Battery cell and electric device

Abstract

The application discloses an electric core and an electric device, and belongs to the technical field of batteries. The electric core comprises a shell and an electrode assembly, the electrode assembly is accommodated in the shell, and the electrode assembly is in a laminated structure. The electrode assembly comprises a first pole piece group and a second pole piece group, the first pole piece group and the second pole piece group are arranged along a first direction, along a second direction, the length of the second pole piece group is greater than that of the first pole piece group, the first pole piece group comprises a first positive pole piece and a first negative pole piece which are arranged in a laminated mode along the first direction, and the second pole piece group comprises a second positive pole piece and a second negative pole piece which are arranged in a laminated mode along the first direction. The two surfaces of the first positive pole current collector, the first negative pole current collector, the second positive pole current collector and the second negative pole current collector along the first direction are all provided with active material layers. 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 electric core has a high energy density.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a battery cell and a power consumption device. BACKGROUND

[0002] 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 put forward for the energy density of battery cells.

[0003] How to improve the energy density of battery cells is a problem to be solved in battery technology. SUMMARY

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

[0005] In a first aspect, the embodiments of the present application provide a battery cell, which 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 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 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 comprises 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 comprises a second positive electrode sheet and a second negative electrode sheet arranged in a stack along the first direction; the first positive electrode sheet comprises a first positive electrode current collector, the first negative electrode sheet comprises a first negative electrode current collector, the second positive electrode sheet comprises a second positive electrode current collector, and the second negative electrode sheet comprises a second negative electrode current collector; 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 are each provided with an active material layer on two 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.

[0006] 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 that two battery cells need to be arranged, 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.

[0007] 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.

[0008] 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, due to the length of the second electrode tab set being 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 smaller number of stacked layers of electrode tabs in the second electrode tab set 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.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] In some embodiments of the first aspect of the application, the first positive pole piece has a thickness of D1, the first negative pole piece has a thickness of D2, the second positive pole piece has a thickness of D3, and the second negative pole piece has a thickness of D4; and the following conditions are met: 0 < |D3-D1| ≤ 180 μm, and 0 < |D4-D2| ≤ 180 μm.

[0016] 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.

[0017] In some embodiments of the first aspect of the present 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 pm≤D1≤200 pm, 20 pm≤D2≤200 pm, 20 pm≤D3≤200 pm, and 20 pm≤D4≤200 pm.

[0018] In one or more optional embodiments above, the thickness of the electrode tab is greater than or equal to 20 pm, which is conducive to making the battery cell have a higher energy density, and the thickness of the electrode tab is less than or equal to 200 pm, which is conducive to making the lithium ions in the battery cell have 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.

[0019] In some embodiments of the first aspect of the present 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 pm.

[0020] In one or more optional embodiments 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 within a reasonable range, which is conducive to making the battery cell have a higher energy density while making the migration distances of the lithium ions in the first electrode tab group and the second electrode tab group similar during the process of stacking 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.

[0021] In some embodiments of the first aspect of the present application, 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.

[0022] In 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, 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.

[0023] In some embodiments of the first aspect of the present 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 ~150mg / mm 2 ; the areal density of the active material layer of the second positive electrode tab is 100 mg / mm 2 ~350mg / mm 2 ; the areal density of the active material layer of the second negative electrode tab is 50 mg / mm 2 ~150mg / mm 2 .

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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: 0.2 mm≤L≤5 mm.

[0032] 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 0.2 mm, so as to provide sufficient space between the first sub-wall and the second tab group, which is conducive to making the first tab group comprise at least one group of positive and negative tab groups during the tab stacking process, reducing the risk of energy density loss caused by a large gap between the first tab group and the first sub-wall, so as to make the first tab group fully utilize the space between the first sub-wall and the second tab group, and 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 5 mm, 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.

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

[0034] In 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 there is sufficient space between the first sub-wall and the second pole piece group, which is conducive to making the first pole piece group include at least a group of positive pole pieces and negative pole pieces during the pole piece stacking process, reducing the risk of energy density loss caused by a large gap between the first pole piece group and the first sub-wall, so that the first pole piece group can fully utilize the space between the first sub-wall and the second pole piece group, 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, and further improve 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.

[0035] In a second aspect, the application provides a use of the battery cell provided by any of the above embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0036] 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 regarded as a limitation on the scope.

[0037] Figure 1 A structural schematic diagram of a battery cell provided by some embodiments of the application;

[0038] Figure 2 A sectional view of an electrode assembly provided by some embodiments of the application;

[0039] Figure 3 A sectional view of an electrode assembly provided by some embodiments of the application; Figure 2 A partial enlarged view of position A in FIG. 1;

[0040] Figure 4 A sectional view of an electrode assembly provided by some embodiments of the application;

[0041] Figure 5 A sectional view of an electrode assembly provided by some embodiments of the application; Figure 4 A partial enlarged view of position B in FIG. 2;

[0042] Figure 6 A sectional view of an electrode assembly provided by some embodiments of the application;

[0043] Figure 7 A sectional view of an electrode assembly provided by some embodiments of the application; Figure 6 A partial enlarged view of position C in FIG. 3;

[0044] Figure 8 A sectional view of an electrode assembly provided by some embodiments of the application;

[0045] Figure 9 Fig. 1 is a schematic view of a battery cell according to an embodiment of the application. Figure 8 Fig. 2 is a partial enlarged view of the middle D of Fig. 1.

[0046] Figure 10 Fig. 3 is a sectional view of an electric cell provided for some embodiments of the application.

[0047] The reference signs in the detailed description of the embodiments are listed as follows:

[0048] 100 - electric cell; 10 - electrode assembly; 1 - first pole piece group; 11 - first positive pole piece; 110 - first outer pole piece; 12 - first negative pole piece; 2 - second pole piece group; 21 - second positive pole piece; 210 - second outer pole piece; 22 - second negative pole piece; 101 - second end pole piece; 301 - first region; 302 - second region; 20 - shell; 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 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 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 can be arranged and designed in various different configurations.

[0050] It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0051] It should be noted that: similar reference signs 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.

[0052] 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 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 is not intended to indicate or imply that the indicated device or element must have a particular position, be constructed and operated in a particular position, and therefore cannot be understood as a limitation on 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.

[0053] At present, from the development of market situation, the application of battery cell is more and more widely. Battery cell is widely used in electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, electric tools, unmanned aerial vehicles, energy storage equipment and other fields. With the continuous expansion of the application field of battery cell, the demand of its market is also increasing.

[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 winding type battery cell and a laminated battery cell. The electrode assembly of the laminated battery cell includes 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 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 insufficient to arrange a group of positive and negative polar plates, there will be excessive gap between the electrode assembly and the shell, resulting in loss of energy density of the battery cell. For some space-limited and complex electric equipment, in order to avoid interference between the battery cell and the wall of the battery compartment or other components of the electric equipment, the shape of the shell is designed to be special-shaped, such as stepped shape, etc. 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 excessive loss of energy density of the battery cell.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] As shown in Figures 1-9 The present application provides 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.

[0059] 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.

[0060] 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.

[0061] 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, the first electrode tab group 1 and the second electrode tab group 2 are arranged along a first direction X, and the length of the second electrode tab group 2 is greater than the length of the first electrode tab group 1 along a second direction Y, 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 electric core 100. In other embodiments, the first direction X is the thickness direction of the laminated electric core 100.

[0063] 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 for insulating and separating the any two adjacent electrode tabs with opposite polarities in the first electrode tab group 1.

[0064] 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, and 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 not playing 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.

[0065] 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.

[0066] 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.

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

[0068] 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).

[0069] 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.

[0070] 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.

[0071] The positive tab includes a positive current collector and a positive active material layer. The positive current collector has at least one side 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. The negative current collector has at least one side 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.

[0072] 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.

[0073] 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, thereby facilitating 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 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 are required, 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 a 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 requirements, so that the battery cell 100 is suitable for electrical equipment with different requirements.

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

[0075] The thickness of the first negative electrode 12 is less than the thickness of the second negative electrode 22, meaning that the thickness of any one of the first negative electrode 12 is less than the thickness of any one of the second negative electrode 22.

[0076] Because the length of the second electrode group 2 is greater than that of the first electrode group 1 along the second direction Y, the area of ​​the electrodes in the second electrode group 2 that can be coated with active material is larger. Therefore, a higher energy density can be achieved by using fewer stacked electrode layers in the second electrode group 2. This reduces the risk of energy density loss due to excessive current collectors in the second electrode group 2 caused by excessive electrode stacking. In other words, the space within the cell 100 is utilized as much as possible by the active material layers, while reducing the space occupied by the current collectors.

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

[0078] like Figures 2-5 As shown, the first electrode group 1 further includes a first outer electrode 110 that is furthest from the second electrode group 2. The first outer electrode 110 includes a first outer current collector, and the first outer current collector has an active material layer only on the side facing the second electrode group 2. The second electrode group 2 further includes a second outer electrode 210 that is furthest from the first electrode group 1. The second outer electrode 210 includes a second outer current collector, and the second outer current collector has an active material layer only on the side facing the first electrode group 1. The first outer electrode 110 and the second outer electrode 210 have the same polarity. The thickness of the first outer electrode 110 is less than the thickness of the second outer electrode 210.

[0079] The first outer electrode 110 can be either a positive or negative electrode. The second outer electrode 210 can also be either a positive or negative electrode. The polarity of the first outer electrode 110 is opposite to that of the electrode closest to it on the side facing the second electrode group 2. The polarity of the second outer electrode 210 is opposite to that of the electrode closest to it on the side facing the first electrode group 1. In some embodiments, such as Figure 5As shown, both the first outer electrode 110 and the second outer electrode 210 are positive electrodes, and the thickness of the first outer electrode 110 is less than the thickness of the second outer electrode 210.

[0080] In one or more of the above optional embodiments, since the first outer current collector has an active material layer only on the side facing the second electrode group 2, and the second outer current collector has an active material layer only on the side facing the first electrode group 1, that is, the first outer current collector and the second current collector only have active material layers on the side where they exert their capacity, which is beneficial to enable the cell 100 to have a higher energy density. Since the thickness of the first outer electrode 110 is less than the thickness of the second outer electrode 210, suitable first outer electrode 110 and second outer electrode 210 can be selected to allow the first electrode group 1 and the second electrode group 2 to fully utilize the internal space of the casing 20, further improving the energy density of the cell 100. At the same time, since the thickness of the first positive electrode 11 is less than the thickness of the second positive electrode 21, and the thickness of the first negative electrode 12 is less than the thickness of the second negative electrode 22, setting the thickness of the first outer electrode 110 to be less than the thickness of the second outer electrode 210 is beneficial to simultaneously design and process all electrodes in the first electrode group 1 and simultaneously process all electrodes in the second electrode group 2.

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

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

[0083] In one or more of the above optional embodiments, the thickness of the first positive electrode 11 is greater than the thickness of the second positive electrode 21, and the thickness of the first negative electrode 12 is greater than the thickness of the second negative electrode 22. This design allows the first electrode group 1 to have a higher energy density and the second electrode group 2 to have a higher charge and discharge rate, enabling the battery cell 100 to achieve both a high charge and discharge rate and a high energy density.

[0084] like Figures 6-9As shown, the first electrode group 1 further includes a first outer electrode 110 that is furthest from the second electrode group 2. The first outer electrode 110 includes a first outer current collector, and the first outer current collector has an active material layer only on the side facing the second electrode group 2. The second electrode group 2 further includes a second outer electrode 210 that is furthest from the first electrode group 1. The second outer electrode 210 includes a second outer current collector, and the second outer current collector has an active material layer only on the side facing the first electrode group 1. The first outer electrode 110 and the second outer electrode 210 have the same polarity. The thickness of the first outer electrode 110 is greater than the thickness of the second outer electrode 210.

[0085] The first outer electrode 110 can be either a positive or negative electrode. The second outer electrode 210 can also be either a positive or negative electrode. The polarity of the first outer electrode 110 is opposite to that of the electrode closest to it on the side facing the second electrode group 2. The polarity of the second outer electrode 210 is opposite to that of the electrode closest to it on the side facing the first electrode group 1. In some embodiments, such as Figure 9 As shown, both the first outer electrode 110 and the second outer electrode 210 are positive electrodes, and the thickness of the first outer electrode 110 is greater than the thickness of the second outer electrode 210.

[0086] In one or more of the above optional embodiments, since the first outer current collector has an active material layer only on the side facing the second electrode group 2, and the second outer current collector has an active material layer only on the side facing the first electrode group 1, that is, the first outer current collector and the second current collector only have active material layers on the side where they exert their capacity, which is beneficial to enable the cell 100 to have a higher energy density. Since the thickness of the first outer electrode 110 is greater than the thickness of the second outer electrode 210, suitable first outer electrode 110 and second outer electrode 210 can be selected to allow the first electrode group 1 and the second electrode group 2 to fully utilize the internal space of the casing 20, further improving the energy density of the cell 100. At the same time, since the thickness of the first positive electrode 11 is greater than the thickness of the second positive electrode 21, and the thickness of the first negative electrode 12 is greater than the thickness of the second negative electrode 22, setting the thickness of the first outer electrode 110 to be greater than the thickness of the second outer electrode 210 is beneficial to simultaneously design and process all electrodes in the first electrode group 1 and simultaneously process all electrodes in the second electrode group 2.

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

[0088] 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, refer to Figure 3 and Figure 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, refer to Figure 7 and Figure 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.

[0089] 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.

[0090] 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 μm, for example, 1 μm, 5 μm, 10 μm, 15 μm, 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, etc.

[0091] 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 μm, for example, 1 μm, 5 μm, 10 μm, 15 μm, 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, etc.

[0092] In one or more of the above optional embodiments, designing the absolute value of the difference between the thickness of the second positive electrode 21 and the thickness of the first positive electrode 11, and the absolute value of the difference between the thickness of the second negative electrode 22 and the thickness of the first negative electrode 12, within a reasonable range is beneficial to ensure that the cell 100 has a high energy density during the electrode stacking process, while also making the migration distance of lithium ions in the first electrode group 1 and the second electrode group 2 similar. This ensures that when the input current of the cell 100 is constant, the difficulty of activating lithium ions in the first electrode group 1 and the second electrode group 2 is similar, reducing the risk that one of the first electrode group 1 and the second electrode group 2 may not be fully utilized during the use of the cell 100, resulting in the usable capacity of the cell 100 being less than the design capacity.

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

[0094] The thickness of the first positive electrode 11 can be any value between 20 μm and 200 μm, for example, 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.

[0095] The thickness of the first negative electrode 12 can be any value between 20 μm and 200 μm, for example, 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 second positive electrode 21 can be any value between 20 μm and 200 μm, for example, 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 negative electrode 22 can be any value between 20 μm and 200 μm, for example, 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.

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

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

[0100] The absolute value of the difference between the thickness of the second outer electrode 210 and the thickness of the first outer electrode 110 can be any value between 0 and 90 μm, such as 1 μm, 5 μm, 10 μm, 15 μm, 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, etc.

[0101] In one or more of the above optional embodiments, designing the absolute value of the difference between the thickness of the second outer electrode 210 and the thickness of the first outer electrode 110 within a reasonable range is beneficial to ensure that the cell 100 has a high energy density during the electrode stacking process, while also making the migration distance of lithium ions in the first electrode group 1 and the second electrode group 2 similar. This ensures that when the input current of the cell 100 is constant, the difficulty of activating lithium ions in the first electrode group 1 and the second electrode group 2 is similar, reducing the risk that one of the first outer electrode 110 and the second outer electrode 210 will not be fully utilized during the use of the cell 100, resulting in the usable capacity of the cell 100 being less than the design capacity.

[0102] like Figures 2-5 As shown, 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.

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

[0104] In one or more of the above optional embodiments, 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. On the one hand, this allows for a more uniform distribution of current in the cell 100, improving the cycle life of the cell 100. On the other hand, when designing and processing electrodes of different thicknesses, only the areal density of the active material layer of the current collector needs to be changed, reducing the processing difficulty of the cell 100.

[0105] like Figures 2-5 As shown, the electrode assembly 10 satisfies one of the following conditions: the areal density of the active material layer of the first positive electrode 11 is 100 mg / mm². 2 ~350mg / mm 2 The areal density of the active material layer of the first negative electrode 12 is 50 mg / mm². 2 ~150mg / mm 2 The areal density of the active material layer of the second positive electrode 21 is 100 mg / mm². 2 ~350mg / mm 2 The areal density of the active material layer of the second negative electrode 22 is 50 mg / mm². 2 ~150mg / mm 2 .

[0106] The areal density of the active material layer of the first positive electrode 11 can be greater than or equal to 100 mg / mm². 2 Less than or equal to 350 mg / mm2 any value between 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 / mm2 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 the like.

[0107] 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 and the like.

[0108] 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 / 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 / mm 2 , 335 mg / mm 2 , 340 mg / mm2 345 mg / mm 2 350 mg / mm 2 etc.

[0109] The areal 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 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.

[0110] In 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 100 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 , it is beneficial for lithium ion migration and for the battery cell 100 to have 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, 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 areal density of the active material layer of the negative electrode tab is greater than or equal to 100 mg / mm 2When the thickness of the active material layer of the negative electrode tab is large, the energy density of the battery cell 100 is large. When the areal density of the active material layer of the negative electrode tab is less than or equal to 350 mg / mm 2 When the areal density of the active material layer of the negative electrode tab is less than or equal to 350 mg / mm

[0112] As Figure 3 and Figure 7 The second end tab 101 in the second tab group 2 closest to the first tab group 1, and the second end tab 101 includes a first region 301 overlapping the first tab group 1 and a second region 302 not overlapping the first tab 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 tab group 1.

[0113] The second end tab 101 can be a positive electrode tab or a negative electrode tab.

[0114] In some embodiments, the current collector of the second end tab 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 tab group 1, and the second metal layer is arranged on the side of the insulating separation layer away from the first tab group 1. Such an arrangement can flexibly design 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 tab 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 tab group 2 during the stacking process of the tabs, thereby making the second end tab 101 flexibly adapt to the variable cross-section position of the special-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 special-shaped battery cell 100, and reducing the loss of energy density.

[0115] In some embodiments, as Figure 10As shown, 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 part 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. The first sub-wall 2011, the second wall 202, and the first connecting wall 2013 collectively define a first accommodating cavity, and the first tab 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 part of the second tab group 2 is located in the second accommodating cavity. In this embodiment, the active substance near the first tab group 1 side of the first region 301 can be located in the first accommodating cavity or the second accommodating cavity.

[0116] 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.

[0117] As shown in Figure 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 part 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, the first sub-wall 2011 is provided in plurality. The shell 20 has a plurality of protrusions arranged at intervals. The protrusions are the first sub-walls 2011 away from the wall part of the second pole piece group 2.

[0119] 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 in a stepped shape, 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.

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

[0121] The distance between the first sub-wall 2011 and the second sub-wall 2012 along the first direction X 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 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 include at least a group of positive and negative pole pieces during the pole piece stacking process, 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 risk of damage to the battery cell 100 when subjected to impact or vibration is lower, 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 conducive to making the battery cell 100 have a higher energy density and a higher structural stability.

[0123] As shown in Figure 10 0.2 mm≤L≤1.5 mm.

[0124] 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.

[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 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 include at least a group of positive and negative pole pieces during the pole piece stacking process, 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, 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 conducive to making the battery cell 100 have a higher energy density while further improving the overall structural stability of the battery cell 100.

[0126] The application also provides a power supply device, which comprises the power cell 100 provided by any of the above embodiments.

[0127] The power cell 100 provided by the above embodiments has a high energy density, which is beneficial to improving the power supply reliability of the power supply device supplied by the power cell 100.

[0128] 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 claim 1, 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 claim 1, 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 claim 1, 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 claim 1, wherein, The electrode assembly meets one of the following conditions: (1), the surface 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 areal density of the active material layer of the second positive electrode tab is 100 mg / mm 2 350 mg / mm 2 ; (4) The areal 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 claim 1, 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 claim 1, 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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