Battery cell, battery, and electrical device

Abstract

Disclosed in the present application are a battery cell, a battery, and an electrical device. The battery cell comprises an electrode assembly and an electrode terminal. The electrode assembly has a top portion and a bottom portion which are arranged in a first direction. The electrode terminal is connected to the top portion. The electrode assembly is formed by winding or stacking. The electrode assembly comprises N layers of isolation films, N being a natural number greater than or equal to 3. Each layer of isolation film comprises a first extension portion extending out of the bottom portion in the first direction. The N layers of first extension portions are arranged in a second direction. In the second direction, the first extension portion located on a first layer to the first extension portion located on an (N-1)th layer are each bent and connected to an adjacent first extension portion. Each isolation film comprises a second extension portion extending out of the top portion, and the second extension portion is connected to the electrode terminal. According to the present application, the energy density of the battery cell and the tensile strength of the electrode terminal can be increased.

Description

Cells, batteries and electrical equipment Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0002] Batteries are currently widely used in drones, electric vehicles, electronic devices, and other fields. Current battery cells often use adhesive wrapping to secure the diaphragm protruding from the electrode sheet. However, this wrapping takes up space along the thickness of the cell, reducing the cell's energy density. Current battery cells typically utilize multi-layer folded electrode terminals. During this bending process, stress accumulates within the multi-layered electrode terminals. During cycling, the electrode assembly expands, pulling on the electrode terminals, which can easily break them and ultimately lead to cell capacity loss.

[0003] Summary of the Invention

[0004] In view of this, it is necessary to provide a battery cell, a battery and an electrical device that can improve the tensile strength of the electrode terminal and the energy density of the battery cell.

[0005] An embodiment of the present application provides a battery cell comprising an electrode assembly and an electrode terminal. The electrode assembly has a top and a bottom arranged along a first direction. The electrode terminal is connected to the top. The electrode assembly is wound or stacked. The electrode assembly includes N layers of separators, where N is a natural number greater than or equal to 3. Each separator layer includes a first extension extending from the bottom in the first direction. The N layers of first extensions are arranged along a second direction. Along the second direction, the first extension located in the first layer is bent to the first extension located in the N-1th layer and connects adjacent first extensions. The separator includes a second extension extending from the top in a direction opposite to the first direction. The second extension is connected to the electrode terminal. The second direction is the thickness direction of the electrode assembly. In the present application, by sequentially bending the first extensions of the separator along the second direction and connecting adjacent first extensions, and by connecting the second extensions to the electrode terminal, the separator can be fixed and the space occupied by the battery cell in the second direction can be reduced. This can improve space utilization, increase the energy density of the battery cell, increase the tensile strength of the electrode terminal, and reduce the risk of electrode terminal fracture due to battery cell expansion.

[0006] Optionally, in some embodiments of the present application, along a direction opposite to the first direction, the projection of any first extension portion overlaps with the projection of an adjacent first extension portion, which can increase the connection area between the first extension portion and the adjacent first extension portion, and improve the connection strength between the adjacent first extension portions. The larger the connection area between the first extension portion and the adjacent first extension portion, the greater the bending amplitude of the first extension portion in the first direction, which can reduce the space occupied by the first extension portion in the first direction.

[0007] Optionally, in some embodiments of the present application, at least a portion of the second extension portion of the connecting electrode terminal is connected to another second extension portion on an adjacent electrode terminal, which can further enhance the tensile strength of the electrode terminal and further reduce the risk of fracture of the electrode terminal due to expansion of the battery cell.

[0008] Optionally, in some embodiments of the present application, the electrode assembly includes a first side portion and a second side portion arranged along a third direction. When the electrode assembly is stacked, each layer of the diaphragm includes a third extension portion extending from the first side portion in a direction opposite to the third direction. The third extension portions of the N layers are arranged along the second direction, and along the second direction, the third extension portion located on the first layer is bent to the third extension portion located on the N-1 layer, and the adjacent third extension portions are connected. The first direction, the second direction, and the third direction are perpendicular to each other, which can fix the diaphragm extending from the first side portion and reduce the space occupied by the battery cell in the second direction, thereby improving space utilization and facilitating improving the energy density of the battery cell.

[0009] Optionally, in some embodiments of the present application, each separator layer includes a fourth extension extending from the second side portion along the third direction. N layers of fourth extensions are arranged along the second direction, with the fourth extension located in the first layer extending to the fourth extension located in the N-1th layer being curved along the second direction, and adjacent fourth extensions being connected. This allows the separator extending from the second side portion to be fixed, further reducing the space occupied by the battery cell in the second direction, further improving space utilization, and further contributing to increasing the energy density of the battery cell.

[0010] Optionally, in some embodiments of the present application, along the first direction, the length of the first extension portion of the Nth layer is less than the length of the first extension portion of any layer from the first layer to the N-1th layer, which can reduce the space occupied by the first extension portion of the Nth layer and help improve space utilization.

[0011] Optionally, in some embodiments of the present application, the length L1 of the first extension portion of each layer from the first layer to the N-1th layer extending from the bottom along the first direction satisfies 0.2mm≤L1<2mm, which is further beneficial to reducing the space occupied by the first extension portion.

[0012] Optionally, in some embodiments of the present application, along the first direction, the length L2 of each layer of the first extension portion extending out of the bottom after bending and connecting satisfies 0.1mm≤L2≤0.8mm, further reducing the space occupied by the first extension portion extending out of the negative electrode sheet, and increasing the space between the battery cell shell and the first extension portion, which is beneficial to improving space utilization.

[0013] Optionally, in some embodiments of the present application, a battery cell includes a battery cell housing and an electrolyte. The electrode assembly is disposed within the battery cell housing. The battery cell housing includes a first wall and a second wall arranged along a first direction. A portion of the electrolyte is located between the second wall and the first extension. Along the first direction, a distance D1 between the second wall and the first extension satisfies 0 mm ≤ D1 ≤ 0.4 mm. This can reduce the distance between the second wall and the first extension along the first direction, thereby improving space utilization and reducing the length of the battery cell along the first direction, which is beneficial for improving the energy density of the battery cell.

[0014] Optionally, in some embodiments of the present application, along the first direction, the length L2 of each layer of the first extension portion extending from the bottom after bending and connecting satisfies 0.1mm≤L2≤0.3mm, further reducing the space occupied by the first extension portion extending out of the negative electrode sheet, and further increasing the space between the battery cell shell and the first extension portion, which is further beneficial to improving space utilization.

[0015] Optionally, in some embodiments of the present application, the battery cell includes a battery cell shell and an electrolyte. The electrode assembly is disposed in the battery cell shell. The battery cell shell includes a first wall and a second wall arranged along a first direction. Part of the electrolyte is located between the second wall and the first extension. Along the first direction, the distance D1 between the second wall and the first extension satisfies 0mm≤D1≤0.7mm. When the distance between the second wall and the negative electrode sheet is fixed, the smaller the length L2 of the first extension extending from the bottom, the larger the space between the second wall and the first extension, the more space there is for storing electrolyte, and the more conducive it is to reduce the risk of liquid swelling.

[0016] Optionally, in some embodiments of the present application, the first extension portion is provided with a first adhesive layer, and adjacent first extension portions are adhesively arranged to facilitate connection of adjacent first extension portions.

[0017] Optionally, in some embodiments of the present application, the electrode assembly includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet, the separator, and the negative electrode sheet are wound or stacked in sequence. The positive electrode sheet includes a first current collector and a first active material layer. Along the thickness direction of the electrode assembly, the first active material layer connects to the surfaces on both sides of the first current collector. A first insulating adhesive layer is provided on both sides of the portion of the first current collector extending beyond the first active material layer. The first insulating adhesive layer can protect the separator and reduce the risk of burrs on the portion of the first current collector extending beyond the first active material layer piercing the separator and causing a short circuit.

[0018] An embodiment of the present application further provides a battery, comprising the battery cell in any of the above embodiments.

[0019] An embodiment of the present application further provides an electrical device, comprising the battery in any one of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 shows an exploded schematic diagram of a battery cell in some embodiments.

[0021] FIG2 is a schematic cross-sectional view of a battery cell along line II-II in some embodiments.

[0022] FIG3 shows a schematic cross-sectional view of a battery cell along line II-II in some other embodiments.

[0023] FIG4 is a schematic cross-sectional view of a battery cell along line III-III in some embodiments.

[0024] FIG5 is a schematic structural diagram of a battery and an electrical device in some embodiments.

[0025] : Description of the main component symbols: Battery cell 100 Electrode assembly 10 Top 10a Bottom 10b First side 10c Second side 10d Separator 11 First separator 11a Second separator 11b Third separator 11c Fourth separator 11d Fifth separator 11e Sixth separator 11f Seventh separator 11g Eighth separator 11h First extension 111 First section 111a Second section 111b Second extension 112 Third extension 113 Fourth extension 114 Positive electrode sheet 12 First positive electrode sheet 12a Second positive electrode sheet 12b Third positive electrode sheet 12c First current collector 121 First active material layer 122 First insulating adhesive layer 123 Negative electrode sheet 13 Second current collector 131 Second active material layer 132 Electrode terminal 20 Battery cell case 30 Main body 31 First case 311 First recess 3111 Second case 312 Second concave portion 3112 First wall 313 Second wall 314 Third wall 315 Fourth wall 316 Sealing portion 32 Fixing adhesive 101 First conductive member 40 Second conductive member 50 Second insulating adhesive layer 60 Battery 200 Electrical device 300 First direction X Second direction Y Third direction Z

[0026] The following specific embodiments will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0027] The following detailed description is illustrative and non-limiting. It is intended to provide a basic understanding of the present application and is not intended to identify the key or decisive elements of the present application or to limit the scope of protection. As long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any manner.

[0028] When a component is referred to as being “disposed on” another component, it can be directly disposed on the other component or there may be a component intervening therebetween. When a component is referred to as being “connected to” another component, it can be directly connected to the other component or there may be a component intervening therebetween.

[0029] It can be understood that the term "perpendicular" is used to describe the ideal state between two components. In actual production or use, there may be a state between the two components that is approximately perpendicular or equal. For example, combined with numerical descriptions, perpendicular can refer to the angle between two straight lines being in the range of 90°±10°, perpendicular can also refer to the dihedral angle between two planes being in the range of 90°±10°, and perpendicular can also refer to the angle between a straight line and a plane being in the range of 90°±10°. The two components described as "perpendicular" may not be absolute straight lines or planes, but may be roughly straight lines or planes. From a macroscopic perspective, a component can be considered a "straight line" or a "plane" if the overall extension direction is a straight line or a plane.

[0030] Unless otherwise defined, the term "plurality" herein, when used to describe the number of components, specifically means that the components are two or more.

[0031] Referring to Figures 1 and 2, one embodiment of the present application provides a battery cell 100 comprising an electrode assembly 10 and an electrode terminal 20. The electrode assembly 10 comprises a top portion 10a and a bottom portion 10b arranged along a first direction X, with the electrode terminal 20 connected to the top portion 10a. The electrode assembly 10 is wound or stacked and includes N layers of separators 11, where N is a natural number greater than or equal to 3. Each separator 11 includes a first extension 111 extending from the bottom portion 10b along the first direction X. The N layers of first extensions 111 are arranged along a second direction Y. Along the second direction Y, the first extension 111 located in the first layer is curved to the first extension 111 located in the N-1th layer, connecting adjacent first extensions 111. The separator 11 includes a second extension 112 extending from the top portion 10a in a direction opposite to the first direction X. The second extension 112 is connected to the electrode terminal 20. The second direction Y is the thickness direction of the electrode assembly 10. The present application achieves fixing of the diaphragm 11 and reduces the space occupied by the battery cell 100 in the second direction Y by bending the first extension portions 111 located in the first layer to the N-1 layer in sequence along the second direction Y and connecting adjacent first extension portions 111, and connecting the second extension portions 112 to the electrode terminals 20, thereby improving space utilization, which is beneficial to improving the energy density of the battery cell 100, improving the tensile strength of the electrode terminal 20, and reducing the risk of breakage of the electrode terminal 20 due to expansion of the battery cell 100.

[0032] In some embodiments, along a direction opposite to the first direction X, a projection of the first extension portion 111 of the first layer does not overlap with a projection of the first extension portion 111 of the Nth layer.

[0033] In some embodiments, along a direction opposite to the first direction X, the projection of the first extension portion 111 on an odd-numbered layer does not overlap with the projection of the first extension portion 111 on an adjacent odd-numbered layer, thereby improving space utilization. For example, the projection of the first extension portion 111 on the first layer does not overlap with the projection of the first extension portion 111 on the third layer.

[0034] In some embodiments, when N is a natural number greater than or equal to 4, the projection of the first extension portion 111 on an even-numbered layer does not overlap with the projection of the first extension portion 111 on an adjacent even-numbered layer along the direction opposite to the first direction X, thereby improving space utilization. For example, the projection of the first extension portion 111 on the second layer does not overlap with the projection of the first extension portion 111 on the fourth layer.

[0035] In some embodiments, when the electrode assembly 10 is wound, the diaphragm 11 extends in the first direction X and forms a first extension portion 111 and a second extension portion 112. The first extension portions 111 are bent and connected in sequence with adjacent first extension portions 111 to fix the diaphragm 11 on the bottom 10b side, and the electrode terminal 20 is connected through the second extension portion 112 to fix the diaphragm 11 on the top 10a side, so that the diaphragm 11 is in an unfolded state along the first direction X. The multi-layer wound diaphragm 11 is connected to form a whole, thereby improving the overall mechanical properties of the diaphragm 11 and reducing the risk of short circuit caused by curling and displacement of the diaphragm 11.

[0036] In some embodiments, the electrode assembly 10 includes a positive electrode sheet 12 and a negative electrode sheet 13, with a separator 11 disposed between the positive electrode sheet 12 and the negative electrode sheet 13. Alternatively, the positive electrode sheet 12, the separator 11, and the negative electrode sheet 13 are wound in sequence. Alternatively, the positive electrode sheet 12, the separator 11, and the negative electrode sheet 13 are stacked in sequence.

[0037] In some embodiments, the positive electrode sheet 12 includes a first current collector 121 and a first active material layer 122. Along the thickness direction of the electrode assembly 10, the first active material layer 122 connects to the surfaces of both sides of the first current collector 121. The electrode terminal 20 connects to the first current collector 121. Optionally, the electrode terminal 20 is welded to the first current collector 121. Optionally, along the first direction X, the electrode terminal 20 is formed by cutting the portion of the first current collector 121 that extends beyond the first active material layer 122.

[0038] In some embodiments, along the second direction Y, a first insulating rubber layer 123 is provided on both sides of the portion of the first current collector 121 extending out of the first active material layer 122 to protect the diaphragm 11 and reduce the risk of burrs on the portion of the first current collector 121 extending out of the first active material layer 122 piercing the diaphragm 11 and causing a short circuit.

[0039] In some embodiments, the negative electrode sheet 13 includes a second current collector 131 and a second active material layer 132. Along the thickness direction of the electrode assembly 10, the second active material layer 132 connects to the surfaces of the second current collector 131 on both sides. Along the second direction Y, a portion of the separator 11 is located between the first active material layer 122 and the second active material layer 132. Another electrode terminal 20 connects to the second current collector 131. Optionally, the other electrode terminal 20 is welded to the second current collector 131. Optionally, along the first direction X, the other electrode terminal 20 is formed by cutting the portion of the second current collector 131 that extends beyond the second active material layer 132.

[0040] In some embodiments, when the electrode assembly 10 is wound, the first current collector 121 may be connected to one electrode terminal 20 , and the second current collector 131 may be connected to one electrode terminal 20 .

[0041] In some embodiments, when the electrode assembly 10 is wound, the first current collector 121 may be connected to a plurality of electrode terminals 20 , and the second current collector 131 may be connected to a plurality of electrode terminals 20 .

[0042] In some embodiments, when the electrode assemblies 10 are stacked, each first current collector 121 is connected to at least one electrode terminal 20 , and each second current collector 131 is connected to at least one electrode terminal 20 .

[0043] In some embodiments, the battery cell 100 includes a cell housing 30 , which includes a main body 31 and a sealing portion 32 . The main body 31 defines a housing space within which the electrode assembly 10 is disposed. The sealing portion 32 seals the electrode assembly 10 within the main body 31 to reduce the risk of leakage.

[0044] Optionally, the main body 31 includes a first housing 311 and a second housing 312. The first housing 311 has a first recess 3111, and the second housing 312 has a second recess 3112. The first housing 311 is connected to the second housing 312 to form a storage space. The electrode assembly 10 is partially located in the first recess 3111, and partially located in the second recess 3112.

[0045] Optionally, the main body 31 includes a first shell 311 and a second shell 312. The first shell 311 has a first recess 3111, and the second shell 312 is flat. The first shell 311 is connected to the second shell 312 to form a storage space. The electrode assembly 10 is located in the first recess 3111.

[0046] In some embodiments, the battery cell 100 includes a fixing adhesive 101 , which can adhere the electrode assembly 10 to the battery cell housing 30 .

[0047] In some embodiments, the battery cell 100 includes an electrolyte, which is disposed within the battery cell housing 30. A portion of the electrolyte soaks into the positive electrode sheet 12, the separator 11, and the negative electrode sheet 13 to conduct ions, while a portion of the electrolyte remains free and adheres to the surface of the battery cell housing 30 and / or the surface of the electrode assembly 10.

[0048] In some embodiments, the battery cell 100 includes a first conductive member 40, which is connected to the electrode terminal 20. Optionally, when the electrode assembly 10 has a wound structure, the first conductive member 40 is connected to the electrode terminal 20 of at least one layer of the positive electrode sheet 12. Optionally, when the electrode assembly 10 has a stacked structure, the first conductive member 40 is connected to the electrode terminal 20 of each layer of the positive electrode sheet 12.

[0049] In some embodiments, the battery cell 100 includes a second conductive member 50, which is connected to another electrode terminal 20. Optionally, when the electrode assembly 10 has a wound structure, the second conductive member 50 is connected to the electrode terminal 20 of at least one layer of the negative electrode sheet 13. Optionally, when the electrode assembly 10 has a stacked structure, the second conductive member 50 is connected to the electrode terminal 20 of each layer of the negative electrode sheet 13.

[0050] In some embodiments, the first conductive member 40 and the second conductive member 50 are used to connect to other devices to achieve input and output of electrical energy.

[0051] In some embodiments, the battery cell 100 includes a second insulating adhesive layer 60. The second insulating adhesive layer 60 covers the portion of the first conductive member 40 located within the battery cell housing 30, insulating the first conductive member 40 and reducing the risk of short circuits. The second insulating adhesive layer 60 covers the portion of the second conductive member 50 located within the battery cell housing 30, insulating the second conductive member 50 and further reducing the risk of short circuits.

[0052] In some embodiments, along the second direction Y, a first adhesive layer (not shown) is provided on the surface of both sides of the first extension portion 111. At a certain temperature, the first adhesive layer has adhesiveness, and adjacent first extension portions 111 are sequentially bonded together by the first adhesive layer. The first adhesive layer can be bonded to the electrode terminal 20. Optionally, the first adhesive layer includes polyvinylidene fluoride (PVDF). Optionally, the first adhesive layer softens at 85°C to 95°C and has a certain degree of adhesiveness. Optionally, the softening temperature of the first adhesive layer can be any one of 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, and 95°C.

[0053] In some embodiments, along the second direction Y, surfaces on both sides of the diaphragm 11 are provided with a first adhesive layer.

[0054] Referring to FIG. 2 , in some embodiments, the projection of any first extension portion 111 overlaps with the projection of an adjacent first extension portion 111 in a direction opposite to the first direction X. This can increase the connection area between the first extension portion 111 and the adjacent first extension portion 111, thereby enhancing the connection strength between the adjacent first extension portions 111. Furthermore, when the first extension portions 111 of each layer of the diaphragm 11 extend to the same length, the larger the connection area between the first extension portion 111 and the adjacent first extension portion 111, the greater the bending amplitude of the first extension portion 111 in the first direction X, thereby reducing the space occupied by the first extension portion 111 in the first direction X. Optionally, the connection length between the first extension portion 111 and the adjacent first extension portion 111 is at least half the length of the adjacent first extension portion 111. For example, the connection length between the first extension portion 111 of the first layer and the first extension portion 111 of the second layer is half the length of the first extension portion 111 of the second layer.

[0055] Please refer to Figures 2 and 3. In some embodiments, along the first direction X, the length of the first extension portion 111 of the Nth layer is less than the length of the first extension portion 111 of any layer from the first layer to the N-1th layer. This can reduce the space occupied by the first extension portion 111 of the Nth layer, which is beneficial to improving space utilization.

[0056] In some embodiments, the first extension portion 111 of the Nth layer includes a first section 111a and a second section 111b. When the first extension portion 111 of the N-1th layer is bent and connected to the first section 111a, the second section 111b is bent to the side of the first extension portion 111 of the N-1th layer facing away from the positive electrode sheet 12. At this time, the first extension portion 111 of the N-1th layer is located between the bent first section 111a and the second section 111b, thereby ensuring the connection strength between the first extension portion 111 of the N-1th layer and the first extension portion 111 of the Nth layer. By cutting the second section 111b, the length of the first extension portion 111 of the Nth layer along the first direction X can be made shorter than the length of the first extension portion 111 of any of the first to N-1 layers.

[0057] In some embodiments, along the first direction X, the length of the first extension portion 111 of the Nth layer is equal to the length of the first extension portion 111 of any layer from the first layer to the N-1th layer. This can improve the connection strength between the first extension portion 111 of the Nth layer and the first extension portion 111 of the N-1th layer, further improving the overall connection strength of the multiple first extension portions 111 connected by bending, which is beneficial for fixing the separator 11. Optionally, the first extension portion 111 of the N-1th layer is bent and connected to the first segment 111a, and the second segment 111b is bent and connected to the side of the first extension portion 111 of the N-1th layer facing away from the positive electrode sheet 12.

[0058] In some embodiments, the length L1 (not shown) of the first extension portion 111 extending from the first layer to the N-1th layer of the bottom portion 10b along the first direction X satisfies 1.6≤L1≤2.9mm, which helps reduce the space occupied by the first extension portion 111. L1 can be any one of 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, and 2.9mm.

[0059] In some embodiments, the length L1 of the first extension portion 111 of each layer extending from the first layer to the N-1th layer extending from the bottom 10b along the first direction X satisfies 0.2 mm ≤ L1 < 2 mm, further facilitating a reduction in the space occupied by the first extension portion 111. L1 can be any one of 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.42 mm, 1.44 mm, 1.46 mm, 1.48 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, or 2.0 mm.

[0060] In one embodiment, the main body 31 includes a first wall 313 and a second wall 314 arranged along a first direction X. Along the first direction X, the first wall 313 is disposed opposite the bottom 10b, and the top 10a is disposed opposite the second wall 314. The first conductive member 40 and the second conductive member 50 extend out of the battery cell casing 30 through the second wall 314. Along the first direction X, a distance H1 between the second wall 314 and the negative electrode sheet 13 satisfies 0.1 mm ≤ H1 ≤ 1.0 mm, where H1 can be any one of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1.0 mm.

[0061] In some embodiments, along the first direction X, the length L2 of each first extension portion 111 extending from the bottom portion 10b after the bending connection satisfies 0.1 mm ≤ L2 ≤ 0.8 mm. This further reduces the space occupied by the first extension portion 111 extending beyond the negative electrode sheet 13, increases the space between the second wall 314 and the first extension portion 111, and improves space utilization. L2 can be any one of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, or 0.8 mm. Along the first direction X, the distance D1 between the second wall 314 and the first extension portion 111 satisfies 0 mm ≤ D1 ≤ 0.4 mm. This can reduce the distance between the second wall 314 and the first extension portion 111 along the first direction X, improve space utilization, and reduce the length of the battery cell 100 along the first direction X, thereby improving the energy density of the battery cell 100. D1 can be any one of 0 mm, 0.1 mm, 0.2 mm, 0.3 mm, or 0.4 mm. It can be understood that the space between the second wall 314 and the first extension portion 111 can still be used to store part of the electrolyte.

[0062] In some embodiments, along the first direction X, the length L2 of each first extension portion 111 extending from the bottom 10b after the bending connection satisfies 0.1 mm ≤ L2 ≤ 0.3 mm. This further reduces the space occupied by the first extension portion 111 extending from the negative electrode sheet 13, further increasing the space between the second wall 314 and the first extension portion 111, and further improving space utilization. L2 can be any one of 0.1 mm, 0.2 mm, and 0.3 mm. Some electrolyte is located between the second wall 314 and the bottom 10b. Along the first direction X, the distance D1 between the second wall 314 and the first extension portion 111 satisfies 0 mm ≤ D1 ≤ 0.7 mm. With the distance between the second wall 314 and the negative electrode sheet 13 fixed, the smaller the length L2 of the first extension portion 111 extending from the bottom 10b, the larger the space between the second wall 314 and the first extension portion 111, increasing the space for electrolyte storage and further reducing the risk of electrolyte swelling. D1 may be any one of 0 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, and 0.7 mm.

[0063] Referring to Figures 2 and 3, in some embodiments, the second extension portion 112 is connected to the electrode terminal 20 connected to the positive electrode sheet 12. Along the second direction Y, the two outermost positive electrode sheets 12 are the first positive electrode sheet 12a and the second positive electrode sheet 12b, and the positive electrode sheet 12 located between the first positive electrode sheet 12a and the second positive electrode sheet 12b is the third positive electrode sheet 12c. The second extension portion 112 of the first layer is connected to the electrode terminal 20 connected to the first positive electrode sheet 12a, the second extension portion 112 of the Nth layer is connected to the electrode terminal 20 connected to the second positive electrode sheet 12b, and the second extension portions 112 of the second to N-1th layers are connected to the electrode terminal 20 connected to the third positive electrode sheet 12c. Along the second direction Y, each electrode terminal 20 connected to the third positive electrode sheet 12c is connected to both sides of a second extension portion 112, which can improve the tensile strength of the electrode terminal 20 connected to the positive electrode sheet 12, and each third positive electrode sheet 12c is connected to both sides of a second extension portion 112, which can further improve the tensile strength of the electrode terminal 20 connected to each third positive electrode sheet 12c, thereby reducing the risk of the electrode terminal 20 being broken due to the expansion of the battery cell 100.

[0064] In some embodiments, the second extension 112 is connected to the electrode terminal 20 connected to the negative electrode sheet 13. Along the second direction Y, each electrode terminal 20 connected to the negative electrode sheet 13 is connected to both sides of the second extension 112, which can improve the tensile strength of the electrode terminal 20 connected to the negative electrode sheet 13 and reduce the risk of the electrode terminal 20 being broken due to expansion of the battery cell 100.

[0065] In some embodiments, the second extension portion 112 is connected to the electrode terminal 20 connected to the positive electrode sheet 12, and the second extension portion 112 is connected to the electrode terminal 20 connected to the negative electrode sheet 13. Along the second direction Y, each electrode terminal 20 connected to the positive electrode sheet 12 is connected to the second extension portion 112, and each electrode terminal 20 connected to the negative electrode sheet 13 is connected to the second extension portion 112. This can improve the tensile strength of each electrode terminal 20 connected to the electrode assembly 10, facilitate balanced force on each electrode terminal 20, and further reduce the risk of fracture of the electrode terminal 20 due to expansion of the battery cell 100.

[0066] In some embodiments, connecting at least a portion of the second extension portion 112 of the electrode terminal 20 to another second extension portion 112 on an adjacent electrode terminal 20 can further enhance the tensile strength of the electrode terminal 20 and further reduce the risk of fracture of the electrode terminal 20 due to expansion of the battery cell 100 .

[0067] Referring to Figures 2 and 3 , the second extension portion 112 is connected to the electrode terminal 20 connected to the positive electrode sheet 12. Optionally, the separator 11 includes a first separator 11a, a second separator 11b, a third separator 11c, a fourth separator 11d, a fifth separator 11e, a sixth separator 11f, a seventh separator 11g, and an eighth separator 11h. The second extension portion 112 of the first separator 11a is connected to the second extension portion 112 of the second separator 11b. The second extension portion 112 of the third separator 11c is connected to the second extension portion 112 of the fourth separator 11d. The second extension portion 112 of the fifth separator 11e is connected to the second extension portion 112 of the sixth separator 11f. The second extension portion 112 of the seventh separator 11g is connected to the second extension portion 112 of the eighth separator 11h.

[0068] In some embodiments, the connection length between the second extension portion 112 and the electrode terminal 20 is W (not shown), where W satisfies 1 mm ≤ W ≤ 3 mm. This improves the connection strength between the second extension portion 112 and the electrode terminal 20 and helps increase the tensile strength of the electrode terminal 20. W can be any one of 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, or 3.0 mm. Optionally, the length of the second extension portion 112 extending beyond the positive electrode sheet 12 can be the connection length W between the second extension portion 112 and the electrode terminal 20. Optionally, the length of the second extension portion 112 extending beyond the positive electrode sheet 12 can be slightly greater than the connection length W between the second extension portion 112 and the electrode terminal 20.

[0069] Referring to Figures 1 and 4 , in some embodiments, the electrode assembly 10 includes a first side portion 10c and a second side portion 10d arranged along a third direction Z. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other. When the electrode assembly 10 is stacked, each separator 11 includes a third extension 113. N layers of third extensions 113 extend from the first side portion 10c in a direction opposite to the third direction Z. Each layer of third extensions 113 is arranged along a second direction Y. Along the second direction Y, the third extensions 113 from the first layer to the third extensions 113 from the N-1th layer are bent and connected to adjacent third extensions 113. By sequentially bending and connecting adjacent third extensions 113 from the first layer to the N-1th layer along the second direction Y, the separator 11 extending from the first side portion 10c is secured, and the space occupied by the battery cell 100 in the second direction Y is reduced, thereby improving space utilization and facilitating increased energy density of the battery cell 100.

[0070] In some embodiments, along the third direction Z, a projection of the third extension portion 113 of the first layer does not overlap with a projection of the third extension portion 113 of the Nth layer.

[0071] In some embodiments, the projection of the third extension 113 overlaps with the projection of an adjacent third extension 113 in a direction opposite to the third direction Z. This can increase the connection area between the third extension 113 and the adjacent third extension 113 and enhance the connection strength between the adjacent third extensions 113. Furthermore, if the third extensions 113 of each layer of diaphragm 11 extend to the same length, the larger the connection area between the third extension 113 and the adjacent third extension 113, the greater the bending amplitude of the third extension 113 in the third direction Z, thereby reducing the space occupied by the third extension 113 in the third direction Z. Optionally, the connection length between the third extension 113 and the adjacent third extension 113 is at least half the length of the adjacent third extension 113. For example, the connection length between the third extension 113 of the first diaphragm layer and the third extension 113 of the second diaphragm layer is half the length of the third extension 113 of the second diaphragm layer.

[0072] In some embodiments, the length of the third extension portion 113 of the Nth layer, along a direction opposite to the third direction Z, is less than the length of the third extension portion 113 of any layer from the first layer to the N-1th layer. This can reduce the space occupied by the third extension portion 113 of the Nth layer, thereby improving space utilization. Optionally, the third extension portion 113 can be cut in the same manner as the first extension portion 111, such that the length of the third extension portion 113 of the Nth layer, along a direction opposite to the third direction Z, is less than the length of the third extension portion 113 of any layer from the first layer to the N-1th layer.

[0073] In some embodiments, along the direction opposite to the third direction Z, the length of the third extension portion 113 of the Nth layer is equal to the length of the third extension portion 113 of any layer from the first layer to the N-1th layer, which can improve the connection strength between the third extension portion 113 of the Nth layer and the third extension portion 113 of the N-1th layer, and further improve the overall connection strength of the multiple third extension portions 113 connected in a curved manner, which is beneficial to fixing the diaphragm 11.

[0074] In some embodiments, the length L3 (not shown) of the third extension portion 113 from the first layer to the N-1th layer satisfies 1.6≤L3≤2.9 mm, which helps to reduce the space occupied by the third extension portion 113. L3 can be any one of 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, and 2.9 mm.

[0075] In some embodiments, the length L3 of the third extension portion 113 from the first layer to the N-1th layer satisfies 1 mm ≤ L3 < 1.5 mm, further facilitating a reduction in the space occupied by the third extension portion 113. L3 can be any one of 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.42 mm, 1.44 mm, 1.46 mm, and 1.48 mm.

[0076] In one embodiment, the main body 31 includes a third wall 315 and a fourth wall 316 arranged along a third direction Z. Along the third direction Z, the third wall 315 is disposed opposite the first side portion 10 c, and the second side portion 10 d is disposed opposite the fourth wall 316. A portion of the electrolyte is located between the third wall 315 and the first side portion 10 c. Along the third direction Z, a distance H2 between the third wall 315 and the negative electrode sheet 13 satisfies 0.1 mm ≤ H2 ≤ 1.0 mm, where H2 can be any one of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1.0 mm.

[0077] In some embodiments, along the first direction X, the length L2 of each layer of the third extension portion 113 extending beyond the first side portion 10c after the bending connection satisfies 0.1 mm ≤ L4 ≤ 0.6 mm. This further reduces the space occupied by the third extension portion 113 extending beyond the negative electrode sheet 13, thereby increasing the space between the third wall 315 and the third extension portion 113 and improving space utilization. L4 can be any one of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, and 0.6 mm. Along the third direction Z, the distance D2 between the third wall 315 and the third extension portion 113 satisfies 0 mm ≤ D2 ≤ 0.4 mm. This distance can be reduced along the third direction Z, improving space utilization and reducing the width of the battery cell 100 along the third direction Z, thereby improving the energy density of the battery cell 100. D2 can be any one of 0 mm, 0.1 mm, 0.2 mm, 0.3 mm, and 0.4 mm. It can be understood that the space between the third wall 315 and the third extension portion 113 can still be used to store part of the electrolyte.

[0078] In some embodiments, along the first direction X, the length L4 of each layer of the third extension portion 113 extending beyond the first side portion 10c after the bending connection satisfies 0.1 mm ≤ L4 ≤ 0.3 mm. This further reduces the space occupied by the third extension portion 113 extending beyond the negative electrode sheet 13, further increasing the space between the third wall 315 and the third extension portion 113, and further improving space utilization. L4 can be any one of 0.1 mm, 0.2 mm, and 0.3 mm. A portion of the electrolyte is located between the third wall 315 and the third extension portion 113. Along the third direction Z, the distance D2 between the third wall 315 and the third extension portion 113 satisfies 0 mm ≤ D2 ≤ 0.7 mm. When the distance between the third wall 315 and the third extension portion 113 is fixed, the shorter the length L4 of the third extension portion 113 extending beyond the first side portion 10c, the larger the space between the third wall 315 and the third extension portion 113, increasing the space for electrolyte storage and further reducing the risk of electrolyte swelling. D2 can be any one of 0 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, and 0.7 mm.

[0079] In some embodiments, when the electrode assembly 10 is stacked, each layer of the separator 11 includes a fourth extension portion 114, and the fourth extension portion 114 extends from the second side portion 10d along the third direction Z. The fourth extension portions 114 of each layer are arranged along the second direction Y. Along the second direction Y, the fourth extension portion 114 located in the first layer to the fourth extension portion 114 located in the N-1 layer are bent and connected to adjacent fourth extension portions 114. By sequentially bending the fourth extension portions 114 from the first layer to the N-1 layer along the second direction Y and connecting adjacent fourth extension portions 114, the separator 11 extending from the second side portion 10d can be fixed, and the space occupied by the battery cell 100 in the second direction Y can be further reduced, which can further improve space utilization and further contribute to improving the energy density of the battery cell 100.

[0080] In some embodiments, along a direction opposite to the third direction Z, a projection of the fourth extending portion 114 of the first diaphragm does not overlap with a projection of the fourth extending portion 114 of the Nth diaphragm.

[0081] In some embodiments, the projection of the fourth extension portion 114 overlaps with the projection of an adjacent fourth extension portion 114 along the third direction Z. This can increase the connection area between the fourth extension portion 114 and the adjacent fourth extension portion 114 and enhance the connection strength between the adjacent fourth extension portions 114. Furthermore, if the extended lengths of the fourth extension portions 114 in each layer are the same, the larger the connection area between the fourth extension portion 114 and the adjacent fourth extension portion 114, the greater the bending amplitude of the fourth extension portion 114 in the third direction Z, thereby reducing the space occupied by the fourth extension portion 114 in the third direction Z. Optionally, the connection length between the fourth extension portion 114 and the adjacent fourth extension portion 114 is at least half the length of the adjacent fourth extension portion 114. For example, the connection length between the fourth extension portion 114 of the first layer and the fourth extension portion 114 of the second layer is half the length of the fourth extension portion 114 of the second layer.

[0082] In some embodiments, along the third direction Z, the length of the fourth extension portion 114 of the Nth layer is less than the length of the fourth extension portion 114 of any layer from the first layer to the N-1th layer. This can reduce the space occupied by the fourth extension portion 114 of the Nth layer, thereby improving space utilization. Optionally, the fourth extension portion 114 can be cut in the same manner as the first extension portion 111, such that, along the third direction Z, the length of the fourth extension portion 114 of the Nth layer is less than the length of the fourth extension portion 114 of any layer from the first layer to the N-1th layer.

[0083] In some embodiments, along the third direction Z, the length of the fourth extension portion 114 of the Nth layer is equal to the length of the fourth extension portion 114 of any layer from the first layer to the N-1th layer, which can improve the connection strength between the fourth extension portion 114 of the Nth layer and the fourth extension portion 114 of the N-1th layer, and further improve the overall connection strength of the multiple fourth extension portions 114 connected in a curved manner, which is beneficial to fixing the diaphragm 11.

[0084] In some embodiments, the length L5 (not shown) of the fourth extension portion 114 from the first layer to the N-1th layer satisfies 1.6≤L5≤2.9 mm, which helps to reduce the space occupied by the fourth extension portion 114. L5 can be any one of 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, and 2.9 mm.

[0085] In some embodiments, the length L5 of the fourth extension portion 114 from the first layer to the N-1th layer satisfies 1 mm ≤ L5 < 1.5 mm, further facilitating reduction of the space occupied by the fourth extension portion 114. L5 can be any one of 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.42 mm, 1.44 mm, 1.46 mm, and 1.48 mm.

[0086] In one embodiment, along the third direction Z, a distance H3 between the fourth wall 316 and the negative electrode sheet 13 satisfies 0.1 mm ≤ H3 ≤ 1.0 mm, and H3 can be any one of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1.0 mm.

[0087] In some embodiments, along the first direction X, the length L6 of each layer of the bent and connected fourth extension portion 114 extending beyond the second side portion 10d satisfies 0.1 mm ≤ L6 ≤ 0.6 mm. This further reduces the space occupied by the fourth extension portion 114 extending beyond the negative electrode sheet 13, increases the space between the fourth wall 316 and the fourth extension portion 114, and improves space utilization. L6 can be any one of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, and 0.6 mm. Along the third direction Z, the distance D3 between the fourth wall 316 and the second side portion 10d satisfies 0 mm ≤ D3 ≤ 0.4 mm. This distance can be reduced along the third direction Z, improving space utilization and further reducing the width of the battery cell 100 along the third direction Z, which is beneficial for improving the energy density of the battery cell 100. D3 can be any one of 0 mm, 0.1 mm, 0.2 mm, 0.3 mm, and 0.4 mm. It can be understood that the space between the fourth wall 316 and the second side portion 10d can still be used to store part of the electrolyte.

[0088] In some embodiments, along the first direction X, the length L6 of each bent and connected fourth extension portion 114 extending beyond the second side portion 10d satisfies 0.1 mm ≤ L6 ≤ 0.3 mm. This further reduces the space occupied by the fourth extension portion 114 extending beyond the negative electrode sheet 13, further increasing the space between the battery cell casing 30 and the fourth extension portion 114, and further improving space utilization. L6 can be any one of 0.1 mm, 0.2 mm, and 0.3 mm. Some electrolyte is located between the fourth wall 316 and the second side portion 10d. Along the third direction Z, the distance D3 between the fourth wall 316 and the second side portion 10d satisfies 0 mm ≤ D3 ≤ 0.7 mm. When the distance between the fourth wall 316 and the second side portion 10d is fixed, a smaller length L6 of the fourth extension portion 114 extending beyond the second side portion 10d increases the space between the fourth wall 316 and the second side portion 10d, thereby increasing the space for electrolyte storage and further reducing the risk of electrolyte swelling. D3 can be any one of 0 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, and 0.7 mm.

[0089] In some embodiments, when the electrode assembly 10 is stacked, the diaphragm 11 extends in the first direction X to form a first extension portion 111 and a second extension portion 112. The diaphragm 11 extends in the third direction Z to form a third extension portion 113 and a fourth extension portion 114. The first extension portions 111 are bent and connected in sequence to form adjacent first extension portions 111, thereby fixing the diaphragm 11 on the bottom 10b side. The electrode terminal 20 is connected to the diaphragm 11 on the top 10a side. The third extension portions 113 are bent and connected in sequence to form adjacent third extension portions 113, thereby fixing the diaphragm 11 on the first side 10c side. The fourth extension portions 114 are bent and connected in sequence to form adjacent fourth extension portions 114, thereby fixing the diaphragm 11 on the second side 10d side. The diaphragm 11 can be unfolded along the first direction X and the third direction Z. The multiple stacked diaphragms 11 are connected to form a whole, thereby improving the overall mechanical properties of the diaphragm 11 and reducing the risk of short circuit caused by curling and displacement of the diaphragm 11.

[0090] The present application will be further described below through specific examples.

[0091] The electrode assembly 10 is a stacked structure. The bottom 10b, first side 10c and second side 10d of the existing electrode assembly 10 containing a wound-gel battery cell are all provided with wound gel. The battery cell 100 with a size of 4.9mm (thickness) * 62mm (width) * 68mm (length) is used as an example.

[0092] As can be seen from the table above, on the side of the electrode assembly 10 where the fixing glue 101 is not provided, each wrapping of the glue can reduce the thickness by 10 μm along the second direction Y, thereby reducing the space occupied by the battery cell 100 in the second direction Y, thereby improving space utilization and increasing the energy density of the battery cell 100. In this application, the second extension 112 is used to connect the electrode terminal 20, which can improve the tensile strength of the electrode terminal 20 and reduce the risk of the electrode terminal 20 breaking and causing low battery capacity.

[0093] 5 , the present application also provides a battery 200 using the battery cell 100 of any of the above embodiments. Specifically, optionally, the battery 200 may be a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, and a lithium ion polymer secondary battery.

[0094] 5 , the present application also provides an electrical device 300 using the battery 200. In one embodiment, the electrical device 300 of the present application may be, but is not limited to, electronic equipment, drones, backup power supplies, electric vehicles, electric motorcycles, electric power-assisted bicycles, power tools, large household batteries, and the like.

[0095] Those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present application and are not intended to limit the present application. As long as they are within the spirit of the present application, appropriate changes and modifications to the above embodiments fall within the scope disclosed in the present application.

Claims

1. A battery cell, It is characterized in that comprising an electrode assembly and an electrode terminal, The electrode assembly has a top and a bottom arranged along a first direction, and the electrode terminal is connected to the top; The electrode assembly is wound or stacked, and the electrode assembly includes N layers of separators, where N is a natural number greater than or equal to 3; Each layer of the diaphragm includes a first extension portion extending from the bottom along the first direction, the first extension portions of the N layers are arranged along the second direction, and along the second direction, the first extension portion located in the first layer is bent to the first extension portion located in the N-1th layer, and adjacent first extension portions are connected; The diaphragm includes a second extension portion extending from the top in a direction opposite to the first direction, the second extension portion being connected to the electrode terminal; The second direction is a thickness direction of the electrode assembly.

2. The battery cell according to claim 1, It is characterized in that Along a direction opposite to the first direction, a projection of any first extending portion overlaps with a projection of an adjacent first extending portion.

3. The battery cell according to claim 1, It is characterized in that At least a portion of the second extension portion connected to the electrode terminal is connected to another second extension portion on an adjacent electrode terminal.

4. The battery cell according to claim 1, It is characterized in that The electrode assembly includes a first side portion and a second side portion arranged along a third direction. When the electrode assembly is stacked, each layer of the diaphragm includes a third extension portion extending out of the first side portion in a direction opposite to the third direction. The third extension portions of the N layers are arranged along the second direction. Along the second direction, the third extension portion located in the first layer is bent to the third extension portion located in the N-1 layer, and adjacent third extension portions are connected. The first direction, the second direction and the third direction are perpendicular to each other.

5. The battery cell according to claim 4, It is characterized in that Each layer of the diaphragm includes a fourth extension portion extending from the second side portion along the third direction, and the fourth extension portions of the N layers are arranged along the second direction. Along the second direction, the fourth extension portion located in the first layer is bent to the fourth extension portion located in the N-1th layer, and adjacent fourth extension portions are connected.

6. The battery cell according to claim 1, It is characterized in that The length L of the first extension portion of each layer from the first layer to the N-1th layer extending from the bottom along the first direction is 1 , satisfying 0.2mm≤L 1 <2mm.

7. The battery cell according to claim 6, It is characterized in that Along the first direction, the length L of each first extension portion extending out of the bottom after bending and connecting is 2 , satisfying 0.1mm≤L 2 ≤0.8mm.

8. The battery cell according to claim 7, It is characterized in that The battery cell comprises a battery cell shell and an electrolyte, the electrode assembly is arranged in the battery cell shell, the battery cell shell comprises a first wall and a second wall arranged along the first direction, part of the electrolyte is located between the second wall and the first extension portion, and along the first direction, the distance D between the second wall and the first extension portion is 1 , satisfying 0mm≤D 1 ≤0.4mm.

9. The battery cell according to claim 7, It is characterized in that Along the first direction, the length L of each first extension portion extending out of the bottom after bending and connecting is 2 , satisfying 0.1mm≤L 2 ≤0.3mm.

10. The battery cell according to claim 9, It is characterized in that The battery cell comprises a battery cell shell and an electrolyte, the electrode assembly is arranged in the battery cell shell, the battery cell shell comprises a first wall and a second wall arranged along the first direction, part of the electrolyte is located between the second wall and the first extension portion, and along the first direction, the distance D between the second wall and the first extension portion is 1 , satisfying 0mm≤D 1 ≤0.7mm.

11. The battery cell according to claim 1, It is characterized in that Along the first direction, a length of the first extension portion of the Nth layer is smaller than a length of the first extension portion of any layer from the first layer to the N-1th layer.

12. The battery cell according to claim 1, It is characterized in that The first extension parts are provided with a first adhesive layer, and adjacent first extension parts are bonded together.

13. The battery cell according to claim 1, It is characterized in that The electrode assembly includes a positive electrode sheet and a negative electrode sheet, and the positive electrode sheet, the separator and the negative electrode sheet are wound or stacked in sequence. The positive electrode sheet includes a first current collector and a first active material layer. Along the thickness direction of the electrode assembly, the first active material layer connects the surfaces on both sides of the first current collector, and the first insulating glue layer is provided on both sides of the part of the first current collector extending out of the first active material layer.

14. A battery, It is characterized in that Comprising a battery cell as described in any one of claims 1 to 13.

15. An electrical device, It is characterized in that Comprising the battery of claim 14.

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