplanar. A part of the first part 11111 and a part of the second part 11112 both protrude from the first inner surface 11121, and the inner surface of the second part 11112 connects the first inner surface 11121 and the inner surface of the first part 11111.

[0240] In this embodiment, the thickness of the second part 11112 shows a decreasing trend in the direction from the end cover 12 towards the electrode assembly 2. On the one hand, it can reduce the influence of the second part 11112 on the electrode assembly 2 and lower the risk of interference between the second part 11112 and the electrode assembly 2. On the other hand, it makes the strengthening effect of the second part 11112 show an increasing trend in the direction from the electrode assembly 2 towards the end cover 12, so that the area of the second part 11112 close to the first part 11111 has a good strengthening effect even under the influence of the first connecting portion 51, reducing the risk of fatigue cracking of the first wall 111 in the second part 11112. On the other hand, through the second part 11112, the transition between the first part 11111 and the second region 1112 can be realized, reducing stress concentration.

[0241] In some embodiments, please refer to Figure 13 and Figure 14 , Figure 13 is an axonometric view of the housing 11 provided in some embodiments of the present application; Figure 14 is 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 pairwise.

[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, so that the first region 1111 is a strip-shaped structure extending along the third direction X.

[0243] As an example, the housing 11 is in the shape of a cuboid. The housing 11 includes two first walls 111 and two second walls 112. The two first walls 111 are oppositely arranged along the second direction Y, and the two second walls 112 are oppositely arranged along the third direction X. The first direction Z, the second direction Y, and the third direction X are perpendicular to each other in pairs. 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 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, so that the dimension of the first region 1111 along the third direction X is larger, so that the strength of more regions of the first wall 111 along the third direction X is enhanced, and further reduces the risk of fatigue cracking in the region of the first wall 111 near the first connecting portion 51.

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

[0246] The first connecting segment 11113 may be a part of the first region 1111, or the first connecting segment 11113 is the first region 1111. The first connecting segment 11113 may be a structure with equal thickness, or a non-equal thickness structure; the first connecting segment 11113 has opposite ends along the third direction X. The first connecting segment 11113 passes through the middle section of the first wall 111, so that the middle section of the first wall 111 is located between the opposite ends of the first connecting segment 11113 along the third direction X. The distances from the opposite ends of the first connecting segment 11113 along the third direction X to the middle section may be equal or unequal. If the distances from the opposite ends of the first connecting segment 11113 along the third direction X to the middle section of the first wall 111 are equal, the first connecting segment 11113 may be a symmetric structure symmetrically arranged with respect to the middle section of the first wall 111. It should be noted that the middle 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 is a structure with equal thickness, and the distances from the opposite ends of the first connecting segment 11113 along the third direction X to the middle section of the first wall 111 are equal.

[0248] Taking the housing 11 as a cuboid as an example, the distance from the middle 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 middle section of the first wall 111 to the two second walls 112 of the housing 11 that are oppositely arranged along the third direction X is equal.

[0249] It should be noted that along the third direction X, the distance from the middle 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 middle section to both ends of the first wall 111 is 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 amount of the middle region of the first wall 111 along the third direction X is larger, and the middle region of the first wall 111 along the third direction X is more prone to fatigue cracking. Since the first connecting section 11113 of the first region 1111 passes through the middle section of the first wall 111, the strength of at least the middle region of the first wall 111 along the third direction X is enhanced, reducing the risk of fatigue cracking in the middle region of the first wall 111 near the first connecting portion 51 along the third direction X.

[0251] In some embodiments, Figure 15 is an axonometric view of the housing 11 provided in some other embodiments of the present application; Figure 16 is Figure 15 a top view of the housing 11 shown in the figure. The first region 1111 further includes a second connecting section 11114 and a third connecting section 11115. The second connecting section 11114, the first connecting section 11113, and the third connecting section 11115 are arranged along the third direction X. The first connecting section 11113 connects the second connecting section 11114 and the third connecting section 11115, and the thickness of the first connecting section 11113 is greater than the thickness of the second connecting section 11114 and the thickness of the third connecting section 11115.

[0252] The first connecting section 11113 is a section of the first region 1111 that passes through the middle section of the first wall 111. The second connecting section 11114 and the third connecting section 11115 are two sections of the first region 1111 located at both ends along the third direction X respectively. The second connecting section 11114 and the first connecting section 11113 can be directly connected or indirectly connected. The third connecting section 11115 and the first connecting section 11113 can be directly connected or indirectly connected.

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

[0254] The dimension of the second connecting section 11114 along the third direction X and the dimension of the third connecting section 11115 along the third direction X can be equal or unequal. If the dimension of the second connecting section 11114 along the third direction X is equal to the dimension of the third connecting section 11115 along the third direction X, the second connecting section 11114 and the third connecting section 11115 can be symmetrically arranged with respect to the middle section plane of the first wall 111.

[0255] It can be understood that in the embodiment where the first region 1111 includes the first part 11111 and the second part 11112, at least one of the first connecting section 11113, the second connecting section 11114, and the third connecting section 11115 can include arranging the first part 11111 and the second part 11112 along the first direction Z.

[0256] A part of the second connecting section 11114 can 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), a part of the first connecting section 11113 can protrude from the first inner surface 11121 and / or the first outer surface 11122, and a part of the third connecting section 11115 can 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 section 11114 and the third connecting section 11115 are directly connected to the first connecting section 11113. The thickness of the second connecting section 11114 gradually decreases in the direction from the third connecting section 11115 towards the second connecting section 11114, and the thickness of the third connecting section 11115 gradually decreases in the direction from the second connecting section 11114 towards the third connecting section 11115. A part of the second connecting section 11114, a part of the first connecting section 11113, and a part of the third connecting section 11115 all protrude from the first inner surface 11121 of the second region 1112. The inner surface of the second connecting section 11114 connects the inner surface of the first connecting section 11113 and the first inner surface 11121, and the inner surface of the third connecting section 11115 connects the inner surface of the first connecting section 11113 and the first inner surface 11121. The outer surfaces of the second connecting section 11114, the first connecting section 11113, and the third connecting section 11115 are coplanar.

[0258] When the first wall 111 is subjected to the expansion force of the electrode assembly 2, the deformation amount 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 a multi-segment structure, and setting the thickness of the first connecting section 11113 located in the middle region to be larger, and setting the thicknesses of the second connecting section 11114 and the third connecting section 11115 respectively located at both ends of the first connecting section 11113 to be smaller, the first region 1111 is designed specifically according to the different deformation amounts of different regions of the first wall 111 along the third direction X, thereby specifically improving the strength of different regions of the first wall 111 along the third direction X. While ensuring that the region of the first wall 111 near the first connecting portion 51 has sufficient strength, the material used in the first region 1111 is reduced, and the production cost is lowered.

[0259] In some embodiments, please refer to Figure 17 and Figure 18 , Figure 17 is an isometric view of the housing 11 provided in still other embodiments of the present application; Figure 18 is Figure 17Top view of the shown housing 11. The first region 1111 further includes a first transition section 11116. The first connection section 11113, the first transition section 11116, and the second connection section 11114 are arranged along the third direction X. The first transition section 11116 connects the second connection section 11114 and the first connection section 11113, and the thickness of the first transition section 11116 shows an increasing trend along the direction from the second connection section 11114 to the first connection section 11113; and / or, the first region 1111 further includes a second transition section 11117. The first connection section 11113, the second transition section 11117, and the third connection section 11115 are arranged along the third direction X. The second transition section 11117 connects the third connection section 11115 and the first connection section 11113, and the thickness of the second transition section 11117 shows an increasing trend along the direction from the third connection section 11115 to the first connection section 11113.

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

[0261] If a first transition section 11116 is provided between the second connection section 11114 and the first connection section 11113, and a second transition section 11117 is provided between the third connection section 11115 and the first connection section 11113, the dimension of the first transition section 11116 along the third direction X and the dimension of the second transition section 11117 along the third direction X can be equal or unequal. If the dimension of the first transition section 11116 along the third direction X is equal to the dimension of the second transition section 11117 along the third direction X, the first transition section 11116 and the second transition section 11117 can be symmetrically arranged with respect to the central cross-section of the first wall 111.

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

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

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

[0265] In some embodiments, please refer to Figure 14 , Figure 16 and Figure 18 , the dimension of the first connecting section 11113 along the third direction X is L 1 , the dimension of the first wall 111 along the third direction X is L, 0.2≤L 1 / 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] L 1 / L can take any one of the point values such as 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, etc. or the range value between any two of them.

[0268] L 1 / L ≥ 0.2 increases the proportion of the dimension of the first connecting segment 11113 along the third direction X in the first wall 111, so that the middle region of the first wall 111 along the third direction X has a larger strengthened range, and improves the strength of the middle region of the first wall 111 along the third direction X; L 1 / L ≤ 0.6 reduces the proportion of the dimension of the first connecting segment 11113 along the third direction X in the first wall 111, reduces the material used for the first connecting segment 11113, and reduces the production cost. Therefore, setting the ratio of the dimension of the first connecting segment 11113 along the third direction X to the dimension of the first wall 111 along the third direction X to 0.2 - 0.6 can, while enabling the first connecting segment 11113 to have sufficient strengthening ability, reduce the material used for the first connecting segment 11113, taking into account both the strengthening ability requirements and economic requirements of the first connecting segment 11113.

[0269] In some embodiments, please continue to refer to Figure 14 、 Figure 16 and Figure 18 , the first connecting segment 11113 has opposite first end 11113a and second end 11113b along the third direction X, the first wall 111 has opposite third end 1113 and fourth end 1114 along the third direction X, the first end 11113a is close to the third end 1113, 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 L 2 , the minimum distance between the second end 11113b and the fourth end 1114 along the third direction X is L 3 ; L 2 / L ≤ 0.3; and / or, L 3 / L ≤ 0.3.

[0270] It can be understood 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 L 2 = L 3 ; It can also be L 2 > L 3 or L 2 < L 3 .

[0272] L 2 L / L can take any one of the point values such as 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, etc. or the range value between any two of them.

[0273] L 3 L / L can take any one of the point values such as 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, etc. or the range value between any two of them.

[0274] If L 2 / 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, so that the strength of more regions of the first wall 111 along the third direction X is enhanced, and the risk of fatigue cracking in the region of the first wall 111 near the first connecting portion 51 is further reduced. If L 3 / 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, so that the strength of more regions of the first wall 111 along the third direction X is enhanced, and the risk of fatigue cracking in the region of the first wall 111 near the first connecting portion 51 is further reduced.

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

[0276] L can take any one of the point values such as 100mm, 120mm, 150mm, 180mm, 200mm, 220mm, 250mm, 260mm, 280mm, 300mm, 310mm, 320mm, 350mm, 390mm, 400mm, 410mm, 420mm, 430mm, 440mm, 450mm, etc., or the range value between any two of them.

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

[0278] Along the third direction X, the first region 1111 has opposite ends. It can be that one end of the first region 1111 extends to one corner wall 113 and the other end does not extend to the other corner wall 113, or both ends of the first region 1111 do not extend to the corner wall 113, so as to achieve that at least one end of the first region 1111 along the third direction X is not in contact with the corner wall 113.

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

[0280] If at least one end of the first region 1111 along the third direction X is not in contact with the corner wall 113, the material used in the first region 1111 can be reduced, and the production cost can be lowered. If both ends of the first region 1111 along the third direction X extend to two corner walls 113 respectively, the length of the first region 1111 is increased, the strengthening ability of the first region 1111 is improved, more regions of the first wall 111 along the third direction X are strengthened, and the risk of fatigue cracking in the region of the first wall 111 near the first connecting portion 51 is further reduced.

[0281] In some embodiments, please refer to Figures 19 - 21 , Figure 19 is a partial view of the battery cell 10 provided in some embodiments of the present application (showing the positive electrode tab 22, the negative electrode tab 23 and the separator 24 of the electrode assembly 2); Figure 20A positional relationship diagram of the positive electrode tab 22, the negative electrode tab 23, and the separator 24 provided by some embodiments of the present application; the figure is a positional relationship diagram of the positive electrode tab 22, the negative electrode tab 23, and the separator 24 provided by some other embodiments of the present application. The electrode assembly 2 further includes a separator 24, and a separator 24 is disposed between the positive electrode tab 22 and the negative electrode tab 23. The positive electrode tab 22 includes a positive electrode main body region 221 and a positive electrode tab 21a protruding from the positive electrode main body region 221, and the positive electrode main body region 221 has a positive electrode active material layer 223. The negative electrode tab 23 includes a negative electrode main body region 231 and a negative electrode tab 21b protruding from the negative electrode main body region 231, and the negative electrode main 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 cover 12, the negative electrode main body region 231 has a sixth end 2311 facing the end cover 12, and the separator 24 has a seventh end 241 facing the end cover 12, and the seventh end 241 is closer to the end cover 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 tab 22 may include a positive electrode current collector 222 and a positive electrode active material layer 223, and the positive electrode active material layer 223 is disposed on one or both surfaces of the positive electrode current collector 222 in its thickness direction. Figure 20 In the illustrated embodiment, the positive electrode tab 22 further includes an insulating layer 224. Insulating layers 224 are disposed on both surfaces of the positive electrode current collector 222 that are opposite to each other in the thickness direction. The insulating layer 224 and the positive electrode active material layer 223 are arranged along the first direction Z. The insulating layer 224 is disposed at the end of the positive electrode active material layer 223. The portion of the positive electrode tab 22 corresponding to the positive electrode active material layer 223 and the insulating layer 224 as a whole is the positive electrode main body region 221. One end of the insulating layer 224 close to the end cover 12 forms the fifth end 2211 of the positive electrode main body region 221, and the portion of the positive electrode current collector 222 that extends beyond the insulating layer 224 forms the positive electrode tab 21a. Figure 21 In the illustrated embodiment, the positive electrode tab 22 is not provided with an insulating layer 224. The portion of the positive electrode tab 22 corresponding to the positive electrode active material layer 223 is the positive electrode main body region 221. One end of the positive electrode active material layer 223 close to the end cover 12 forms the fifth end 2211 of the positive electrode main body region 221, and the portion of the positive electrode current collector 222 that extends beyond the positive electrode active material layer 223 forms the positive electrode tab 21a.

[0284] The negative electrode plate 23 may include a negative electrode current collector 232 and a negative electrode active material layer 233. The negative electrode active material layer 233 is disposed on one or both surfaces of the negative electrode current collector 232 in its thickness direction. The portion of the negative electrode plate 23 corresponding to the negative electrode active material layer 233 is the negative electrode main body region 231. One end of the negative electrode active material layer 233 close to the end cap 12 forms the sixth end 2311 of the negative electrode main body region 231, and 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] It may be that the fifth end 2211 is flush with the sixth end 2311; as Figure 20 shown, it may also be that the fifth end 2211 is closer to the end cap 12 than the sixth end 2311 ( Figure 19 shown in); as Figure 21 shown, it may also be that the sixth end 2311 is closer to the end cap 12 than the fifth end 2211 ( Figure 19 shown in).

[0286] In this embodiment, the seventh end 241 of the separator 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 separator 24 has a portion that extends beyond the fifth end 2211 and the sixth end 2311, enhancing the insulation effect of the separator 24 between the positive electrode plate 22 and the negative electrode plate 23 and reducing 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 separator 24 includes an extending region 242 that extends beyond the fifth end 2211 and the sixth end 2311 in the first direction Z. In the projection plane perpendicular to the second direction Y, the positive projection of the extending region 242 partially overlaps with the positive projection of the first region 1111.

[0288] The extending region 242 is the portion of the separator 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 can be understood that, as Figure 20 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 separator 24 that extends beyond the fifth end 2211 is the extending region 242; as Figure 21 shown, in the embodiment where the sixth end 2311 is closer to the end cap 12 than the fifth end 2211, the portion of the separator 24 that extends beyond the sixth end 2311 is the extending region 242.

[0289] As an example, in Figures 19 - 21 , the portions of the positive electrode plate 22, the negative electrode plate 23, and the separator 24 in the electrode assembly 2 located in the flat region 25 ( Figures 19 - 21 not shown) 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 exceeding area 242 partially overlaps with the orthographic projection of the first area 1111. Such a structure can increase the dimension of the first area 1111 along the first direction Z, improve the strengthening ability of the first area 1111, enable more areas of the first wall 111 along the first direction Z to be strengthened, and further reduce the risk of fatigue cracking in the area of the first wall 111 near the first connection part 51.

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

[0292] The first protruding part 11118 is the part of the first area 1111 protruding from the first inner surface 11121 of the second area 1112. The first protruding part 11118 can be an equal-thickness structure or a non-equal-thickness structure. Along the first direction Z, the first protruding part 11118 can extend to the first connection part 51, so that the first protruding part 11118 is directly connected to the first connection part 51.

[0293] It can be understood that in the embodiment where the first area 1111 includes a first part 11111 and a second part 11112 arranged along the first direction Z, a part of the first protruding part 11118 can be located in the first part 11111 and another part can be located in the second part 11112. In the embodiment where the first area 1111 includes a first connection segment 11113, a second connection segment 11114, and a third connection segment 11115 arranged along the third direction X, a part of the first protruding part 11118 can be located in the first connection segment 11113, another part of the first protruding part 11118 can be located in the second connection segment 11114, and still another part of the first protruding part 11118 can be located in the third connection segment 11115.

[0294] As an example, in the Figures 19 - 21 embodiment, in the projection plane perpendicular to the second direction Y, the orthographic projection of the positive electrode main body area 221 does not overlap with the orthographic projection of the first protruding part 11118, and the orthographic projection of the negative electrode main body area 231 does not overlap with the orthographic projection of the first protruding part 11118.

[0295] If, in the projection plane perpendicular to the second direction Y, the positive projection of the positive electrode main body region 221 does not overlap with the positive projection of the first convex portion 11118, 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 directly applies an expansion force to the first convex portion 11118, reducing the deformation amount of the first wall 111, and further reducing the risk of fatigue cracking in the region of the first wall 111 near the first connection portion 51. If, in the projection plane perpendicular to the second direction Y, the positive projection of the negative electrode main body region 231 does not overlap with the positive projection of the first convex portion 11118, 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 directly applies an expansion force to the first convex portion 11118, reducing the deformation amount of the first wall 111, and further reducing the risk of fatigue cracking in the region of the first wall 111 near the first connection portion 51.

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

[0297] The negative electrode active material layer 233 may be provided only on one side of the negative electrode current collector 232, that is, the negative electrode active material layer 233 is provided on only one surface of the negative electrode current collector 232 in the thickness direction; or the negative electrode active material layer 233 may be provided on both opposite sides of the negative electrode current collector 232, that is, the negative electrode active material layer 233 is provided on both opposite surfaces of the negative electrode current collector 232 in 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 portion 2331 and a negative electrode thinning portion 2332. The negative electrode main body portion 2331 and the negative electrode thinning portion 2332 are arranged along the first direction Z. Along the first direction Z, a negative electrode thinning portion 2332 is provided at one end of the negative electrode main body portion 2331 close to the end cap 12.

[0300] The thickness of the negative electrode main body portion 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 portion 2331 that is close to the end cap 12 along the first direction Z, or the negative electrode thinning portions 2332 may be provided at both ends of the negative electrode main body portion 2331 along the first direction Z. The negative electrode main body portion 2331 may be a structure with uniform thickness or a non-uniform thickness structure, and the negative electrode thinning portion 2332 may be a structure with uniform thickness or a non-uniform thickness structure. If at least one of the negative electrode main body portion 2331 and the negative electrode thinning portion 2332 is a non-uniform thickness structure, 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 portion 2331, so as to achieve that the thickness of the negative electrode main body portion 2331 is greater than the thickness of the negative electrode thinning portion 2332.

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

[0302] In this embodiment, a negative electrode thinning portion 2332 is provided at one end of the negative electrode main body portion 2331 close to the end cap 12, and the electrode assembly 2 has a larger expansion gap in the area corresponding to the negative electrode thinning portion 2332. The force exerted on the first wall 111 by the area of the electrode assembly 2 corresponding to the negative electrode thinning portion 2332 after expansion is smaller, 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 the projection plane perpendicular to the second direction Y, the positive projection of the negative electrode thinning portion 2332 located at one end of the negative electrode main body portion 2331 close to the end cap 12 is spaced apart from the positive projection of the first area 1111 along the first direction Z.

[0304] It can be understood that in the projection plane perpendicular to the second direction Y, the positive projection of the negative electrode thinning portion 2332 located at one end of the negative electrode main body portion 2331 close to the end cap 12 does not overlap with the positive projection of the first area 1111.

[0305] In this embodiment, in the projection plane perpendicular to the second direction Y, the positive projection of the negative electrode thinning portion 2332 located at one end of the negative electrode main body portion 2331 close to the end cap 12 is spaced apart from the positive projection of the first area 1111 along the first direction Z, which can reduce the influence of the negative electrode thinning portion 2332 on the first area 1111 and reduce the risk of the electrode assembly 2 directly applying an expansion force to the first area 1111 during expansion, further reducing the risk of fatigue cracking in the area of the first wall 111 near the first connection portion 51.

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

[0307] In the projection plane perpendicular to the second direction Y, the spacing dimension along the first direction Z between the orthographic projection of the negative electrode thinning portion 2332 at one end of the negative electrode main body portion 2331 close to the end cap 12 and the orthographic projection of the first region 1111 is W 1 , W 1 ≥1 mm, and this spacing dimension is the minimum distance along the first direction Z between the orthographic projections of the negative electrode thinning portion 2332 and the first region 1111 in the projection plane perpendicular to the second direction Y. W 1 can take any one of the point values such as 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, etc. or the range value between any two of them.

[0308] In this embodiment, W 1 ≥1 mm makes the orthographic projections of the negative electrode thinning portion 2332 and the first region 1111 farther apart along the first direction Z in the projection plane perpendicular to the second direction Y, 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 ~170 mg / 1540 mm 2 .

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

[0311] When measuring the single-sided coating weight of the negative electrode active material layer 233, a single-sided coated negative electrode plate 23 can be taken (if it is a double-sided coated negative electrode plate 23, the negative electrode active material layer 233 on one side can be wiped off first), and it is punched into small round pieces with an area of S 1 , and its weight is measured and recorded as M 1 . Then, wipe off the negative electrode active material layer 233 of the above-mentioned weighed negative electrode plate 23, weigh the weight of the negative electrode current collector 232, and record it as M 2 . The single-sided coating weight of the negative electrode active material layer 233 = (M 1 - M 2 ) / S 1 .

[0312] The single-sided coating weight of the negative electrode active material layer 233 is related to the swelling of the negative electrode active material layer 233. Setting the single-sided coating weight of the negative electrode active material layer 233 at 90 mg / 1540 mm 2 to 170 mg / 1540 mm 2 can, to a certain extent, balance the requirements for high energy density of the battery cell 10 and the low swelling requirements of the negative electrode plate 23, so as to reduce the influence of the swelling of the negative electrode plate 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 portion 51.

[0313] In some embodiments, the single-sided coating weight of the negative electrode active material layer 233 is 110 mg / 1540 mm 2 to 150 mg / 1540 mm 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 , 115 mg / 1540 mm 2 , 120 mg / 1540 mm 2 , 125 mg / 1540 mm 2 , 130 mg / 1540 mm 2 , 135 mg / 1540 mm 2 , 140 mg / 1540 mm 2 , 145 mg / 1540 mm 2 , 150 mg / 1540 mm 2 and so on, any one of the point values or the range values between any two of them.

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

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

[0317] The porosity of the negative electrode sheet 23 can take any point value among 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, etc. or a range value between any two of them.

[0318] The porosity of the negative electrode sheet 23 can be the percentage of the pore volume in the negative electrode sheet 23 to the total volume of the negative electrode sheet 23. As an example, when the battery cell 10 is in a 0% state of charge, the double-sided coated negative electrode sheet 23 is taken; the porosity of the negative electrode sheet 23 is measured by the true density meter AccuPyc II 1340 in accordance with the national standard GB / T24586-2009.

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

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

[0321] The mass content of silicon element in the silicon-based material in the negative electrode active material can take any point value among 0.3%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc. or a range value between any two of them.

[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 sheet 22 includes a positive electrode current collector 222 and a positive electrode active material layer 223 provided on at least one side of the positive electrode current collector 222, and the positive electrode active material layer 223 includes a positive electrode active material.

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

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

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

[0327] The thickness of the positive electrode main body portion 2231 is greater than the thickness of the positive electrode thinning portion 2232. It may be that the positive electrode thinning portion 2232 is provided only at one end of the positive electrode main body portion 2231 close to the end cap 12 along the first direction Z, or it may be that positive electrode thinning portions 2232 are provided at both ends of the positive electrode main body portion 2231 along the first direction Z. The positive electrode main body portion 2231 may be a structure with equal thickness or a non-equal thickness structure, and the positive electrode thinning portion 2232 may be a structure with equal thickness or a non-equal thickness structure. If at least one of the positive electrode main body portion 2231 and the positive electrode thinning portion 2232 is a non-equal thickness structure, 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 portion 2231, so as to make the thickness of the positive electrode main body portion 2231 greater than the thickness of the positive electrode thinning portion 2232.

[0328] As an example, the positive electrode main body portion 2231 is a structure with equal thickness, and the thickness of the positive electrode thinning portion 2232 shows a decreasing trend along the direction from the positive electrode main body portion 2231 to the positive electrode thinning portion 2232.

[0329] In this embodiment, a positive electrode thinning portion 2232 is provided at one end of the positive electrode main body portion 2231 close to the end cap 12. The electrode assembly 2 has a larger expansion gap in the area corresponding to the positive electrode thinning portion 2232. The force exerted on the first wall 111 by the area of the electrode assembly 2 corresponding to the positive electrode thinning portion 2232 after expansion is smaller, 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 the projection plane perpendicular to the second direction Y, the positive projection of the positive electrode thinning portion 2232 located at one end of the positive electrode main body portion 2231 close to the end cap 12 is spaced apart from the positive projection of the first region 1111 along the first direction Z.

[0331] It can be understood that in the projection plane perpendicular to the second direction Y, the positive projection of the positive electrode thinning portion 2232 located at one end of the positive electrode main body portion 2231 close to the end cap 12 does not overlap with the positive 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 at one end of the positive electrode main body portion 2231 close to the end cap 12 is spaced from the orthographic projection of the first region 1111 along the first direction Z, which 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 directly applies an expansion force to the first region 1111, and further reduce the risk of fatigue cracking in the region of the first wall 111 near the first connection portion 51.

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

[0334] In the projection plane perpendicular to the second direction Y, the spacing dimension between the orthographic projection of the positive electrode thinning portion 2232 at one end of the positive electrode main body portion 2231 close to the end cap 12 and the orthographic projection of the first region 1111 along the first direction Z is W 2 , W 2 ≥1 mm, and this spacing dimension 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 the projection plane perpendicular to the second direction Y. Among them, it can be W 1 =W 2 ; it can also be W 1 ≤W 2 ; it can also be W 1 ≥W 2 . W 2 can take any one of the point values such as 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 or the range value between any two of them.

[0335] In this embodiment, W 2 ≥1 mm, so that in the projection plane perpendicular to the second direction Y, the orthographic projection of the positive electrode thinning portion 2232 is farther from the orthographic projection of the first region 1111 along the first direction Z, 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 ~370 mg / 1540 / mm 2 .

[0337] The single-sided coating weight of the positive electrode active material layer 223 can take 200 mg / 1540 mm2 , 210 mg / 1540 mm 2 , 220 mg / 1540 mm 2 , 230 mg / 1540 mm 2 , 240 mg / 1540 mm 2 , 250 mg / 1540 mm 2 , 260 mg / 1540 mm 2 , 270 mg / 1540 mm 2 , 280 mg / 1540 mm 2 , 290 mg / 1540 mm 2 , 300 mg / 1540 mm 2 , 310 mg / 1540 mm 2 , 320 mg / 1540 mm 2 , 330 mg / 1540 mm 2 , 340 mg / 1540 mm 2 , 350 mg / 1540 mm 2 , 360 mg / 1540 mm 2 , 370 mg / 1540 mm 2 Any one of the above values or the range value between any two of them.

[0338] When measuring the single-sided coating weight of the positive electrode active material layer 223, the single-sided coated positive electrode plate 22 can be taken (if it is a double-sided coated positive electrode plate 22, the positive electrode active material layer 223 on one side can be wiped off first), and punched into small round pieces with an area of S 2 , weighed, and recorded as M 3 . Then wipe off the positive electrode active material layer 223 of the above-mentioned weighed positive electrode plate 22, weigh the positive electrode current collector 222, and record it as M 4 . The single-sided coating weight of the positive electrode active material layer 223 = (M 3 - M 4 ) / S 2 .

[0339] The single-sided coating weight of the positive electrode active material layer 223 is related to the swelling of the positive electrode active material layer 223. Setting the single-sided coating weight of the positive electrode active material layer 223 at 200 mg / 1540 mm 2 ~370 mg / 1540 / mm 2 can, to a certain extent, balance the requirements for high energy density of the battery cell 10 and the low swelling requirements of the positive electrode plate 22, so as to reduce the influence of the swelling of the positive electrode plate 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 part 51.

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

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

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

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

[0344] In some embodiments, please refer to Figures 22 - 24 , Figure 22 which is a partial view of the battery cell 10 provided in some embodiments of the present application (showing the first wall 111); Figure 23 is Figure 22 a partial view of the first wall 111 shown in Figure 24 is Figure 22Axonometric view of the housing 11 shown. The material of the housing 11 includes steel. The maximum thickness of the second region 1112 is D 1 , the dimension of the housing 11 in the second direction Y is D, 0.001 ≤ D 1 / D ≤ 0.012.

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

[0346] In this embodiment, a part of the first region 1111 can protrude from the first inner surface 11121 and / or the first outer surface 11122. As an example, in Figures 22 - 24 the embodiment shown, a part 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 relatively arranged first walls 111 of the housing 11 is the dimension of the housing 11 in the second direction Y. It can be understood that when measuring the dimension of the housing 11 in 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 relatively arranged first walls 111 are parallel.

[0348] For the housing 11 made of steel, D 1 / D can take any one of the point values such as 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.011, 0.012 or the range value between any two of them.

[0349] For the housing 11 made of steel, D 1 / D ≥ 0.001, increasing the thickness ratio of the second region 1112 in the housing 11, so that the second region 1112 has sufficient strength to meet the strength requirements of the housing 11; D 1 / D ≤ 0.012, reducing the thickness ratio of the second region 1112 in the housing 11. When the volume of the housing 11 is certain, the internal space of the housing 11 can be increased, and then more space can be vacated for the electrode assembly 2 to meet the requirements of the battery cell 10 for volume energy density.

[0350] For the housing 11 made of steel, since it is necessary to meet the requirements of the battery cell 10 for volume energy density, it is necessary to make D 1The / D control is below 0.012. If the thickness of the entire first wall 111 adopts the thickness of the second zone 1112, the first wall 111 is prone to deformation when subjected to the expansion force of the electrode assembly 2. Over time, it will cause fatigue cracking in the area of the first wall 111 near the first connection part 51. Therefore, a thicker first zone 1111 is provided in the first wall 111 to enhance the strength of the area of the first wall 111 near the first connection part 51 through the first zone 1111 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 zone 1112 is D 1 , 0.08 mm ≤ D 1 ≤ 0.35 mm; and / or, the maximum thickness of the first zone 1111 is D 2 , 0.1 mm ≤ D 2 ≤ 0.6 mm.

[0352] The thickness at the thickest position of the second zone 1112 is the maximum thickness of the second zone 1112. The thickness at the thickest position of the first zone 1111 is the maximum thickness of the first zone 1111. It can be understood that the maximum thickness of the second zone 1112 is less than the maximum thickness of the first zone 1111, that is, D 1 <D 2 .

[0353] For the housing 11 made of steel, D 1 can take any one point value or the range value between any two of 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.25 mm, 0.28 mm, 0.3 mm, 0.32 mm, 0.35 mm, etc.; D 2 can take any one point value or the range value between any two of 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, etc.

[0354] For the housing 11 made of steel, if the maximum thickness of the second zone 1112 is set to 0.08 mm to 0.35 mm, it can not only meet the strength requirements of the second zone 1112 but also meet the requirements of the battery cell 10 for the volume energy density. If the maximum thickness of the first zone 1111 is set to 0.1 mm to 0.6 mm, the first zone 1111 has sufficient strength to enhance the strength of the area of the first wall 111 near the first connection part 51.

[0355] In some embodiments, the material of the housing 11 includes aluminum alloy. The maximum thickness of the second zone 1112 is D 1, the dimension of the housing 11 in the second direction Y is D, 0.005 ≤ D 1 / D ≤ 0.065.

[0356] For the housing 11 made of aluminum alloy, D 1 / D can take any one of the point values such as 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, etc. or the range values between any two of them.

[0357] For the housing 11 made of aluminum alloy, D 1 / D ≥ 0.005, increasing the thickness ratio of the second region 1112 in the housing 11, so that the second region 1112 has sufficient strength to meet the strength requirements of the housing 11; D 1 / D ≤ 0.065, reducing the thickness ratio of the second region 1112 in the housing 11. When the volume of the housing 11 is certain, the internal space of the housing 11 can be increased, and then more space can be vacated for the electrode assembly 2 to meet the requirements of the battery cell 10 for the volume energy density.

[0358] For the housing 11 made of aluminum alloy, since it is necessary to meet the requirements of the battery cell 10 for the volume energy density, D 1 / D needs to be controlled below 0.065. If the thickness of the entire first wall 111 adopts the thickness of the second region 1112, the first wall 111 is likely to deform when subjected to the expansion force of the electrode assembly 2. Over time, it will cause 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 material of the housing 11 includes aluminum alloy. The maximum thickness of the second region 1112 is D 1 , 0.4mm ≤ D 1 ≤ 0.8mm; and / or, the maximum thickness of the first region 1111 is D 2 , 0.5mm ≤ D 2 ≤ 1.5mm.

[0360] For the housing 11 made of aluminum alloy, D 1It can take any one of the point values such as 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, etc. or the range value between any two of them; D 2 It can take any one of the point values such as 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, etc. or the range value between any two of them.

[0361] For the housing 11 made of aluminum alloy, if the maximum thickness of the second region 1112 is set to 0.4mm - 0.8mm, it can not only meet the strength requirements of the second region 1112, but also meet the requirements of the battery cell 10 for volume energy density. If the maximum thickness of the first region 1111 is set to 0.5mm - 1.5mm, the first region 1111 has sufficient strength to enhance the strength of the region of the first wall 111 near the first connection portion 51.

[0362] In some embodiments, the aluminum alloy includes 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%, other single elements ≤ 0.03%. This aluminum alloy has good processing and forming properties, which is convenient for the forming of the housing 11.

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

[0364] In some embodiments, please refer to Figure 25 and Figure 26 , Figure 25 is a partial view of the battery cell 10 provided in some other embodiments of the present application (showing the first wall 111), Figure 26 is Figure 25 the partial enlarged view at C in. The first region 1111 is directly connected to the first connection portion 51.

[0365] The first region 1111 and the first connection portion 51 can be point contact, line contact or surface contact to achieve their direct connection.

[0366] In this embodiment, the first region 1111 is directly connected to the first connecting portion 51, such that the first region 1111 and the first connecting portion 51 are closer along the first direction Z, such that the first region 1111 is located near the first connecting portion 51, further reducing the risk of fatigue cracking in the region where the first wall 111 is located near the first connecting portion 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. The first transition region 1117 is connected to one 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. A first connection interface 511 is formed at the connection position between the first transition region 1117 and the first connecting portion 51. The first connection 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 one end of the first region 1111 that is away from the second region 1112 along the first direction Z.

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

[0369] The first connection interface 511 is formed at the connection position between the first transition region 1117 and the first connecting portion 51. The first transition region 1117 and the first connecting portion 51 are demarcated at the first connection interface 511. The first connection interface 511 may be a plane or a curved surface.

[0370] The first region 1111 and the first transition region 1117 are demarcated by a first demarcation interface U. The first demarcation interface U is a virtual plane. The first demarcation interface U passes through the first position 5111. The first demarcation interface U is perpendicular to the first direction Z. The first transition region 1117 and the first connecting portion 51 are located above the first demarcation interface U. The first region 1111 is located below the first demarcation interface U.

[0371] In this embodiment, the first transition region 1117 is connected to the first connecting portion 51 to form the first connection interface 511, such that the first transition region 1117 and the first connecting portion 51 have a sufficiently large contact area, improving the firmness after the first wall 111 and the end cap 12 are welded.

[0372] In some embodiments, at least a portion of the first connection interface 511 extends obliquely with respect to the second direction Y.

[0373] The first connection interface 511 may extend obliquely as a whole with respect to the second direction Y, or the first connection interface 511 may extend obliquely locally with respect to the second direction Y.

[0374] It can be understood that the extension direction of the portion of the first connection interface 511 that extends obliquely with respect 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 during solidification, and the first connecting portion 51 will generate 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 connection interface 511 extends obliquely at least partially with respect to the second direction Y, near the portion of the first connection interface 511 that extends obliquely with respect to the second direction Y, the tensile stress generated by the shrinkage of the first connecting portion 51 on the first transition region 1117 and the tensile stress generated by the deformation of the first wall 111 on the first connecting portion 51 are not on the same straight line, reducing the risk of fatigue cracking in the region of the first transition region 1117 near the first connection interface 511.

[0376] In some embodiments, please continue to refer to Figure 26 , the first connection interface 511 includes a first interface 5112, and the first interface 5112 extends obliquely from the first position 5111 in the direction approaching the end cap 12. Along the second direction Y, at least a portion of the first transition region 1117 is located between the first interface 5112 and the end cap 12.

[0377] It can be understood that the first interface 5112 extends obliquely with respect 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 region 1111), and the first interface 5112 extends obliquely from the first position 5111 in the direction approaching the end cap 12, that is, the first interface 5112 extends obliquely upward from the first position 5111 in the direction approaching the end cap 12.

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

[0380] In this embodiment, along the second direction Y, at least a part of the first transition region 1117 is located between the first interface 5112 and the end cover 12. 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 force application process is blocked by the first connecting portion 51, reducing the risk of fatigue cracking in the region 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 region 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 that extends along the third direction X, and the position 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 the third position 5114. Along the first direction Z, the third position 5114 is farther from the first region 1111 than the first position 5111. The first transition region 1117 is generally triangular.

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

[0384] In some embodiments, please refer to Figure 27 and Figure 28 , Figure 27 is a partial view of the battery cell 10 provided in still other embodiments of the present application (showing the first wall 111); Figure 28 is Figure 27 a partial enlarged view at D in. The first connection interface 511 includes a second interface 5113 that extends obliquely away from the end cover 12 from the first position 5111. Along the second direction Y, at least a part of the first transition region 1117 is located on the side of the second interface 5113 facing away from the end cover 12.

[0385] It can be understood that the second interface 5113 extends obliquely with respect to the second direction Y. The second interface 5113 can be a plane or a curved surface. Along the second direction Y, at least a part of the first connecting portion 51 is located between the second interface 5113 and the end cover 12.

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

[0387] Along the second direction Y, the first transition region 1117 may be entirely located on the side of the second interface 5113 facing away from the end cap 12, or only a part of the first transition region 1117 may be located on the side of the second interface 5113 facing away from the end cap 12.

[0388] In this embodiment, along the second direction Y, at least a part of the first transition region 1117 is located on the side of the second interface 5113 facing away from the end cap 12, so that the first transition region 1117 restricts the first connecting portion 51, reducing the risk of the first connecting portion 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 that extends along the third direction X, and the position 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 the first direction Z, the fourth position 5115 is farther from the first region 1111 than the first position 5111. The first transition region 1117 is generally triangular.

[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 portion 51 are in a directly connected state, making the first region 1111 and the first connecting portion 51 closer along the first direction Z, further reducing the risk of fatigue cracking in the region of the first wall 111 near the first connecting portion 51 due to the expansion of the electrode assembly 2.

[0392] In some embodiments, please refer to Figure 29 and Figure 30 , Figure 29 is a partial view of the battery cell 10 provided in still other embodiments of the present application (showing the first wall 111); Figure 30 is Figure 29Partial enlarged view at position 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 towards the end cap 12, and the second interface 5113 extends obliquely from the first position 5111 away from the end cap 12. Along the second direction Y, a part of the first transition region 1117 is located between the first interface 5112 and the end cap 12, and another part 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 region 1117 at the third position 5114, and the second interface 5113 is connected to the outer surface of the first transition region 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 connection part 51.

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

[0396] If the Vickers hardness of the first transition region 1117 is less than the Vickers hardness of the second region 1112, such that the first transition region 1117 with lower Vickers hardness is connected to the first connection part 51, it can relieve the rigid pulling between the first wall 111 and the first connection part 51 when the first wall 111 deforms, and reduce the risk of separation between the first wall 111 and the first connection part 51. If the Vickers hardness of the first transition region 1117 is less than the Vickers hardness of the first connection part 51, such that the first transition region 1117 is more likely to deform compared to the first connection part 51, it can relieve the rigid pulling between the first wall 111 and the first connection part 51 when the first wall 111 deforms, and reduce the risk of separation between the first wall 111 and the first connection part 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 facing away from the electrode assembly 2 is the outer surface 121 of the end cap.

[0399] In Figure 25 and Figure 26 In the embodiments shown, 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] In Figure 27 and Figure 28In 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] In Figure 29 and Figure 30 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 than the outer surface 121 of the end cap along the first direction Z, such that the first connection portion 51 can sink to a deeper position in the first wall 111, effectively improving 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 which provides an isometric view of the housing 11 for still further embodiments of the present application; Figure 32 is Figure 31 a partial enlarged view at F in . The housing 11 further 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 connection portion 5. The first connection portion 51 and the third connection portion 5 are both part of the connection portion 5. The second wall 112 can be a uniform-thickness structure or a non-uniform-thickness structure.

[0405] In Figure 31 and Figure 32 the embodiments, the second wall 112 is a uniform-thickness structure. In other embodiments, the second wall 112 can also be a non-uniform-thickness structure. The structure of the second wall 112 can be the same as the structure of the first wall 111. For example, the second wall 112 includes a fifth region and a sixth region arranged along the first direction Z, and the thickness of the fifth region is greater than the thickness of the sixth region. The fifth region is located between the third connection portion 5 and the sixth region, which can reduce the risk of fatigue cracking in the region of the second wall 112 near the third connection portion 5. Among them, the structure of the fifth region can be the same as the structure of the first region 1111, and the structure of the sixth region can be the same as the structure of the second region 1112.

[0406] The first wall 111 and the second wall 112 in the housing 11 are indirectly connected through the corner wall 113, and the sum of the numbers of the first wall 111 and the second wall 112 is equal to the number of the corner wall 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 in an arc shape, 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 via a corner wall 113 , so that the first wall 111 can transition to the second wall 112 via the corner wall 113 , which can effectively reduce the risk of stress concentration at the corner of the housing 11 .

[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 the present application (showing a corner wall 113); Figure 34 A schematic diagram of the structure of a corner wall 113 provided in some embodiments of the present application; Figure 35 Schematic diagram of the structure of the corner wall 113 provided in some other embodiments of the present application. The corner wall 113 is welded with the end cover 12 to form the second connecting portion 52. The corner wall 113 includes a third area 1131 and a fourth area 1132 arranged along the first direction Z, the thickness of the third area 1131 is greater than the thickness of the fourth area 1132, and the third area 1131 is located between the fourth area 1132 and the second connecting portion 52.

[0410] The third area 1131 may be an area where the thickness of the corner wall 113 is thickened. The third area 1131 is thicker than the fourth area 1132. The fourth area 1132 may be a portion of the corner wall 113 located on the side of the third area 1131 away from the second connection portion 52 along the first direction Z. The third area 1131 may be directly connected to the second connection portion 52 or indirectly connected; the third area 1131 may be directly connected to the fourth area 1132 or indirectly connected. The third area 1131 may be an equal thickness structure or a non-equal thickness structure; the fourth area 1132 may be an equal thickness structure or a non-equal thickness structure. If at least one of the third area 1131 and the fourth area 1132 is a non-equal thickness structure, the maximum thickness of the fourth area 1132 may be less than or equal to the minimum thickness of the fourth area 1132, so as to achieve that the thickness of the third area 1131 is greater than the thickness of the fourth area 1132.

[0411] The fourth area 1132 has a second inner surface 11321 facing the inner space of the housing 11 and a second outer surface 11322 facing away from the inner space of the housing 11. The third area 1131 may partially protrude from the second inner surface 11321 and / or the second outer surface 11322. Figure 33 and Figure 34 In the illustrated embodiment, a portion of the third region 1131 protrudes from the second inner surface 11321, and an outer surface of the third region 1131 is coplanar with the second outer surface 11322; Figure 35In 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 to the corner wall 113 one by one. The second connecting portion 52 is the portion where a welding mark is formed after the end cap 12 and the corner wall 113 are welded, and it can be the portion where the end cap 12 and the corner wall 113 are welded and fused together as 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 stitch welding or by penetration welding. Both the second connecting portion 52 and the first connecting portion 51 are part of the connecting portion 5.

[0413] 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 second connecting portion 52 and the fourth region 1132, such that the third region 1131 with a greater thickness is closer to the second connecting portion 52 compared to the fourth region 1132. The third region 1131 strengthens the region of the corner wall 113 near the second connecting portion 52, reducing the risk of fatigue cracking in the region of the corner wall 113 near the second connecting portion 52, and thus improving the service life of the battery cell 10.

[0414] In some embodiments, please continue to refer to Figure 32 that the third region 1131 is directly connected to the first region 1111.

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

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

[0417] Connecting the third region 1131 directly to the first region 1111 makes the first region 1111 and the third region 1131 form a whole. The third region 1131 and the first region 1111 have a promoting effect on each other, enhancing the strengthening effect of the first region 1111 on the first wall 111 and the strengthening effect of the second region 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 connection end 1133 and a second connection end 1134. The first wall 111 is connected to the first connection end 1133, the second wall 112 is connected to the second connection end 1134, and the thickness of the third region 1131 shows a decreasing trend in the direction from the first connection end 1133 to the second connection end 1134.

[0419] As an example, the thickness of the third region 1131 gradually decreases in the direction from the first connection end 1133 to the second connection end 1134. The second wall 112 has a uniform thickness structure. The inner surface of the third region 1131 connects 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 connects 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 drive the deformation of the corner wall 113. Along the circumference of the opening, the closer the corner wall 113 is to the first wall 111, the greater the influence of the first wall 111 on it, and the greater the deformation amount of the region of the corner wall 113 closer to the first wall 111. The thickness of the third region 1131 shows a decreasing trend in the direction from the first connection end 1133 to the second connection end 1134, making the region of the third region 1131 closer to the first wall 111 along the circumference of the opening have greater strength. Thus, the influence of the deformation of the first wall 111 on the corner wall 113 is reduced. While ensuring that the corner wall 113 has sufficient strength in the vicinity of the second connection portion 52, the material used in the third region 1131 is reduced, and the production cost is lowered.

[0421] In some embodiments, please refer to Figure 36 and Figure 37 , Figure 36 which is a partial view (showing the corner wall 113) of the battery cell 10 provided in other embodiments of the present application; Figure 37 is Figure 36 the partial enlarged view at G in

[0422] The third region 1131 is directly connected to the second connection portion 52.

[0423] The third region 1131 and the second connection portion 52 may be in point contact, line contact or surface contact to achieve their direct connection.

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

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

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

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

[0428] In this embodiment, the second transition region 1135 is connected to the second connecting portion 52 to form the second connection interface 521, so that the second transition region 1135 and the second connecting portion 52 have a sufficiently large contact area, improving the firmness after welding the corner wall 113 and the end cover 12.

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

[0430] The second connection interface 521 may extend obliquely as a whole with respect to the thickness direction of the corner wall 113, or may extend obliquely locally with respect to the thickness direction of the corner wall 113.

[0431] Near the portion where the second connection interface 521 extends obliquely in the thickness direction of the corner wall 113, the tensile stress generated by the shrinkage of the second connection portion 52 on the second transition region 1135 and the tensile stress generated by the deformation of the corner wall 113 on the second connection portion 52 in the second transition region 1135 are not in the same straight line, reducing the risk of fatigue cracking in the region of the second transition region 1135 near the second connection interface 521.

[0432] In some embodiments, continue to refer to Figure 37 , the second connection interface 521 includes a third interface 5212, and the third interface 5212 extends obliquely from the second position 5211 in the direction close to the end cover 12. Along the thickness direction of the corner wall 113, at least a part of the second transition region 1135 is located between the third interface 5212 and the end cover 12.

[0433] It can be understood that the third interface 5212 extends obliquely in 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 region 1131), and the third interface 5212 extends obliquely from the second position 5211 in the direction close to the end cover 12, that is, the third interface 5212 extends obliquely upward from the second position 5211 in the direction close to the end cover 12.

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

[0436] In this embodiment, along the thickness direction of the corner wall 113, at least a part of the second transition region 1135 is located between the third interface 5212 and the end cover 12, and the second connection portion 52 plays a protective role on the second transition region 1135. When the second transition region 1135 deforms outward, it will be blocked by the second connection portion 52, reducing the risk of fatigue cracking in the region of the second transition region 1135 near the third interface 5212.

[0437] In some embodiments, 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 that extends along the third direction X, and the position where the second straight line is located 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, and along the first direction Z, the fifth position 5214 is farther from the third region 1131 than the second position 5211. The second transition region 1135 is generally 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, such that the third region 1131 and the second connection portion 52 are in a directly connected state, and the third region 1131 and the second connection portion 52 are closer along the first direction Z, further reducing the risk of fatigue cracking in the region of the corner wall 113 near the second connection portion 52.

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

[0441] It can be understood that the fourth interface 5213 extends obliquely with respect to the second direction Y. The fourth interface 5213 can be a plane or a curved surface. Along the thickness direction of the corner wall 113, at least a part 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 region 1111), and the fourth interface 5213 extends obliquely away from the end cap 12 from the second position 5211, that is, the fourth interface 5213 extends obliquely upward away from the end cap 12 from the second position 5211.

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

[0444] In this embodiment, at least a part 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 connecting portion 52 and reduces the risk of the second connecting 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, the second straight line extends along the third direction X, and the position where the second straight line is located is the second position 5211. The fourth interface 5213 is connected to the outer surface of the second transition region 1135 at the sixth position 5215. Along the first direction Z, the sixth position 5215 is farther from the third region 1131 than the second position 5211. The second transition region 1135 is generally triangular.

[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 portion 52 are in a directly connected state, making the third region 1131 and the second connecting portion 52 closer along the first direction Z, and further reducing the risk of fatigue cracking in the region of the corner wall 113 near the second connecting portion 52.

[0448] In some embodiments, please refer to Figure 40 and Figure 41 , Figure 40 is a partial view of the battery cell 10 provided in still other embodiments of the present application (showing the corner wall 113); Figure 41 is Figure 40 is a partial enlarged view at I in. The second connection interface 521 includes a third interface 5212 and a fourth interface 5213. The third interface 5212 extends obliquely in a direction close to the end cap 12 from the second position 5211, and the fourth interface 5213 extends obliquely in a direction away from the end cap 12 from the second position 5211. Along the thickness direction of the corner wall 113, a part of the second transition region 1135 is located between the third interface 5212 and the end cap 12, and another part 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 region 1132 is less than the Vickers hardness of the second connecting portion 52.

[0452] If the Vickers hardness of the second transition region 1135 is less than the Vickers hardness of the fourth region 1132, and the second transition region 1135 with lower Vickers hardness is connected to the second connecting portion 52, it can relieve the rigid pulling between the corner wall 113 and the second connecting portion 52 when the corner wall 113 deforms, and reduce the risk of separation between the corner wall 113 and the second connecting portion 52. If the Vickers hardness of the second transition region 1135 is less than the Vickers hardness of the second connecting portion 52, making the second transition region 1135 more likely to deform compared to the second connecting portion 52, it can relieve the rigid pulling between the corner wall 113 and the second connecting portion 52 when the corner wall 113 deforms, and reduce 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] In Figure 36 and Figure 37 shown in the embodiments, 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] In Figure 38 and Figure 39 shown in the embodiments, along the first direction Z, both the sixth position 5215 and the second position 5211 are closer to the second region 1112 than the outer surface 121 of the end cap.

[0456] In Figure 40 and Figure 41 shown in the embodiments, along the first direction Z, the fifth position 5214, the sixth position 5215 and the second position 5211 are all closer to the second region 1112 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 than the outer surface 121 of the end cap along the first direction Z, so that the second connecting portion 52 can sink to a deeper position of 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 to each other along the second direction Y, and the two second walls 112 are arranged opposite to 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 in pairs.

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

[0460] In this embodiment, the housing 11 is generally in the shape of a cuboid, and the size of the housing 11 can be made larger, which is beneficial to meeting the requirements of large capacitance of the battery cell 10.

[0461] In some embodiments, the Vickers hardness of at least part 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 region 1111 is less than the Vickers hardness of the second region 1112, or it can be that the Vickers hardness of only a part of the first region 1111 is less than the Vickers hardness of the second region 1112.

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

[0464] When the second region 1112 deforms due to the expansion force of the electrode assembly 2, the region in the first region 1111 with a smaller Vickers hardness compared to the second region 1112 can reduce the influence of the deformation of the second region 1112 on the region of the first wall 111 near the first connection portion 51, and reduce the risk of fatigue cracking of the region of the first wall 111 near the first connection portion 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 of the positional relationship before welding the end cap 12 and the side wall in some embodiments of the present 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 limit the movement of the end cap 12 in the direction close to 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 at the opening end of the housing 11, or the limiting surface 1115 can also be a stepped surface on the first wall 111, and the stepped surface is at a certain distance from the end face of the first wall 111 at the opening end of the housing 11.

[0467] The limiting surface 1115 limits the end cover 12, reducing the risk of the end cover 12 moving toward the electrode assembly 2 when welded to the shell 11, which can effectively improve the welding quality of the end cover 12 and the shell 11 and reduce the difficulty of welding the end cover 12 and the shell 11.

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

[0469] As an example, the end cover 12 is at least partially accommodated in the shell 11, so that the limiting area 1116 and the end cover 12 are arranged opposite to each other along the second direction Y.

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

[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 to the shell 11, further improving the welding quality of the end cover 12 and the shell 11, and reducing the difficulty of welding the end cover 12 and the shell 11.

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

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

[0474] In this embodiment, the electrode assembly 2 is a wound electrode assembly, which has a more compact structure and a stronger anti-extrusion capability.

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

[0476] As an example, there is one more negative electrode sheet 23 than positive electrode sheet 22 .

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

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

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

[0480] In this embodiment, along the third direction X, the size of the first region 1111 is greater than the size of the positive electrode plate 22 and / or the size of the negative electrode plate 23, such that the size of the first region 1111 along the third direction X is larger, so that the strength of more regions of the first wall 111 along the third direction X is enhanced, further reducing the risk of fatigue cracking in the region of the first wall 111 near the first connection portion 51.

[0481] In some embodiments, please refer to Figure 43 , Figure 43 is a schematic connection diagram of the end cap 12 and the electrode terminal 3 provided in some embodiments of the present application. The battery cell 10 further includes two electrode terminals 3, the two electrode terminals 3 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 an extraction hole, the electrode terminal 3 includes a terminal body 31, a first limiting portion 32, and a second limiting portion 33, the terminal body 31 connects the first limiting portion 32 and the second limiting portion 33, the terminal body 31 passes through the extraction hole, along the first direction Z, the first limiting portion 32 is located on the side of the end cap 12 facing away from the electrode assembly 2, and the second limiting portion 33 is located on the side of the end cap 12 facing the electrode assembly 2.

[0482] The first limiting portion 32 and the second limiting portion 33 have a limiting function, the first limiting portion 32 and the second limiting portion 33 are respectively connected to both ends of the terminal body 31, and the first limiting portion 32 and the second limiting portion 33 cooperate to limit the terminal body 31 from disengaging from the extraction hole. Along the first direction Z, the projected area of the first limiting portion 32 and the projected area of the second limiting portion 33 are both greater than the projected area of the terminal body 31. It may be that the projected area of the first limiting portion 32 is greater than the projected area of the second limiting portion 33, or it may be that the projected area of the second limiting portion 33 is greater than the projected area of the first limiting portion 32. The first limiting portion 32, the second limiting portion 33, and the terminal body 31 may be integrally formed, or one of the first limiting portion 32 and the second limiting portion 33 may be integrally formed with the terminal body 31, and the other may be separately provided and connected to the terminal body 31.

[0483] As an example, the battery cell 10 may further 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 has low installation difficulty and better economy.

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

[0486] An embodiment of the present application provides an electrical device, including the battery cell 10 provided in any one of the above embodiments. The battery cell 10 is used to provide electrical energy for the electrical device.

[0487] An embodiment of the present application further provides a battery cell 10. The battery cell 10 includes a housing 11, an end cap 12, and an electrode assembly 2. One end of the housing 11 in the first direction Z forms an opening. The end cap 12 is welded to the housing 11 to close the opening of the housing 11. At least a part of the electrode assembly 2 is accommodated in the housing 11. The housing 11 is in the shape of a cuboid and includes two first walls 111, two second walls 112, and four corner walls 113. The first wall 111 is the wall with the largest outer surface area of the housing 11. The adjacent first wall 111 and second wall 112 are connected by a corner wall 113. The two first walls 111 are disposed opposite to each other in the second direction Y. The two second walls 112 are disposed opposite to each other in the third direction X. The first direction Z, the second direction Y, and the third direction X are perpendicular to each other in pairs. The electrode assembly 2 includes a positive electrode plate 22, a negative electrode plate 23, and a separator 24. A separator 24 is disposed between the positive electrode plate 22 and the negative electrode plate 23. The electrode assembly 2 has a flat area 25. The part of the positive electrode plate 22 located in the flat area 25, the part of the negative electrode plate 23 located in the flat area 25, and the part of the separator 24 located in the flat area 25 are stacked in the second direction Y. The 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 the electrode assembly 2. The first wall 111 is disposed opposite to the first surface 27 in the second direction Y.

[0488] The first wall 111 and the end cap 12 are welded to form a first connection portion 51. The first wall 111 includes a first region 1111 and a second region 1112 arranged in 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. The material of the housing 11 includes aluminum alloy. The maximum thickness of the second region 1112 is D 1 , and the maximum thickness of the first region 1111 is D2 The dimension of the housing 11 in the second direction Y is D, where 0.005 ≤ D 1 / D ≤ 0.065, 0.4 mm ≤ D 1 ≤ 0.8 mm, 0.5 mm ≤ D 2 ≤ 1.5 mm. The corner wall 113 is welded to the end cap 12 to form the second connection 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 that of the fourth region 1132, and the third region 1131 is located between the fourth region 1132 and the second connection portion 52. The dimension of the first region 1111 in the third direction X is greater than the dimension of the second region 1112 in the first direction Z. The two ends of the first region 1111 in 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 connection end 1133 and a second connection end 1134. The first wall 111 is connected to the first connection end 1133, and the second wall 112 is connected to the second connection end 1134. The thickness of the third region 1131 decreases in the direction from the first connection end 1133 to the second connection 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 that of the second part 11112, and the thickness of the second part 11112 decreases in the direction from the end cap 12 to the electrode assembly 2.

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

[0490] The first wall 111 further includes a first transition region 1117. The first transition region 1117 is connected to one 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. The connection position between the first transition region 1117 and the first connecting portion 51 forms a first connection interface 511. The first connection 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 one end of the first region 1111 that is away from the second region 1112 along the first direction Z. The first connection interface 511 includes a second interface 5113. The second interface 5113 extends obliquely away from the end cap 12 from the first position 5111. Along the second direction Y, a part 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 further includes a second transition region 1135. The second transition region 1135 is connected to one 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. The connection position between the second transition region 1135 and the second connecting portion 52 forms a second connection interface 521. The second connection 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 one end of the third region 1131 that is away from the fourth region 1132 along the first direction Z. The second connection interface 521 includes a fourth interface 5213. The fourth interface 5213 extends obliquely away from the end cap 12 from the second position 5211. Along the thickness direction of the corner wall 113, a part 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] In an embodiment of the present application, a battery cell 10 is further provided. The battery cell 10 includes a housing 11, an end cap 12, and an electrode assembly 2. One end of the housing 11 in the first direction Z forms an opening. The end cap 12 is welded to the housing 11 to close the opening of the housing 11, and the electrode assembly 2 is at least partially accommodated in the housing 11. The housing 11 is in the shape of a cuboid and includes two first walls 111, two second walls 112, and four corner walls 113. The first wall 111 is the wall with the largest outer surface area of the housing 11. The adjacent first wall 111 and second wall 112 are connected by a corner wall 113. The two first walls 111 are disposed opposite to each other in the second direction Y, and the two second walls 112 are disposed opposite to each other in the third direction X. The first direction Z, the second direction Y, and the third direction X are perpendicular to each other in pairs. The electrode assembly 2 includes a positive electrode plate 22, a negative electrode plate 23, and a separator 24. A separator 24 is disposed between the positive electrode plate 22 and the negative electrode plate 23. The electrode assembly 2 has a flat area 25. The part of the positive electrode plate 22 located in the flat area 25, the part of the negative electrode plate 23 located in the flat area 25, and the part of the separator 24 located in the flat area 25 are stacked in the second direction Y. The 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 the electrode assembly 2. The first wall 111 is disposed opposite to the first surface 27 in the second direction Y.

[0493] The first wall 111 is welded to the end cap 12 to form a first connection portion 51. The first wall 111 includes a first region 1111 and a second region 1112 arranged in 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. The material of the housing 11 includes aluminum alloy, and the maximum thickness of the second region 1112 is D 1 , and the maximum thickness of the first region 1111 is D 2 , the dimension of the housing 11 in the second direction Y is D, 0.005 ≤ D 1 / D ≤ 0.065, 0.4 mm ≤ D 1 ≤ 0.8 mm, 0.5 mm ≤ D 2 ≤ 1.5 mm.

[0494] The dimension of the first region 1111 in the third direction X is greater than the dimension of the first region 1111 in the first direction Z. The first region 1111 includes a first part 11111 and a second part 11112 arranged in 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, and the thickness of the second part 11112 shows a decreasing trend in the direction from the end cap 12 to the electrode assembly 2.

[0495] Both ends of the first region 1111 along the third direction X are not in contact with the corner wall 113. The first region 1111 includes a second connection segment 11114, a first connection segment 11113, and a third connection segment 11115 arranged along the third direction X. The first connection segment 11113 passes through the middle cross-section. The thickness of the first connection segment 11113 is greater than the thicknesses of the second connection segment 11114 and the third connection segment 11115. The first connection segment 11113 connects the second connection segment 11114 and the third connection segment 11115. The dimension of the first connection segment 11113 along the third direction X is L 1 , the dimension of the first wall 111 along the third direction X is L, and 0.2 ≤ L 1 / L ≤ 0.6. The first connection segment 11113 has opposite first and second ends 11113a and 11113b along the third direction X. The first wall 111 has opposite third and fourth ends 1113 and 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, and the minimum distance between the first end 11113a and the third end 1113 along the third direction X is L 2 , and the minimum distance between the second end 11113b and the fourth end 1114 along the third direction X is L 3 , L 2 / L ≤ 0.3, L 3 / L ≤ 0.3, and 100 mm ≤ L ≤ 450 mm.

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

[0497] The first wall 111 further includes a first transition region 1117. The first transition region 1117 is connected to one 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. The connection position between the first transition region 1117 and the first connecting portion 51 forms a first connection interface 511. The first connection 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 one end of the first region 1111 away from the second region 1112 along the first direction Z. The first connection interface 511 includes a second interface 5113. The second interface 5113 extends obliquely away from the end cap 12 from the first position 5111. Along the second direction Y, a part 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, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other.

[0499] The above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, characterized in that: include: A housing having an opening at at least one end along a first direction, the housing comprising a first wall; An end cover, closing the opening, wherein the first wall and the end cover are welded to form a first connecting portion; an electrode assembly, at least partially contained in the housing, the electrode assembly comprising 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 being stacked along a second direction, the second direction being parallel to a thickness direction of the first wall, and the first direction intersecting the second direction; The first wall includes 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 portion and the second area.

2. The battery cell according to claim 1, characterized in that: The electrode assembly has a straight area, and a portion of the positive electrode sheet located in the straight area and a portion of the negative electrode sheet located in the straight area are stacked along the second direction.

3. The battery cell according to claim 2, characterized in that: The electrode assembly includes a first surface and a second surface adjacent to each other, the first surface is perpendicular to the second direction, an area of ​​the first surface is larger than an area of ​​the second surface, and the first surface is arranged opposite to the first wall along the second direction.

4. The battery cell according to claim 3, characterized in that: The first surface is a surface with the largest area among the outer surfaces of the electrode assembly.

5. The battery cell according to claim 3, characterized in that: The electrode assembly is a winding structure, and the electrode assembly further has a corner area, and the corner area is provided at least at one end of the straight area along the third direction, and 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, and at least a part of the second surface is an arc surface.

6. The battery cell according to claim 3, characterized in that: The electrode assembly is a laminated structure, the straight area includes a plurality of positive electrode sheets and a plurality of negative electrode sheets, the plurality of positive electrode sheets and the plurality of negative electrode sheets are stacked along the second direction, and the first surface is perpendicular to the second surface.

7. The battery cell according to claim 1, characterized in that: The first wall is a wall with the largest outer surface area in the shell.

8. The battery cell according to claim 1, characterized in that: The shell includes two first walls, which are arranged opposite to each other along the second direction, and the electrode assembly is located between the two first walls.

9. The battery cell according to claim 1, characterized in that: The first region includes a first portion and a second portion arranged along the first direction, the second portion connects the first portion and the second region, and a thickness of the first portion is greater than a thickness of the second portion.

10. The battery cell according to claim 9, characterized in that: The thickness of the second portion decreases along a direction from the end cover to the electrode assembly.

11. The battery cell according to claim 1, characterized in that: A size of the first region along the third direction is greater than a size 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 according to claim 11, characterized in that: The first area includes a first connecting segment, the first connecting segment passes through a middle section of the first wall, the middle section is perpendicular to the third direction, and the distances from the middle section to both ends of the first wall along the third direction are equal.

13. The battery cell according to claim 12, characterized in that: The first zone also 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, 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.

14. The battery cell according to claim 13, characterized in that: The first zone also includes a first transition section, the first connecting section, the first transition section and the second connecting section are arranged along the third direction, the first transition section connects the second connecting section and the first connecting section, and the thickness of the first transition section increases along the direction from the second connecting section to the first connecting section; and / or, the first zone also includes a second transition section, the first connecting section, the second transition section and the third connecting section are arranged along the third direction, the second transition section connects the third connecting section and the first connecting section, and the thickness of the second transition section increases along the direction from the third connecting section to the first connecting section.

15. The battery cell according to claim 12, characterized in that: A dimension of the first connecting section along the third direction is L1, a dimension of the first wall along the third direction is L, and 0.2≤L1 / L≤0.

6.

16. The battery cell according to claim 12, characterized in that: The first connecting section 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, a dimension of the first wall along the third direction is L, a minimum distance between the first end and the third end along the third direction is L2, and a 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 according to claim 16, characterized in that: 100mm≤L≤450mm.

18. The battery cell according to claim 11, characterized in that: The shell comprises a corner wall, and both ends of the first wall along the third direction are connected to the corner wall; At least one end of the first area along the third direction is not in contact with the corner wall; or, both ends of the first area along the third direction extend to the two corner walls respectively.

19. The battery cell according to any one of claims 1 to 18, characterized in that: The electrode assembly further includes a separator, which is disposed between the positive electrode sheet and the negative electrode sheet; The positive electrode plate includes a positive electrode main area and a positive electrode ear protruding from the positive electrode main area, the positive electrode main area has a positive electrode active material layer, the negative electrode plate includes a negative electrode main area and a negative electrode ear protruding from the negative electrode main area, the negative electrode main area has a negative electrode active material layer, along the first direction, the positive electrode main area has a fifth end facing the end cover, the negative electrode main area has a sixth end facing the end cover, the isolation member has a seventh end facing the end cover, and the seventh end is closer to the end cover than the fifth end and the sixth end.

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

21. The battery cell according to claim 19, characterized in that The second region has a first inner surface facing the inner 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 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 area does not overlap with the orthographic projection of the first protrusion.

22. The battery cell according to any one of claims 1 to 18, characterized in that: The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material.

23. The battery cell according to claim 22, characterized in that: The negative electrode active material layer includes a negative electrode main body and a negative electrode thinning portion, the negative electrode main body and the negative electrode thinning portion are arranged along the first direction, and the negative electrode thinning portion is provided at one end of the negative electrode main body close to the end cover along the first direction.

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

25. The battery cell according to claim 24, characterized in that In a projection plane perpendicular to the second direction, a spacing dimension between an orthographic projection of the negative electrode thinned portion and an orthographic projection of the first region along the first direction is greater than or equal to 1 mm.

26. The battery cell according to 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 , optional 110mg / 1540mm 2 ~150mg / 1540mm 2 .

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

28. The battery cell according to claim 22, characterized in that The negative electrode active material comprises a silicon-based material, and the mass content of silicon in the silicon-based material is 0.3% to 10%, and can be optionally 1% to 6%.

29. The battery cell according to claim 28, characterized in that The silicon-based material includes at least one of a silicon-oxygen compound and a silicon-carbon composite.

30. The battery cell according to any one of claims 1 to 18, characterized in that: The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector, wherein the positive electrode active material layer includes a positive electrode active material.

31. The battery cell according to claim 30, characterized in that The positive electrode active material layer includes a positive electrode main body and a positive electrode thinning portion, the positive electrode main body and the positive electrode thinning portion are arranged along the first direction, and the positive electrode thinning portion is provided at one end of the positive electrode main body close to the end cover along the first direction.

32. The battery cell according to claim 31, characterized in that In a projection plane perpendicular to the second direction, an orthographic projection of the positive electrode thinned portion and an orthographic projection of the first region are spaced apart along the first direction.

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

34. The battery cell according to 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 ; Optional: 240mg / 1540mm 2 ~330mg / 1540mm 2 .

35. The battery cell according to claim 30, characterized in that The positive electrode active material is a lithium-containing phosphate.

36. The battery cell according to any one of claims 1 to 18, characterized in that: The material of the shell includes steel; The maximum thickness of the second zone is D1, the dimension of the shell along the second direction is D, and 0.001≤D1 / D≤0.

012.

37. The battery cell according to any one of claims 1 to 18, characterized in that: The material of the shell includes steel; The maximum thickness of the second region is D1, 0.08 mm ≤ D1 ≤ 0.35 mm; and / or the maximum thickness of the first region is D2, 0.1 mm ≤ D2 ≤ 0.6 mm.

38. The battery cell according to any one of claims 1 to 18, characterized in that: The material of the shell includes aluminum alloy; The maximum thickness of the second zone is D1, the dimension of the shell along the second direction is D, and 0.005≤D1 / D≤0.

065.

39. The battery cell according to any one of claims 1 to 18, characterized in that: The material of the shell includes aluminum alloy; The maximum thickness of the second region is D1, 0.4 mm ≤ D1 ≤ 0.8 mm; and / or the maximum thickness of the first region is D2, 0.5 mm ≤ D2 ≤ 1.5 mm.

40. The battery cell according to any one of claims 1 to 18, characterized in that: The shell is made of aluminum alloy, which includes the following components in percentage by mass: 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 single elements ≤ 0.03%.

41. The battery cell according to any one of claims 1 to 18, characterized in that: The first region is directly connected to the first connecting portion.

42. The battery cell according to any one of claims 1 to 18, characterized in that: The first wall also includes a first transition zone, which is connected to one end of the first zone away from the second zone along the first direction, and the first transition zone is connected to the first connecting portion. The connecting position of the first transition zone and the first connecting portion forms a first connecting interface, and the first connecting interface has a first position closest to the first zone along the first direction, and the first position is located at one end of the first zone away from the second zone along the first direction.

43. The battery cell according to claim 42, characterized in that At least a portion of the first connection interface extends obliquely relative to the second direction.

44. The battery cell according to claim 43, characterized in that The first connection interface includes a first interface, the first interface extends obliquely from the first position toward the end cover, and along the second direction, at least a portion of the first transition zone is located between the first interface and the end cover.

45. The battery cell according to claim 44, characterized in that The first interface is connected to the outer surface of the first region at the first location.

46. ​​The battery cell according to any one of claims 43 to 45, characterized in that: The first connection interface includes a second interface, the second interface extends obliquely from the first position in a direction away from the end cover, and along the second direction, at least a portion of the first transition zone is located on a side of the second interface away from the end cover.

47. The battery cell according to claim 46, characterized in that The second interface is connected to the inner surface of the first region at the first position.

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

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

50. The battery cell according to any one of claims 1 to 18, characterized in that: The housing further includes a second wall and a corner wall. The first wall, the corner wall and the second wall are arranged along the circumference of the opening. The corner wall connects the first wall and the second wall.

51. The battery cell according to claim 50, characterized in that The corner wall and the end cover are welded to form a second connection portion; The corner wall includes a third area and a fourth area arranged along the first direction, the thickness of the third area is greater than the thickness of the fourth area, and the third area is located between the fourth area and the second connecting portion.

52. The battery cell according to claim 51, characterized in that The third region is directly connected to the first region.

53. The battery cell according to 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 is connected to the first connecting end, the second wall is connected to the second connecting end, and the thickness of the third zone tends to decrease in the direction from the first connecting end to the second connecting end.

54. The battery cell according to any one of claims 51 to 53, characterized in that: The third region is directly connected to the second connecting portion.

55. The battery cell according to any one of claims 51 to 53, characterized in that: The corner wall also includes a second transition zone, which is connected to an end of the third zone along the first direction away from the fourth zone, and the second transition zone is connected to the second connecting portion. The connecting position of the second transition zone and the second connecting portion forms a second connecting interface, and the second connecting interface has a second position closest to the third zone along the first direction, and the second position is located at an end of the third zone along the first direction away from the fourth zone.

56. The battery cell according to claim 55, characterized in that At least a portion of the second connection interface extends obliquely relative to a thickness direction of the corner wall.

57. The battery cell according to claim 56, characterized in that The second connection interface includes a third interface, and the third interface extends obliquely from the second position toward the end cover. Along the thickness direction of the corner wall, at least a part of the second transition zone is located between the third interface and the end cover.

58. The battery cell according to 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 according to any one of claims 56 to 58, characterized in that: The second connection interface includes a fourth interface, which extends obliquely from the second position away from the end cover, and along the thickness direction of the corner wall, at least part of the second transition zone is located on a side of the fourth interface away from the end cover.

60. The battery cell according to claim 59, characterized in that The fourth interface is connected to the inner surface of the third region at the second position.

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

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

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

64. The battery cell according to any one of claims 1 to 18, characterized in that: The Vickers hardness of at least a portion of the first region is less than the Vickers hardness of the second region.

65. The battery cell according to any one of claims 1 to 18, characterized in that: Along the first direction, the first wall has a limiting surface facing the end cover, and the limiting surface abuts against the end cover to limit the end cover from moving in a direction close to the electrode assembly.

66. The battery cell according to claim 65, characterized in that The first wall further includes a limiting area arranged on the limiting surface, the limiting area and the end cover are arranged opposite to each other along the second direction, and the limiting area and the end cover are welded to form the first connecting portion.

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

68. The battery cell according to claim 67, characterized in that The number of the negative electrode sheets is greater than the number of the positive electrode sheets, and one positive electrode sheet is arranged between two adjacent negative electrode sheets.

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

71. The battery cell according to any one of claims 1 to 18, characterized in that: The battery cell further includes two electrode terminals, which are disposed on the end cap, have opposite polarities, and are both electrically connected to the electrode assembly; The end cover is provided with a lead-out hole, and the electrode terminal includes a terminal body, a first limiting portion and a second limiting portion, the terminal body connects the first limiting portion and the second limiting portion, and the terminal body is passed through the lead-out hole. Along the first direction, the first limiting portion is located on the side of the end cover away from the electrode assembly, and the second limiting portion is located on the side of the end cover facing the electrode assembly.

72. A battery, characterized in that: Comprising a battery cell as described in any one of claims 1-71.

73. An electrical device, characterized in that: It comprises a battery cell as described in any one of claims 1-71, and the battery cell is used to provide electrical energy to the electrical device.

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