Battery cell and electric device

Abstract

The present application belongs to the technical field of batteries. Disclosed are a battery cell and an electric device. The battery cell comprises a casing and an electrode assembly. The electrode assembly is accommodated in the casing, and is of a stacked structure. The electrode assembly comprises a first electrode sheet group and a second electrode sheet group, which are arranged in a first direction. In a second direction, the length of the second electrode sheet group is greater than the length of the first electrode sheet group. The first electrode sheet group comprises a first positive electrode sheet and a first negative electrode sheet, which are stacked in the first direction, and the second electrode sheet group comprises a second positive electrode sheet and a second negative electrode sheet, which are stacked in the first direction. Active material layers are provided on both surfaces of each of a first positive current collector, a first negative current collector, a second positive current collector and a second negative current collector in the first direction. 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. The battery cell has a relatively high energy density.

Description

Battery cell and electric device Cross-reference to related applications

[0001] This application claims priority to Chinese Patent Application 2024113197079, filed on September 20, 2024, entitled "Battery cell and electric device", the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a battery cell and an electric device. BACKGROUND

[0003] With the rapid development of new energy technology, battery cells have been widely used in electronic devices, electric vehicles, electric two-wheel vehicles, electric tools and other fields. With the increasing application of battery cells, higher requirements are placed on the energy density of battery cells.

[0004] How to improve the energy density of battery cells is a problem that needs to be solved in battery technology. SUMMARY

[0005] In view of the above problems, the present application provides a battery cell and an electric device, which can improve the energy density of the battery cell.

[0006] In a first aspect, the embodiments of the present application provide a battery cell, which includes 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 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, and along a 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 arranged in a stack along the first direction, and the second electrode sheet group includes a second positive electrode sheet and a second negative electrode sheet arranged in a stack along the first direction; the first positive electrode sheet includes a first positive electrode current collector, the first negative electrode sheet includes a first negative electrode current collector, the second positive electrode sheet includes a second positive electrode current collector, and the second negative electrode sheet includes a second negative electrode current collector; the two surfaces of the first positive electrode current collector, the first negative electrode current collector, the second positive electrode current collector and the second negative electrode current collector along the first direction are each provided with an active material layer; 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.

[0007] In one or more optional embodiments above, in one aspect, when producing the battery cell, due to the thickness difference between the at least two electrode tabs in the electrode assembly, different sizes of electrode assemblies can be arranged based on the shell to make full use of the internal space of the shell, reduce the risk of losing energy density due to excessive gap between the electrode assembly and the shell caused by insufficient space of the shell to arrange a set of positive and negative electrode tabs during the electrode tab stacking process due to the consistent specifications of each electrode tab, and thus facilitate to improve the energy density of the battery cell. In another aspect, in order to realize the assembly of the battery cell and the battery compartment of the electrical device, the battery cell can be designed as a special-shaped battery cell, at this time, the first electrode tab set and the second electrode tab set can be arranged along the first direction, and in the second direction, the length of the second electrode tab set is designed to be greater than the length of the first electrode tab set. Such a setting is due to the space limitation of the battery compartment on the profile and volume of the shell, so two battery cells are needed, at this time, the volume of the shell is certain, and designing the thickness of the electrode tabs in the first electrode tab set and the second electrode tab set as different values can make the battery cell have higher energy density while adapting to different assembly environments, and improve the adaptability of the battery cell to the electrical device.

[0008] In some embodiments of the first aspect of the application, the thickness of the first positive electrode tab is less than the thickness of the second positive electrode tab, and the thickness of the first negative electrode tab is less than the thickness of the second negative electrode tab.

[0009] In one or more optional embodiments above, the thickness of the first positive electrode tab is less than the thickness of the second positive electrode tab, and the thickness of the first negative electrode tab is less than the thickness of the second negative electrode tab. Such a design can make the first electrode tab set have a higher charge and discharge rate, and the second electrode tab set have a higher energy density, so that the battery cell can have both a higher charge and discharge rate and a higher energy density. At the same time, since the length of the second electrode tab set is greater than the length of the first electrode tab set along the second direction, the electrode tabs in the second electrode tab set can have a larger area coated with active material, and a second electrode tab set with fewer stacked layers of electrode tabs can be used to achieve the effect of the second electrode tab set having a higher energy density, thereby reducing the risk of the second electrode tab set losing energy density due to containing too many current collectors caused by too many stacked layers of electrode tabs in the second electrode tab set.

[0010] In some embodiments of the first aspect of the application, the first group of pole pieces further comprises a first outer pole piece farthest from the second group of pole pieces, the first outer pole piece comprising a first outer current collector, the first outer current collector being provided with an active material layer on only one side facing the second group of pole pieces; the second group of pole pieces further comprises a second outer pole piece farthest from the first group of pole pieces, the second outer pole piece comprising a second outer current collector, the second outer current collector being provided with an active material layer on only one side facing the first group of pole pieces; the first outer pole piece and the second outer pole piece have the same polarity; the first outer pole piece has a smaller thickness than the second outer pole piece.

[0011] In one or more optional embodiments above, since the first outer current collector is provided with an active material layer on only one side facing the second group of pole pieces, and the second outer current collector is provided with an active material layer on only one side facing the first group of pole pieces, i.e., the first outer current collector and the second current collector are provided with an active material layer on only one side where they play a capacity, it is beneficial to make the battery cell have a higher energy density. Moreover, since the first outer pole piece has a smaller thickness than the second outer pole piece, suitable first outer pole pieces and second outer pole pieces can be selected to make the first group of pole pieces and the second group of pole pieces fully utilize the internal space of the shell, further improving the energy density of the battery cell. At the same time, since the first positive pole piece has a smaller thickness than the second positive pole piece, and the first negative pole piece has a smaller thickness than the second negative pole piece, setting the thickness of the first outer pole piece to be smaller than the thickness of the second outer pole piece is beneficial to synchronously design and process all the pole pieces in the first group of pole pieces and synchronously process all the pole pieces in the second group of pole pieces.

[0012] In some embodiments of the first aspect of the application, the first positive pole piece has a larger thickness than the second positive pole piece, and the first negative pole piece has a larger thickness than the second negative pole piece.

[0013] In one or more optional embodiments above, the first positive pole piece has a larger thickness than the second positive pole piece, and the first negative pole piece has a larger thickness than the second negative pole piece. Such a design can make the first group of pole pieces have a higher energy density, and the second group of pole pieces have a higher charge and discharge rate, so that the battery cell can have both a higher charge and discharge rate and a higher energy density. At the same time, since the length of the second group of pole pieces is greater than the length of the first group of pole pieces along the second direction, the pole pieces in the second group of pole pieces can have a larger area coated with active material, so that the battery cell can have a relatively larger energy storage in a shorter time during the charging process.

[0014] In some embodiments of the first aspect of the application, the first group of pole pieces further comprises a first outer pole piece farthest from the second group of pole pieces, the first outer pole piece comprising a first outer current collector, the first outer current collector being provided with an active material layer on only one side facing the second group of pole pieces; the second group of pole pieces further comprises a second outer pole piece farthest from the first group of pole pieces, the second outer pole piece comprising a second outer current collector, the second outer current collector being provided with an active material layer on only one side facing the first group of pole pieces; the first outer pole piece and the second outer pole piece have the same polarity; the first outer pole piece has a greater thickness than the second outer pole piece.

[0015] In one or more optional embodiments above, since the first outer current collector is provided with an active material layer on only one side facing the second group of pole pieces, and the second outer current collector is provided with an active material layer on only one side facing the first group of pole pieces, i.e., the first outer current collector and the second current collector are provided with an active material layer on only one side where they play a capacity, it is beneficial to make the battery cell have a higher energy density. Moreover, since the first outer pole piece has a greater thickness than the second outer pole piece, suitable first outer pole pieces and second outer pole pieces can be selected to make the first group of pole pieces and the second group of pole pieces fully utilize the internal space of the shell, further improving the energy density of the battery cell. At the same time, since the first positive pole piece has a greater thickness than the second positive pole piece, and the first negative pole piece has a greater thickness than 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 beneficial to synchronously design and process all pole pieces in the first group of pole pieces and synchronously process all pole pieces in the second group of pole pieces.

[0016] In some embodiments of the first aspect of the application, the thickness of the first positive pole piece is D1, the thickness of the first negative pole piece is D2, the thickness of the second positive pole piece is D3, and the thickness of the second negative pole piece is D4; and the following conditions are met: 0 < |D3-D1| ≤ 180 μm, and 0 < |D4-D2| ≤ 180 μm.

[0017] In one or more optional embodiments above, the absolute value of the difference between the thickness of the second positive pole piece and the thickness of the first positive pole piece, and the absolute value of the difference between the thickness of the second negative pole piece and the thickness of the first negative pole piece are designed within a reasonable range, which is beneficial to make the battery cell have a higher energy density while making the migration distances of lithium ions in the first group of pole pieces and the second group of pole pieces similar, so that when the input current of the battery cell is constant, the difficulty of activating lithium ions in the first group of pole pieces and lithium ions in the second group of pole pieces is similar, reducing the risk that one of the first group of pole pieces and the second group of pole pieces is not fully utilized, resulting in the available capacity of the battery cell being less than the designed capacity.

[0018] In some embodiments of the first aspect of the application, the thickness of the first positive electrode tab is D1, the thickness of the first negative electrode tab is D2, the thickness of the second positive electrode tab is D3, and the thickness of the second negative electrode tab is D4; and the following conditions are met: 20 μm≤D1≤200 μm, 20 μm≤D2≤200 μm, 20 μm≤D3≤200 μm, and 20 μm≤D4≤200 μm.

[0019] In one or more optional embodiments described above, the thickness of the electrode tab is greater than or equal to 20 μm, which is conducive to providing the battery cell with a higher energy density, and the thickness of the electrode tab is less than or equal to 200 μm, which is conducive to providing the lithium ions in the battery cell with a shorter migration distance, thereby improving the charge and discharge rate of the battery cell. Therefore, by setting the thickness of the electrode tab within a reasonable range, the battery cell can have both a higher energy density and a higher charge and discharge rate.

[0020] In some embodiments of the first aspect of the application, the thickness of the first outer tab is D5, and the thickness of the second outer tab group is D6; and the following condition is met: 0<|D6-D5|≤90 μm.

[0021] In one or more optional embodiments described above, the absolute value of the difference between the thickness of the second outer tab and the thickness of the first outer tab is designed to be within a reasonable range, which is conducive to providing the battery cell with a higher energy density while making the migration distance of the lithium ions in the first electrode tab group and the second electrode tab group similar during the stacking of the electrode tabs, so that when the input current of the battery cell is constant, the difficulty of activating the lithium ions in the first electrode tab group and the lithium ions in the second electrode tab group is similar, thereby reducing the risk that one of the first outer tab and the second outer tab is not fully utilized during the use of the battery cell, resulting in a usable capacity of the battery cell being less than the designed capacity.

[0022] In some embodiments of the first aspect of the application, the thickness of the first positive electrode current collector and the thickness of the second positive electrode current collector are the same, and the thickness of the first negative electrode current collector and the thickness of the second negative electrode current collector are the same.

[0023] In one or more optional embodiments described above, the thickness of the first positive electrode current collector and the thickness of the second positive electrode current collector are the same, and the thickness of the first negative electrode current collector and the thickness of the second negative electrode current collector are the same. On the one hand, this can make the distribution of current in the battery cell more uniform, thereby improving the cycle life of the battery cell. On the other hand, when designing and processing electrode tabs of different thicknesses, only the area density of the active material layer of the current collector needs to be changed, thereby reducing the processing difficulty of the battery cell.

[0024] In some embodiments of the first aspect of the application, the electrode assembly meets one of the following conditions: the area density of the active material layer of the first positive electrode tab is 100 mg / mm 2 ~ 350 mg / mm 2; the areal density of the active material layer of the first negative electrode tab is 50 mg / mm 2 ~ 150 mg / mm 2 ; the areal density of the active material layer of the second positive electrode tab is 100 mg / mm 2 ~ 350 mg / mm 2 ; the areal density of the active material layer of the second negative electrode tab is 50 mg / mm 2 ~ 150 mg / mm 2 .

[0025] In the one or more optional embodiments above, when the areal density of the active material layer of the positive electrode tab is greater than or equal to 100 mg / mm 2 , the thickness of the active material layer of the positive electrode tab is greater, and the energy density of the battery cell is greater. When the areal density of the active material layer of the positive electrode tab is less than or equal to 350 mg / mm 2 , lithium ion migration is facilitated, and the battery cell has a higher charge and discharge rate. Therefore, by setting the areal density of the active material layer of the positive electrode tab within a reasonable range, the battery cell can have both a high energy density and a high charge and discharge rate.

[0026] When the areal density of the active material layer of the negative electrode tab is greater than or equal to 100 mg / mm 2 , the thickness of the active material layer of the negative electrode tab is greater, and the energy density of the battery cell is greater. When the areal density of the active material layer of the negative electrode tab is less than or equal to 350 mg / mm 2 , lithium ion migration is facilitated, and the battery cell has a higher charge and discharge rate. Therefore, by setting the areal density of the active material layer of the negative electrode tab within a reasonable range, the battery cell can have both a high energy density and a high charge and discharge rate.

[0027] In some embodiments of the first aspect of the application, the second tab group has a second end tab closest to the first tab group, and the second end tab includes a first region overlapping the first tab group and a second region not overlapping the first tab group.

[0028] In the first direction, the first region has active material layers on both sides, and the second region has an active material layer only on the side facing away from the first tab group.

[0029] In one or more optional embodiments above, the second tab group has a size in the second direction that is greater than a size of the first tab group in the second direction, the second tab group includes a second end tab closest to the first tab group, and the second end tab includes a first region that overlaps the first tab group and a second region that does not overlap the first tab group. In the first direction, the first region has active material layers on both sides, and the second region has an active material layer on only one side facing away from the first tab group. In one aspect, the first region has active material layers on both sides, and the active material layer on the side of the first region facing the first tab group can serve as an outermost tab of the first tab group, equivalent to the outermost tab of the first tab group and the outermost tab of the second tab group sharing a current collector, which, compared to the scheme of bonding the current collector of the outermost single-sided active material layer tab of the second tab group to the current collector of the outermost single-sided active material layer tab of the first tab group through the adhesive layer, reduces the space occupied by the adhesive layer and reduces the energy density loss of the battery in the first direction. In another aspect, compared to the scheme of bonding the current collector of the outermost single-sided active material layer tab of the second tab group to the current collector of the outermost single-sided active material layer tab of the first tab group through the adhesive layer, the present scheme reduces the number of single-sided active material layer tabs in the battery by providing the second end tab, thereby reducing the number of current collectors in the battery and reducing the energy density loss of the battery in the first direction. In yet another aspect, the single-sided active material layer tab has a relatively large thickness of the current collector to alleviate the problem of warping and rolling, which also leads to a loss of energy density of the battery. In the present scheme, the current collector of the second end tab has active material layers on both sides, and the active material layers on both sides of the current collector of the second end tab can offset the stress, reducing the risk of warping and rolling of the second end tab, and allowing the current collector of the second end tab to be relatively thinner than the current collector of the single-sided active material layer tab, further reducing the energy density loss of the battery in the first direction. In yet another aspect, the second region of the current collector of the second end tab has an active material layer on only one side facing away from the first tab group, reducing the amount of active material that does not contribute to capacity and avoiding the occupation of space by the active material that does not contribute to capacity, further reducing the energy density loss of the battery in the first direction. Therefore, compared to the scheme of bonding the single-sided active material layer tab of the second tab group closest to the first tab group and the single-sided active material layer tab of the first tab group closest to the second tab group through the adhesive layer, the battery of the present scheme has a higher energy density.

[0030] In some embodiments of the first aspect of the application, the shell comprises a first wall and a second wall oppositely arranged along a 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 along a direction away from the second wall, and the first connecting wall connects the first sub-wall and the second sub-wall; a part of the second tab group is located between the second sub-wall and the second wall, and the first tab group is located between the second tab group and the first sub-wall.

[0031] In one or more optional embodiments above, 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 shell is in a stepped shape, so as to make the battery cell suitable for limited assembly space and increase the adaptability range of the battery cell.

[0032] In some embodiments of the first aspect of the application, along the first direction, the distance between the first sub-wall and the second sub-wall is L, which satisfies: 0.2mm≤L≤5mm.

[0033] In one or more optional embodiments above, 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 as to provide sufficient space between the first sub-wall and the second tab group, facilitate the first tab group to comprise at least one group of positive and negative tab groups during the tab stacking process, reduce the risk of energy density loss caused by a large gap between the first tab group and the first sub-wall, and thus make the first tab group fully utilize the space between the first sub-wall and the second tab group, so as to make the battery cell have 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, so as to reduce the risk of damage to the battery cell when it is subjected to impact or vibration, and increase the structural stability of the battery cell as a whole. Therefore, by setting the distance between the first sub-wall and the second sub-wall along the first direction within a reasonable range, the battery cell can have both a higher energy density and a higher structural stability.

[0034] In some embodiments of the first aspect of the application, 0.2mm≤L≤1.5mm.

[0035] In the one or more optional embodiments above, the distance between the first sub-wall and the second sub-wall in the first direction is greater than or equal to 0.2 mm, so that sufficient space is provided between the first sub-wall and the second sub-wall for the first sub-wall and the first electrode tab group, which at least includes a group of positive electrode tabs and negative electrode tabs, to be stacked in the process of stacking the electrode tabs, thereby reducing the risk of a large gap between the first electrode tab group and the first sub-wall resulting in a loss of energy density, so that the first electrode tab group can make full use of the space between the first sub-wall and the second sub-wall, and the battery cell has a higher energy density. The distance between the first sub-wall and the second sub-wall in the first direction is less than or equal to 1.5 mm, which can further reduce the risk of damage to the battery cell when subjected to impact or vibration, thereby further improving the overall structural stability of the battery cell. Therefore, by setting the distance between the first sub-wall and the second sub-wall in the first direction within a reasonable range, the battery cell can have a higher energy density while further improving the overall structural stability of the battery cell.

[0036] In a second aspect, the application provides a use of the battery cell provided in any of the above embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the application, and therefore should not be considered as limiting the scope.

[0038] FIG. 1 is a structural schematic view of a battery cell provided in some embodiments of the application;

[0039] FIG. 2 is a cross-sectional view of an electrode assembly provided in some embodiments of the application;

[0040] FIG. 3 is a partial enlarged view of A in FIG. 2;

[0041] FIG. 4 is a cross-sectional view of an electrode assembly provided in some other embodiments of the application;

[0042] FIG. 5 is a partial enlarged view of B in FIG. 4;

[0043] FIG. 6 is a cross-sectional view of an electrode assembly provided in some other embodiments of the application;

[0044] FIG. 7 is a partial enlarged view of C in FIG. 6;

[0045] FIG. 8 is a cross-sectional view of an electrode assembly provided in some other embodiments of the application;

[0046] FIG. 9 is a partial enlarged view of D in FIG. 8;

[0047] FIG. 10 is a cross-sectional view of a battery cell provided in some embodiments of the application.

[0048] The reference signs in the detailed description of the embodiments are as follows:

[0049] 100 - cell; 10 - electrode assembly; 1 - first tab group; 11 - first positive tab; 110 - first outer tab; 12 - first negative tab; 2 - second tab group; 21 - second positive tab; 210 - second outer tab; 22 - second negative tab; 101 - second end tab; 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

[0050] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0051] It should be noted that the embodiments and features in the present application can be combined with each other without conflict.

[0052] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0053] In the description of the embodiments of the present application, it should be noted that the indicated position or location relationship is based on the position or location relationship shown in the drawings, or the position or location relationship commonly placed when the product of the present application is used, or the position or location relationship commonly understood by the person 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 indicated device or element must have a particular position, be constructed and operated in a particular position, therefore, it cannot be understood as a limitation to the present application. In addition, the terms "first", "second", "third" and the like are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0054] At present, from the development of market situation, the application of the cell is more and more widely. The cell is widely used in electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, electric tools, unmanned aerial vehicles, energy storage equipment and many other fields. With the continuous expansion of the application field of the cell, the demand of its market is also increasing.

[0055] The electric core generally comprises a shell and an electrode assembly, and the electrode assembly is accommodated in the shell. The electric core includes a winding type electric core and a laminated electric core. The electrode assembly of the laminated electric core comprises a plurality of polar plates with opposite polarities which are alternately stacked. The volume and shape of the shell are generally determined according to the assembly environment of the electric core. When the volume and shape of the shell are determined, during the stacking of the electrode assembly, if the remaining space of the shell is insufficient to arrange a group of positive and negative polar plates, there will be an excessive gap between the electrode assembly and the shell, resulting in a loss of energy density of the electric core. For some limited and complex electric devices, in order to avoid interference between the electric core and the wall of the battery compartment or other components of the electric device, the shape of the shell is designed to be special, such as stepped or the like. At this time, if the same specification of polar plate is still used to stack the electrode assembly at one time, it will significantly increase the risk of excessive gap between the electrode assembly and the shell, resulting in a large loss of energy density of the electric core.

[0056] In view of the above, in order to reduce the loss of energy density of the battery cell and improve the energy density of the battery cell, an embodiment of the present application provides a battery cell, which comprises a shell and an electrode assembly accommodated in the shell, and the electrode assembly is of a stacked structure; the electrode assembly comprises a first electrode plate group and a second electrode plate group, the first electrode plate group and the second electrode plate group are arranged along a first direction, and along a second direction, the length of the second electrode plate group is greater than the length of the first electrode plate group, and the second direction is perpendicular to the first direction; the first electrode plate group comprises a first positive electrode plate and a first negative electrode plate stacked along the first direction, and the second electrode plate group comprises a second positive electrode plate and a second negative electrode plate stacked along the first direction; the first positive electrode plate comprises a first positive electrode current collector, the first negative electrode plate comprises a first negative electrode current collector, the second positive electrode plate comprises a second positive electrode current collector, and the second negative electrode plate comprises a second negative electrode current collector; both surfaces of the first positive electrode current collector, the first negative electrode current collector, the second positive electrode current collector and the second negative electrode current collector along the first direction are provided with an active material layer; wherein the thickness of the first positive electrode plate is different from the thickness of the second positive electrode plate, and the thickness of the first negative electrode plate is different from the thickness of the second negative electrode plate. On the one hand, when producing the battery cell, the space of the battery compartment limits the profile and volume of the shell, and the stepped battery comprises the first electrode plate group and the second electrode plate group, the sizes of the two electrode plate groups are different, and if the same thickness of the electrode plate is used, it may cause that one of the shells cannot be filled. Therefore, the thicknesses of the electrode plates in the first electrode plate group and the second electrode plate group are different, the electrode assembly of different sizes can be arranged based on the shell, the internal space of the shell is fully utilized, the risk of loss of energy density due to excessive gap between the electrode assembly and the shell caused by insufficient space of the shell for arranging a group of positive electrode plates and negative electrode plates in the process of stacking the electrode plates is reduced, and the energy density of the battery cell is improved. 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 is designed as a special-shaped battery cell, at this time, the first electrode plate group and the second electrode plate group can be arranged along the first direction, and in the second direction, the length of the second electrode plate group is designed to be greater than the length of the first electrode plate group. Such a design is because the space of the battery compartment limits the profile and volume of the shell, so two battery cells need to be arranged, at this time, the volume of the shell is certain, and the different thicknesses of the electrode plates in the first electrode plate group and the second electrode plate group can make the battery cell have a high energy density while adapting to different assembly environments, and improve the adaptability of the battery cell and the electric device. On the other hand, thicker electrode plates are beneficial to improve the energy density of the battery cell, and thinner electrode plates are beneficial to improve the charge and discharge rate of the battery cell. The different thicknesses of the electrode plates in the first electrode plate group and the second electrode plate group can balance the relationship between the charge and discharge rate and the energy density according to the demand, so that the battery cell is suitable for electric devices with different demands.

[0057] In the present application, the first positive electrode tab thickness and the second positive electrode tab thickness are different, which means that any one of the first positive electrode tab thickness is different from any one of the second positive electrode tab thickness; the first negative electrode tab thickness and the second negative electrode tab thickness are different, which means that any one of the first negative electrode tab thickness is different from any one of the second negative electrode tab thickness.

[0058] The electric core provided by the embodiments of the present application can be used in electric two-wheeled vehicles, electric tools, unmanned aerial vehicles, energy storage devices, mobile terminals and other electric devices. The electric core formed by the electrode tab provided by the embodiments of the present application can also be used as a power supply system of an electric device.

[0059] As shown in FIGS. 1-9, the embodiments of the present application provide an electric core 100, which comprises a shell 20 and an electrode assembly 10, and the electrode assembly 10 is accommodated in the shell 20.

[0060] The shell 20 can be a hard shell, such as a stainless steel shell, an aluminum hard shell, forming a steel shell battery or an aluminum shell battery.

[0061] The shell 20 can also be formed of a relatively soft material, such as an aluminum plastic film or a steel plastic film, forming a soft package electric core 100.

[0062] The electrode assembly 10 is a laminated structure. The electrode assembly 10 comprises a first electrode tab group 1 and a second electrode tab group 2, and the first electrode tab group 1 and the second electrode tab group 2 are arranged along a first direction X and along a second direction Y. The length of the second electrode tab group 2 is greater than the length of the first electrode tab group 1, and the second direction Y is perpendicular to the first direction X.

[0063] In some embodiments, the first direction X is the stacking direction of the laminated electric core 100. In other embodiments, the first direction X is the thickness direction of the laminated electric core 100.

[0064] The first electrode tab group 1 comprises a plurality of electrode tabs arranged in a laminated manner along the first direction X. The polarities of any two adjacent electrode tabs in the first electrode tab group 1 are opposite, that is, one of the any two adjacent electrode tabs in the first electrode tab group 1 is a positive electrode tab, and the other is a negative electrode tab. An isolation film is arranged between the any two adjacent electrode tabs in the first electrode tab group 1, and the isolation film is used to insulate and separate the any two adjacent electrode tabs with opposite polarities in the first electrode tab group 1.

[0065] In some embodiments, the first electrode tab group 1 comprises a first outer side electrode tab 110 farthest from the second electrode tab group 2. The first outer side electrode tab 110 can be an electrode tab with a single active material layer, which is beneficial to reduce the active material that does not play a capacity and improve the energy density of the electric core 100. Of course, the first outer side electrode tab 110 can also be an electrode tab with a double active material layer. The first outer side electrode tab 110 can be a positive electrode tab or a negative electrode tab.

[0066] The second tab group 2 includes a plurality of tabs stacked along the first direction X. Adjacent two tabs in the second tab group 2 have opposite polarities, that is, one of the adjacent two tabs in the second tab group 2 is a positive tab and the other is a negative tab. An isolation film is arranged between the adjacent two tabs in the second tab group 2, and the isolation film is used to insulate and separate the adjacent two tabs with opposite polarities in the second tab group 2.

[0067] In some embodiments, the second tab group 2 includes a second outer tab 210 farthest from the first tab group 1. The second outer tab 210 can be a single-sided active material layer coated tab, which is beneficial to reduce the active material not playing a capacity and improve the energy density of the battery cell 100. Of course, the second outer tab 210 can also be a double-sided active material coated tab. The second outer tab 210 can be a positive tab or a negative tab.

[0068] The first tab group 1 and the second tab group 2 are insulated and separated by the isolation film.

[0069] The isolation film insulates and separates two tabs with opposite polarities, reducing the risk of short circuit of the battery cell 100. The material of the isolation film can include PP (polypropylene) or PE (polyethylene) and the like.

[0070] The number of tabs in the first tab group 1 can be the same as or different from the number of tabs in the second tab group 2.

[0071] The electrode assembly 10 includes positive tabs and negative tabs. The positive tab includes a positive current collector and a positive active material layer arranged on the surface of the positive current collector. The negative tab includes a negative current collector and a negative active material layer arranged on the surface of the negative current collector. The thickness of the positive active material layer of at least two positive tabs in the electrode assembly 10 is different, and / or the thickness of the negative active material layer of at least two negative tabs in the electrode assembly 10 is different.

[0072] The positive tab includes a positive current collector and a positive active material layer. At least one side of the positive current collector is provided with the positive active material layer. The material of the positive current collector can include aluminum. The positive active material can be lithium cobaltate, lithium iron phosphate, ternary lithium, or lithium manganate, etc. The negative tab includes a negative current collector and a negative active material layer. At least one side of the negative current collector is provided with the negative active material layer. The material of the negative current collector can include copper. The negative active material can be carbon or silicon, etc.

[0073] The 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 X are each provided with an active material layer; wherein the thickness of the first positive electrode sheet 11 and the thickness of the second positive electrode sheet 21 are different, and the thickness of the first negative electrode sheet 12 and the thickness of the second negative electrode sheet 22 are different. The thickness of the first positive electrode sheet 11 refers to the sum of the thickness of the first positive current collector and the thickness of the two layers of active material layers, the thickness of the first negative electrode sheet 12 refers to the sum of the thickness of the first negative current collector and the thickness of the two layers of active material layers, the thickness of the second positive electrode sheet 21 refers to the sum of the thickness of the second positive current collector and the thickness of the two layers of active material layers, and the thickness of the second negative electrode sheet 22 refers to the sum of the thickness of the second negative current collector and the thickness of the two layers of active material layers. The thickness of the first positive current collector, the first negative current collector, the second positive current collector and the second negative current collector can be the same or different.

[0074] In one or more optional embodiments above, on the one hand, when producing the battery cell 100, since the thicknesses of the at least two electrode sheets in the electrode assembly 10 are different, different sizes of electrode assemblies 10 can be arranged based on the shell 20, so that the electrode assembly 10 fully utilizes the internal space of the shell 20, and reduces the risk of energy density loss due to excessive gap between the electrode assembly 10 and the shell 20 caused by insufficient space of the shell 20 for arranging a group of positive electrode sheets and negative electrode sheets in the process of stacking the electrode sheets due to the same specifications of each electrode sheet, thereby facilitating the improvement of 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 can be designed as a special-shaped battery cell 100, at this time, the first electrode sheet group 1 and the second electrode sheet group 2 can be arranged along the first direction X, and in the second direction Y, the length of the second electrode sheet group 2 is designed to be greater than the length of the first electrode sheet group 1. Such a setting is due to the space limitation of the battery compartment on the profile and volume of the shell 20, so that two battery cells 100 need to be arranged, at this time, the volume of the shell 20 is certain, and the design of different thicknesses of the electrode sheets in the first electrode sheet group 1 and the second electrode sheet group 2 can make the battery cell 100 have higher energy density while adapting to different assembly environments, thereby improving the adaptability of the battery cell to the electrical equipment. On the other hand, since thicker electrode sheets are beneficial to improve the energy density of the battery cell 100, and thinner electrode sheets are beneficial to improve the charge and discharge rate of the battery cell 100. The design of different thicknesses of the electrode sheets in the first electrode sheet group 1 and the second electrode sheet group 2 can balance the relationship between the charge and discharge rate and the energy density according to the demand, so that the battery cell 100 is suitable for electrical equipment with different demands.

[0075] As shown in FIGS. 2-5, the thickness of the first positive electrode tab 11 is less than the thickness of the second positive electrode tab 21, and the thickness of the first negative electrode tab 12 is less than the thickness of the second negative electrode tab 22. The thickness of the first positive electrode tab 11 being less than the thickness of the second positive electrode tab 21 means that the thickness of any one first positive electrode tab 11 is less than the thickness of any one second positive electrode tab 21.

[0076] The thickness of the first negative electrode tab 12 being less than the thickness of the second negative electrode tab 22 means that the thickness of any one first negative electrode tab 12 is less than the thickness of any one second negative electrode tab.

[0077] Since the length of the second tab group 2 is greater than the length of the first tab group 1 along the second direction Y, the area of the tabs in the second tab group 2 that can be coated with active material is larger, and fewer layers of the tabs in the second tab group 2 can be stacked to achieve the effect of the second tab group 2 having a higher energy density, thereby reducing the risk that the number of layers of the tabs in the second tab group 2 being stacked is too large, causing the second tab group 2 to contain too much current collector and lose energy density. That is, the space within the battery cell 100 is used as much as possible by the active material layer, and the space occupied by the current collector is reduced.

[0078] In one or more optional embodiments above, the thickness of the first positive electrode tab 11 is less than the thickness of the second positive electrode tab 21, and the thickness of the first negative electrode tab 12 is less than the thickness of the second negative electrode tab 22. Such a design can make the first tab group 1 have a higher charge and discharge rate, and the second tab group 2 have a higher energy density, so that the battery cell 100 has both a higher charge and discharge rate and a higher energy density.

[0079] As shown in FIGS. 2-5, the first tab group 1 further includes a first outer tab 110 farthest from the second tab group 2, the first outer tab 110 including a first outer current collector, the first outer current collector being provided with an active material layer only on a side facing the second tab group 2; the second tab group 2 further includes a second outer tab 210 farthest from the first tab group 1, the second outer tab 210 including a second outer current collector, the second outer current collector being provided with an active material layer only on a side facing the first tab group 1; the first outer tab 110 and the second outer tab 210 have the same polarity; and the thickness of the first outer tab 110 is less than the thickness of the second outer tab 210.

[0080] The first outer tab 110 can be a positive tab or a negative tab. The second outer tab 210 can be a positive tab or a negative tab. The polarity of the first outer tab 110 is opposite to the polarity of the tab closest to the second tab group 2 on the side of the first outer tab 110 facing the second tab group 2. The polarity of the second outer tab 210 is opposite to the polarity of the tab closest to the first tab group 1 on the side of the second outer tab 210 facing the first tab group 1. In some embodiments, as shown in FIG. 5, the first outer tab 110 and the second outer tab 210 are both positive tabs, and the thickness of the first outer tab 110 is less than the thickness of the second outer tab 210.

[0081] 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 tab group 2, and the second outer current collector is provided with an active material layer only on the side facing the first tab 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 play a capacity, it is beneficial to make the battery cell 100 have a higher energy density. And since the thickness of the first outer tab 110 is less than the thickness of the second outer tab 210, appropriate first outer tab 110 and second outer tab 210 can be selected to make the first tab group 1 and the second tab 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 tab 11 is less than the thickness of the second positive tab 21, and the thickness of the first negative tab 12 is less than the thickness of the second negative tab 22, setting the thickness of the first outer tab 110 to be less than the thickness of the second outer tab 210 is beneficial to synchronously design and process all the tabs in the first tab group 1 and synchronously process all the tabs in the second tab group 2.

[0082] As shown in FIGS. 2-5, the thickness of the first positive tab 11 is greater than the thickness of the second positive tab 21, and the thickness of the first negative tab 12 is greater than the thickness of the second negative tab 22.

[0083] Since the length of the second tab group 2 is greater than the length of the first tab group 1 along the second direction Y, the tabs in the second tab group 2 can have a larger area coated with active material, which can make the battery cell 100 have a relatively large energy storage in a shorter time during charging.

[0084] In one or more optional embodiments above, the thickness of the first positive tab 11 is greater than the thickness of the second positive tab 21, and the thickness of the first negative tab 12 is greater than the thickness of the second negative tab 22. Such a design can make the first tab group 1 have a higher energy density, and the second tab group 2 have a higher charge and discharge rate, so that the battery cell 100 can have both a higher charge and discharge rate and a higher energy density.

[0085] As shown in FIGS. 6-9, the first pole piece group 1 further includes a first outer side pole piece 110 farthest from the second pole piece group 2, the first outer side pole piece 110 including a first outer side current collector provided with an active material layer on only one side facing the second pole piece group 2; the second pole piece group 2 further includes a second outer side pole piece 210 farthest from the first pole piece group 1, the second outer side pole piece 210 including a second outer side current collector provided with an active material layer on only one side facing the first pole piece group 1; the first outer side pole piece 110 and the second outer side pole piece 210 have the same polarity; the thickness of the first outer side pole piece 110 is greater than the thickness of the second outer side pole piece 210.

[0086] The first outer side pole piece 110 can be a positive pole piece or a negative pole piece. The second outer side pole piece 210 can be a positive pole piece or a negative pole piece. The polarity of the first outer side pole piece 110 is opposite to the polarity of the pole piece closest to the first outer side pole piece 110 on the side of the first outer side pole piece 110 facing the second pole piece group 2. The polarity of the second outer side pole piece 210 is opposite to the polarity of the pole piece closest to the second outer side pole piece 210 on the side of the second outer side pole piece 210 facing the first pole piece group 1. In some embodiments, as shown in FIG. 9, the first outer side pole piece 110 and the second outer side pole piece 210 are both positive pole pieces, and the thickness of the first outer side pole piece 110 is greater than the thickness of the second outer side pole piece 210.

[0087] In the above one or more optional embodiments, since the first outer side current collector is provided with an active material layer on only one side facing the second pole piece group 2, and the second outer side current collector is provided with an active material layer on only one side facing the first pole piece group 1, i.e., the first outer side current collector and the second current collector are provided with active material layers on only one side where they play a capacity, it is beneficial to make the battery cell 100 have a higher energy density. Moreover, the thickness of the first outer side pole piece 110 is greater than the thickness of the second outer side pole piece 210, so that suitable first outer side pole pieces 110 and second outer side pole pieces 210 can be selected to make the first pole piece group 1 and the second pole piece group 2 fully utilize the internal space of the shell 20, and further improve the energy density of the battery cell 100. Meanwhile, since the thickness of the first positive pole piece 11 is greater than the thickness of the second positive pole piece 21, and the thickness of the first negative pole piece 12 is greater than the thickness of the second negative pole piece 22, setting the thickness of the first outer side pole piece 110 to be greater than the thickness of the second outer side pole piece 210 is beneficial to synchronously design and process all the pole pieces in the first pole piece group 1 and synchronously process all the pole pieces in the second pole piece group 2.

[0088] As shown in FIGS. 1-9, the thickness of the first positive pole piece 11 is D1, the thickness of the first negative pole piece 12 is D2, the thickness of the second positive pole piece 21 is D3, and the thickness of the second negative pole piece 22 is D4; it is satisfied that 0<|D3-D1|≤180μm and 0<|D4-D2|≤180μm.

[0089] The thickness of the first negative electrode tab 12 can be greater than or less than the thickness of the second negative electrode tab 22, and the thickness of the first positive electrode tab 11 can be greater than or less than the thickness of the second positive electrode tab 21. For example, referring to FIGS. 3 and 5, the thickness of the first negative electrode tab 12 is less than the thickness of the second negative electrode tab 22, and the thickness of the first positive electrode tab 11 is less than the thickness of the second positive electrode tab 21. For example, referring to FIGS. 7 and 9, the thickness of the first negative electrode tab 12 is greater than the thickness of the second negative electrode tab 22, and the thickness of the first positive electrode tab 11 is greater than the thickness of the second positive electrode tab 21.

[0090] The thickness of the first negative electrode tab 12 being greater than the thickness of the second negative electrode tab 22 means that the thickness of any one of the first negative electrode tabs 12 is greater than the thickness of any one of the second negative electrode tabs 22, and the thickness of the first positive electrode tab 11 being greater than the thickness of the second positive electrode tab 21 means that the thickness of any one of the first positive electrode tabs 11 is greater than the thickness of any one of the second positive electrode tabs 21.

[0091] The absolute value of the difference between the thickness of the second positive electrode tab 21 and the thickness of the first positive electrode tab 11 can be any value between greater than 0 and less than or equal to 180 pm, for example, 1 pm, 5 pm, 10 pm, 15 pm, 20 pm, 25 pm, 30 pm, 35 pm, 40 pm, 45 pm, 50 pm, 55 pm, 60 pm, 65 pm, 70 pm, 75 pm, 80 pm, 85 pm, 90 pm, 95 pm, 100 pm, 105 pm, 110 pm, 115 pm, 120 pm, 125 pm, 130 pm, 135 pm, 140 pm, 145 pm, 150 pm, 155 pm, 160 pm, 165 pm, 170 pm, 175 pm, 180 pm, etc.

[0092] The absolute value of the difference between the thickness of the second negative electrode tab 22 and the thickness of the first negative electrode tab 12 can be any value between greater than 0 and less than or equal to 180 pm, for example, 1 pm, 5 pm, 10 pm, 15 pm, 20 pm, 25 pm, 30 pm, 35 pm, 40 pm, 45 pm, 50 pm, 55 pm, 60 pm, 65 pm, 70 pm, 75 pm, 80 pm, 85 pm, 90 pm, 95 pm, 100 pm, 105 pm, 110 pm, 115 pm, 120 pm, 125 pm, 130 pm, 135 pm, 140 pm, 145 pm, 150 pm, 155 pm, 160 pm, 165 pm, 170 pm, 175 pm, 180 pm, etc.

[0093] In the above one or more optional embodiments, the absolute value of the difference between the thickness of the second positive electrode tab 21 and the thickness of the first positive electrode tab 11, and the absolute value of the difference between the thickness of the second negative electrode tab 22 and the thickness of the first negative electrode tab 12 are designed within a reasonable range, which is beneficial to making the migration distance of lithium ions in the first electrode tab group 1 and the second electrode tab group 2 similar when the energy density of the battery cell 100 is high during the stacking of the electrode tabs, so that the difficulty of activating lithium ions in the first electrode tab group 1 and lithium ions in the second electrode tab group 2 is similar when the input current of the battery cell 100 is constant, thereby reducing the risk that one of the first electrode tab group 1 and the second electrode tab group 2 is not fully utilized, resulting in the available capacity of the battery cell 100 being less than the designed capacity.

[0094] As shown in FIGS. 2-5, the thickness of the first positive electrode tab 11 is D1, the thickness of the first negative electrode tab 12 is D2, the thickness of the second positive electrode tab 21 is D3, and the thickness of the second negative electrode tab 22 is D4; and the following conditions are met: 20 μm≤D1≤200 μm, 20 μm≤D2≤200 μm, 20 μm≤D3≤200 μm, and 20 μm≤D4≤200 μm.

[0095] The thickness of the first positive electrode tab 11 can be any value greater than or equal to 20 μm and less than or equal to 200 μm, such as 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm, 155 μm, 160 μm, 165 μm, 170 μm, 175 μm, 180 μm, 185 μm, 190 μm, 195 μm, 200 μm, etc.

[0096] The thickness of the first negative electrode tab 12 can be any value greater than or equal to 20 μm and less than or equal to 200 μm, such as 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm, 155 μm, 160 μm, 165 μm, 170 μm, 175 μm, 180 μm, 185 μm, 190 μm, 195 μm, 200 μm, etc.

[0097] The thickness of the second positive electrode tab 21 can be any value between greater than or equal to 20 pm and less than or equal to 200 pm, for example, 20 pm, 25 pm, 30 pm, 35 pm, 40 pm, 45 pm, 50 pm, 55 pm, 60 pm, 65 pm, 70 pm, 75 pm, 80 pm, 85 pm, 90 pm, 95 pm, 100 pm, 105 pm, 110 pm, 115 pm, 120 pm, 125 pm, 130 pm, 135 pm, 140 pm, 145 pm, 150 pm, 155 pm, 160 pm, 165 pm, 170 pm, 175 pm, 180 pm, 185 pm, 190 pm, 195 pm, 200 pm, or the like.

[0098] The thickness of the second negative electrode tab 22 can be any value between greater than or equal to 20 pm and less than or equal to 200 pm, for example, 20 pm, 25 pm, 30 pm, 35 pm, 40 pm, 45 pm, 50 pm, 55 pm, 60 pm, 65 pm, 70 pm, 75 pm, 80 pm, 85 pm, 90 pm, 95 pm, 100 pm, 105 pm, 110 pm, 115 pm, 120 pm, 125 pm, 130 pm, 135 pm, 140 pm, 145 pm, 150 pm, 155 pm, 160 pm, 165 pm, 170 pm, 175 pm, 180 pm, 185 pm, 190 pm, 195 pm, 200 pm, or the like.

[0099] In one or more optional embodiments above, the thickness of the tab is greater than or equal to 20 pm, which is conducive to the battery cell 100 having a higher energy density, and the thickness of the tab is less than or equal to 200 pm, which is conducive to the lithium ions in the battery cell 100 having a shorter migration distance, thereby improving the charge and discharge rate of the battery cell 100. Therefore, by setting the thickness of the tab within a reasonable range, the battery cell 100 can have both a higher energy density and a higher charge and discharge rate.

[0100] As shown in FIGS. 5 and 9, the thickness of the first outer tab 110 is D5, and the thickness of the second outer tab 210 group is D6, which satisfies: 0 < |D6-D5| ≤ 90 pm.

[0101] The absolute value of the difference between the thickness of the second outer tab 210 and the thickness of the first outer tab 110 can be any value between greater than 0 and less than or equal to 90 pm, for example, 1 pm, 5 pm, 10 pm, 15 pm, 20 pm, 25 pm, 30 pm, 35 pm, 40 pm, 45 pm, 50 pm, 55 pm, 60 pm, 65 pm, 70 pm, 75 pm, 80 pm, 85 pm, 90 pm, or the like.

[0102] In the one or more optional embodiments above, the absolute value of the difference between the thickness of the second outer tab 210 and the thickness of the first outer tab 110 is designed within a reasonable range, which is conducive to making the migration distance of lithium ions in the first tab group 1 and the second tab group 2 similar when the energy density of the battery cell 100 is high during the stacking of the tabs, so that the difficulty of activating lithium ions in the first tab group 1 and lithium ions in the second tab group 2 is similar when the input current of the battery cell 100 is constant, thereby reducing the risk that one of the first outer tab 110 and the second outer tab 210 is not fully utilized during use of the battery cell 100, resulting in the available capacity of the battery cell 100 being less than the designed capacity.

[0103] As shown in FIGS. 2-5, the thickness of the first positive current collector and the thickness of the second positive current collector are the same, and the thickness of the first negative current collector and the thickness of the second negative current collector are the same.

[0104] The thickness of the current collector needs to consider the processing tolerance, for example, when the thickness of two current collectors is between ±3 pm, the thickness of the two current collectors can be considered the same.

[0105] In the one or more optional embodiments above, the thickness of the first positive current collector and the thickness of the second positive current collector are the same, and the thickness of the first negative current collector and the thickness of the second negative current collector are the same. On the one hand, the distribution of current in the battery cell 100 can be more uniform, thereby improving the cycle life of the battery cell 100. On the other hand, when designing and processing tabs of different thicknesses, only the area density of the active material layer of the current collector needs to be changed, thereby reducing the processing difficulty of the battery cell 100.

[0106] As shown in FIGS. 2-5, the electrode assembly 10 satisfies one of the following conditions: the area density of the active material layer of the first positive tab 11 is 100 mg / mm 2 350 mg / mm 2 ; the area density of the active material layer of the first negative tab 12 is 50 mg / mm 2 150 mg / mm 2 ; the area density of the active material layer of the second positive tab 21 is 100 mg / mm 2 350 mg / mm 2 ; and the area density of the active material layer of the second negative tab 22 is 50 mg / mm 2 150 mg / mm 2 .

[0107] The area density of the active material layer of the first positive tab 11 can be any value greater than or equal to 100 mg / mm 2 less than or equal to 350 mg / mm 2 , for example, 100 mg / mm 2, 105 mg / mm 2 , 110 mg / mm 2 , 115 mg / mm 2 , 120 mg / mm 2 , 125 mg / mm 2 , 130 mg / mm 2 , 135 mg / mm 2 , 140 mg / mm 2 , 145 mg / mm 2 , 150 mg / mm 2 , 155 mg / mm 2 , 160 mg / mm 2 , 165 mg / mm 2 , 170 mg / mm 2 , 175 mg / mm 2 , 180 mg / mm 2 , 185 mg / mm 2 , 190 mg / mm 2 , 195 mg / mm 2 , 200 mg / mm 2 , 205 mg / mm 2 , 210 mg / mm 2 , 215 mg / mm 2 , 220 mg / mm 2 , 225 mg / mm 2 , 230 mg / mm 2 , 235 mg / mm 2 , 240 mg / mm 2 , 245 mg / mm 2 , 250 mg / mm 2 , 255 mg / mm 2 , 260 mg / mm 2 , 265 mg / mm 2 , 270 mg / mm 2 , 275 mg / mm 2 , 280 mg / mm 2 , 285 mg / mm 2 , 290 mg / mm 2 , 295 mg / mm 2 , 300 mg / mm 2 , 305 mg / mm 2 , 310 mg / mm 2 , 315 mg / mm 2 , 320 mg / mm 2 , 325 mg / mm 2 , 330 mg / mm2 335 mg / mm 2 340 mg / mm 2 345 mg / mm 2 350 mg / mm 2 etc.

[0108] The areal density of the active material layer of the first negative electrode tab 12 can be greater than or equal to 50 mg / mm 2 less than or equal to 150 mg / mm 2 any value between, for example, 50 mg / mm 2 55 mg / mm 2 60 mg / mm 2 65 mg / mm 2 70 mg / mm 2 75 mg / mm 2 80 mg / mm 2 85 mg / mm 2 90 mg / mm 2 95 mg / mm 2 100 mg / mm 2 105 mg / mm 2 110 mg / mm 2 115 mg / mm 2 120 mg / mm 2 125 mg / mm 2 130 mg / mm 2 135 mg / mm 2 140 mg / mm 2 145 mg / mm 2 150 mg / mm 2 etc.

[0109] The areal density of the active material layer of the second positive electrode tab 21 can be greater than or equal to 100 mg / mm 2 less than or equal to 350 mg / mm 2 any value between, for example, 100 mg / mm 2 105 mg / mm 2 110 mg / mm 2 115 mg / mm 2 120 mg / mm 2 125 mg / mm 2 130 mg / mm 2 135 mg / mm 2 140 mg / mm 2 145 mg / mm 2 150 mg / mm2 155 mg / mm 2 160 mg / mm 2 165 mg / mm 2 170 mg / mm 2 175 mg / mm 2 180 mg / mm 2 185 mg / mm 2 190 mg / mm 2 195 mg / mm 2 200 mg / mm 2 205 mg / mm 2 210 mg / mm 2 215 mg / mm 2 220 mg / mm 2 225 mg / mm 2 230 mg / mm 2 235 mg / mm 2 240 mg / mm 2 245 mg / mm 2 250 mg / mm 2 255 mg / mm 2 260 mg / mm 2 265 mg / mm 2 270 mg / mm 2 275 mg / mm 2 280 mg / mm 2 285 mg / mm 2 290 mg / mm 2 295 mg / mm 2 300 mg / mm 2 305 mg / mm 2 310 mg / mm 2 315 mg / mm 2 320 mg / mm 2 325 mg / mm 2 330 mg / mm 2 335 mg / mm 2 340 mg / mm 2 345 mg / mm 2 350 mg / mm 2 and so on.

[0110] The face density of the active material layer of the second negative electrode tab 22 can be greater than or equal to 50 mg / mm 2 less than or equal to 150 mg / mm 2any value between 50 mg / mm 2 and 55 mg / mm 2 and 60 mg / mm 2 and 65 mg / mm 2 and 70 mg / mm 2 and 75 mg / mm 2 and 80 mg / mm 2 and 85 mg / mm 2 and 90 mg / mm 2 and 95 mg / mm 2 and 100 mg / mm 2 and 105 mg / mm 2 and 110 mg / mm 2 and 115 mg / mm 2 and 120 mg / mm 2 and 125 mg / mm 2 and 130 mg / mm 2 and 135 mg / mm 2 and 140 mg / mm 2 and 145 mg / mm 2 and 150 mg / mm 2 and the like.

[0111] In the above one or more optional embodiments, when the face density of the active material layer of the positive electrode tab is greater than or equal to 100 mg / mm 2 , the thickness of the active material layer of the positive electrode tab is greater, and the energy density of the battery cell 100 is greater. When the face density of the active material layer of the positive electrode tab is less than or equal to 350 mg / mm 2 , lithium ion migration is facilitated, and the battery cell 100 is facilitated to have a higher charge and discharge rate. Therefore, the face density of the active material layer of the positive electrode tab is set within a reasonable range, which is conducive to the battery cell 100 to have a higher energy density and a higher charge and discharge rate.

[0112] When the face density of the active material layer of the negative electrode tab is greater than or equal to 100 mg / mm 2 , the thickness of the active material layer of the negative electrode tab is greater, and the energy density of the battery cell 100 is greater. When the face density of the active material layer of the negative electrode tab is less than or equal to 350 mg / mm 2 , lithium ion migration is facilitated, and the battery cell 100 is facilitated to have a higher charge and discharge rate. Therefore, the face density of the active material layer of the negative electrode tab is set within a reasonable range, which is conducive to the battery cell 100 to have a higher energy density and a higher charge and discharge rate.

[0113] As shown in FIG. 3 and FIG. 7, the second end pole piece 101 in the second pole piece group 2 closest to the first pole piece group 1 includes a first region 301 overlapping the first pole piece group 1 and a second region 302 not overlapping the first pole piece group 1. Along the first direction X, the first region 301 is provided with an active material layer on both sides, and the second region 302 is provided with an active material layer only on the side away from the first pole piece group 1.

[0114] The second end pole piece 101 can be a positive pole piece or a negative pole piece.

[0115] In some embodiments, the current collector of the second end pole piece 101 includes a first metal layer, an insulating separation layer, and a second metal layer, the first metal layer is arranged on the side of the insulating separation layer facing the first pole piece group 1, and the second metal layer is arranged on the side of the insulating separation layer away from the first pole piece group 1. With such an arrangement, the sum of the thickness of the first metal layer and the active material on the side of the first metal layer 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 of the second metal layer facing the second pole piece group 2 can be flexibly designed during the stacking of the pole pieces, thereby enabling the second end pole piece 101 to flexibly adapt to the variable cross-section position of the shaped battery cell 100, reducing the risk of excessive gap between the electrode assembly 10 and the variable cross-section position, fully utilizing the internal space of the shaped battery cell 100, and reducing the loss of energy density.

[0116] In some embodiments, as shown in FIG. 10, the shell 20 includes a first wall 201 and a second wall 202 oppositely arranged along the 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. The first sub-wall 2011, the second wall 202, and the first connecting wall 2013 collectively 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 collectively 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 on the side of the first region 301 close to the first pole piece group 1 can be located in the first accommodating cavity or the second accommodating cavity.

[0117] In one or more optional embodiments above, the second tab group 2 has a dimension in the second direction Y that is greater than a dimension of the first tab group 1 in the second direction Y, the second tab group 2 includes a second end tab 101 closest to the first tab group 1, and the second end tab 101 includes a first region 301 that overlaps the first tab group 1 and a second region 302 that does not overlap the first tab group 1. In the first direction X, the first region 301 has active material layers on both sides, and the second region 302 has an active material layer on only one side facing away from the first tab group 1. On the one hand, the first region 301 has active material layers on both sides, and the active material layer on the side of the first region 301 facing the first tab group 1 can serve as an outermost tab of the first tab group 1, equivalent to the outermost tab of the first tab group 1 and the outermost tab of the second tab group 2 sharing one current collector, compared to the scheme of bonding the current collector of the single-sided active material layer tab of the outermost tab of the second tab group 2 and the current collector of the single-sided active material layer tab of the outermost tab of the first tab group 1 through the adhesive layer, this scheme 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 to the scheme of bonding the current collector of the single-sided active material layer tab of the outermost tab of the second tab group 2 and the current collector of the single-sided active material layer tab of the outermost tab of the first tab group 1 through the adhesive layer, this scheme reduces the number of single-sided active material layer tabs in the battery cell 100 by providing the second end tab 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, to alleviate the problem of warping and rolling, the thickness of the current collector of the single-sided active material layer tab is relatively large, which also leads to a loss of energy density of the battery cell 100. In this scheme, the current collector of the second end tab 101 in the battery cell 100 has active material layers on both sides, and the active material layers on both sides of the current collector of the second end tab 101 can offset the stress, reducing the risk of warping and rolling of the second end tab 101, and allowing the thickness of the current collector of the second end tab 101 to be smaller than that of the current collector of the single-sided active material layer tab, 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 tab 101 has an active material layer on only one side facing away from the first tab group 1, reducing the amount of active material that does not contribute to capacity and avoiding the occupation of space by the active material that does not contribute to capacity, further reducing the energy density loss of the battery cell 100 in the first direction X. Therefore, compared to the scheme of bonding the single-sided active material layer tab closest to the first tab group 1 of the second tab group 2 and the single-sided active material layer tab closest to the second tab group 2 of the first tab group 1 through the adhesive layer, the battery cell 100 of this scheme has a higher energy density.

[0118] As shown in FIG. 10, the shell 20 includes a first wall 201 and a second wall 202 oppositely arranged along the first direction X, the first wall 201 including a first sub-wall 2011, a second sub-wall 2012, and a first connecting wall 2013, the first sub-wall 2011 protruding from the second sub-wall 2012 in a direction away from the second wall 202, and the first connecting wall 2013 connecting the first sub-wall 2011 and the second sub-wall 2012. A portion of the second tab group 2 is located between the second sub-wall 2012 and the second wall 202, and the first tab group 1 is located between the second tab group 2 and the first sub-wall 2011.

[0119] In some embodiments, a plurality of first sub-walls 2011 are provided. The shell 20 has a plurality of protrusions arranged at intervals. The protrusions are first sub-walls 2011 away from the wall portion of the second tab group 2.

[0120] In one or more optional embodiments above, 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 shell 20 is stepped, so as to facilitate the application of the battery cell 100 to limited assembly space and increase the adaptation range of the battery cell 100.

[0121] As shown in FIG. 10, along the first direction X, the distance between the first sub-wall 2011 and the second sub-wall 2012 is L, which satisfies: 0.2mm≤L≤5mm.

[0122] 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 0.2mm and less than or equal to 5mm, for example, 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3mm, 3.2mm, 3.4mm, 3.6mm, 3.8mm, 4mm, 4.2mm, 4.4mm, 4.6mm, 4.8mm, 5mm, etc.

[0123] 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 sufficient space between the first sub-wall 2011 and the second pole piece group 2, which is conducive to making the first pole piece group 1 at least include a group of positive and negative pole pieces, reducing the risk of energy density loss caused by a large gap between the first pole piece group 1 and the first sub-wall 2011, so that the first pole piece group 1 can make full use of the space between the first sub-wall 2011 and the second pole piece group 2, and 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, so that the battery cell 100 has a lower risk of damage when subjected to impact or vibration, and the overall structural stability of the battery cell 100 is higher. Therefore, by setting the distance between the first sub-wall 2011 and the second sub-wall 2012 along the first direction X within a reasonable range, the battery cell 100 can have both a higher energy density and a higher structural stability.

[0124] As shown in FIG. 10, 0.2 mm ≤ L ≤ 1.5 mm.

[0125] The distance between the first sub-wall 2011 and the second sub-wall 2012 along the first direction X can be any value between 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.

[0126] 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 sufficient space between the first sub-wall 2011 and the second pole piece group 2, which is conducive to making the first pole piece group 1 at least include a group of positive and negative pole pieces, reducing the risk of energy density loss caused by a large gap between the first pole piece group 1 and the first sub-wall 2011, so that the first pole piece group 1 can make full use of the space between the first sub-wall 2011 and the second pole piece group 2, and 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 subjected to impact or vibration, and further improve the overall structural stability of the battery cell 100. Therefore, by setting the distance between the first sub-wall 2011 and the second sub-wall 2012 along the first direction X within a reasonable range, the battery cell 100 can have both a higher energy density and a higher structural stability.

[0127] The application further provides a power utilization device, which comprises the battery cell 100 provided by any of the above embodiments.

[0128] The battery cell 100 provided by the above embodiments has a high energy density, which is beneficial to improving the power utilization reliability of the power utilization device powered by the battery cell 100.

[0129] The above merely provides the preferred embodiments of the application, but is not intended to limit the application. For those skilled in the art, the application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. An electric cell, characterized by, The battery includes a shell and an electrode assembly accommodated in the shell, the electrode assembly being a laminated structure; The electrode assembly includes a first electrode plate group and a second electrode plate group, the first electrode plate group and the second electrode plate group are arranged along a first direction, and the length of the second electrode plate group is greater than the length of the first electrode plate group along a second direction perpendicular to the first direction; The first electrode plate group includes a first positive electrode plate and a first negative electrode plate arranged in a laminated manner along the first direction, and the second electrode plate group includes a second positive electrode plate and a second negative electrode plate arranged in a laminated manner along the first direction; The first positive electrode plate includes a first positive electrode current collector, the first negative electrode plate includes a first negative electrode current collector, the second positive electrode plate includes a second positive electrode current collector, and the second negative electrode plate includes a second negative electrode current collector, and the two surfaces of the first positive electrode current collector, the first negative electrode current collector, the second positive electrode current collector, and the second negative electrode current collector along the first direction are provided with active material layers; The thickness of the first positive electrode plate is different from the thickness of the second positive electrode plate, and the thickness of the first negative electrode plate is different from the thickness of the second negative electrode plate.

2. The electric cell of claim 1, wherein, 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.

3. The electric cell of claim 2, wherein, The first electrode plate group further includes a first outer electrode plate farthest from the second electrode plate group, and the first outer electrode plate includes a first outer electrode current collector provided with an active material layer on only one side facing the second electrode plate group; The second electrode plate group further includes a second outer electrode plate farthest from the first electrode plate group, and the second outer electrode plate includes a second outer electrode current collector provided with an active material layer on only one side facing the first electrode plate group; The first outer electrode plate and the second outer electrode plate have the same polarity. The thickness of the first outer electrode plate is less than the thickness of the second outer electrode plate.

4. The electric cell of claim 1, wherein, The thickness of the first positive electrode plate is greater than the thickness of the second positive electrode plate, and the thickness of the first negative electrode plate is greater than the thickness of the second negative electrode plate.

5. The electric cell of claim 4, wherein, The first electrode plate group further includes a first outer electrode plate farthest from the second electrode plate group, and the first outer electrode plate includes a first outer electrode current collector provided with an active material layer on only one side facing the second electrode plate group; The second electrode plate group further includes a second outer electrode plate farthest from the first electrode plate group, and the second outer electrode plate includes a second outer electrode current collector provided with an active material layer on only one side facing the first electrode plate group; The first outer electrode plate and the second outer electrode plate have the same polarity. The thickness of the first outer electrode plate is greater than the thickness of the second outer electrode plate.

6. The electric cell of any one of claims 1-5, wherein, The thickness of the first positive electrode plate is D1, the thickness of the first negative electrode plate is D2, the thickness of the second positive electrode plate is D3, and the thickness of the second negative electrode plate is D4; 0<|D3-D1|≤180μm, and 0<|D4-D2|≤180μm.

7. The electric cell of any one of claims 1-6, wherein, The thickness of the first positive electrode tab is D1, the thickness of the first negative electrode tab is D2, the thickness of the second positive electrode tab is D3, and the thickness of the second negative electrode tab is D4. The following conditions are met: 20 μm≤D1≤200 μm, 20 μm≤D2≤200 μm, 20 μm≤D3≤200 μm, and 20 μm≤D4≤200 μm.

8. The cell of claim 3 or 5, wherein, The thickness of the first outer tab is D5, and the thickness of the second outer tab group is D6, and the following condition is met: 0<|D6-D5|≤90 μm.

9. The electric cell of any one of claims 1-8, wherein, The thickness of the first positive current collector is the same as the thickness of the second positive current collector, and the thickness of the first negative current collector is the same as the thickness of the second negative current collector.

10. The electric cell of any one of claims 1-9, wherein, The electrode assembly meets one of the following conditions: (1) the areal density of the active material layer of the first positive electrode tab is 100 mg / mm 2 ~ 350 mg / mm 2 ; (2) the areal density of the active material layer of the first negative electrode sheet is 50 mg / mm 2 ~ 150 mg / mm 2 ; (3) the face density of the active material layer of the second positive electrode tab is 100 mg / mm 2 ~ 350 mg / mm 2 ; (4) the face density of the active material layer of the second negative electrode sheet is 50 mg / mm 2 ~ 150 mg / mm 2 .

11. The electric cell of any one of claims 1-10, wherein, The second tab group closest to the first tab group in the second tab group is a second end tab, and the second end tab includes a first region overlapping the first tab group and a second region not overlapping the first tab group. Along the first direction, the first region is provided with an active material layer on both sides, and the second region is provided with an active material layer only on one side away from the first tab group.

12. The electric cell of any one of claims 1-11, wherein, The housing includes a first wall and a second wall arranged opposite to each other along the 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 part of the second tab group is located between the second sub-wall and the second wall, and the first tab group is located between the second tab group and the first sub-wall.

13. The electric cell of claim 12, wherein, Along the first direction, the distance between the first sub-wall and the second sub-wall is L, and the following condition is met: 0.2 mm≤L≤5 mm.

14. The electric cell of claim 13, wherein, 0.2 mm≤L≤1.5 mm.

15. An electrical device, characterized by An electric cell as claimed in any one of claims 1-14 is used to provide electrical energy.

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