Battery cell and electric equipment

Abstract

The invention discloses a battery cell and electric equipment, and belongs to the technical field of batteries. The battery cell comprises a shell and an electrode assembly, the electrode assembly is accommodated in the shell, and the electrode assembly 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 the first direction, the length of the second pole piece set is larger than that of the first pole piece set in the second direction, and the first pole piece set comprises a first positive pole piece and a first negative pole piece which are stacked in the first direction; the second pole piece group comprises a second positive pole piece and a second negative pole piece which are laminated along the first direction; active material layers are arranged on two surfaces of the first positive current collector, the first negative current collector, the second positive current collector and the second negative current collector along the first direction; wherein the thickness of the first positive pole piece is different from that of the second positive pole piece, and the thickness of the first negative pole piece is different from that of the second negative pole piece. The battery cell has relatively high energy density.

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.

[0003] How to improve the energy density of battery cells is an urgent problem to be solved in battery technology. Summary of the invention

[0004] In view of the above problems, the present application provides a battery cell and an electrical device, which can improve the energy density of the battery cell.

[0005] In a first aspect, an embodiment of the present application provides a battery cell, which includes a shell and an electrode assembly, wherein the electrode assembly is accommodated in the shell, 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 arranged along a first direction, along the second direction, the length of the second electrode sheet group is greater than the length of the first electrode sheet group, and the second direction is perpendicular to the first direction; the first electrode sheet group includes a first positive electrode sheet and a first negative electrode sheet stacked along the first direction, and the second electrode sheet group includes a second positive electrode sheet and a second negative electrode sheet stacked along the first direction; the first positive electrode sheet includes a first positive electrode collector, the first negative electrode sheet includes a first negative electrode collector, the second positive electrode sheet includes a second positive electrode collector, and the second negative electrode sheet includes a second negative electrode collector, and active material layers are provided on both surfaces of the first positive electrode collector, the first negative electrode collector, the second positive electrode collector, and the second negative electrode collector along the first direction; wherein the thickness of the first positive electrode sheet is different from the thickness of the second positive electrode sheet, and the thickness of the first negative electrode sheet is different from the thickness of the second negative electrode sheet.

[0006] In one or more optional embodiments above, on the one hand, when producing a battery cell, since the thickness of at least two pole pieces in the electrode assembly is different, electrode assemblies of different sizes can be arranged based on the shell, so that the electrode assembly can fully utilize the internal space of the shell, and reduce the risk of energy density loss due to excessive gap between the electrode assembly and the shell due to the fact that the remaining space of the shell is insufficient to arrange a group of positive pole pieces and negative pole pieces during the pole piece stacking process due to the consistent specifications of each pole piece, thereby facilitating the improvement of the energy density of the battery cell. On the other hand, in order to realize the assembly of the battery cell and the battery compartment of the electric device, the battery cell will be designed as a special-shaped battery cell. At this time, the first pole piece group and the second pole piece group may be arranged in the first direction, and in the second direction, the length of the second pole piece group is designed to be greater than the length of the first pole piece group. Such a setting is because the space of the battery compartment limits the outline and volume of the shell, so it is necessary to set two two battery cells. At this time, the volume of the shell is certain, and the pole piece thicknesses in the first pole piece group and the second pole piece group are designed to be different values. The battery cell has a higher energy density and adapts to different assembly environments, thereby improving the adaptability of the battery cell to the electric device. On the other hand, since thicker pole pieces are conducive to improving the energy density of the battery cell, and thinner pole pieces are conducive to improving the charge and discharge rate of the battery cell, the thickness of the pole pieces in the first pole piece group and the second pole piece group is designed to be different, and the relationship between the charge and discharge rate and the energy density can be balanced according to the needs, so that the battery cell is suitable for electrical equipment with different needs.

[0007] In some embodiments of the first aspect of the present application, the thickness of the first positive electrode sheet is smaller than the thickness of the second positive electrode sheet, and the thickness of the first negative electrode sheet is smaller than the thickness of the second negative electrode sheet.

[0008] In one or more optional embodiments above, the thickness of the first positive electrode plate is less than the thickness of the second positive electrode plate, and the thickness of the first negative electrode plate is less than the thickness of the second negative electrode plate. Such a design can enable the first electrode plate group to have a higher charge and discharge rate, and the second electrode plate group to have a higher energy density, so that the battery cell can take into account both a higher charge and discharge rate and a higher energy density. At the same time, since the length of the second electrode plate group is greater than the length of the first electrode plate group along the second direction, the area of ​​the electrode plate in the second electrode plate group that can be coated with the active material is larger, and the electrode plates of the second electrode plate group with fewer layers can be stacked to achieve the effect of the second electrode plate group having a higher energy density, thereby reducing the risk of the second electrode plate group containing too many current collectors and losing energy density due to the excessive number of layers of electrode plates in the second electrode plate group.

[0009] In some embodiments of the first aspect of the present application, the first pole piece group also includes a first outer pole piece farthest from the second pole piece group, the first outer pole piece includes a first outer current collector, and the first outer current collector is only provided with an active material layer on the side facing the second pole piece group; the second pole piece group also includes a second outer pole piece farthest from the first pole piece group, the second outer pole piece includes a second outer current collector, and the second outer current collector is only provided with an active material layer on the side facing the first pole piece group; the first outer pole piece and the second outer pole piece have the same polarity; the thickness of the first outer pole piece is less than the thickness of the second outer pole piece.

[0010] In one or more optional embodiments above, since the first outer current collector is only provided with an active material layer on the side facing the second pole piece group, and the second outer current collector is only provided with an active material layer on the side facing the first pole piece group, that is, the first outer current collector and the second current collector are only provided with an active material layer on the side where they exert their capacity, which is conducive to making the battery cell have a higher energy density. The thickness of the first outer pole piece is less than the thickness of the second outer pole piece. The first outer pole piece and the second outer pole piece can be selected appropriately so that the first pole piece group and the second pole piece group can make full use of the internal space of the shell, further improving the energy density of the battery cell. At the same time, since the thickness of the first positive pole piece is less than the thickness of the second positive pole piece, and the thickness of the first negative pole piece is less than the thickness of the second negative pole piece, setting the thickness of the first outer pole piece to be less than the thickness of the second outer pole piece is conducive to the synchronous design and processing of all pole pieces in the first pole piece group and the synchronous processing of all pole pieces in the second pole piece group.

[0011] In some embodiments of the first aspect of the present application, the thickness of the first positive electrode sheet is greater than the thickness of the second positive electrode sheet, and the thickness of the first negative electrode sheet is greater than the thickness of the second negative electrode sheet.

[0012] In one or more optional embodiments above, the thickness of the first positive electrode sheet is greater than the thickness of the second positive electrode sheet, and the thickness of the first negative electrode sheet is greater than the thickness of the second negative electrode sheet. Such a design can enable the first electrode sheet group to have a higher energy density, and the second electrode sheet group to have a higher charge and discharge rate, so that the battery cell can take into account both a higher charge and discharge rate and a higher energy density. At the same time, since the length of the second electrode sheet group is greater than the length of the first electrode sheet group along the second direction, the electrode sheet in the second electrode sheet group can be coated with a larger area of ​​active material, and during the charging process of the battery cell, the battery cell can have a relatively large energy storage capacity in a shorter time.

[0013] In some embodiments of the first aspect of the present application, the first pole piece group also includes a first outer pole piece farthest from the second pole piece group, the first outer pole piece includes a first outer current collector, and the first outer current collector is only provided with an active material layer on the side facing the second pole piece group; the second pole piece group also includes a second outer pole piece farthest from the first pole piece group, the second outer pole piece includes a second outer current collector, and the second outer current collector is only provided with an active material layer on the side facing the first pole piece group; the first outer pole piece and the second outer pole piece have the same polarity; the thickness of the first outer pole piece is greater than the thickness of the second outer pole piece.

[0014] In one or more optional embodiments above, since the first outer current collector is provided with an active material layer only on the side facing the second pole piece group, and the second outer current collector is provided with an active material layer only on the side facing the first pole piece group, that is, the first outer current collector and the second current collector are provided with an active material layer only on the side where they exert their capacity, which is conducive to making the battery cell have a higher energy density. The thickness of the first outer pole piece is greater than the thickness of the second outer pole piece. Suitable first outer pole pieces and second outer pole pieces can be selected to make the first pole piece group and the second pole piece group fully utilize the internal space of the shell, further improving the energy density of the battery cell. At the same time, since the thickness of the first positive pole piece is greater than the thickness of the second positive pole piece, and the thickness of the first negative pole piece is greater than the thickness of the second negative pole piece, setting the thickness of the first outer pole piece to be greater than the thickness of the second outer pole piece is conducive to the synchronous design and processing of all pole pieces in the first pole piece group and the synchronous processing of all pole pieces in the second pole piece group.

[0015] In some embodiments of the first aspect of the present application, the thickness of the first positive electrode sheet is D1, the thickness of the first negative electrode sheet is D2, the thickness of the second positive electrode sheet is D3, and the thickness of the second negative electrode sheet is D4; satisfying: 0<|D3-D1|≤180μm, 0<|D4-D2|≤180μm.

[0016] In one or more of the above optional embodiments, the absolute value of the difference between the thickness of the second positive electrode sheet and the thickness of the first positive electrode sheet, and the absolute value of the difference between the thickness of the second negative electrode sheet and the thickness of the first negative electrode sheet are designed to be within a reasonable range, which is beneficial for making the battery cell have a higher energy density during the process of stacking the electrode sheets, while making the migration distance of lithium ions in the first electrode sheet group and the second electrode sheet group similar, so that when the input current of the battery cell is constant, the difficulty of activating the lithium ions in the first electrode sheet group and the lithium ions in the second electrode sheet group is similar, thereby reducing the risk of one of the first electrode sheet group and the second electrode sheet group not being fully utilized during the use of the battery cell, resulting in the available capacity of the battery cell being less than the designed capacity.

[0017] In some embodiments of the first aspect of the present application, the thickness of the first positive electrode sheet is D1, the thickness of the first negative electrode sheet is D2, the thickness of the second positive electrode sheet is D3, and the thickness of the second negative electrode sheet is D4; satisfying: 20μm≤D1≤200μm, 20μm≤D2≤200μm, 20μm≤D3≤200μm, 20μm≤D4≤200μm.

[0018] In one or more of the above optional embodiments, the thickness of the electrode sheet is greater than or equal to 20 μm, which is conducive to the battery cell having a higher energy density. The thickness of the electrode sheet is less than or equal to 200 μm, which is conducive to the lithium ions in the battery cell having a shorter migration distance, thereby improving the charge and discharge rate of the battery cell. Therefore, setting the thickness of the electrode sheet within a reasonable range is conducive to the battery cell having both a higher energy density and a higher charge and discharge rate.

[0019] In some embodiments of the first aspect of the present application, the thickness of the first outer pole piece is D5, and the thickness of the second outer pole piece group is D6, satisfying: 0<|D6-D5|≤90μm.

[0020] In one or more of the above optional embodiments, the absolute value of the difference between the thickness of the second outer pole sheet and the thickness of the first outer pole sheet is designed to be within a reasonable range, which is beneficial for making the battery cell have a higher energy density during the process of stacking the pole sheets while making the migration distance of lithium ions in the first pole sheet group and the second pole sheet group similar, so that when the input current of the battery cell is constant, the difficulty of activating the lithium ions in the first pole sheet group and the lithium ions in the second pole sheet group is similar, thereby reducing the risk of one of the first outer pole sheet and the second outer pole sheet not being fully utilized during the use of the battery cell, resulting in the available capacity of the battery cell being less than the designed capacity.

[0021] In some embodiments of the first aspect of the present application, the thickness of the first positive electrode collector is the same as the thickness of the second positive electrode collector, and the thickness of the first negative electrode collector is the same as the thickness of the second negative electrode collector.

[0022] In one or more optional embodiments above, the thickness of the first positive electrode current collector is the same as the thickness of the second positive electrode current collector, and the thickness of the first negative electrode current collector is the same as the thickness of the second negative electrode current collector. On the one hand, the current can be distributed more evenly in the battery cell, thereby improving the cycle life of the battery cell. On the other hand, when designing and processing pole pieces of different thicknesses, it is only necessary to change the surface density of the active material layer of the current collector, thereby reducing the difficulty of processing the battery cell.

[0023] In some embodiments of the first aspect of the present application, the electrode assembly satisfies one of the following conditions: the surface density of the active material layer of the first positive electrode sheet is 100 mg / mm 2 ~350mg / mm 2; The surface density of the active material layer of the first negative electrode sheet is 50 mg / mm 2 ~150mg / mm 2 ; The surface density of the active material layer of the second positive electrode sheet is 100 mg / mm 2 ~350mg / mm 2 ; The surface density of the active material layer of the second negative electrode sheet is 50 mg / mm 2 ~150mg / mm 2 .

[0024] In one or more of the above optional embodiments, when the surface density of the active material layer of the positive electrode sheet is greater than or equal to 100 mg / mm 2 When the surface density of the active material layer of the positive electrode sheet is less than or equal to 350 mg / mm 2 When the surface density of the active material layer of the positive electrode sheet is set within a reasonable range, it is beneficial for the battery cell to have both a higher energy density and a higher charge and discharge rate.

[0025] When the surface density of the active material layer of the negative electrode is greater than or equal to 100 mg / mm 2 When the surface density of the active material layer of the negative electrode sheet is less than or equal to 350 mg / mm 2 When the surface density of the active material layer of the negative electrode sheet is set within a reasonable range, it is beneficial for the battery cell to have both a higher energy density and a higher charge and discharge rate.

[0026] In some embodiments of the first aspect of the present application, a pole piece in the second pole piece group that is closest to the first pole piece group is a second end pole piece, and the second end pole piece includes a first region overlapping with the first pole piece group and a second region that does not overlap with the first pole piece group;

[0027] Along the first direction, active material layers are arranged on both sides of the first region, and active material layers are arranged only on the side of the second region away from the first electrode assembly.

[0028] In one or more optional embodiments above, the size of the second pole piece group in the second direction is greater than the size of the first pole piece group in the second direction, the second pole piece group includes a second end pole piece closest to the first pole piece group, and the second end pole piece includes a first region overlapping with the first pole piece group and a second region not overlapping with the first pole piece group. Along the first direction, both sides of the first region are provided with active material layers, and the second region is provided with active material layers only on the side away from the first pole piece group. On the one hand, both sides of the first region are provided with active material layers, and the active material layer on the side of the first region facing the first pole piece group can be used as an outermost pole piece of the first pole piece group, which is equivalent to sharing a current collector with an outermost pole piece of the first pole piece group and an outermost pole piece of the second pole piece group. Compared with the scheme in which the current collector of a pole piece with an outermost single-sided active material layer coated on the second pole piece group and the current collector of a pole piece with an outermost single-sided active material layer coated on the first pole piece group are bonded by a glue layer, this scheme reduces the space occupied by the glue 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 second pole piece group is bonded to the current collector of the outermost single-sided active material layer-coated pole piece of the first 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 second end 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. The current collector of the second end pole piece in the battery cell of this scheme is provided with active material layers on both sides. The active material layers on both sides of the current collector of the second end pole piece can offset the effect of stress. The risk of warping and curling of the second end pole piece is low, and the thickness of the current collector of the second end 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 second end electrode sheet is provided with an active material layer only on the side away from the first electrode sheet 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 electrode sheet of the second electrode sheet group closest to the first electrode sheet group and the single-sided coated electrode sheet of the first electrode sheet group closest to the second electrode sheet group are bonded by an adhesive layer, the battery cell of this solution has a higher energy density.

[0029] In some embodiments of the first aspect of the present application, the housing includes a first wall and a second wall arranged opposite to each other along a first direction, the first wall includes a first sub-wall, a second sub-wall and a first connecting wall, the first sub-wall protrudes from the second sub-wall in a direction away from the second wall, and the first connecting wall connects the first sub-wall and the second sub-wall; a portion of the second pole piece group is located between the second sub-wall and the second wall, and the first pole piece group is located between the second pole piece group and the first sub-wall.

[0030] In one or more of the above optional embodiments, the first sub-wall protrudes from the second sub-wall, the first connecting wall connects the first sub-wall and the second sub-wall, and the outer shell is stepped so that the battery cell can fit into a limited assembly space, thereby increasing the adaptability of the battery cell.

[0031] In some embodiments of the first aspect of the present application, along the first direction, a distance between the first sub-wall and the second sub-wall is L, satisfying: 0.2 mm ≤ L ≤ 5 mm.

[0032] In one or more of the above optional embodiments, the distance between the first sub-wall and the second sub-wall along the first direction is greater than or equal to 0.2mm, so that there is enough space between the first sub-wall and the second electrode sheet group. In the process of electrode sheet stacking, it is beneficial for the first electrode sheet group to include at least one group of positive electrode sheets and negative electrode sheets, reducing the risk of energy density loss caused by a large gap between the first electrode sheet group and the first sub-wall, so that the first electrode sheet group can make full use of the space between the first sub-wall and the second electrode sheet group, so that the battery cell has a higher energy density. The distance between the first sub-wall and the second sub-wall along the first direction is less than or equal to 5mm, and the battery cell has a lower risk of damage when it is impacted or vibrated, and the overall structural stability of the battery cell is higher. Therefore, setting the distance between the first sub-wall and the second sub-wall along the first direction within a reasonable range is beneficial for the battery cell to have both a higher energy density and a higher structural stability.

[0033] In some embodiments of the first aspect of the present application, 0.2 mm ≤ L ≤ 1.5 mm.

[0034] In one or more of the above optional embodiments, the distance between the first sub-wall and the second sub-wall along the first direction is greater than or equal to 0.2mm, so that there is enough space between the first sub-wall and the second electrode sheet group. In the process of electrode sheet stacking, it is beneficial for the first electrode sheet group to include at least one group of positive electrode sheets and negative electrode sheets, reducing the risk of energy density loss caused by a large gap between the first electrode sheet group and the first sub-wall, so that the first electrode sheet group can make full use of the space between the first sub-wall and the second electrode sheet group, so that the battery cell has a higher energy density. The distance between the first sub-wall and the second sub-wall along the first direction is less than or equal to 1.5mm, which can further reduce the risk of damage to the battery cell when it is impacted or vibrated, and further improve the overall structural stability of the battery cell. Therefore, setting the distance between the first sub-wall and the second sub-wall along the first direction within a reasonable range is beneficial for the battery cell to have a higher energy density while further improving the overall structural stability of the battery cell.

[0035] 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

[0036] 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.

[0037] Figure 1 A schematic diagram of the structure of a battery cell provided in some embodiments of the present application;

[0038] Figure 2 A cross-sectional view of an electrode assembly provided in some embodiments of the present application;

[0039] Figure 3 for Figure 2 A partial enlarged view of the middle A;

[0040] Figure 4 A cross-sectional view of an electrode assembly provided in some other embodiments of the present application;

[0041] Figure 5 for Figure 4 A partial enlarged view of point B in the middle;

[0042] Figure 6 A cross-sectional view of an electrode assembly provided in some further embodiments of the present application;

[0043] Figure 7 for Figure 6 A partial enlarged view of point C in the middle;

[0044] Figure 8 A cross-sectional view of an electrode assembly provided for some other embodiments of the present application;

[0045] Fig. 9 for Figure 8 A partial enlarged view of point D in the middle;

[0046] Fig.10 A cross-sectional view of a battery cell provided in some embodiments of the present application.

[0047] The reference numerals in the specific implementation manner are as follows:

[0048] 100-battery cell; 10-electrode assembly; 1-first electrode plate group; 11-first positive electrode plate; 110-first outer electrode plate; 12-first negative electrode plate; 2-second electrode plate group; 21-second positive electrode plate; 210-second outer electrode plate; 22-second negative electrode plate; 101-second end electrode plate; 301-first region; 302-second region; 20-housing; 201-first wall; 2011-first sub-wall; 2012-second sub-wall; 2013-first connecting wall; 202-second wall; X-first direction; Y-second direction. DETAILED DESCRIPTION

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] The battery cell generally includes a shell and an electrode assembly, and the electrode assembly is accommodated in the shell. 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. The volume and shape of the shell are generally determined according to the assembly environment of the battery cell. When the volume and shape of the shell are determined, during the stacking of the electrode assembly, when the remaining space of the shell is not enough to arrange a set of positive pole pieces and negative pole pieces, there will be a too large gap between the electrode assembly and the shell, resulting in a loss of energy density of the battery cell. For some electrical equipment with limited and complex space, in order to avoid interference between the battery cell and the wall of the battery compartment of the electrical equipment or other components, the shape of the shell is designed to be irregular, such as a step shape. At this time, if pole pieces of the same specification are still stacked at one time to form an electrode assembly, the risk of excessive loss of energy density of the battery cell due to excessive gap between the electrode assembly and the shell will be significantly increased.

[0055] 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, the battery cell includes a shell and an electrode assembly, the electrode assembly is accommodated in the shell, 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 arranged along a first direction, along the second direction, the length of the second electrode sheet group is greater than the length of the first electrode sheet group, and the second direction is perpendicular to the first direction; the first electrode sheet group includes a first positive electrode sheet and a first negative electrode sheet stacked along the first direction, and the second electrode sheet group It includes a second positive electrode sheet and a second negative electrode sheet stacked along a first direction; the first positive electrode sheet includes a first positive electrode collector, the first negative electrode sheet includes a first negative electrode collector, the second positive electrode sheet includes a second positive electrode collector, the second negative electrode sheet includes a second negative electrode collector, and the first positive electrode collector, the first negative electrode collector, the second positive electrode collector, and the second negative electrode collector are all provided with active material layers on both surfaces along the first direction; wherein the thickness of the first positive electrode sheet is different from the thickness of the second positive electrode sheet, and the thickness of the first negative electrode sheet is different from the thickness of the second negative electrode sheet. On the one hand, when producing battery cells, the space in the battery compartment limits the outline and volume of the shell, and the stepped battery includes a first electrode group and a second electrode group. The sizes of the two electrode groups are different. If the electrodes of the same thickness are used, it may not be possible to fill one of the shells. Therefore, the electrode thicknesses in the first electrode group and the second electrode group are different, and electrode assemblies of different sizes can be arranged based on the shell, so that the electrode assembly can fully utilize the internal space of the shell, and reduce the risk of energy density loss due to excessive gaps between the electrode assembly and the shell due to the lack of sufficient remaining space in the shell to arrange a group of positive and negative electrodes during the electrode stacking process due to the consistent specifications of each electrode. This is conducive to improving the energy density of the battery cell. On the other hand, in order to realize the assembly of the battery cell and the battery compartment of the electrical equipment, the battery cell will be designed as a special-shaped battery cell. At this time, the first electrode group and the second electrode group may be arranged along the first direction, and in the second direction, the length of the second electrode group is designed to be greater than the length of the first electrode group. This arrangement is due to the fact that the space in the battery compartment limits the outline and volume of the outer shell, so two battery cells need to be arranged. At this time, the volume of the outer shell is constant. Designing the thickness of the pole pieces in the first pole piece group and the second pole piece group to different values ​​can make the battery cell have a higher energy density while adapting to different assembly environments, thereby improving the compatibility of the battery cell with electrical equipment. On the other hand, since thicker pole pieces are conducive to improving the energy density of the battery cell, thinner pole pieces are conducive to improving the charge and discharge rate of the battery cell. Designing the thickness of the pole pieces in the first pole piece group and the second pole piece group to different values ​​can balance the relationship between the charge and discharge rate and the energy density according to demand, so that the battery cell is suitable for electrical equipment with different needs.

[0056] In the present application, the thickness of the first positive electrode sheet is different from the thickness of the second positive electrode sheet, which means that the thickness of any first positive electrode sheet is different from the thickness of any second positive electrode sheet; the thickness of the first negative electrode sheet is different from the thickness of the second negative electrode sheet, which means that the thickness of any first negative electrode sheet is different from the thickness of any second negative electrode sheet.

[0057] 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, mobile terminals and other electrical equipment. The battery cell formed by the electrode sheet having the working conditions of the present application can also be used as the power supply system of the electrical equipment.

[0058] like Figure 1-Figure 9 As shown, an embodiment of the present application provides a battery cell 100 , which includes a housing 20 and an electrode assembly 10 , wherein the electrode assembly 10 is accommodated in the housing 20 .

[0059] The shell 20 may be a hard shell, for example, the shell 20 may be a stainless steel shell or an aluminum hard shell, forming a steel shell battery or an aluminum shell battery.

[0060] The outer shell 20 may also be formed of a relatively soft material, for example, the outer shell 20 is an aluminum-plastic film or a steel-plastic film, forming a soft-pack battery cell 100 .

[0061] The electrode assembly 10 is a laminated structure. The electrode assembly 10 includes a first electrode group 1 and a second electrode group 2, the first electrode group 1 and the second electrode group 2 are arranged along a first direction X, along a second direction Y, the length of the second electrode group 2 is greater than the length of the first electrode group 1, and the second direction Y is perpendicular to the first direction X.

[0062] In some embodiments, the first direction X is the stacking direction of the laminated battery core 100 . In some other embodiments, the first direction X is the thickness direction of the laminated battery core 100 .

[0063] The first pole piece group 1 includes a plurality of pole pieces stacked along a first direction X. Two adjacent pole pieces in the first pole piece group 1 have opposite polarities, that is, one of the two adjacent pole pieces in the first pole piece group 1 is a positive pole piece and the other is a negative pole piece. An isolation film is provided between two adjacent pole pieces in the first pole piece group 1, and the isolation film is used for insulating and separating two adjacent pole pieces in the first pole piece group 1 with opposite polarities.

[0064] In some embodiments, the first pole piece group 1 includes a first outer pole piece 110 farthest from the second pole piece group 2. The first outer pole piece 110 may 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 a capacity role and improve the energy density of the battery cell 100. Of course, the first outer pole piece 110 may also be a pole piece coated with active material on both sides. The first outer pole piece 110 may be a positive pole piece or a negative pole piece.

[0065] The second pole piece group 2 includes a plurality of pole pieces stacked along the first direction X. Two adjacent pole pieces in the second pole piece group 2 have opposite polarities, that is, one of the two adjacent pole pieces in the second pole piece group 2 is a positive pole piece and the other is a negative pole piece. An isolation film is provided between the two adjacent pole pieces in the second pole piece group 2, and the isolation film is used for insulating and separating the two adjacent pole pieces in the second pole piece group 2 with opposite polarities.

[0066] In some embodiments, the second pole piece group 2 includes a second outer pole piece 210 farthest from the first pole piece group 1. The second outer pole piece 210 may 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 a capacity role and improve the energy density of the battery cell 100. Of course, the second outer pole piece 210 may also be a pole piece coated with active material on both sides. The second outer pole piece 210 may be a positive pole piece or a negative pole piece.

[0067] The first pole piece group 1 and the second pole piece group 2 are insulated and separated by an isolation film.

[0068] The isolation film insulates and separates two pole pieces with opposite polarities, thereby reducing the risk of short circuit of the battery cell 100. The isolation film may be made of PP (polypropylene) or PE (polyethylene).

[0069] The number of pole pieces in the first pole piece group 1 may be the same as or different from the number of pole pieces in the second pole piece group 2 .

[0070] The electrode assembly 10 includes a positive electrode sheet and a negative electrode sheet. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer arranged on the surface of the positive electrode collector. The negative electrode sheet includes a negative electrode collector and a negative electrode active material layer arranged on the surface of the negative electrode collector. The thickness of the positive electrode active material layer of at least two positive electrode sheets in the electrode assembly 10 is different, and / or the thickness of the negative electrode active material layer of at least two negative electrode sheets in the electrode assembly 10 is different.

[0071] 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.

[0072] The first positive electrode collector, the first negative electrode collector, the second positive electrode collector, and the second negative electrode collector are all provided with active material layers on both surfaces along the first direction X; wherein the thickness of the first positive electrode sheet 11 is different from the thickness of the second positive electrode sheet 21, and the thickness of the first negative electrode sheet 12 is different from the thickness of the second negative electrode sheet 22. The thickness of the first positive electrode sheet 11 refers to the sum of the thickness of the first positive electrode collector and the thickness of the two active material layers, the thickness of the first negative electrode sheet 12 refers to the sum of the thickness of the first negative electrode collector and the thickness of the two active material layers, the thickness of the second positive electrode sheet 21 refers to the sum of the thickness of the second positive electrode collector and the thickness of the two active material layers, and the thickness of the second negative electrode sheet 22 refers to the sum of the thickness of the second negative electrode collector and the thickness of the two active material layers. wherein the thickness of the first positive electrode collector, the first negative electrode collector, the second positive electrode collector, and the second negative electrode collector may be the same or different.

[0073] In one or more of the above optional embodiments, on the one hand, when producing the battery cell 100, since the thickness of at least two pole pieces in the electrode assembly 10 is different, the electrode assemblies 10 of different sizes can be arranged based on the shell 20, so that the electrode assembly 10 can fully utilize the internal space of the shell 20, and reduce the risk of energy density loss due to excessive gap between the electrode assembly 10 and the shell 20 due to the fact that the specifications of each pole piece are consistent and the remaining space of the shell 20 is insufficient to arrange a group of positive pole pieces and negative pole pieces during the pole piece stacking process, thereby helping to improve the energy density of the battery cell 100. On the other hand, in order to realize the assembly of the battery cell 100 with the battery compartment of the electrical equipment, the battery cell 100 will be designed as a special-shaped battery cell 100, at which time the first pole piece group 1 and the second pole piece group 2 may be arranged along the first direction X, and in the second direction Y, the length of the second pole piece group 2 is designed to be greater than the length of the first pole piece group 1. This arrangement is due to the fact that the space in the battery compartment limits the outline and volume of the outer shell 20, so two battery cells 100 need to be arranged. At this time, the volume of the outer shell 20 is constant. Designing the thickness of the pole pieces in the first pole piece group 1 and the second pole piece group 2 to different values ​​can make the battery cell 100 have a higher energy density while adapting to different assembly environments, thereby improving the compatibility of the battery cell with electrical equipment. On the other hand, since thicker pole pieces are conducive to improving the energy density of the battery cell 100, thinner pole pieces are conducive to improving the charge and discharge rate of the battery cell 100. Designing the thickness of the pole pieces in the first pole piece group 1 and the second pole piece group 2 to different values ​​can balance the relationship between the charge and discharge rate and the energy density according to demand, so that the battery cell 100 is suitable for electrical equipment with different needs.

[0074] like Figure 2-Figure 5As shown, the thickness of the first positive electrode sheet 11 is less than the thickness of the second positive electrode sheet 21, and the thickness of the first negative electrode sheet 12 is less than the thickness of the second negative electrode sheet 22. The thickness of the first positive electrode sheet 11 is less than the thickness of the second positive electrode sheet 21, which means that the thickness of any first positive electrode sheet 11 is less than the thickness of any second positive electrode sheet 21.

[0075] The thickness of the first negative electrode sheet 12 is smaller than the thickness of the second negative electrode sheet 22 , which means that the thickness of any one of the first negative electrode sheets 12 is smaller than the thickness of any one of the second negative electrode sheets.

[0076] Since the length of the second electrode set 2 is greater than that of the first electrode set 1 along the second direction Y, the electrode in the second electrode set 2 can be coated with a larger area of ​​active material, and the electrode of the second electrode set 2 with fewer layers can be stacked to achieve the effect of the second electrode set 2 having a higher energy density, thereby reducing the risk of the second electrode set 2 containing too many current collectors and losing energy density due to the excessive number of stacked layers of electrode in the second electrode set 2. That is, the space in the battery cell 100 is used as much as possible by the active material layer, while reducing the space occupied by the current collector.

[0077] In one or more optional embodiments above, the thickness of the first positive electrode sheet 11 is less than the thickness of the second positive electrode sheet 21, and the thickness of the first negative electrode sheet 12 is less than the thickness of the second negative electrode sheet 22. Such a design can enable the first electrode sheet group 1 to have a higher charge and discharge rate, and the second electrode sheet group 2 to have a higher energy density, so that the battery cell 100 has both a higher charge and discharge rate and a higher energy density.

[0078] like Figure 2-Figure 5 As shown, the first pole piece group 1 also includes a first outer pole piece 110 farthest from the second pole piece group 2, the first outer pole piece 110 includes a first outer current collector, and the first outer current collector is provided with an active material layer only on the side facing the second pole piece group 2; the second pole piece group 2 also includes a second outer pole piece 210 farthest from the first pole piece group 1, the second outer pole piece 210 includes a second outer current collector, and the second outer current collector is provided with an active material layer only on the side facing the first pole piece group 1; the first outer pole piece 110 and the second outer pole piece 210 have the same polarity; the thickness of the first outer pole piece 110 is less than the thickness of the second outer pole piece 210.

[0079] The first outer pole piece 110 can be a positive pole piece or a negative pole piece. The second outer pole piece 210 can be a positive pole piece or a negative pole piece. The polarity of the first outer pole piece 110 is opposite to the polarity of the pole piece closest to the side facing the second pole piece group 2. The polarity of the second outer pole piece 210 is opposite to the polarity of the pole piece closest to the side facing the first pole piece group 1. In some embodiments, Figure 5As shown, the first outer pole piece 110 and the second outer pole piece 210 are both positive pole pieces, and the thickness of the first outer pole piece 110 is less than the thickness of the second outer pole piece 210 .

[0080] In one or more optional embodiments above, since the first outer current collector is provided with an active material layer only on the side facing the second electrode sheet group 2, and the second outer current collector is provided with an active material layer only on the side facing the first electrode sheet group 1, that is, the first outer current collector and the second current collector are provided with an active material layer only on the side where they exert their capacity, which is conducive to making the battery cell 100 have a higher energy density. The thickness of the first outer electrode sheet 110 is less than the thickness of the second outer electrode sheet 210. Suitable first outer electrode sheets 110 and second outer electrode sheets 210 can be selected to make the first electrode sheet group 1 and the second electrode sheet group 2 fully utilize the internal space of the shell 20, further improving the energy density of the battery cell 100. At the same time, since the thickness of the first positive electrode sheet 11 is less than the thickness of the second positive electrode sheet 21, and the thickness of the first negative electrode sheet 12 is less than the thickness of the second negative electrode sheet 22, setting the thickness of the first outer electrode sheet 110 to be less than the thickness of the second outer electrode sheet 210 is conducive to the synchronous design and processing of all the electrodes in the first electrode sheet group 1 and the synchronous processing of all the electrodes in the second electrode sheet group 2.

[0081] like Figure 2-Figure 5 As shown, the thickness of the first positive electrode plate 11 is greater than the thickness of the second positive electrode plate 21 , and the thickness of the first negative electrode plate 12 is greater than the thickness of the second negative electrode plate 22 .

[0082] Since the length of the second electrode group 2 along the second direction Y is greater than that of the first electrode group 1, the electrode in the second electrode group 2 can be coated with a larger area of ​​active material, so that during the charging process of the battery cell 100, the battery cell 100 can have a relatively large energy storage capacity in a shorter time.

[0083] In one or more optional embodiments above, the thickness of the first positive electrode sheet 11 is greater than the thickness of the second positive electrode sheet 21, and the thickness of the first negative electrode sheet 12 is greater than the thickness of the second negative electrode sheet 22. Such a design can make the first electrode sheet group 1 have a higher energy density, and the second electrode sheet group 2 have a higher charge and discharge rate, so that the battery cell 100 has both a higher charge and discharge rate and a higher energy density.

[0084] like Figure 6-Figure 9As shown, the first pole piece group 1 also includes a first outer pole piece 110 farthest from the second pole piece group 2, the first outer pole piece 110 includes a first outer current collector, and the first outer current collector is provided with an active material layer only on the side facing the second pole piece group 2; the second pole piece group 2 also includes a second outer pole piece 210 farthest from the first pole piece group 1, the second outer pole piece 210 includes a second outer current collector, and the second outer current collector is provided with an active material layer only on the side facing the first pole piece group 1; the first outer pole piece 110 and the second outer pole piece 210 have the same polarity; the thickness of the first outer pole piece 110 is greater than the thickness of the second outer pole piece 210.

[0085] The first outer pole piece 110 can be a positive pole piece or a negative pole piece. The second outer pole piece 210 can be a positive pole piece or a negative pole piece. The polarity of the first outer pole piece 110 is opposite to the polarity of the pole piece closest to the side facing the second pole piece group 2. The polarity of the second outer pole piece 210 is opposite to the polarity of the pole piece closest to the side facing the first pole piece group 1. In some embodiments, Fig. 9 As shown, the first outer pole piece 110 and the second outer pole piece 210 are both positive pole pieces, and the thickness of the first outer pole piece 110 is greater than the thickness of the second outer pole piece 210 .

[0086] In one or more optional embodiments above, since the first outer current collector is provided with an active material layer only on the side facing the second electrode sheet group 2, and the second outer current collector is provided with an active material layer only on the side facing the first electrode sheet group 1, that is, the first outer current collector and the second current collector are provided with an active material layer only on the side where they exert their capacity, which is conducive to making the battery cell 100 have a higher energy density. The thickness of the first outer electrode sheet 110 is greater than the thickness of the second outer electrode sheet 210. The first outer electrode sheet 110 and the second outer electrode sheet 210 can be selected appropriately so that the first electrode sheet group 1 and the second electrode sheet group 2 can fully utilize the internal space of the shell 20, further improving the energy density of the battery cell 100. At the same time, since the thickness of the first positive electrode sheet 11 is greater than the thickness of the second positive electrode sheet 21, and the thickness of the first negative electrode sheet 12 is greater than the thickness of the second negative electrode sheet 22, setting the thickness of the first outer electrode sheet 110 to be greater than the thickness of the second outer electrode sheet 210 is conducive to the synchronous design and processing of all the electrodes in the first electrode sheet group 1 and the synchronous processing of all the electrodes in the second electrode sheet group 2.

[0087] like Figure 1-Figure 9 As shown, the thickness of the first positive electrode sheet 11 is D1, the thickness of the first negative electrode sheet 12 is D2, the thickness of the second positive electrode sheet 21 is D3, and the thickness of the second negative electrode sheet 22 is D4; satisfying: 0<|D3-D1|≤180μm, 0<|D4-D2|≤180μm.

[0088] The thickness of the first negative electrode sheet 12 may be greater than or less than the thickness of the second negative electrode sheet 22, and the thickness of the first positive electrode sheet 11 may be greater than or less than the thickness of the second positive electrode sheet 21. For example, please refer to Figure 3 and Figure 5 , the thickness of the first negative electrode sheet 12 is less than the thickness of the second negative electrode sheet 22, and the thickness of the first positive electrode sheet 11 is less than the thickness of the second positive electrode sheet 21. For example, please refer to Figure 7 and Fig. 9 , the thickness of the first negative electrode plate 12 is greater than the thickness of the second negative electrode plate 22 , and the thickness of the first positive electrode plate 11 is greater than the thickness of the second positive electrode plate 21 .

[0089] The thickness of the first negative electrode sheet 12 is greater than the thickness of the second negative electrode sheet 22, which means that the thickness of any one of the first negative electrode sheets 12 is greater than the thickness of any one of the second negative electrode sheets 22; the thickness of the first positive electrode sheet 11 is greater than the thickness of the second positive electrode sheet 21, which means that the thickness of any one of the first positive electrode sheets 11 is greater than the thickness of any one of the second positive electrode sheets 21.

[0090] The absolute value of the difference between the thickness of the second positive electrode plate 21 and the thickness of the first positive electrode plate 11 can be any value greater than 0 and less than or equal to 180μm, for example, 1μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, 155μm, 160μm, 165μm, 170μm, 175μm, 180μm, etc.

[0091] The absolute value of the difference between the thickness of the second negative electrode plate 22 and the thickness of the first negative electrode plate 12 can be any value greater than 0 and less than or equal to 180μm, for example, 1μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, 155μm, 160μm, 165μm, 170μm, 175μm, 180μm, etc.

[0092] In one or more of the above optional embodiments, the absolute value of the difference between the thickness of the second positive electrode sheet 21 and the thickness of the first positive electrode sheet 11, and the absolute value of the difference between the thickness of the second negative electrode sheet 22 and the thickness of the first negative electrode sheet 12 are designed to be within a reasonable range, which is beneficial for making the battery cell 100 have a higher energy density during the process of stacking the electrodes while making the migration distance of the lithium ions in the first electrode sheet group 1 and the second electrode sheet group 2 similar, so that when the input current of the battery cell 100 is constant, the difficulty of activating the lithium ions in the first electrode sheet group 1 and the lithium ions in the second electrode sheet group 2 is similar, thereby reducing the risk that during the use of the battery cell 100, one of the first electrode sheet group 1 and the second electrode sheet group 2 is not fully utilized, resulting in the available capacity of the battery cell 100 being less than the designed capacity.

[0093] like Figure 2-Figure 5 As shown, the thickness of the first positive electrode sheet 11 is D1, the thickness of the first negative electrode sheet 12 is D2, the thickness of the second positive electrode sheet 21 is D3, and the thickness of the second negative electrode sheet 22 is D4; satisfying: 20μm≤D1≤200μm, 20μm≤D2≤200μm, 20μm≤D3≤200μm, 20μm≤D4≤200μm.

[0094] The thickness of the first positive electrode plate 11 can be any value greater than or equal to 20μm and less than or equal to 200μm, for example, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, 155μm, 160μm, 165μm, 170μm, 175μm, 180μm, 185μm, 190μm, 195μm, 200μm, etc.

[0095] The thickness of the first negative electrode plate 12 can be any value greater than or equal to 20μm and less than or equal to 200μm, for example, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, 155μm, 160μm, 165μm, 170μm, 175μm, 180μm, 185μm, 190μm, 195μm, 200μm, etc.

[0096] The thickness of the second positive electrode plate 21 can be any value greater than or equal to 20μm and less than or equal to 200μm, for example, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, 155μm, 160μm, 165μm, 170μm, 175μm, 180μm, 185μm, 190μm, 195μm, 200μm, etc.

[0097] The thickness of the second negative electrode plate 22 can be any value greater than or equal to 20μm and less than or equal to 200μm, for example, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, 105μm, 110μm, 115μm, 120μm, 125μm, 130μm, 135μm, 140μm, 145μm, 150μm, 155μm, 160μm, 165μm, 170μm, 175μm, 180μm, 185μm, 190μm, 195μm, 200μm, etc.

[0098] In one or more of the above optional embodiments, the thickness of the electrode sheet is greater than or equal to 20 μm, which is beneficial for the battery cell 100 to have a higher energy density. The thickness of the electrode sheet is less than or equal to 200 μm, which is beneficial for the lithium ions in the battery cell 100 to have a shorter migration distance, thereby improving the charge and discharge rate of the battery cell 100. Therefore, setting the thickness of the electrode sheet within a reasonable range is beneficial for the battery cell 100 to have both a higher energy density and a higher charge and discharge rate.

[0099] like Figure 5 and Fig. 9 The thickness of the first outer pole piece 110 is D5, and the thickness of the second outer pole piece 210 is D6, satisfying: 0<|D6-D5|≤90μm.

[0100] The absolute value of the difference between the thickness of the second outer pole piece 210 and the thickness of the first outer pole piece 110 can be any value greater than 0 and less than or equal to 90μm, for example, 1μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, etc.

[0101] In one or more of the above optional embodiments, the absolute value of the difference between the thickness of the second outer pole sheet 210 and the thickness of the first outer pole sheet 110 is designed to be within a reasonable range, which is beneficial for making the battery cell 100 have a higher energy density during the process of stacking the pole sheets, while making the migration distances of lithium ions in the first pole sheet group 1 and the second pole sheet group 2 similar, so that when the input current of the battery cell 100 is constant, the difficulty of activating the lithium ions in the first pole sheet group 1 and the lithium ions in the second pole sheet group 2 is similar, thereby reducing the risk of one of the first outer pole sheet 110 and the second outer pole sheet 20 not being fully utilized during the use of the battery cell 100, resulting in the available capacity of the battery cell 100 being less than the designed capacity.

[0102] like Figure 2-Figure 5 As shown, the thickness of the first positive electrode collector is the same as the thickness of the second positive electrode collector, and the thickness of the first negative electrode collector is the same as the thickness of the second negative electrode collector.

[0103] The thickness of the current collector needs to take into account the processing tolerance. For example, when the thickness of two current collectors is between ±3 μm, the thickness of the two current collectors can be considered to be the same.

[0104] In one or more optional embodiments above, the thickness of the first positive electrode current collector is the same as the thickness of the second positive electrode current collector, and the thickness of the first negative electrode current collector is the same as the thickness of the second negative electrode current collector. On the one hand, the current can be distributed more evenly in the battery cell 100, thereby improving the cycle life of the battery cell 100. On the other hand, when designing and processing pole pieces of different thicknesses, it is only necessary to change the surface density of the active material layer of the current collector, thereby reducing the processing difficulty of the battery cell 100.

[0105] like Figure 2-Figure 5 As shown, the electrode assembly 10 satisfies one of the following conditions: the surface density of the active material layer of the first positive electrode plate 11 is 100 mg / mm 2 ~350mg / mm 2 The surface density of the active material layer of the first negative electrode plate 12 is 50 mg / mm 2 ~150mg / mm 2 The surface density of the active material layer of the second positive electrode plate 21 is 100 mg / mm 2 ~350mg / mm 2 The surface density of the active material layer of the second negative electrode plate 22 is 50 mg / mm 2 ~150mg / mm 2 .

[0106] The surface density of the active material layer of the first positive electrode plate 11 can be greater than or equal to 100 mg / mm 2 Less than or equal to 350mg / mm 2Any value between, for example, 100 mg / mm 2 , 105mg / mm 2 , 110mg / mm 2 、115mg / mm 2 、120mg / mm 2 , 125mg / mm 2 、130mg / mm 2 、135mg / mm 2 、140mg / mm 2 , 145mg / mm 2 、150mg / mm 2 、155mg / mm 2 、160mg / mm 2 、165mg / mm 2 、170mg / mm 2 、175mg / mm 2 、180mg / mm 2 、185mg / mm 2 、190mg / mm 2 、195mg / mm 2 , 200mg / mm 2 , 205mg / mm 2 , 210mg / mm 2 , 215mg / mm 2 , 220mg / mm 2 , 225mg / mm 2 、230mg / mm 2 , 235mg / mm 2 , 240mg / mm 2 , 245mg / mm 2 , 250mg / mm 2 , 255mg / mm 2 、260mg / mm 2 、265mg / mm 2 、270mg / mm 2 , 275mg / mm 2 、280mg / mm 2 、285mg / mm 2 、290mg / mm 2 、295mg / mm 2 、300mg / mm 2 、305mg / mm 2 、310mg / mm 2 、315mg / mm 2 、320mg / mm 2、325mg / mm 2 、330mg / mm 2 、335mg / mm 2 、340mg / mm 2 、345mg / mm 2 、350mg / mm 2 wait.

[0107] The surface density of the active material layer of the first negative electrode plate 12 may be greater than or equal to 50 mg / mm 2 Less than or equal to 150mg / mm 2 Any value between, for example, 50mg / mm 2 , 55mg / mm 2 、60mg / mm 2 、65mg / mm 2 、70mg / mm 2 、75mg / mm 2 、80mg / mm 2 、85mg / mm 2 、90mg / mm 2 , 95mg / mm 2 , 100mg / mm 2 , 105mg / mm 2 、110mg / mm 2 、115mg / mm 2 、120mg / mm 2 , 125mg / mm 2 、130mg / mm 2 、135mg / mm 2 、140mg / mm 2 、145mg / mm 2 、150mg / mm 2 wait.

[0108] The surface density of the active material layer of the second positive electrode plate 21 can be greater than or equal to 100 mg / mm 2 Less than or equal to 350mg / mm 2 Any value between, for example, 100 mg / mm 2 , 105mg / mm 2 、110mg / mm 2 、115mg / mm 2 、120mg / mm 2 , 125mg / mm 2 、130mg / mm 2 、135mg / mm 2 、140mg / mm 2、145mg / mm 2 、150mg / mm 2 、155mg / mm 2 、160mg / mm 2 、165mg / mm 2 、170mg / mm 2 、175mg / mm 2 、180mg / mm 2 、185mg / mm 2 、190mg / mm 2 、195mg / mm 2 , 200mg / mm 2 , 205mg / mm 2 , 210mg / mm 2 , 215mg / mm 2 , 220mg / mm 2 , 225mg / mm 2 、230mg / mm 2 , 235mg / mm 2 , 240mg / mm 2 , 245mg / mm 2 , 250mg / mm 2 , 255mg / mm 2 、260mg / mm 2 、265mg / mm 2 、270mg / mm 2 , 275mg / mm 2 、280mg / mm 2 、285mg / mm 2 、290mg / mm 2 、295mg / mm 2 、300mg / mm 2 、305mg / mm 2 、310mg / mm 2 、315mg / mm 2 、320mg / mm 2 、325mg / mm 2 、330mg / mm 2 、335mg / mm 2 、340mg / mm 2 、345mg / mm 2 、350mg / mm 2 wait.

[0109] The surface density of the active material layer of the second negative electrode plate 22 may be greater than or equal to 50 mg / mm 2Less than or equal to 150mg / mm 2 Any value between, for example, 50mg / mm 2 , 55mg / mm 2 、60mg / mm 2 、65mg / mm 2 、70mg / mm 2 、75mg / mm 2 、80mg / mm 2 、85mg / mm 2 、90mg / mm 2 , 95mg / mm 2 , 100mg / mm 2 , 105mg / mm 2 、110mg / mm 2 、115mg / mm 2 、120mg / mm 2 , 125mg / mm 2 、130mg / mm 2 、135mg / mm 2 、140mg / mm 2 、145mg / mm 2 、150mg / mm 2 wait.

[0110] In one or more of the above optional embodiments, when the surface density of the active material layer of the positive electrode sheet is greater than or equal to 100 mg / mm 2 When the thickness of the active material layer of the positive electrode sheet is large, the energy density of the battery cell 100 is large. When the surface density of the active material layer of the positive electrode sheet is less than or equal to 350 mg / mm 2 When the surface density of the active material layer of the positive electrode sheet is set within a reasonable range, it is beneficial for the battery cell 100 to have both a higher energy density and a higher charge and discharge rate.

[0111] When the surface density of the active material layer of the negative electrode is greater than or equal to 100 mg / mm 2 When the surface density of the active material layer of the negative electrode sheet is less than or equal to 350 mg / mm 2 When the surface density of the active material layer of the negative electrode sheet is set within a reasonable range, it is beneficial for the battery cell 100 to have both a higher energy density and a higher charge and discharge rate.

[0112] like Figure 3 and Figure 7 , the electrode sheet closest to the first electrode sheet group 1 in the second electrode sheet group 2 is the second end electrode sheet 101, and the second end electrode sheet 101 includes a first region 301 overlapping with the first electrode sheet group 1 and a second region 302 not overlapping with the first electrode sheet group 1. Along the first direction X, both sides of the first region 301 are provided with active material layers, and the second region 302 is provided with an active material layer only on the side away from the first electrode sheet group 1.

[0113] The second end electrode sheet 101 may be a positive electrode sheet or a negative electrode sheet.

[0114] In some embodiments, the current collector of the second end pole piece 101 includes a first metal layer, an insulating separator layer, and a second metal layer, wherein the first metal layer is disposed on the side of the insulating separator layer facing the first pole piece group 1, and the second metal layer is disposed on the side of the insulating separator layer facing away from the first pole piece group 1. With such a configuration, in the process of stacking pole pieces, the sum of the thickness of the first metal layer and the active material on the side thereof facing the first pole piece group 1, and the sum of the thickness of the second metal layer and the active material on the side thereof facing the second pole piece group 2 can be flexibly designed, thereby enabling the second end pole piece 101 to flexibly adapt to the variable cross-section position of the special-shaped battery cell 100, reducing the risk of an excessively large gap between the electrode assembly 10 and the variable cross-section position, making full use of the internal space of the special-shaped battery cell 100, and reducing energy density loss.

[0115] In some embodiments, Fig.10 As shown, the housing 20 includes a first wall 201 and a second wall 202 that are arranged opposite to each other along a first direction X, the first wall 201 includes a first sub-wall 2011, a second sub-wall 2012, and a first connecting wall 2013, in a direction away from the second wall 202, the first sub-wall 2011 protrudes from the second sub-wall 2012, and the first connecting wall 2013 connects the first sub-wall 2011 and the second sub-wall 2012. A portion of the second pole piece group 2 is located between the second sub-wall 2012 and the second wall 202, and the first pole piece group 1 is located between the second pole piece group 2 and the first sub-wall 2011. The first sub-wall 2011, the second wall 202, and the first connecting wall 2013 jointly define a first accommodating cavity, and the first pole piece group 1 is located in the first accommodating cavity. The second sub-wall 2012 and the second wall 202 jointly define a second accommodating cavity, and a portion of the second pole piece group 2 is located in the second accommodating cavity. In this embodiment, the active material in the first region 301 close to the first electrode assembly 1 can be located in the first accommodation cavity or in the second accommodation cavity.

[0116] In one or more optional embodiments above, the size of the second electrode set 2 in the second direction Y is greater than the size of the first electrode set 1 in the second direction Y, the second electrode set 2 includes a second end electrode 101 closest to the first electrode set 1, and the second end electrode 101 includes a first region 301 overlapping with the first electrode set 1 and a second region 302 not overlapping with the first electrode set 1. Along the first direction X, both sides of the first region 301 are provided with active material layers, and the second region 302 is provided with an active material layer only on the side away from the first electrode set 1. On the one hand, active material layers are provided on both sides of the first region 301. The active material layer on the side of the first region 301 facing the first electrode group 1 can serve as an outermost electrode of the first electrode group 1, which is equivalent to an outermost electrode of the first electrode group 1 and an outermost electrode of the second electrode group 2 sharing a current collector. Compared with the solution in which the current collector of an outermost electrode of the second electrode group 2 coated with an active material layer on one side is bonded to the current collector of an outermost electrode of the first electrode group 1 coated with an active material layer on one side 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 single-sided electrode sheet coated with an active material layer of the second electrode sheet group 2 is bonded to the current collector of the outermost single-sided electrode sheet coated with an active material layer of the first electrode sheet group 1 through an adhesive layer, this scheme reduces the number of electrode sheets coated with an active material layer on one side in the battery cell 100 by setting a second end electrode sheet 101, thereby reducing the number of current collectors 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 problem 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 single-sided pole piece is relatively large, which will also cause the energy density loss of the battery cell 100. The active material layer is arranged on both sides of the current collector of the second end pole piece 101 in the battery cell 100 of this solution. The active material layers on both sides of the current collector of the second end pole piece 101 can offset the effect of stress, and the risk of warping and curling of the second end pole piece 101 is low. It also makes the thickness of the current collector of the second end pole piece 101 smaller than that of the pole piece coated with an active material layer on one side, further reducing the energy density loss of the battery cell 100 in the first direction X. On the other hand, the second region 302 of the current collector of the second end pole piece 101 is only arranged with an active material layer on the side away from the first pole piece group 1, reducing the active material that does not play the capacity and avoiding the active material that does not play the capacity occupying space, 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 plate of the second electrode group 2 which is closest to the first electrode group 1 and the single-sided coated electrode plate of the first electrode group 1 which is closest to the second electrode group 2 and is coated with an active material layer on one side are bonded together through an adhesive layer, the battery cell 100 of this scheme has a higher energy density.

[0117] like Fig.10 As shown, the housing 20 includes a first wall 201 and a second wall 202 that are arranged opposite to each other along a first direction X, the first wall 201 includes a first sub-wall 2011, a second sub-wall 2012, and a first connecting wall 2013, the first sub-wall 2011 protrudes from the second sub-wall 2012 in a direction away from the second wall 202, and the first connecting wall 2013 connects the first sub-wall 2011 and the second sub-wall 2012. A portion of the second pole piece group 2 is located between the second sub-wall 2012 and the second wall 202, and the first pole piece group 1 is located between the second pole piece group 2 and the first sub-wall 2011.

[0118] In some embodiments, a plurality of first sub-walls 2011 are provided. The housing 20 has a plurality of convex portions arranged at intervals. The wall portion of the convex portion away from the second pole piece group 2 is the first sub-wall 2011 .

[0119] In one or more of the above optional embodiments, the first sub-wall 2011 protrudes from the second sub-wall 2012, the first connecting wall 2013 connects the first sub-wall 2011 and the second sub-wall 2012, and the outer shell 20 is stepped so that the battery cell 100 can be adapted to a limited assembly space, thereby increasing the adaptability of the battery cell 100.

[0120] like Fig.10 As shown, along the first direction X, the distance between the first sub-wall 2011 and the second sub-wall 2012 is L, which satisfies: 0.2 mm≤L≤5 mm.

[0121] Along the first direction X, the distance between the first sub-wall 2011 and the second sub-wall 2012 can be any value greater than or equal to 0.2 mm and less than or equal to 5 mm, for example, 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4 mm, 4.2 mm, 4.4 mm, 4.6 mm, 4.8 mm, 5 mm, etc.

[0122] In one or more optional embodiments above, the distance between the first sub-wall 2011 and the second sub-wall 2012 along the first direction X is greater than or equal to 0.2 mm, so that there is enough space between the first sub-wall 2011 and the second electrode group 2. In the electrode stacking process, it is beneficial for the first electrode group 1 to include at least one group of positive electrode sheets and negative electrode sheets, and reduce the risk of energy density loss caused by a large gap between the first electrode group 1 and the first sub-wall 2011, so that the first electrode group 1 can fully utilize the space between the first sub-wall 2011 and the second electrode group 2, so that the battery cell 100 has a higher energy density. The distance between the first sub-wall 2011 and the second sub-wall 2012 along the first direction X is less than or equal to 5 mm, and the battery cell 100 has a lower risk of damage when it is impacted or vibrated, and the overall structural stability of the battery cell 100 is higher. Therefore, setting the distance between the first sub-wall 2011 and the second sub-wall 2012 along the first direction X within a reasonable range is beneficial for the battery cell 100 to have both a higher energy density and a higher structural stability.

[0123] like Fig.10 As shown, 0.2mm≤L≤1.5mm.

[0124] Along the first direction X, the distance between the first sub-wall 2011 and the second sub-wall 2012 can be any value greater than or equal to 0.2 mm and less than or equal to 1.5 mm, for example, 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 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, etc.

[0125] In one or more optional embodiments above, the distance between the first sub-wall 2011 and the second sub-wall 2012 along the first direction X is greater than or equal to 0.2 mm, so that there is enough space between the first sub-wall 2011 and the second electrode group 2. In the electrode stacking process, it is beneficial for the first electrode group 1 to include at least one group of positive electrode sheets and negative electrode sheets, reducing the risk of energy density loss caused by a large gap between the first electrode group 1 and the first sub-wall 2011, so that the first electrode group 1 can fully utilize the space between the first sub-wall 2011 and the second electrode group 2, so that the battery cell 100 has a higher energy density. The distance between the first sub-wall 2011 and the second sub-wall 2012 along the first direction X is less than or equal to 1.5 mm, which can further reduce the risk of damage to the battery cell 100 when it is impacted or vibrated, and further improve the overall structural stability of the battery cell 100. Therefore, setting the distance between the first sub-wall 2011 and the second sub-wall 2012 along the first direction X within a reasonable range is beneficial for making the battery cell 100 have a higher energy density while further improving the overall structural stability of the battery cell 100 .

[0126] An embodiment of the present application further provides an electrical device, which includes the battery cell 100 provided in any of the above embodiments.

[0127] 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 .

[0128] 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: It comprises a shell and an electrode assembly, wherein the electrode assembly is accommodated in the shell and is a laminated structure; The electrode assembly comprises a first electrode group and a second electrode group, the first electrode group and the second electrode group are arranged along a first direction, along the second direction, the length of the second electrode group is greater than the length of the first electrode group, and the second direction is perpendicular to the first direction; The first electrode sheet group includes a first positive electrode sheet and a first negative electrode sheet stacked along the first direction, and the second electrode sheet group includes a second positive electrode sheet and a second negative electrode sheet stacked along the first direction; The first positive electrode plate includes a first positive electrode collector, the first negative electrode plate includes a first negative electrode collector, the second positive electrode plate includes a second positive electrode collector, the second negative electrode plate includes a second negative electrode collector, and both surfaces of the first positive electrode collector, the first negative electrode collector, the second positive electrode collector, and the second negative electrode collector along the first direction are all provided with an active material layer; The thickness of the first positive electrode sheet is different from the thickness of the second positive electrode sheet, and the thickness of the first negative electrode sheet is different from the thickness of the second negative electrode sheet.

2. The battery cell according to claim 1, characterized in that: The thickness of the first positive electrode sheet is smaller than the thickness of the second positive electrode sheet, and the thickness of the first negative electrode sheet is smaller than the thickness of the second negative electrode sheet.

3. The battery cell according to claim 2, characterized in that: The first pole piece group further includes a first outer pole piece farthest from the second pole piece group, the first outer pole piece includes a first outer current collector, and the first outer current collector is provided with an active material layer only on a side facing the second pole piece group; The second pole piece group further includes a second outer pole piece farthest from the first pole piece group, the second outer pole piece includes a second outer current collector, and the second outer current collector is provided with an active material layer only on a side facing the first pole piece group; The first outer pole piece and the second outer pole piece have the same polarity; The thickness of the first outer pole piece is smaller than the thickness of the second outer pole piece.

4. The battery cell according to claim 1, characterized in that: The thickness of the first positive electrode sheet is greater than the thickness of the second positive electrode sheet, and the thickness of the first negative electrode sheet is greater than the thickness of the second negative electrode sheet.

5. The battery cell according to claim 4, characterized in that: The first pole piece group further includes a first outer pole piece farthest from the second pole piece group, the first outer pole piece includes a first outer current collector, and the first outer current collector is provided with an active material layer only on a side facing the second pole piece group; The second pole piece group further includes a second outer pole piece farthest from the first pole piece group, the second outer pole piece includes a second outer current collector, and the second outer current collector is provided with an active material layer only on a side facing the first pole piece group; The first outer pole piece and the second outer pole piece have the same polarity; The thickness of the first outer pole piece is greater than the thickness of the second outer pole piece.

6. The battery cell according to claim 1, characterized in that: The thickness of the first positive electrode sheet is D1, the thickness of the first negative electrode sheet is D2, the thickness of the second positive electrode sheet is D3, and the thickness of the second negative electrode sheet is D4; Satisfies: 0<|D3-D1|≤180μm, 0<|D4-D2|≤180μm.

7. The battery cell according to claim 1, characterized in that: The thickness of the first positive electrode sheet is D1, the thickness of the first negative electrode sheet is D2, the thickness of the second positive electrode sheet is D3, and the thickness of the second negative electrode sheet is D4; Satisfies: 20μm≤D1≤200μm, 20μm≤D2≤200μm, 20μm≤D3≤200μm, 20μm≤D4≤200μm.

8. The battery cell according to claim 3 or 5, characterized in that: The thickness of the first outer pole piece is D5, and the thickness of the second outer pole piece group is D6, satisfying: 0<|D6-D5|≤90μm.

9. The battery cell according to claim 1, characterized in that: The thickness of the first positive electrode collector is the same as the thickness of the second positive electrode collector, and the thickness of the first negative electrode collector is the same as the thickness of the second negative electrode collector.

10. The battery cell according to claim 1, characterized in that: The electrode assembly satisfies one of the following conditions: (1) The surface density of the active material layer of the first positive electrode sheet is 100 mg / mm 2 ~350mg / mm 2 ; (2) The surface density of the active material layer of the first negative electrode sheet is 50 mg / mm 2 ~150mg / mm 2 ; (3) The surface density of the active material layer of the second positive electrode sheet is 100 mg / mm 2 ~350mg / mm 2 ; (4) The surface density of the active material layer of the second negative electrode plate is 50 mg / mm 2 ~150mg / mm 2 .

11. The battery cell according to claim 1, characterized in that: The pole piece in the second pole piece group closest to the first pole piece group is a second end pole piece, and the second end pole piece includes a first area overlapping with the first pole piece group and a second area not overlapping with the first pole piece group; Along the first direction, active material layers are disposed on both sides of the first region, and an active material layer is disposed only on a side of the second region away from the first pole piece group.

12. The battery cell according to claim 1, characterized in that: The housing comprises a first wall and a second wall arranged opposite to each other along the first direction, the first wall comprises a first sub-wall, a second sub-wall and a first connecting wall, the first sub-wall protrudes from the second sub-wall in a direction away from the second wall, and the first connecting wall connects the first sub-wall and the second sub-wall; A portion of the second pole piece group is located between the second sub-wall and the second wall, and the first pole piece group is located between the second pole piece group and the first sub-wall.

13. The battery cell according to claim 12, characterized in that: Along the first direction, the distance between the first sub-wall and the second sub-wall is L, which satisfies: 0.2 mm≤L≤5 mm.

14. The battery cell according to claim 13, characterized in that: 0.2mm≤L≤1.5mm.

15. An electrical equipment, characterized in that: The invention comprises a battery cell as claimed in any one of claims 1 to 14, wherein the battery cell is used to provide electrical energy.

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