Battery cell and electric equipment

Abstract

The invention provides an electrode battery cell and electric equipment. An electrode assembly of the battery cell is of a laminated structure; the electrode assembly comprises a first pole piece set and a second pole piece set, the first pole piece set and the second pole piece set are arranged in a stacked mode in the first direction, in the second direction, the length of the first pole piece set is larger than that of the second pole piece set, and the second direction is perpendicular to the first direction; the first pole piece group is provided with a first pole piece closest to the second pole piece group, the first pole piece comprises a current collector and active substance layers, the current collector comprises a first area and a second area, the active substance layers are arranged on the two sides of the first area in the thickness direction of the current collector, and the active substance layers are arranged on the side, deviating from the second pole piece group, of the second area. The first area is at least partially overlapped with the first pole piece group, and the second area is at least partially not overlapped with the first pole piece group.

Description

Technical Field

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

[0002] With the rapid development of new energy technologies, battery cells have been widely used in electronic equipment, electric vehicles, electric two-wheeled vehicles, power tools, etc. As the application of battery cells becomes more and more extensive, higher requirements are placed on the energy density of battery cells. Summary of the invention

[0003] The embodiments of the present application provide a battery cell and an electrical device to improve the energy density of the battery cell.

[0004] In the first aspect, the embodiment of the present application provides a battery cell, which includes a package and an electrode assembly. The electrode assembly is contained in the package, and the electrode assembly is a laminated structure; the electrode assembly includes a first electrode sheet group and a second electrode sheet group, the first electrode sheet group and the second electrode sheet group are stacked along a first direction, along the second direction, the length of the first electrode sheet group is greater than the length of the second electrode sheet group, and the second direction is perpendicular to the first direction. The first electrode sheet group has a first electrode sheet closest to the second electrode sheet group, the first electrode sheet includes a current collector and an active material layer, the current collector includes a first region and a second region, along the thickness direction of the current collector, both sides of the first region are provided with active material layers, the second region is only provided with an active material layer on the side away from the second electrode sheet group, the first region and the first electrode sheet group at least partially overlap, and the second region and the first electrode sheet group at least partially do not overlap.

[0005] In one or more optional embodiments above, the size of the first pole piece group in the second direction is greater than the size of the second pole piece group in the second direction, the first pole piece group includes a first pole piece closest to the second pole piece group, and the current collector of the first pole piece includes a first region at least partially overlapping with the second pole piece group and a second region at least partially not overlapping with the second pole piece group. On the one hand, active material layers are provided on both sides of the first region, and the active material layer on the side of the first region facing the second pole piece group can be used as an outermost pole piece of the second pole piece group, which is equivalent to an outermost pole piece of the second pole piece group and an outermost pole piece of the first pole piece group sharing a current collector. Compared with the scheme in which the current collector of a pole piece of the outermost single-sided active material layer of the first pole piece group and the current collector of a pole piece of the outermost single-sided active material layer of the second pole piece group are bonded by an adhesive layer, this scheme reduces the space occupied by the adhesive layer and reduces the energy density loss of the battery cell in the first direction. On the other hand, compared with the scheme in which the current collector of the outermost single-sided active material layer-coated pole piece of the first pole piece group is bonded to the current collector of the outermost single-sided active material layer-coated pole piece of the second pole piece group through an adhesive layer, this scheme reduces the number of pole pieces coated with active material layers on one side in the battery cell by setting the first pole piece, thereby reducing the number of current collectors in the battery cell and reducing the energy density loss of the battery cell in the first direction. On the other hand, in order to alleviate the problems of warping and curling of the pole piece coated with active material layer on one side, the thickness of the current collector of the single-sided pole piece is large, which will also lead to the loss of energy density of the battery cell. In this scheme, the current collector of the first pole piece in the battery cell is provided with active material layers on both sides. The active material layers on both sides of the current collector of the first pole piece can offset the effect of stress, and the risk of warping and curling of the first pole piece is low. It also makes the first region of the current collector of the first pole piece relatively thinner than the current collector of the pole piece coated with active material layer on one side, further reducing the energy density loss of the battery cell in the first direction. On the other hand, the second region of the current collector of the first pole piece is provided with an active material layer only on the side away from the second pole piece group, which reduces the active material that does not exert its capacity and avoids the space occupied by the active material that does not exert its capacity, and further reduces the energy density loss of the battery cell in the first direction. Therefore, compared with the solution in which the single-sided coated pole piece of the first pole piece group closest to the second pole piece group and the single-sided coated pole piece of the second pole piece group closest to the first pole piece group are bonded by a glue layer, the battery cell of this solution has a higher energy density.

[0006] In some embodiments of the first aspect of the present application, the packaging forms a accommodating cavity, the accommodating cavity includes a first accommodating cavity and a second accommodating cavity, the first accommodating cavity and the second accommodating cavity are arranged along a first direction, and along the second direction, the length of the second accommodating cavity is greater than the length of the first accommodating cavity; the active material layer includes a first active material layer arranged on the side of the current collector facing the second pole piece group and a second active material layer arranged on the side of the current collector away from the second pole piece group, at least a portion of the first active material layer and the second pole piece group are accommodated in the first accommodating cavity, and the current collector and the second active material layer are accommodated in the second accommodating cavity.

[0007] In one or more of the above optional embodiments, at least a portion of the first active material layer and the second electrode group are accommodated in the first accommodating cavity, and the current collector and the second active material layer are accommodated in the second accommodating cavity, so as to make full use of the space in the package in the first direction and reduce the gap between the first electrode group and the second electrode group and the inner wall of the package in the first direction, which is beneficial to improve the energy density of the battery cell.

[0008] In some embodiments of the first aspect of the present application, the current collector is a first metal layer.

[0009] In one or more of the above optional embodiments, the current collector of the first pole piece is a metal layer, so that the current collector has better conductivity.

[0010] In some embodiments of the first aspect of the present application, the current collector includes an insulating separation layer, a first metal layer and a second metal layer, the first metal layer is arranged on a side of the insulating separation layer facing the second pole piece group, and the second metal layer is arranged on a side of the insulating separation layer facing away from the second pole piece group.

[0011] In one or more of the above optional embodiments, the current collector of the first pole piece includes an insulating separator layer, a first metal layer and a second metal layer. The insulating separator layer is used as a mechanical support skeleton of the current collector so that the current collector has better mechanical properties. The thickness of the first metal layer and the second metal layer can be smaller, thereby reducing the metal burrs caused by mechanical damage to the first pole piece, which is beneficial to improving the safety performance of the battery cell.

[0012] In some embodiments of the first aspect of the present application, the material of the packaging piece is the same as the material of the first metal layer.

[0013] In one or more of the above optional embodiments, the material of the packaging is the same as that of the first metal layer, so as to avoid a large difference in electrode potential between the packaging and the second area, thereby reducing the risk of electrochemical corrosion, which is beneficial to improving the safety performance of the battery cell and extending the service life of the battery cell.

[0014] In some embodiments of the first aspect of the present application, the material of the packaging is different from the material of the first metal layer; the battery cell also includes an insulating layer, and along the first direction, the insulating layer is arranged between the surface of the second region facing the second electrode group and the packaging to separate the packaging and the second region.

[0015] In one or more of the above optional embodiments, the material of the package is different from the material of the first metal layer, which facilitates the selection of better materials for the package and the current collector, so that the performance of each of the package and the current collector can be better. The material of the package is different from the material of the first metal layer, and the insulating layer is arranged between the package and the second area of ​​the current collector to separate the package and the second area, reducing the risk of electrochemical corrosion when the electrode potential difference between the package and the second area is too large, which is conducive to improving the safety performance of the battery cell and extending the service life of the battery cell.

[0016] In some embodiments of the first aspect of the present application, the insulating layer is disposed in the second region.

[0017] In one or more of the above optional embodiments, the insulating layer is disposed in the second region of the current collector, which can separate the second region and the package in the first direction, so as to reduce the risk of electrochemical corrosion when the electrode potential difference between the package and the second region is too large, which is beneficial to improving the safety performance of the battery cell and extending the service life of the battery cell. Since the active material layer is not disposed on the side of the second region facing the second electrode sheet group, the insulating layer disposed in the second region can also alleviate the problem of warping and curling of the first electrode sheet in the second region.

[0018] In some embodiments of the first aspect of the present application, the thickness of the current collector is H, 0.003 mm≤H≤0.030 mm.

[0019] In one or more of the above optional embodiments, the current collector of the first pole piece is greater than or equal to 0.003 mm, so that the current collector has good mechanical properties and conductive properties. The current collector of the first pole piece is less than or equal to 0.030 mm, and the thickness of the current collector of the first pole piece is controlled within a reasonable range, thereby reducing the space occupied by the current collector of the first pole piece, thereby reducing the energy density loss of the battery cell, which is beneficial to improving the energy density of the battery cell.

[0020] In some embodiments of the first aspect of the present application, 0.004 mm≤H≤0.020 mm.

[0021] In one or more of the above optional embodiments, the current collector of the first pole piece is greater than or equal to 0.004 mm, so that the current collector has better mechanical properties and conductive properties. The current collector of the first pole piece is less than or equal to 0.020 mm, and the thickness of the current collector of the first pole piece is controlled within a reasonable range, further reducing the space occupied by the current collector of the first pole piece, thereby further reducing the energy density loss of the battery cell, thereby further improving the energy density of the battery cell.

[0022] In some embodiments of the first aspect of the present application, the package includes a main body portion, the main body portion includes a first main body portion and a second main body portion, the first main body portion and the second main body portion are arranged side by side along the second direction, the second main body portion has a first outer surface in the first direction, and the first main body portion protrudes from the first outer surface; when viewed along the first direction, the first electrode group includes a first part overlapping with the second electrode group and a second part not overlapping with the second electrode group, the first part and the second part are arranged and connected along the second direction; the first part and the second electrode group are accommodated in the second main body portion, and the second part is accommodated in the first main body portion.

[0023] In one or more of the above optional embodiments, the main body includes a first main body and a second main body, the first main body and the second main body are arranged side by side along the second direction, the second main body has a first outer surface in the first direction, the first main body protrudes from the first surface, the first part and the second electrode group are accommodated in the second main body, and the second part is accommodated in the first main body, so that the structural form of the electrode assembly matches the structural form of the packaging, which is conducive to making full use of the internal space of the packaging and reducing energy density loss.

[0024] In a second aspect, an embodiment of the application provides an electrical device, comprising a battery cell provided by any of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope.

[0026] Figure 1 A schematic diagram of the structure of a battery cell provided in some embodiments of the present application;

[0027] Figure 2 A schematic diagram of the structure of a package provided in some embodiments of the present application;

[0028] Figure 3 for Figure 2 A1-A1 sectional view;

[0029] Figure 4 for Figure 3 The enlarged image of P1 in the middle;

[0030] Figure 5 for Figure 3 The enlarged view of P2 in the middle;

[0031] Figure 6 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application;

[0032] Figure 7 for Figure 6 A2-A2 sectional view;

[0033] Figure 8 A schematic diagram of the structure of a first pole piece provided in some embodiments of the present application;

[0034] Fig. 9 for Figure 1 A3-A3 sectional view;

[0035] Fig.10 for Fig. 9 The enlarged image of P3 in the middle;

[0036] Fig.11 A schematic diagram of the structure of a battery cell provided in some other embodiments of the present application;

[0037] Fig.12 for Fig.11 A4-A4 sectional view;

[0038] Fig.13 for Fig.12 The enlarged image of P4 in the middle;

[0039] Fig.14 A schematic diagram of the structure of a first pole piece provided in some other embodiments of the present application;

[0040] Fig.15 for Fig.12 Schematic diagram of a first pole piece in which an insulating layer is provided.

[0041] Icons: 100-battery core; 10-packaging; 11-accommodation cavity; 111-first accommodation cavity; 112-second accommodation cavity; 113-first wall; 114-second wall; 115-third wall; 116-fourth wall; 117-fifth wall; 118-sixth wall; 119-seventh wall; 1110-eighth wall; 12-main body; 121-first main body; 122-second main body; 1221-first outer surface; 13-first sealing portion; 14-second sealing portion; 20-electrode assembly; 20a-pole piece; 20b-isolation film ;21-first pole piece group;211-first pole piece;2111-current collector;2111a-first region;2111b-second region;21111-insulating separation layer;21112-first metal layer;2113-second metal layer;2112-active material layer;2112a-first active material layer;2112b-second active material layer;212-first part;213-second part;22-second pole piece group;30-insulating layer;40-positive electrode ear;50-negative electrode ear;X-first direction;Y-second direction;Z-third direction. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0043] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0044] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0045] In the description of the embodiments of the present application, it should be noted that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, or the orientation or positional relationship commonly understood by those skilled in the art, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0046] At present, judging from the development of the market situation, the application of battery cells is becoming more and more extensive. Battery cells are widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, as well as electric tools, drones, energy storage equipment and other fields. With the continuous expansion of the application field of battery cells, the market demand is also constantly expanding.

[0047] The battery cell includes a wound battery cell and a laminated battery cell. The electrode assembly of the laminated battery cell includes a plurality of pole pieces with opposite polarities alternately stacked. As a type of laminated battery cell, the electrode assembly of the step battery cell includes at least a first pole piece group and a second pole piece group, the first pole piece group and the second pole piece group are stacked along a first direction, along the second direction, the length of the first pole piece group is greater than the length of the second pole piece group, the second direction is perpendicular to the first direction, the first pole piece group includes a plurality of pole pieces stacked along the first direction X, along the first direction, the two pole pieces farthest apart in the first pole piece group are pole pieces coated with an active material layer on one side, the second pole piece group includes a plurality of pole pieces stacked along the first direction, along the first direction, the two pole pieces farthest apart in the second pole piece group are pole pieces coated with an active material layer on one side. The pole piece of the first pole piece group that is closest to the second pole piece group and the pole piece of the second pole piece group that is closest to the first pole piece group and coated with an active material layer on one side are bonded by a glue layer, resulting in a large energy density loss of the step battery cell in the first direction, resulting in a low energy density of the battery cell.

[0048] Based on the above considerations, in order to reduce the energy density loss of the battery cell and improve the energy density of the battery cell, an embodiment of the present application provides a battery cell, which includes a package and an electrode assembly, the electrode assembly is accommodated in the package, and the electrode assembly is a stacked structure; the electrode assembly includes a first electrode sheet group and a second electrode sheet group, the first electrode sheet group and the second electrode sheet group are stacked along a first direction, along the second direction, the length of the first electrode sheet group is greater than the length of the second electrode sheet group, and the second direction is perpendicular to the first direction; the first electrode sheet group has a first electrode sheet closest to the second electrode sheet group, the first electrode sheet includes a current collector and an active material layer, a first region and a second region, along the thickness direction of the current collector, active material layers are arranged on both sides of the first region, and the second region is only provided with an active material layer on the side away from the second electrode sheet group, the first region at least partially overlaps with the first electrode sheet group, and the second region at least partially does not overlap with the first electrode sheet group.

[0049] The size of the first pole piece group in the second direction is larger than the size of the second pole piece group in the second direction, the first pole piece group includes a first pole piece closest to the second pole piece group, and the current collector of the first pole piece includes a first region at least partially overlapping with the second pole piece group and a second region at least partially not overlapping with the second pole piece group. On the one hand, active material layers are provided on both sides of the first region, and the active material layer on the side of the first region facing the second pole piece group can be used as an outermost pole piece of the second pole piece group, which is equivalent to an outermost pole piece of the second pole piece group and an outermost pole piece of the first pole piece group sharing a current collector. Compared with the solution in which the current collector of an outermost pole piece of the first pole piece group with an active material layer coated on one side and the current collector of an outermost pole piece of the second pole piece group with an active material layer coated on one side are bonded by an adhesive layer, this solution reduces the space occupied by the adhesive layer and reduces the energy density loss of the battery cell in the first direction. On the other hand, compared with the scheme in which the current collector of the outermost single-sided active material layer-coated pole piece of the first pole piece group is bonded to the current collector of the outermost single-sided active material layer-coated pole piece of the second pole piece group through an adhesive layer, this scheme reduces the number of pole pieces coated with active material layers on one side in the battery cell by setting the first pole piece, thereby reducing the number of current collectors in the battery cell and reducing the energy density loss of the battery cell in the first direction. On the other hand, in order to alleviate the problems of warping and curling of the pole piece coated with active material layer on one side, the thickness of the current collector of the single-sided pole piece is large, which will also lead to the loss of energy density of the battery cell. In the battery cell of this scheme, active material layers are arranged on both sides of the first region of the current collector of the first pole piece. The active material layers on both sides of the first region of the current collector of the first pole piece can offset the effect of stress. The risk of warping and curling of the first pole piece is low, and the thickness of the current collector of the first pole piece can be made smaller than that of the current collector of the pole piece coated with active material layer on one side, further reducing the energy density loss of the battery cell in the first direction. On the other hand, the second region of the current collector of the first pole piece is provided with an active material layer only on the side away from the second pole piece group, which reduces the active material that does not exert its capacity and avoids the space occupied by the active material that does not exert its capacity, and further reduces the energy density loss of the battery cell in the first direction. Therefore, compared with the solution in which the single-sided coated pole piece of the first pole piece group closest to the second pole piece group and the single-sided coated pole piece of the second pole piece group closest to the first pole piece group are bonded by a glue layer, the battery cell of this solution has a higher energy density.

[0050] The battery cell disclosed in the embodiment of the present application can be used in, but not limited to, electric two-wheeled vehicles, electric tools, drones, energy storage devices and other electrical equipment. The battery cell formed by the pole piece having the working conditions of the present application can also be used as the power supply system of the electrical equipment.

[0051] The present application provides an electric device using a battery cell as a power source, and the electric device may be, but is not limited to, electronic equipment, electric tools, electric vehicles, drones, and energy storage devices. Among them, electronic equipment may include mobile phones, tablets, laptops, etc., electric tools may include electric drills, electric saws, etc., and electric vehicles may include electric cars, electric motorcycles, electric bicycles, etc.

[0052] like Figure 1 , Figure 2 As shown, the embodiment of the present application provides a battery cell 100 , which includes a package 10 and an electrode assembly 20 . The electrode assembly 20 is accommodated in the package 10 .

[0053] The package 10 may be a hard shell, for example, the package 10 is a stainless steel shell or an aluminum hard shell, forming a steel shell battery or an aluminum shell battery.

[0054] The packaging member 10 may also be formed of a relatively soft material, for example, the packaging member 10 is an aluminum-plastic film or a steel-plastic film, forming a soft-package battery cell 100 .

[0055] like Figure 2 and Figure 3 As shown, a receiving cavity 11 is formed inside the package 10. The electrode assembly 20 is received in the receiving cavity 11. In some embodiments, the receiving cavity 11 includes a first receiving cavity 111 and a second receiving cavity 112. The first receiving cavity 111 and the second receiving cavity 112 are arranged along a first direction X, and along a second direction Y, the length of the second receiving cavity 112 is greater than the length of the first receiving cavity 111. Figure 3 As shown, along the second direction Y, one end of the first accommodating cavity 111 is flush with one end of the second accommodating cavity 112 , and the other end of the second accommodating cavity 112 exceeds the other end of the first accommodating cavity 111 . Specifically, the package 10 includes a first wall portion 113 and a second wall portion 114 opposite to each other along the second direction Y, the second accommodating cavity 112 is located between the surface of the first wall portion 113 and the inner surface of the second wall portion 114, the package 10 includes a third wall portion 115 and a fourth wall portion 116 opposite to each other along the second direction Y, the first accommodating cavity 111 is located between the inner surface of the third wall portion 115 and the inner surface of the fourth wall portion 116, the inner surface of the first wall portion 113 and the inner surface of the third wall portion 115 are parallel and connected, along the second direction Y, the inner surface of the second wall portion 114 is farther away from the inner surface of the first wall portion 113 relative to the inner surface of the fourth wall portion 116, so that one end of the first accommodating cavity 111 is flush with one end of the second accommodating cavity 112, and the second accommodating cavity 112 exceeds the first accommodating cavity 111 in the direction from the first wall portion 113 to the second wall portion 114. The second direction Y is perpendicular to the first direction X. The first direction X can be the thickness direction of the battery cell 100. It should be noted that, Figure 4In the figure, the dotted line parallel to the second direction Y is to show the boundary between the first accommodating cavity 111 and the second accommodating cavity 112 in the first direction X, which facilitates the understanding of the structure, but should not be understood as a limitation on the structure of the package 10.

[0056] like Figure 2 , Figure 3 As shown, in some embodiments, the package 10 includes a main body portion 12, the main body portion 12 includes a first main body portion 121 and a second main body portion 122, the first main body portion 121 and the second main body portion 122 are arranged side by side along the second direction Y, the second main body portion 122 has a first outer surface 1221 in the first direction X, and the first main body portion 121 protrudes from the first outer surface 1221.

[0057] It should be noted that Figure 3 In the figure, the dotted line parallel to the first direction X is to show the boundary between the first main body 121 and the second main body 122 in the second direction Y to facilitate the understanding of the structure, but it should not be understood as a limitation on the structure of the package 10.

[0058] The first wall portion 113 , the third wall portion 115 , and the fourth wall portion 116 are wall portions of the second main body portion 122 . The second main body portion 122 further includes a fifth wall portion 117 and a sixth wall portion 118 that are opposite to each other along the first direction X.

[0059] The second wall portion 114 is a wall portion of the first main body portion 121, and the first main body portion 121 also includes a seventh wall portion 119 and an eighth wall portion 1110 that are opposite to each other along the first direction X. The inner surface of the sixth wall portion 118 is parallel to and connected to the inner surface of the eighth wall portion 1110. The sixth wall portion 118 and the eighth wall portion 1110 can be an integrally formed structure. The fifth wall portion 117 is farther away from the sixth wall portion 118 along the first direction X relative to the seventh wall portion 119, and the fifth wall portion 117 and the seventh wall portion 119 are connected through the fourth wall portion 116, so that the first main body portion 121 protrudes from the outer surface of the fourth wall portion 116 in the second direction Y, wherein the outer surface of the fourth wall portion 116 is the first outer surface 1221 of the second main body portion 122 in the first direction X, and the outer surface (first outer surface 1221) of the fourth wall portion 116 in the second direction Y is a step surface, and the battery cell 100 is a step battery.

[0060] The third wall portion 115, the fourth wall portion 116 and the fifth wall portion 117 are partial wall portions that define the first accommodating cavity 111, the first wall portion 113 and the sixth wall portion 118 of the second main body portion 122 and the second wall portion 114, the seventh wall portion 119 and the eighth wall portion 1110 of the first main body portion 121 are partial wall portions that define the second accommodating cavity 112, and the contour of the main body portion 12 matches the contour shape of the accommodating cavity 11.

[0061] like Figure 4As shown, in some embodiments, the package 10 further includes a first sealing portion 13, which is connected to the side of the second main body 122 away from the first main body 121. The first sealing portion 13 can be folded around an axis parallel to the third direction Z to fit with the side of the second main body 122 away from the first main body 121, so as to reduce the size of the battery cell 100 in the second direction Y and improve space utilization. The first direction X, the second direction Y and the third direction Z are perpendicular to each other.

[0062] like Figure 5 As shown, in some embodiments, the package 10 further includes a second sealing portion 14, which is connected to a side of the first main body portion 121 away from the second main body portion 122. The second sealing portion 14 can be folded around an axis parallel to the third direction Z to fit with the side of the first main body portion 121 away from the second main body portion 122, so as to reduce the size of the battery cell 100 in the second direction Y and improve space utilization.

[0063] like Figure 6 , Figure 7 As shown, the electrode assembly 20 is a laminated structure. The electrode assembly 20 includes a first electrode set 21 and a second electrode set 22, which are stacked along a first direction X. Along a second direction Y, the length of the first electrode set 21 is greater than the length of the second electrode set 22.

[0064] The first pole piece group 21 includes a plurality of pole pieces 20a stacked along the first direction X. The two adjacent pole pieces 20a in the first pole piece group 21 have opposite polarities, that is, one of the two adjacent pole pieces 20a in the first pole piece group 21 is a positive pole piece and the other is a negative pole piece. An isolation film 20b is provided between the two adjacent pole pieces 20a in the first pole piece group 21, and the isolation film 20b is used to insulate and separate the two adjacent pole pieces 20a with opposite polarities in the first pole piece group 21. The first pole piece group 21 includes a first outer pole piece farthest from the second pole piece group 22, and the first outer pole piece 20a can be a pole piece coated with an active material layer on one side, which is beneficial to reduce the active material that does not play the capacity and improve the energy density of the battery cell 100. Of course, the first outer pole piece can also be a pole piece coated with active material on both sides. The first outer pole piece can be a positive pole piece or a negative pole piece.

[0065] The second pole piece group 22 includes a plurality of pole pieces 20a stacked along the first direction X. Two adjacent pole pieces 20a in the second pole piece group 22 have opposite polarities, that is, one of the two adjacent pole pieces 20a in the second pole piece group 22 is a positive pole piece and the other is a negative pole piece. An isolation film 20b is provided between the two adjacent pole pieces 20a in the second pole piece group 22, and the isolation film 20b is used to insulate and separate the two adjacent pole pieces 20a with opposite polarities in the second pole piece group 22. The second pole piece group 22 includes a second outer pole piece farthest from the first pole piece group 21, and the second outer pole piece can be a pole piece coated with an active material layer on one side, which is conducive to reducing the active material that does not play a capacity and improving the energy density of the battery cell 100. Of course, the second outer pole piece can also be a pole piece coated with active material on both sides. The second outer pole piece can be a positive pole piece or a negative pole piece.

[0066] The first pole piece group 21 and the second pole piece group 22 are insulated and separated by an isolation film 20 b.

[0067] The isolation film 20b insulates and separates the two pole pieces 20a with opposite polarities, thereby reducing the risk of short circuit of the battery cell 100. The isolation film 20b may be made of PP (polypropylene) or PE (polyethylene).

[0068] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, at least one side of the positive electrode current collector is provided with a positive electrode active material layer, the material of the positive electrode current collector may include aluminum, and the positive electrode active material may be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, at least one side of the negative electrode current collector is provided with a negative electrode active material layer, the material of the negative electrode current collector may include copper, and the negative electrode active material may be carbon or silicon, etc.

[0069] like Figure 6 , Figure 7 , Figure 8 As shown, the first electrode plate group 21 has a first electrode plate 211 closest to the second electrode plate group 22, the first electrode plate 211 includes a current collector 2111 and an active material layer 2112, the current collector 2111 includes a first region 2111a at least partially overlapping with the second electrode plate group 22 and a second region 2111b at least partially not overlapping with the second electrode plate group 22, the active material layer 2112 is arranged on both sides of the first region 2111a, and the active material layer 2112 is arranged only on the side of the second region 2111b away from the second electrode plate group 22.

[0070] Figure 7 The dotted line parallel to the first direction X is the boundary between the first region 2111a and the second region 2111b of the first current collector 2111, and is also the boundary between the first portion 212 and the second portion 213 described below.

[0071] The size of the first electrode group 21 in the second direction Y is greater than the size of the second electrode group 22 in the second direction Y. The first electrode group 21 includes a first electrode 211 closest to the second electrode group 22. The current collector 2111 of the first electrode 211 includes a first region 2111a that at least partially overlaps with the second electrode group 22 and a second region 2111b that at least partially does not overlap with the second electrode group 22. On the one hand, active material layers 2112 are provided on both sides of the first region 2111a. The active material layer on the side of the first region 2111a facing the second electrode group 22 2112 can serve as an outermost pole piece of the second pole piece group 22, which is equivalent to an outermost pole piece 20a of the second pole piece group 22 and an outermost pole piece 20a of the first pole piece group 21 sharing a current collector 2111. Compared with the solution in which the current collector of an outermost pole piece with an active material layer 2112 on one side coated with an active material layer in the first pole piece group 21 and the current collector of an outermost pole piece with an active material layer on one side coated with an active material layer in the second pole piece group 22 are bonded through an adhesive layer, this solution reduces the space occupied by the adhesive layer and reduces the energy density loss of the battery cell 100 in the first direction X. On the other hand, compared with the scheme in which the current collector of the outermost pole piece of the first pole piece group 21 with an active material layer coated on one side is bonded to the current collector of the outermost pole piece of the second pole piece group 22 with an active material layer coated on one side through an adhesive layer, this scheme reduces the number of pole pieces with an active material layer coated on one side in the battery cell 100 by setting the first pole piece 211, thereby reducing the number of current collectors 2111 in the battery cell 100 and reducing the energy density loss of the battery cell 100 in the first direction X. On the other hand, in order to alleviate the problems of warping and curling of the pole piece coated with an active material layer on one side, the thickness of the current collector of the pole piece coated with an active material layer on one side is relatively large, which will also lead to the loss of energy density of the battery cell 100. In the battery cell 100 of this scheme, active material layers 2112 are provided on both sides of the current collector 2111 of the first pole piece 211. The active material layers 2112 on both sides of the first area 2111a of the current collector 2111 of the first pole piece 211 can offset the effect of stress, so that the risk of warping and curling of the first pole piece 211 as a whole is relatively low, and the thickness of the current collector 2111 of the first pole piece 211 can be made smaller than that of the current collector of the pole piece coated with an active material layer on one side, thereby further reducing the energy density loss of the battery cell 100 in the first direction X. On the other hand, the second region 2111b of the current collector 2111 of the first electrode 211 is provided with an active material layer 2112 only on the side away from the second electrode group 22, thereby reducing the active materials that do not exert their capacity and avoiding the space occupied by the active materials that do not exert their capacity, thereby further reducing the energy density loss of the battery cell 100 in the first direction X.Therefore, compared with the scheme in which the single-sided coated electrode 20a with an active material layer on one side that is closest to the second electrode group 22 in the first electrode group 21 and the single-sided coated electrode 20a with an active material layer on one side that is closest to the first electrode group 21 in the second electrode group 22 are bonded together through a glue layer, the battery cell 100 of this scheme has a higher energy density.

[0072] Please refer to Figure 7 , Fig. 9 , Fig.10 , observed along the first direction X, the first pole piece group 21 includes a first part 212 overlapping with the second pole piece group 22 and a second part 213 not overlapping with the second pole piece group 22, and the first part 212 and the second part 213 are arranged and connected along the second direction Y; the first part 212 and the second pole piece group 22 are accommodated in the second main body 122, and the second part 213 is accommodated in the first main body 121.

[0073] Fig. 9 The dotted line parallel to the first direction X is used to illustrate the boundary between the first portion 212 and the second portion 213 in the second direction Y to facilitate understanding of the structure, but should not be understood as a limitation on the structure of the battery cell 100 .

[0074] The polarity of the active material layer 2112 on the side of the current collector 2111 of the first electrode sheet 211 facing the second electrode sheet group 22 is opposite to the polarity of the electrode sheet 20a of the second electrode sheet group 22 closest to the first electrode sheet group 21. For example, if the electrode sheet 20a of the second electrode sheet group 22 closest to the first electrode sheet group 21 is a positive electrode electrode sheet, the active material layer 2112 on the side of the current collector 2111 facing the second electrode sheet group 22 is a negative electrode active material layer, and if the electrode sheet 20a of the second electrode sheet group 22 closest to the first electrode sheet group 21 is a negative electrode electrode sheet, the active material layer 2112 on the side of the current collector 2111 facing the second electrode sheet group 22 is a positive electrode active material layer.

[0075] The polarity of the active material layer 2112 on the side of the current collector 2111 of the first electrode sheet 211 away from the second electrode sheet group 22 is opposite to the polarity of the electrode sheet 20a closest to the first electrode sheet 211 in the first electrode sheet group 21. For example, if the electrode sheet 20a closest to the first electrode sheet 211 in the first electrode sheet group 21 is a positive electrode electrode sheet, the active material layer 2112 on the side of the current collector 2111 away from the second electrode sheet group 22 is a negative electrode active material layer, and if the electrode sheet 20a closest to the first electrode sheet 211 in the second electrode sheet group 22 is a negative electrode electrode sheet, the active material layer 2112 on the side of the current collector 2111 away from the second electrode sheet group 22 is a positive electrode active material layer.

[0076] The active material layer 2112 includes a first active material layer 2112a arranged on the side of the current collector 2111 facing the second electrode group 22 and a second active material layer 2112b arranged on the side of the current collector 2111 away from the second electrode group 22. At least a portion of the first active material layer 2112a and the second electrode group 22 are accommodated in the first accommodating cavity 111, and the current collector 2111 and the second active material layer 2112b are accommodated in the second accommodating cavity 112.

[0077] At least a portion of the first active material layer 2112a and the second electrode assembly 22 are accommodated in the first accommodating cavity 111, and the current collector 2111 and the second active material layer 2112b are accommodated in the second accommodating cavity 112, so that the space in the package 10 in the first direction X is fully utilized, and the gap between the first electrode assembly 21 and the second electrode assembly 22 and the inner wall of the package 10 in the first direction X is reduced, which is beneficial to improving the energy density of the battery cell 100.

[0078] The polarity of the first active material layer 2112a is opposite to the polarity of the electrode 20a of the second electrode group 22 closest to the first electrode group 21. The polarity of the second active material layer 2112b is opposite to the polarity of the electrode 20a of the first electrode group 21 closest to the first electrode 211.

[0079] The second pole piece group 22 is entirely located in the first accommodation cavity 111 .

[0080] like Fig. 9 , Fig.10 As shown, in some embodiments, the first active material layer 2112a may also be entirely located in the first accommodation cavity 111 along the first direction X, and then the projection of the first active material layer 2112a is located within the projection of the fourth wall portion 116 when observed along the second direction Y. In the embodiment in which the first active material layer 2112a may also be entirely located in the first accommodation cavity 111 along the first direction X, the surface of the first active material layer 2112a facing the current collector 2111 may be flush with the inner surface of the seventh wall portion 119. In the embodiment in which the first active material layer 2112a may also be entirely located in the first accommodation cavity 111 along the first direction X, the surface of the first active material layer 2112a facing the current collector 2111 is further away from the inner surface of the eighth wall portion 1110 than the inner surface of the seventh wall portion 119.

[0081] like Fig. 9 , Fig.10As shown, in some embodiments, the surface of the second region 2111b away from the second active material layer 2112b can be in contact with the wall (seventh wall) of the package 10, so that the first active material layer 2112a is completely located in the first accommodating cavity 111, so as to avoid a gap between the wall of the package 10 and the surface of the second region 2111b away from the second active material layer 2112b in the first direction X, thereby improving space utilization and facilitating improving the energy density of the battery cell 100.

[0082] like Fig.11 , Fig.12 , Fig.13 As shown, in other embodiments, a portion of the first active material layer 2112a along the first direction X is located in the first accommodating cavity 111, and another portion of the first active material layer 2112a along the first direction X is located in the second accommodating cavity 112. Then, when observed along the second direction Y, the projection of the inner surface of the wall portion (the seventh wall portion 119) of the package 10 opposite to the second area 2111b in the first direction X is located within the projection of the first active material layer 2112a.

[0083] like Figure 8 As shown, in some embodiments, the thickness of the current collector 2111 is H, 0.003 mm ≤ H ≤ 0.030 mm.

[0084] The thickness of the current collector 2111 is the distance between two surfaces of the current collector 2111 opposite to each other in the first direction X. For example, H may be 0.003 mm, 0.004 mm, 0.004 mm, 0.005 mm, 0.006 mm, 0.007 mm, 0.009 mm, 0.011 mm, 0.013 mm, 0.015 mm, 0.017 mm, 0.019 mm, 0.021 mm, 0.023 mm, 0.025 mm, 0.027 mm, 0.030 mm, etc.

[0085] The thickness of the current collector 2111 of the first pole piece 211 is greater than or equal to 0.003 mm, so that the current collector 2111 has good mechanical properties and conductive properties. The current collector 2111 of the first pole piece 211 is less than or equal to 0.030 mm, and the thickness of the current collector 2111 of the first pole piece 211 is controlled within a reasonable range, reducing the space occupied by the current collector 2111 of the first pole piece 211, thereby reducing the energy density loss of the battery cell 100, which is beneficial to improving the energy density of the battery cell 100.

[0086] Furthermore, 0.004mm≤H≤0.020mm.

[0087] Illustratively, H may be 0.004 mm, 0.005 mm, 0.006 mm, 0.008 mm, 0.010 mm, 0.012 mm, 0.014 mm, 0.016 mm, 0.018 mm, 0.020 mm, etc.

[0088] The current collector 2111 of the first pole piece 211 is greater than or equal to 0.004 mm, so that the current collector 2111 has better mechanical properties and conductive properties. The current collector 2111 of the first pole piece 211 is less than or equal to 0.020 mm, and the thickness of the current collector 2111 of the first pole piece 211 is controlled within a reasonable range, thereby further reducing the space occupied by the current collector 2111 of the first pole piece 211, thereby further reducing the energy density loss of the battery cell 100, thereby further improving the energy density of the battery cell 100.

[0089] like Figure 8 As shown, in some embodiments, the current collector 2111 is a first metal layer 21112. It can be understood that the current collector 2111 can be a foil. The current collector 2111 of the first pole piece 211 is a metal layer, so that the current collector 2111 has better conductivity.

[0090] In the embodiment where the first current collector 2111 is the first metal layer 21112, the polarities of the active material layers 2112 on both sides of the current collector 2111 of the first pole piece 211 may be the same, that is, the first active material layer 2112a and the second active material layer 2112b have the same polarity. The first active material layer 2112a and the second active material layer 2112b may both be positive electrode active material layers, that is, the first pole piece 211 may be a positive electrode pole piece. The first active material layer 2112a and the second active material layer 2112b may both be negative electrode active material layers, that is, the first pole piece 211 may also be a negative electrode pole piece.

[0091] like Fig.14 As shown, in some embodiments, the current collector 2111 includes an insulating separator layer 21111, a first metal layer 21112, and a second metal layer 2113. The first metal layer 21112 is disposed on a side of the insulating separator layer 21111 facing the second pole piece group 22, and the second metal layer 2113 is disposed on a side of the insulating separator layer 21111 facing away from the second pole piece group 22. It can be understood that the current collector 2111 including the insulating separator layer 21111, the first metal layer 21112, and the second metal layer 2113 is a composite current collector.

[0092] The current collector 2111 of the first pole piece 211 includes an insulating separation layer 21111, a first metal layer 21112 and a second metal layer 2113. The insulating separation layer 21111 is used as a mechanical support skeleton of the current collector 2111 so that the current collector 2111 has better mechanical properties. The thickness of the first metal layer 21112 and the second metal layer 2113 can be smaller, thereby reducing the metal burrs caused by mechanical damage to the first pole piece 211, which is beneficial to improving the safety performance of the battery cell 100.

[0093] In an embodiment where the current collector 2111 includes an insulating separation layer 21111, a first metal layer 21112 and a second metal layer 2113, the thickness of the current collector 2111 is the distance along the first direction X between the surface of the first metal layer 21112 facing away from the insulating separation layer 21111 and the surface of the second metal layer 2113 facing away from the insulating separation layer 21111.

[0094] In the embodiment where the current collector 2111 includes an insulating separation layer 21111, a first metal layer 21112, and a second metal layer 2113, the polarities of the active material layers 2112 on both sides of the current collector 2111 of the first pole piece 211 may be the same, that is, the first active material layer 2112a and the second active material layer 2112b have the same polarity. The first active material layer 2112a and the second active material layer 2112b may both be positive electrode active material layers, that is, the first pole piece 211 may be a positive electrode pole piece. The first active material layer 2112a and the second active material layer 2112b may both be negative electrode active material layers, that is, the first pole piece 211 may also be a negative electrode pole piece.

[0095] In an embodiment where the current collector 2111 includes an insulating separation layer 21111, a first metal layer 21112 and a second metal layer 2113, the polarities of the active material layers 2112 on both sides of the current collector 2111 of the first electrode 211 can be opposite, that is, the polarities of the first active material layer 2112a and the second active material layer 2112b are opposite, one of the first active material layer 2112a and the second active material layer 2112b is a positive electrode active material layer, and the other of the first active material layer 2112a and the second active material layer 2112b is a negative electrode active material layer.

[0096] The materials of the first metal layer 21112 and the second metal layer 2113 may be the same or different. For example, when the first active material layer 2112a and the second active material layer 2112b have the same polarity, the first metal layer 21112 and the second metal layer 2113 may be made of the same material; when the first active material layer 2112a and the second active material layer 2112b have opposite polarities, the first metal layer 21112 and the second metal layer 2113 may be made of different materials.

[0097] In some embodiments, the material of the package 10 is the same as the material of the first metal layer 21112. For example, if the material of the package 10 is aluminum foil or aluminum hard shell, the material of the first metal layer 21112 can be aluminum foil.

[0098] The material of the package 10 is the same as that of the first metal layer 21112 , which avoids a large difference in electrode potential between the package 10 and the second area 2111b, thereby reducing the risk of electrochemical corrosion and helping to improve the safety performance of the battery cell 100 and extend the service life of the battery cell 100 .

[0099] In some embodiments, the material of the package 10 can be similar to the material of the first metal layer 21112. The material of the package 10 can be similar to the material of the first metal layer 21112 means that the material of the package 10 is not completely the same as the material of the first metal layer 21112, but during the cycle of the battery cell 100, the electrode potential difference between the package 10 and the first metal layer 21112 is very small, and electrochemical corrosion is unlikely to occur. Exemplarily, the material of the package 10 is stainless steel foil or stainless steel hard shell, and the material of the first metal layer 21112 can be copper foil.

[0100] The material of the package is similar to that of the first metal layer 21112 , which reduces the electrode potential difference between the package 10 and the second area 2111b , thereby reducing the risk of electrochemical corrosion, which is beneficial to improving the safety performance of the battery cell 100 and extending the service life of the battery cell 100 .

[0101] like Fig.12 , Fig.13 , Fig.15 As shown, in some embodiments, the material of the package 10 is different from the material of the first metal layer 21112; the battery cell 100 also includes an insulating layer 30, along the first direction X, the insulating layer 30 is arranged between the surface of the second area 2111b facing the second electrode group 22 and the package 10 to separate the package 10 and the second area 2111b.

[0102] Along the first direction X, the insulating layer 30 is disposed between the second region 2111 b and the seventh wall portion 119 to insulate and separate the portion of the first metal layer 21112 located in the second region 2111 b and the seventh wall.

[0103] Exemplarily, the material of the package 10 is aluminum foil or aluminum hard shell, and the material of the first metal layer 21112 can be copper foil; the material of the package 10 is stainless steel foil or stainless steel hard shell, and the material of the first metal layer 21112 can be aluminum foil.

[0104] The material of the insulating layer 30 includes but is not limited to plastic and ceramic.

[0105] The material of the package 10 is different from the material of the first metal layer 21112, which facilitates the selection of a better material for the package 10 and the current collector 2111, so that the performance of the package 10 and the current collector 2111 can be better. The material of the package 10 is different from the material of the first metal layer 21112, and the insulating layer 30 is disposed between the package 10 and the second region 2111b of the current collector 2111 to separate the package 10 and the second region 2111b, reducing the risk of electrochemical corrosion when the electrode potential difference between the package 10 and the second region 2111b is too large, which is conducive to improving the safety performance of the battery cell 100 and extending the service life of the battery cell 100.

[0106] The insulating layer 30 may be disposed on the surface of the package 10 facing the second region 2111b in the first direction X, and the insulating layer 30 may also be disposed on the isolation film 20b between the first pole piece 211 and the second pole piece assembly 22. In some embodiments, the insulating layer 30 is disposed in the second region 2111b. Specifically, the insulating layer 30 is disposed on the surface of the first metal layer 21112 located in the second region 2111b that is away from the insulating separation layer 21111. The insulating layer 30 may be bonded to the second region 2111b.

[0107] The insulating layer 30 is disposed in the second region 2111b of the current collector 2111, and can separate the second region 2111b and the package 10 in the first direction X, so as to reduce the risk of electrochemical corrosion when the electrode potential difference between the package 10 and the second region 2111b is too large, which is beneficial to improving the safety performance of the battery cell 100 and extending the service life of the battery cell 100. Since the active material layer 2112 is not disposed on the side of the second region 2111b facing the second electrode sheet group 22, the insulating layer 30 disposed in the second region 2111b can also alleviate the problem of warping and curling of the first electrode sheet 211 in the second region 2111b.

[0108] The thickness of the insulating layer 30 may be smaller than the thickness of the active material layer 2112 of the current collector 2111 of the first electrode 211 facing the second electrode assembly 22, that is, the thickness of the insulating layer 30 may be smaller than the thickness of the first active material layer 2112a, so as to reduce the influence of the insulating layer 30 on the space utilization of the battery cell 100. The surface of the insulating layer 30 away from the second region 2111b may be in contact with the inner surface of the package 10.

[0109] In an embodiment where the battery cell 100 includes an insulating layer 30, a portion of the first active material layer 2112a in the first direction X is located in the first accommodating cavity 111, that is, a portion of the first active material layer 2112a that extends beyond the insulating layer 30 along the first direction X is located in the first accommodating cavity 111, and another portion of the first active material layer 2112a in the first direction X is located in the first accommodating cavity 111.

[0110] like Figure 1 As shown, the battery cell 100 further includes a positive electrode tab 40 and a negative electrode tab 50. The positive electrode tab 40 is electrically connected to the positive electrode sheet and extends out of the package 10, and the negative electrode tab 50 is electrically connected to the negative electrode sheet and extends out of the package 10. Figure 1 As shown, the positive electrode tab 40 and the negative electrode tab 50 may extend from the same end of the package 10 along the third direction Z. In other embodiments, the positive electrode tab 40 and the negative electrode tab 50 may also extend from opposite ends of the package 10 .

[0111] The positive electrode tab 40 and the current collector of the positive electrode sheet can be integrally formed, for example, the positive electrode tab 40 and the current collector of the positive electrode sheet are formed by die-cutting the substrate, thereby realizing the integral forming of the positive electrode tab 40 and the current collector of the positive electrode sheet. The positive electrode tab 40 and the current collector of the positive electrode sheet can be separately set, and then connected into one by welding connection, conductive adhesive connection, riveting connection, etc.

[0112] The negative electrode tab 50 and the current collector of the negative electrode sheet can be integrally formed, for example, the negative electrode tab 50 and the current collector of the negative electrode sheet are formed by die-cutting the substrate, thereby realizing the integral forming of the negative electrode tab 50 and the current collector of the negative electrode sheet. The negative electrode tab 50 and the current collector of the negative electrode sheet can be separately set, and then connected into one by welding connection, conductive adhesive connection, riveting connection, etc.

[0113] An embodiment of the present application further provides an electrical device, and the electrical device includes the battery cell 100 provided in any of the above embodiments.

[0114] The battery cell 100 provided in the above embodiment has a high energy density, which is beneficial to improving the power reliability of the electrical equipment powered by the laminated battery cell 100 .

[0115] The above are only preferred embodiments 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 modifications and variations. 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 package and an electrode assembly, wherein the electrode assembly is contained in the package and is a laminated structure; The electrode assembly comprises: The first pole piece group; A second pole piece group, wherein the first pole piece group and the second pole piece group are stacked along a first direction, along a second direction, the length of the first pole piece group is greater than the length of the second pole piece group, and the second direction is perpendicular to the first direction; The first pole piece group has a first pole piece closest to the second pole piece group, the first pole piece includes a current collector and an active material layer, the current collector includes a first region and a second region, along the thickness direction of the current collector, the active material layer is arranged on both sides of the first region, and the second region is only provided with the active material layer on the side away from the second pole piece group, the first region at least partially overlaps with the first pole piece group, and the second region at least partially does not overlap with the first pole piece group.

2. The battery cell according to claim 1, characterized in that: The packaging piece forms a receiving cavity, the receiving cavity includes a first receiving cavity and a second receiving cavity, the first receiving cavity and the second receiving cavity are arranged along the first direction, and along the second direction, the length of the second receiving cavity is greater than the length of the first receiving cavity; The active material layer includes a first active material layer arranged on the side of the current collector facing the second pole piece group and a second active material layer arranged on the side of the current collector away from the second pole piece group. At least a portion of the first active material layer and the second pole piece group are accommodated in the first accommodating cavity, and the current collector and the second active material layer are accommodated in the second accommodating cavity.

3. The battery cell according to claim 1, characterized in that: The current collector is a first metal layer.

4. The battery cell according to claim 1, characterized in that: The current collector includes an insulating separation layer, a first metal layer and a second metal layer. The first metal layer is arranged on a side of the insulating separation layer facing the second pole piece group, and the second metal layer is arranged on a side of the insulating separation layer away from the second pole piece group.

5. The battery cell according to claim 3 or 4, characterized in that: The material of the packaging piece is the same as that of the first metal layer.

6. The battery cell according to claim 3 or 4, characterized in that: The material of the packaging member is different from the material of the first metal layer; The battery cell further includes an insulating layer, and along the first direction, the insulating layer is disposed between a surface of the second region facing the second electrode assembly and the packaging member to separate the packaging member and the second region.

7. The battery cell according to claim 6, characterized in that: The insulating layer is disposed in the second region.

8. The battery cell according to claim 1, characterized in that: The thickness of the current collector is H, 0.003 mm ≤ H ≤ 0.030 mm.

9. The battery cell according to claim 8, characterized in that: 0.004mm≤H≤0.020mm.

10. The battery cell according to claim 1, characterized in that: The package comprises a main body, the main body comprises a first main body and a second main body, the first main body and the second main body are arranged side by side along the second direction, the second main body has a first outer surface in the first direction, and the first main body protrudes from the first outer surface; When viewed along the first direction, the first pole piece group includes a first portion overlapping with the second pole piece group and a second portion not overlapping with the second pole piece group, and the first portion and the second portion are arranged and connected along the second direction; The first part and the second pole piece group are accommodated in the second main body, and the second part is accommodated in the first main body.

11. An electrical device, characterized in that: Comprising the battery cell according to any one of claims 1-10.

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