Battery cell, battery device, and electric device

Abstract

A battery cell, a battery device and a power utilization device are provided. The battery cell includes a positive electrode sheet including a positive electrode current collector and a positive electrode active material layer, the positive electrode current collector has a first surface provided with the positive electrode active material layer along a thickness direction of the positive electrode current collector. The positive electrode active material layer includes a main body region and a thinned region arranged along a width direction of the positive electrode sheet, the main body region has a thickness greater than that of the thinned region. The main body region has a second surface facing away from the positive electrode current collector, and the thinned region has a connecting surface connecting the first surface and the second surface. The positive electrode sheet includes an insulating layer including a first portion and a second portion, the first portion is arranged on the first surface and covers a part of the connecting surface, and the second portion is arranged on the connecting surface and is spaced apart from the first portion. The first portion and the second portion can play a protective role, reduce the risk of short circuit caused by contact between lithium dendrites and the thinned region during lithium precipitation, and improve the reliability of the battery cell.

Description

Technical Field

[0001] This application relates to the field of batteries, and more specifically, to a battery cell, a battery device, and an electrical device. Background Technology

[0002] Batteries are widely used in the new energy field, such as in electric vehicles and new energy vehicles, which have become a new trend in the automotive industry. The development of battery technology must consider multiple design factors simultaneously, such as energy density, discharge capacity, and charge / discharge rate. Furthermore, battery reliability must also be considered. However, current battery reliability is relatively poor. Summary of the Invention

[0003] The purpose of this application is to provide a battery cell, a battery device, and an electrical device, which aims to improve the problem of poor battery reliability in related technologies.

[0004] In a first aspect, embodiments of this application provide a battery cell, the battery cell including an electrode assembly, the electrode assembly including a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active material layer, the positive current collector having a first surface along the thickness direction of the positive current collector, the first surface having the positive active material layer disposed thereon, the positive active material layer including a main body region and a thinned region arranged along the width direction of the positive electrode sheet, the thickness of the main body region being greater than the thickness of the thinned region, at least one end of the main body region along the width direction being connected to the thinned region, the main body region having a second surface facing away from the positive current collector, the thinned region having a connecting surface, the connecting surface connecting the first surface and the second surface; wherein, the positive electrode sheet further includes an insulating layer, the insulating layer including a first portion and a second portion, the first portion being disposed on the first surface and covering a portion of the connecting surface, the second portion being disposed on the connecting surface and spaced apart from the first portion, so that active ions can be transported from the region between the first portion and the second portion.

[0005] In the above technical solution, the first part covers a portion of the connecting surface, and the second part is disposed on the connecting surface and spaced apart from the first part. On the one hand, both the first and second parts can protect the thinned area. When lithium plating occurs on the negative electrode sheet, they can, to a certain extent, prevent lithium dendrites from contacting the thinned area, reduce the risk of short circuits, and improve the reliability of the battery cell. On the other hand, the spacing between the first and second parts facilitates the transport of active ions from the area between the first and second parts to the negative electrode sheet, reducing the waste of capacity in the thinned area and contributing to a higher energy density in the battery cell.

[0006] As an optional technical solution in this application embodiment, the positive electrode sheet further includes a transition layer, which is disposed on the connection surface and located between the first part and the second part. The material of the transition layer includes the material of the insulating layer and the active material of the positive electrode active material layer.

[0007] In the above technical solution, by setting a transition layer between the first and second parts and covering the connection surface, the transition layer can protect the thinned area. When lithium plating occurs on the negative electrode, it can prevent lithium dendrites from contacting the thinned area to a certain extent, reducing the risk of short circuits and improving the reliability of the battery cell. Furthermore, active ions can also be transported from the transition layer to the negative electrode, which helps reduce the waste of capacity in the thinned area and contributes to a higher energy density for the battery cell.

[0008] As an optional technical solution in this application embodiment, the transition layer connects the first part and the second part.

[0009] In the above technical solution, the first part and the second part are connected by a transition layer, which helps to improve the protection effect on the thinned area and improve the reliability of the battery cell.

[0010] As an optional technical solution in this application embodiment, the transition layer is connected to the first part, and the connection surface forms an exposed area between the transition layer and the second part.

[0011] In the above technical solution, the transition layer is connected to the first part, and the connection surface forms an exposed area between the transition layer and the second part. This results in a shorter distance between the exposed area and the negative electrode sheet, which helps to shorten the ion path and reduce the risk of lithium plating. Furthermore, the presence of the exposed area facilitates the determination of the boundary position of the positive electrode active material layer during manufacturing.

[0012] As an optional technical solution in this application embodiment, the transition layer is connected to the second part, and the connection surface forms an exposed area between the transition layer and the first part.

[0013] In the above technical solution, the transition layer is connected to the second part, and the connection surface forms an exposed area between the transition layer and the first part. The exposed area is closer to the edge of the thinned area, which allows for more accurate determination of the boundary position of the positive electrode active material layer during manufacturing. In addition, active ions can also be transported from the exposed area to the negative electrode sheet, which helps to reduce the waste of capacity in the thinned area and helps to enable the battery cell to have a higher energy density.

[0014] As an optional technical solution in this application embodiment, the positive electrode sheet includes a plurality of transition layers, the plurality of transition layers including a first transition layer and a second transition layer, the first transition layer being connected to the first portion, the second transition layer being connected to the second portion, and the connection surface forming an exposed area between the first transition layer and the second transition layer.

[0015] In the above technical solution, the first transition layer is connected to the first part, and the second transition layer is connected to the second part. This results in a larger area covered by the transition layers, which is beneficial for improving the protection of the thinned area and enhancing the reliability of the battery cell. The connection surface forms an exposed area between the first and second transition layers. During manufacturing, the boundary position of the positive electrode active material layer can be determined by the location of this exposed area. Furthermore, active ions can also be transported from the exposed area to the negative electrode, which helps reduce the waste of capacity in the thinned area and contributes to a higher energy density in the battery cell.

[0016] As an optional technical solution in this application embodiment, along the width direction, the size of the first transition layer is X1, the size of the exposed area is X2, and the size of the second transition layer is X3, satisfying: X1+X2+X3≤10mm, and optionally, X1+X2+X3≤2mm.

[0017] In the above technical solution, when X1+X2+X3≤10mm, the sum of the size of the first transition layer, the size of the exposed area, and the size of the second transition layer is smaller, which is beneficial to a higher energy density of the battery cell. When X1+X2+X3≤2mm, the sum of the size of the first transition layer, the size of the exposed area, and the size of the second transition layer is even smaller, which is beneficial to a higher energy density of the battery cell.

[0018] As an optional technical solution in this application embodiment, X1≤3mm.

[0019] In the above technical solution, when X1≤3mm, the size of the first transition layer is smaller, which is beneficial to the better dynamics of active ions in the thinned area and to the higher energy density of the battery cell.

[0020] As an optional technical solution in this application embodiment, X2≤2mm.

[0021] In the above technical solution, when X2≤2mm, the size of the exposed area is small. When lithium plating occurs on the negative electrode sheet, the risk of short circuit caused by lithium dendrites contacting the exposed area is low, which is beneficial to improving the reliability of the battery cell.

[0022] As an optional technical solution in this application embodiment, X3≤3mm.

[0023] In the above technical solution, when X3≤3mm, the size of the second transition layer is smaller, which is beneficial to the better dynamics of active ions in the thinned area and to the higher energy density of the battery cell.

[0024] As an optional technical solution in this application embodiment, the minimum distance between the exposed area and the first surface is H1, and the thickness of the main body area is H2, satisfying: 0.4≤H1 / H2≤0.6.

[0025] In the above technical solution, when H1 / H2≥0.4, the minimum distance between the exposed area and the first surface is relatively large, which is beneficial to shorten the ion path and reduce the risk of lithium plating. When H1 / H2≤0.6, the minimum distance between the exposed area and the first surface is not too large, and the boundary position of the positive electrode active material layer can be more accurately determined by the position of the exposed area during manufacturing.

[0026] As an optional technical solution in this application embodiment, along the direction from the positive current collector to the positive active material layer, the first part, the transition layer and the second part do not extend beyond the second surface.

[0027] In the above technical solution, by ensuring that the first part, the transition layer and the second part do not extend beyond the second surface in the direction from the positive current collector to the positive active material layer, it is beneficial to make the second surface closer to the negative electrode, thereby shortening the ion path and reducing the risk of lithium plating.

[0028] As an optional technical solution in this application embodiment, the connecting surface forms an exposed area between the first part and the second part.

[0029] In the above technical solution, by forming an exposed area between the first and second parts on the connecting surface, the boundary position of the positive electrode active material layer can be more accurately determined during manufacturing by the location of the exposed area. Furthermore, active ions can also be transported from the exposed area to the negative electrode, which helps reduce the waste of capacity in the thinned area and contributes to a higher energy density in the battery cell.

[0030] As an optional technical solution in this application embodiment, the width of the second part along the width direction is X4, satisfying: X4≤3mm, and optionally, X4≤1mm.

[0031] In the above technical solution, when X4 ≤ 3 mm, the width of the second part along the width direction is smaller, which helps to reduce the risk that the second part extends beyond the second surface in the direction from the positive current collector to the positive active material layer. When X4 ≤ 1 mm, the width of the second part along the width direction is even smaller, which further helps to reduce the risk that the second part extends beyond the second surface in the direction from the positive current collector to the positive active material layer.

[0032] As an optional technical solution in this application embodiment, the battery cell further includes an electrolyte, a portion of which is contained within the first portion and / or the second portion.

[0033] In the above technical solution, by containing a portion of the electrolyte within the first and / or second portions, the first and / or second portions can transport active ions to a certain extent, which helps to reduce the waste of capacity in the thinned area and helps to give the battery cell a higher energy density.

[0034] As an optional technical solution in this application embodiment, the connecting surface includes a first arc surface, a first plane and a second arc surface connected in sequence. The first arc surface is connected to the first surface, the second arc surface is connected to the second surface, the first part covers at least a part of the first arc surface, and the second part is disposed on the second arc surface.

[0035] In the above technical solution, lithium dendrites can more easily come into contact with the thinned area from the first arc surface and the second arc surface. By making the first part cover the first arc surface and the second part set on the second arc surface, the blocking effect on lithium dendrites is better, which is conducive to further reducing the risk of short circuit and improving the reliability of the battery cell.

[0036] As an optional technical solution in this application embodiment, the first part includes a first region disposed on the first surface and a second region disposed on the connecting surface. The first region and the second region are connected and arranged along the width direction, and the thickness of the first region is greater than the thickness of the second region.

[0037] In the above technical solutions, when the positive electrode current collector comes into contact with lithium dendrites and a short circuit occurs, a large amount of heat is generated, which can easily lead to fire and explosion, representing the most severe short circuit mode. By setting the first region on the first surface and making the thickness of the first region greater than the thickness of the second region, the blocking effect on lithium dendrites is better, which helps to further reduce the risk of short circuits and improve the reliability of the battery cell.

[0038] As an optional technical solution in this application embodiment, the electrode assembly includes a positive electrode tab, which is disposed at one end of the positive current collector along the width direction, and the first region covers a portion of the positive electrode tab.

[0039] In the above technical solution, by covering part of the positive electrode tab with the first region, it is beneficial to reduce the risk of short circuit caused by burrs on the electrode tab piercing the insulating element and coming into contact with the negative electrode plate when the electrode tab is folded.

[0040] As an optional technical solution in this application embodiment, the thickness of the first region is H3, which satisfies: 3μm≤H3≤50μm, and optionally, 3μm≤H3≤30μm.

[0041] In the above technical solution, when H3 ≥ 3 μm, the thickness of the first region is relatively large, which is beneficial for covering the burrs on the tabs and reducing the risk of short circuits caused by the burrs on the tabs piercing the insulating component and contacting the negative electrode plate when the tabs are folded. When H3 ≤ 50 μm, the thickness of the first region is not too large, which facilitates the cutting of the tabs.

[0042] When H3 ≥ 3 μm, the thickness of the first region is relatively large, which helps to cover the burrs on the tabs and reduces the risk of short circuits caused by the burrs piercing the separator and contacting the negative electrode plate when the tabs are folded. When H3 ≤ 30 μm, the thickness of the first region is not too large, which facilitates the cutting of the tabs.

[0043] As an optional technical solution in this application embodiment, in a cross section perpendicular to the length direction of the positive electrode sheet, the cross-sectional area of ​​the second region is A1, and the cross-sectional area of ​​the portion of the thinned region located between the second region and the positive current collector is A2, satisfying: 0.01≤A2 / (A1+A2)<1, optionally, 0.2≤A2 / (A1+A2)≤0.8.

[0044] In the above technical solutions, when 0.01≤A2 / (A1+A2)<1, it provides good protection for the thinned area while reducing the waste of capacity in the thinned area, which is beneficial for the battery cell to have a higher energy density, resulting in higher reliability and energy density. When 0.2≤A2 / (A1+A2)≤0.8, it can better balance the reliability and energy density of the battery cell.

[0045] Secondly, embodiments of this application also provide a battery device, which includes the aforementioned battery cell.

[0046] Thirdly, embodiments of this application also provide an electrical device, which includes the aforementioned battery cell, and the battery cell is used to provide electrical energy to the electrical device. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0049] Figure 2Exploded views of battery devices provided in some embodiments of this application;

[0050] Figure 3 This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0051] Figure 4 Exploded views of a single battery cell provided in some embodiments of this application;

[0052] Figure 5 This is a schematic diagram of the structure of an electrode assembly provided in some embodiments of this application;

[0053] Figure 6 Cross-sectional views of the positive electrode sheet provided in some embodiments of this application;

[0054] Figure 7 Cross-sectional views of the positive electrode sheet provided in other embodiments of this application;

[0055] Figure 8 A cross-sectional view of the positive electrode sheet provided in some embodiments of this application;

[0056] Figure 9 A cross-sectional view of the positive electrode sheet provided in some embodiments of this application;

[0057] Figure 10 This is a top view of the unfolded positive electrode sheet provided in some embodiments of this application;

[0058] Figure 11 This application also provides cross-sectional views of positive electrode sheets in some embodiments.

[0059] Icons: 10-Box body; 11-First box body; 12-Second box body; 20-Battery cell; 21-Outer shell; 211-Shell; 212-End cap; 22-Electrode assembly; 221-Main body; 222-Taper; 223-Negative electrode; 224-Positive electrode; 2241-Positive current collector; 22411-First surface; 2242-Positive active material layer; 22421-Main body area; 22422-Thinned area; 2243-Second surface; 2244-Connection surface; 2244 1-Exposed area; 22442-First arc surface; 22443-First plane; 22444-Second arc surface; 2245-Positive electrode tab; 225-Separator; 23-Insulating layer; 231-First part; 2311-First area; 2312-Second area; 232-Second part; 24-Transition layer; 241-First transition layer; 242-Second transition layer; 25-Electrode terminal; 27-Insulating component; 100-Battery device; 200-Controller; 300-Motor; 1000-Vehicle. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0061] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0062] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0063] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0064] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0065] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0066] In this application, "multiple" means two or more (including two).

[0067] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0068] Battery cells include, but are not limited to, lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0069] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, reduces the risk of short circuits while allowing active ions to pass through.

[0070] In some embodiments, the positive electrode can be a positive electrode sheet, which may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector.

[0071] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0072] As an example, the positive electrode current collector can be a foil or a composite current collector. For example, as a foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0073] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials in battery cells may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0074] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloys, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal can also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0075] In some embodiments, the negative electrode can be a negative electrode sheet, and the negative electrode sheet can include a negative current collector.

[0076] As an example, the negative electrode current collector can be a foil, a foamed metal, or a composite current collector. For example, as a foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, or titanium, etc. The foamed metal can be nickel foam, copper foam, aluminum foam, foam alloy, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0077] As an example, the negative electrode sheet may include a negative current collector and a negative active material disposed on at least one surface of the negative current collector.

[0078] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0079] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials in battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0080] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0081] In some embodiments, the separator is a separator membrane. The separator membrane can be any known porous structure separator membrane with good chemical and mechanical stability.

[0082] As an example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. The separator may be a separate component located between the positive and negative electrodes, or it may be attached to the surfaces of the positive and negative electrodes.

[0083] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0084] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include electrolyte salts and solvents.

[0085] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0086] In some embodiments, the solvent may include at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0087] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0088] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0089] As an example, polymer solid electrolytes can be polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0090] As an example, inorganic solid electrolytes may include one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphate sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0091] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0092] In some embodiments, the electrode assembly is a wound structure. The positive electrode and the negative electrode are wound into a wound structure.

[0093] In some implementations, the electrode assembly is a stacked structure.

[0094] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0095] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0096] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0097] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0098] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0099] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0100] In some implementations, the electrode assembly has tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0101] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, or a composite metal (such as a copper-aluminum composite housing).

[0102] In some embodiments, the housing can be a sealed structure or a non-sealed structure. As an example, when the housing is a sealed structure, it can protect the electrode assembly and prevent, to some extent, electrolyte leakage. When the housing is a non-sealed structure, it can still protect the electrode assembly, and a sealing bag may be included between the housing and the electrode assembly to encapsulate the electrode assembly and electrolyte. Specifically, the sealing bag can be a bag-shaped insulating component or an aluminum-plastic film.

[0103] As an example, a battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic battery cells, such as hexagonal prismatic battery cells.

[0104] The battery device mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0105] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells; as an example, a battery cell assembly can be a battery module, which is formed by arranging multiple battery cells and fixing them together to form an independent module.

[0106] As an example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0107] In some embodiments, the battery device may be a battery pack, which may include a housing and one or more individual battery cell assemblies housed within the housing.

[0108] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be housed in the housing by fixing the battery module in the housing.

[0109] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0110] As an example, the enclosure may include a first enclosure body and a second enclosure body. The first enclosure body and the second enclosure body are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, which can be either sealed or unsealed. The first enclosure body may be a top cover or a bottom plate.

[0111] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0112] As an example, the housing can be part of the vehicle's chassis structure. For instance, the housing's roof can be at least part of the vehicle's floor, or the housing's frame can be at least part of the vehicle's crossbeams and longitudinal beams.

[0113] In some embodiments, the battery device refers to an energy storage device, which includes a housing with a door on at least one side. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0114] Currently, judging from market trends, battery applications are becoming increasingly widespread. Batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of battery applications, market demand is also constantly increasing.

[0115] The development of battery technology must consider multiple design factors simultaneously, such as energy density, discharge capacity, and charge / discharge rate. Additionally, battery reliability must also be considered. However, current battery reliability is relatively poor.

[0116] Electrode assemblies are the components in a battery cell where electrochemical reactions occur. They include positive and negative electrodes. During the charging and discharging process of a battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. To reduce the risk of lithium plating, the lithium insertion capacity of the negative electrode is typically greater than the lithium extraction capacity of the positive electrode. However, during the coating process of the positive electrode, the coating weight of the active material slurry fluctuates, and surface shrinkage during the drying process causes the active material slurry to migrate, resulting in bulging at the edges of the positive electrode active material layer. This increases the lithium extraction capacity at the edges of the positive electrode and decreases the CB value (the ratio of the lithium insertion capacity of the negative electrode to the lithium extraction capacity of the positive electrode) at the edges, leading to an increased risk of lithium plating. Lithium dendrites are more likely to form on the surface of the negative electrode. These dendrites can easily pierce the separator and contact the positive electrode, causing a short circuit and resulting in poor battery reliability.

[0117] In view of this, embodiments of this application provide a battery cell, which includes an electrode assembly. The electrode assembly includes a positive electrode sheet, which includes a positive current collector and a positive active material layer. Along the thickness direction of the positive current collector, the positive current collector has a first surface, on which the positive active material layer is disposed. The positive active material layer includes a main region and a thinned region arranged along the width direction of the positive electrode sheet. The thickness of the main region is greater than the thickness of the thinned region, and at least one end of the main region along the width direction is connected to the thinned region. The main region has a second surface facing away from the positive current collector, and the thinned region has a connecting surface that connects the first surface and the second surface. The positive electrode sheet also includes an insulating layer, which includes a first portion and a second portion. The first portion is disposed on the first surface and covers a portion of the connecting surface, and the second portion is disposed on the connecting surface and spaced apart from the first portion, so that active ions can be transported from the region between the first portion and the second portion.

[0118] The first part covers a portion of the connecting surface, and the second part is disposed on the connecting surface and spaced apart from the first part. On the one hand, both the first and second parts can protect the thinned area. When lithium plating occurs on the negative electrode, they can, to some extent, prevent lithium dendrites from contacting the thinned area, reducing the risk of short circuits and improving the reliability of the battery cell. On the other hand, the spacing between the first and second parts facilitates the transport of active ions from the area between the first and second parts to the negative electrode, reducing the waste of capacity in the thinned area and contributing to a higher energy density in the battery cell.

[0119] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery cells and battery devices, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles and spacecraft.

[0120] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0121] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of this application. A battery device 100 is disposed inside the vehicle 1000, and the battery device 100 may be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 100 can serve as the operating power source for the vehicle 1000.

[0122] The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, for the power needs of the vehicle 1000 during startup, navigation and driving.

[0123] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0124] Please refer to Figure 2 , Figure 2 This is an exploded view of a battery device 100 provided in some embodiments of this application. The battery device 100 may include a housing 10 and battery cells 20, the housing 10 being used to house the battery cells 20.

[0125] The housing 10 has an enclosed space inside for accommodating the battery cells 20. The housing 10 can have various structures. In some embodiments, the housing 10 may include a first housing body 11 and a second housing body 12, which are interlocked. The first housing body 11 and the second housing body 12 can have various shapes, such as cuboids or cylinders. The first housing body 11 can be a hollow structure open on one side, and the second housing body 12 can also be a hollow structure open on one side. The open side of the second housing body 12 interlocks with the open side of the first housing body 11, thus forming a housing 10 with an enclosed space. Alternatively, the first housing body 11 can be a hollow structure open on one side, and the second housing body 12 can be a plate-like structure, with the second housing body 12 interlocked with the open side of the first housing body 11, thus forming a housing 10 with an accommodating chamber.

[0126] In the battery device 100, there can be one or more battery cells 20. If there are multiple battery cells 20, they can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that multiple battery cells 20 are connected in both series and parallel. Alternatively, multiple battery cells 20 can be first connected in series, parallel, or in a mixed configuration to form a battery module, and then multiple battery modules can be connected in series, parallel, or in a mixed configuration to form a whole, which is then housed within the housing 10. Another option is that all battery cells 20 can be directly connected in series, parallel, or in a mixed configuration, and then the whole consisting of all battery cells 20 is housed within the housing 10.

[0127] In some embodiments, the battery device 100 may further include a busbar component, through which multiple battery cells 20 can be electrically connected to each other to achieve series, parallel, or mixed connection of the multiple battery cells 20. The busbar component may be a metallic conductor, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0128] Please refer to Figure 3 , Figure 4 , Figure 5 and Figure 6 , Figure 3 This is a schematic diagram of the structure of a battery cell 20 provided in some embodiments of this application. Figure 4 An exploded view of a battery cell 20 provided in some embodiments of this application. Figure 5 This is a schematic diagram of the structure of the electrode assembly 22 provided in some embodiments of this application. Figure 6This is a cross-sectional view of the positive electrode 224 provided in some embodiments of this application. Embodiments of this application provide a battery cell 20, which includes an electrode assembly 22. The electrode assembly 22 includes a positive electrode 224. The positive electrode 224 includes a positive current collector 2241 and a positive active material layer 2242. Along the thickness direction of the positive current collector 2241, the positive current collector 2241 has a first surface 22411, and the positive active material layer 2242 is disposed on the first surface 22411. The positive active material layer 2242 includes a main region 22421 and a thinned region 22422 arranged along the width direction of the positive electrode 224. The thickness of the main region 22421 is greater than the thickness of the thinned region 22422. At least one end of the main region 22421 along the width direction is connected to the thinned region 22422. The main body region 22421 has a second surface 2243 facing away from the positive electrode current collector 2241, and the thinned region 22422 has a connecting surface 2244, which connects the first surface 22411 and the second surface 2243. The positive electrode sheet 224 further includes an insulating layer 23, which includes a first portion 231 and a second portion 232. The first portion 231 is disposed on the first surface 22411 and covers a portion of the connecting surface 2244, while the second portion 232 is disposed on the connecting surface 2244 and spaced apart from the first portion 231, so that active ions can be transported from the region between the first portion 231 and the second portion 232.

[0129] Battery cell 20 refers to the smallest unit that makes up battery device 100.

[0130] The housing 21 includes a housing 211 and an end cap 212. The housing 211 has a receiving space with an opening at one end for accommodating the electrode assembly 22. The end cap 212 is connected to the housing 211 and closes the opening.

[0131] End cap 212 refers to a component that covers the opening of housing 211 to isolate the internal environment of battery cell 20 from the external environment. The shape of end cap 212 can be adapted to the shape of housing 211 to fit it. Optionally, end cap 212 can be made of a material with certain hardness and strength (such as aluminum alloy), so that end cap 212 is not easily deformed under pressure and impact, giving battery cell 20 higher structural strength and improved reliability. The material of end cap 212 can include, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. Battery cell 20 also includes an insulating member 27, which is disposed inside end cap 212. The insulating member 27 can be used to isolate the electrical connection components inside housing 211 from end cap 212 to reduce the risk of short circuit. For example, insulating member 27 can be plastic, rubber, etc.

[0132] The housing 211 is a component used to cooperate with the end cap 212 to form the internal environment of the battery cell 20. This internal environment can accommodate the electrode assembly 22, electrolyte, and other components. The housing 211 and the end cap 212 can be independent components. An opening can be provided on the housing 211, and the end cap 212 can be used to close the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 212 and the housing 211 can be integrated. Specifically, the end cap 212 and the housing 211 can form a common mating surface before other components are inserted into the housing. When it is necessary to encapsulate the interior of the housing 211, the end cap 212 closes the housing 211. The housing 211 can have various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 211 can be determined according to the specific shape and size of the electrode assembly 22. The material of the housing 211 can include, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0133] In some embodiments, the housing 211 may have an opening at only one end, with one end cap 212 correspondingly provided. In other embodiments, the housing 211 may have openings at both ends, with two end caps 212 correspondingly provided, the two end caps 212 respectively closing the two opposite openings of the housing 211. Figure 3 and Figure 4 In the embodiment shown, the housing 211 has an opening at only one end, and an end cap 212 is provided accordingly.

[0134] Electrode terminals 25 may also be provided on the end cap 212 or the housing 211. These terminals are used for electrical connection to the tabs 222 of the electrode assembly 22 to input or output electrical energy from the battery cell 20. The electrode terminals 25 and tabs 222 can be directly connected, for example, by direct welding. Alternatively, they can be indirectly connected, for example, through a current collector. The current collector can be a metallic conductor, such as copper, iron, aluminum, steel, or aluminum alloy.

[0135] Electrode assembly 22 is the component in the battery cell 20 where electrochemical reactions occur. The housing 211 may contain one or more electrode assemblies 22. The electrode assembly 22 is mainly formed by winding or stacking positive electrode 224 and negative electrode 223, and typically a separator 225 is provided between the positive electrode 224 and the negative electrode 223. The portions of the positive electrode 224 and the negative electrode 223 containing active material constitute the main body 221 of the electrode assembly 22, while the portions of the positive electrode 224 and the negative electrode 223 without active material each constitute a tab 222. The positive electrode tab 2245 and the negative electrode tab 2225 may be located together at one end of the main body 221 or separately at both ends of the main body 221. During the charging and discharging process of the battery cell 20, the positive and negative active materials react with the electrolyte.

[0136] The electrode assembly 22 includes a positive electrode 224, a separator 225, and a negative electrode 223, which are wound or stacked. In other words, the electrode assembly 22 can be a wound electrode assembly or a stacked electrode assembly.

[0137] Please refer to Figure 6 The thickness direction of the positive current collector 2241 is the X direction shown in the figure.

[0138] The positive electrode 224 includes a positive current collector 2241 and a positive active material layer 2242. In some embodiments, one surface of the positive current collector 2241 is a first surface 22411 along the thickness direction of the positive current collector 2241. In this case, the positive active material layer 2242 is disposed only on one surface of the positive current collector 2241 along the thickness direction of the positive current collector 2241. In other embodiments, both surfaces of the positive current collector 2241 that are disposed opposite to each other along the thickness direction of the positive current collector 2241 are both first surfaces 22411. In this case, the positive active material layer 2242 is disposed on both surfaces of the positive current collector 2241 that are disposed opposite to each other along the thickness direction of the positive current collector 2241.

[0139] The positive electrode current collector 2241 can be a foil or a composite current collector. For example, as a foil, it can be aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0140] The positive electrode active material layer 2242 includes a positive electrode active material, which may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for battery cells 20 may also be used. These positive electrode active materials may be used alone or in combination of two or more.

[0141] For wound electrode assemblies, the width direction of the positive electrode 224 is generally parallel to the winding axis of the electrode assembly 22. For stacked electrode assemblies, both the width and length directions of the positive electrode 224 are perpendicular to its thickness direction. The width of the positive electrode 224 is smaller than its length. Generally, the positive electrode tab 2245 is located at one end of the width direction of the positive electrode 224, and its position can be used to determine the width direction of the positive electrode 224. Please refer to... Figure 6 The width direction of the positive electrode 224 is the Y direction shown in the figure.

[0142] The positive electrode active material layer 2242 includes a main region 22421 and a thinned region 22422, which are arranged along the width direction of the positive electrode sheet 224.

[0143] The main body region 22421 is the main part of the positive electrode active material layer 2242, and it performs the main functions of the positive electrode active material layer 2242. The thinned region 22422 is the thinned portion of the positive electrode active material layer 2242 located at one end of the main body region 22421 along the width direction of the positive electrode sheet 224. "The thickness of the main body region 22421 is greater than the thickness of the thinned region 22422" means that the minimum thickness of the main body region 22421 is greater than the maximum thickness of the thinned region 22422, or in other words, the thickness of the main body region 22421 at any position is greater than the thickness of the thinned region 22422 at any position. In some embodiments, the thinned region 22422 is connected to only one end of the main body region 22421 along the width direction of the positive electrode sheet 224, that is, the thinned region 22422 is only disposed at one end of the main body region 22421 along the width direction of the positive electrode sheet 224. In some other embodiments, the main body region 22421 is connected to both ends of the positive electrode plate 224 along the width direction of the positive electrode plate 224 by a thinning region 22422, that is, the thinning region 22422 is disposed at both ends of the main body region 22421 along the width direction of the positive electrode plate 224.

[0144] The second surface 2243 is the surface of the main body region 22421 that is away from the positive current collector 2241 along the thickness direction of the positive electrode sheet 224. The connecting surface 2244 is the surface of the thinned region 22422 that connects the first surface 22411 and the second surface 2243. The connecting surface 2244 can be an arc surface, an inclined surface, or a surface formed by a combination of arc surfaces, inclined surfaces, or planes.

[0145] The insulating layer 23 is an insulating coating. The material of the insulating layer 23 can be a polymer or a ceramic. The insulating layer 23 includes a first portion 231 and a second portion 232 spaced apart. The first portion 231 is disposed on the first surface 22411 and covers a portion of the connecting surface 2244; that is, one part of the first portion 231 covers the first surface 22411, and the other part of the first portion 231 covers a portion of the connecting surface 2244. The second portion 232 is completely disposed on the connecting surface 2244. The second portion 232 and the first portion 231 respectively cover two different areas of the connecting surface 2244, and there is a gap between the second portion 232 and the first portion 231, meaning that the second portion 232 and the first portion 231 do not contact each other.

[0146] The first part 231 covers a portion of the connecting surface 2244, and the second part 232 is disposed on the connecting surface 2244 and spaced apart from the first part 231. On the one hand, both the first part 231 and the second part 232 can protect the thinned area 22422. When lithium plating occurs on the negative electrode 223, they can prevent lithium dendrites from contacting the thinned area 22422 to a certain extent, reducing the risk of short circuit and improving the reliability of the battery cell 20. On the other hand, the spaced arrangement of the first part 231 and the second part 232 facilitates the transport of active ions from the area between the first part 231 and the second part 232 to the negative electrode 223, reducing the waste of capacity in the thinned area 22422 and enabling the battery cell 20 to have a higher energy density.

[0147] Please refer to Figure 3 , Figure 4 , Figure 5 and Figure 6 In some embodiments, the positive electrode 224 further includes a transition layer 24 disposed on the connection surface 2244 and located between the first portion 231 and the second portion 232. The material of the transition layer 24 includes the material of the insulating layer 23 and the active material of the positive electrode active material layer 2242.

[0148] The material of the transition layer 24 includes the material of the insulating layer 23 and the active material of the positive electrode active material layer 2242. The part belonging to the transition layer 24 can be determined based on the different materials of the thinned region 22422, the insulating layer 23, and the transition layer 24. For example, the thinned region 22422, the insulating layer 23, and the transition layer 24 can be distinguished by observing with a scanning electron microscope.

[0149] The transition layer 24 is completely disposed on the connection surface 2244. The transition layer 24 is located between the first part 231 and the second part 232. The transition layer 24 can be connected to the first part 231 and spaced apart from the second part 232; the transition layer 24 can also be connected to the second part 232 and spaced apart from the first part 231; the transition layer 24 can also be spaced apart from both the first part 231 and the second part 232.

[0150] By providing a transition layer 24 between the first part 231 and the second part 232, and covering the connection surface 2244, the transition layer 24 can protect the thinned region 22422. When lithium plating occurs on the negative electrode 223, it prevents lithium dendrites from contacting the thinned region 22422 to a certain extent, reducing the risk of short circuits and improving the reliability of the battery cell 20. Furthermore, active ions can also be transported from the transition layer 24 to the negative electrode 223, reducing the waste of capacity in the thinned region 22422 and contributing to a higher energy density in the battery cell 20.

[0151] Please refer to Figure 3 , Figure 4 , Figure 5 and Figure 6 In some embodiments, the transition layer 24 connects the first portion 231 and the second portion 232.

[0152] One end of the transition layer 24 is connected to the first part 231, and the other end of the transition layer 24 is connected to the second part 232. The transition layer 24 covers the area of ​​the connection region located between the first part 231 and the second part 232.

[0153] The first part 231 and the second part 232 are connected by the transition layer 24, which helps to improve the protection effect of the thinned area 22422 and improve the reliability of the battery cell 20.

[0154] Please refer to Figure 7 , Figure 7 This is a cross-sectional view of the positive electrode 224 provided for other embodiments of this application. In some embodiments, the transition layer 24 is connected to the first portion 231, and the connection surface 2244 forms an exposed area 22441 between the transition layer 24 and the second portion 232.

[0155] The transition layer 24 is connected to the first part 231, and the transition layer 24 is spaced apart from the second part 232. The area of ​​the connecting surface 2244 between the transition layer 24 and the second part 232 forms an exposed area 22441. The exposed area 22441 is not covered by other structures, and the thinned area 22422 can be observed from the exposed area 22441.

[0156] The transition layer 24 is connected to the first portion 231, and the connection surface 2244 forms an exposed region 22441 between the transition layer 24 and the second portion 232. This results in the exposed region 22441 being close to the negative electrode 223, which helps to shorten the ion path and reduce the risk of lithium plating. Furthermore, the presence of the exposed region 22441 facilitates the determination of the boundary position of the positive electrode active material layer 2242 during manufacturing.

[0157] Please refer to Figure 8 , Figure 8 This is a cross-sectional view of a positive electrode 224 provided for some embodiments of this application. In some embodiments, the transition layer 24 is connected to the second portion 232, and the connection surface 2244 forms an exposed area 22441 between the transition layer 24 and the first portion 231.

[0158] The transition layer 24 is connected to the second part 232, and the transition layer 24 is spaced apart from the first part 231. The area of ​​the connecting surface 2244 between the transition layer 24 and the first part 231 forms an exposed area 22441. The exposed area 22441 is not covered by other structures, and the thinned area 22422 can be observed from the exposed area 22441.

[0159] The transition layer 24 is connected to the second part 232, and the connection surface 2244 forms an exposed area 22441 between the transition layer 24 and the first part 231. The exposed area 22441 is closer to the edge of the thinned area 22422, which allows for more accurate determination of the boundary position of the positive electrode active material layer 2242 during manufacturing. In addition, active ions can also be transported from the exposed area 22441 to the negative electrode sheet 223, which helps to reduce the waste of capacity in the thinned area 22422 and helps to give the battery cell 20 a higher energy density.

[0160] Please refer to Figure 9 , Figure 9 This is a cross-sectional view of a positive electrode 224 provided in some embodiments of this application. In some embodiments, the positive electrode 224 includes a plurality of transition layers 24, including a first transition layer 241 and a second transition layer 242. The first transition layer 241 is connected to a first portion 231, and the second transition layer 242 is connected to a second portion 232. A connection surface 2244 forms an exposed area 22441 between the first transition layer 241 and the second transition layer 242.

[0161] The first transition layer 241 is the transition layer 24 connected to the first portion 231 among a plurality of transition layers 24. The second transition layer 242 is the transition layer 24 connected to the second portion 232 among a plurality of transition layers 24. The materials of the first transition layer 241 and the second transition layer 242 both include the material of the insulating layer 23 and the material of the positive electrode active material layer 2242.

[0162] The area between the first transition layer 241 and the second transition layer 242 of the connecting surface 2244 forms an exposed area 22441. The exposed area 22441 is not covered by other structures, and the thinned area 22422 can be observed from the exposed area 22441.

[0163] The first transition layer 241 is connected to the first portion 231, and the second transition layer 242 is connected to the second portion 232. This results in a larger coverage area for the transition layer 24, which improves the protection of the thinned area 22422 and enhances the reliability of the battery cell 20. The connection surface 2244 forms an exposed area 22441 between the first transition layer 241 and the second transition layer 242. During manufacturing, the boundary position of the positive electrode active material layer 2242 can be determined by the position of the exposed area 22441. In addition, active ions can also be transported from the exposed area 22441 to the negative electrode sheet 223, which helps reduce the waste of capacity in the thinned area 22422 and helps the battery cell 20 to have a higher energy density.

[0164] Please refer to Figure 9 and Figure 10 , Figure 10 This is a top view of the unfolded positive electrode 224 provided in some embodiments of this application. In some embodiments, along the width direction, the size of the first transition layer 241 is X1, the size of the exposed area 22441 is X2, and the size of the second transition layer 242 is X3, satisfying: X1+X2+X3≤10mm.

[0165] X1 represents the dimension of the first transition layer 241 along the width direction of the positive electrode 224, that is, the distance from one end of the first transition layer 241 to the other end along the width direction of the positive electrode 224.

[0166] X2 represents the dimension of the exposed area 22441 along the width direction of the positive electrode 224, which is also the distance between the first transition layer 241 and the second transition layer 242 along the width direction of the positive electrode 224.

[0167] X3 represents the dimension of the second transition layer 242 along the width direction of the positive electrode 224, that is, the distance from one end of the second transition layer 242 to the other end along the width direction of the positive electrode 224.

[0168] The sum of the dimensions of the first transition layer 241 along the width direction of the positive electrode 224, the dimensions of the exposed area 22441 along the width direction of the positive electrode 224, and the dimensions of the second transition layer 242 along the width direction of the positive electrode 224 is less than or equal to 10 mm.

[0169] X1+X2+X3 can be in the following sizes: 10mm, 9mm, 8mm, 7mm, 6mm, 5mm, 4mm, 3mm, 2mm, 1mm, etc.

[0170] When X1+X2+X3≤10mm, the sum of the size of the first transition layer 241, the size of the exposed area 22441, and the size of the second transition layer 242 is relatively small, which is beneficial to the higher energy density of the battery cell 20.

[0171] Optionally, X1+X2+X3≤2mm.

[0172] X1+X2+X3 can be in the following sizes: 2mm, 1.8mm, 1.5mm, 1.2mm, 1mm, 0.8mm, 0.5mm, etc.

[0173] When X1+X2+X3≤2mm, the sum of the size of the first transition layer 241, the size of the exposed area 22441, and the size of the second transition layer 242 is smaller, which is beneficial to higher energy density of the battery cell 20.

[0174] In some embodiments, X1 ≤ 3 mm.

[0175] X1 can be made of: 3mm, 2.8mm, 2.5mm, 2.2mm, 2mm, 1.8mm, 1.5mm, 1.2mm, 1mm, etc.

[0176] When X1≤3mm, the size of the first transition layer 241 is smaller, which is beneficial to the better dynamics of active ions in the thinned region 22422 and to the higher energy density of the battery cell 20.

[0177] In some embodiments, X2 ≤ 2 mm.

[0178] X2 can be in the following sizes: 2mm, 1.8mm, 1.5mm, 1.2mm, 1mm, 0.8mm, 0.5mm, etc.

[0179] When X2≤2mm, the size of the exposed area 22441 is small. When lithium plating occurs on the negative electrode 223, the risk of short circuit caused by lithium dendrites contacting the exposed area 22441 is low, which is beneficial to improving the reliability of the battery cell 20.

[0180] In some embodiments, X3 ≤ 3 mm.

[0181] X3 can be made of the following thicknesses: 3mm, 2.8mm, 2.5mm, 2.2mm, 2mm, 1.8mm, 1.5mm, 1.2mm, 1mm, etc.

[0182] When X3≤3mm, the size of the second transition layer 242 is smaller, which is beneficial to the better dynamics of active ions in the thinned region 22422 and to the higher energy density of the battery cell 20.

[0183] Please refer to Figure 9 and Figure 10 In some embodiments, the minimum distance between the exposed area 22441 and the first surface 22411 is H1, and the thickness of the main body area 22421 is H2, satisfying: 0.4≤H1 / H2≤0.6.

[0184] H1 represents the minimum distance between the exposed area 22441 and the first surface 22411. During measurement, the distance between the position of the exposed area 22441 closest to the first surface 22411 and the first surface 22411 can be measured as H1.

[0185] H2 represents the thickness of the main body area 22421. During measurement, multiple measurements can be taken and the average value can be used as H2.

[0186] H1 / H2 represents the ratio of the minimum distance between the exposed area 22441 and the first surface 22411 to the thickness of the main body area 22421.

[0187] H1 / H2 can take values ​​of: 0.4, 0.42, 0.45, 0.48, 0.5, 0.52, 0.55, 0.59, 0.6, etc.

[0188] When H1 / H2 ≥ 0.4, the minimum distance between the exposed area 22441 and the first surface 22411 is relatively large, which helps to shorten the ion path and reduce the risk of lithium plating. When H1 / H2 ≤ 0.6, the minimum distance between the exposed area 22441 and the first surface 22411 is not too large, and the boundary position of the positive electrode active material layer 2242 can be more accurately determined by the position of the exposed area 22441 during manufacturing.

[0189] Please refer to Figure 9 and Figure 10 In some embodiments, along the direction from the positive current collector 2241 to the positive active material layer 2242, the first portion 231, the transition layer 24, and the second portion 232 do not extend beyond the second surface 2243.

[0190] "In the direction from the positive current collector 2241 to the positive active material layer 2242, the first part 231, the transition layer 24, and the second part 232 do not extend beyond the second surface 2243." That is, the first part 231, the transition layer 24, and the second part 232 do not extend beyond the second surface 2243 in the direction from the positive current collector 2241 to the positive active material layer 2242.

[0191] By ensuring that the first part 231, the transition layer 24, and the second part 232 do not extend beyond the second surface 2243 in the direction from the positive current collector 2241 to the positive active material layer 2242, it is beneficial to bring the second surface 2243 closer to the negative electrode plate 223, thereby shortening the ion path and reducing the risk of lithium plating.

[0192] Please refer to Figure 11 , Figure 11 This application also provides a cross-sectional view of the positive electrode 224 according to some embodiments. In some embodiments, the connecting surface 2244 forms an exposed area 22441 between the first portion 231 and the second portion 232.

[0193] The area of ​​the connecting surface 2244 between the first part 231 and the second part 232 forms an exposed area 22441. The exposed area 22441 is not covered by other structures, and the thinned area 22422 can be observed from the exposed area 22441.

[0194] By forming an exposed area 22441 between the first portion 231 and the second portion 232 on the connecting surface 2244, the boundary position of the positive electrode active material layer 2242 can be more accurately determined during manufacturing by the position of the exposed area 22441. In addition, active ions can also be transported from the exposed area 22441 to the negative electrode sheet 223, which helps to reduce the waste of capacity in the thinned area 22422 and helps to enable the battery cell 20 to have a higher energy density.

[0195] Please refer to this again. Figure 10 In some embodiments, the width of the second portion 232 along the width direction is X4, satisfying: X4≤3mm.

[0196] X4 represents the width of the second part 232 along the width direction of the positive electrode 224, that is, the distance from one end of the second part 232 to the other end along the width direction of the positive electrode 224.

[0197] X4 can be made of: 3mm, 2.8mm, 2.5mm, 2.2mm, 2mm, 1.8mm, 1.5mm, 1.2mm, 1mm, etc.

[0198] When X4≤3mm, the width of the second part 232 along the width direction is smaller, which helps to reduce the risk that the second part 232 extends beyond the second surface 2243 along the direction from the positive current collector 2241 to the positive active material layer 2242.

[0199] Optionally, X4 ≤ 1 mm.

[0200] X4 can be selected from: 1mm, 0.9mm, 0.8mm, 0.7mm, 0.6mm, 0.5mm, 0.4mm, 0.3mm, 0.2mm, etc.

[0201] When X4≤1mm, the width of the second part 232 along the width direction is smaller, which is more conducive to reducing the risk that the second part 232 extends beyond the second surface 2243 along the direction from the positive current collector 2241 to the positive active material layer 2242.

[0202] In some embodiments, the battery cell 20 further includes an electrolyte, a portion of which is contained within a first portion 231 and / or a second portion 232.

[0203] Alternatively, a portion of the electrolyte may be contained within the first portion 231, while the second portion 232 may not contain any electrolyte. Another option is that a portion of the electrolyte may be contained within the second portion 232, while the first portion 231 may not contain any electrolyte. Yet another option is that a portion of the electrolyte may be contained within the first portion 231, and a portion within the second portion 232, meaning that both the first portion 231 and the second portion 232 contain electrolyte.

[0204] By containing a portion of the electrolyte within the first portion 231 and / or the second portion 232, the first portion 231 and / or the second portion 232 can transport active ions to a certain extent, which helps to reduce the waste of capacity in the thinned region 22422 and helps to give the battery cell 20 a higher energy density.

[0205] Please refer to Figure 11 In some embodiments, the connecting surface 2244 includes a first arcuate surface 22442, a first plane 22443, and a second arcuate surface 22444 connected in sequence. The first arcuate surface 22442 is connected to the first surface 22411, and the second arcuate surface 22444 is connected to the second surface 2243. A first portion 231 covers at least a portion of the first arcuate surface 22442, and a second portion 232 is disposed on the second arcuate surface 22444.

[0206] The first arc surface 22442 is a curved surface on the connecting surface 2244 that is connected to the first surface 22411. The first arc surface 22442 can be a circular arc surface, an elliptical arc surface, etc.

[0207] The first plane 22443 is a plane connected to the end of the first arc surface 22442 that is away from the first surface 22411. The first plane 22443 may be inclined or parallel to the first surface 22411.

[0208] The second arc surface 22444 is a curved surface on the connecting surface 2244 that connects the first plane 22443 and the second surface 2243. The second arc surface 22444 can be a circular arc surface, an elliptical arc surface, etc.

[0209] The first part 231 can cover a portion of the first arc surface 22442, or the first part 231 can cover the entire first arc surface 22442.

[0210] The second part 232 is disposed on the second arc surface 22444. The second part 232 can cover a portion of the second arc surface 22444, or the second part 232 can cover the entire second arc surface 22444.

[0211] Lithium dendrites are more likely to come into contact with the thinned area 22422 from the first arc surface 22442 and the second arc surface 22444. By making the first part 231 cover the first arc surface 22442 and the second part 232 set on the second arc surface 22444, the blocking effect on lithium dendrites is better, which helps to further reduce the risk of short circuit and improve the reliability of the battery cell 20.

[0212] Please refer to Figure 11 In some embodiments, the first portion 231 includes a first region 2311 disposed on a first surface 22411 and a second region 2312 disposed on a connecting surface 2244. The first region 2311 and the second region 2312 are connected and arranged along the width direction. The thickness of the first region 2311 is greater than the thickness of the second region 2312.

[0213] The first region 2311 is the portion of the first part 231 disposed on the first surface 22411. The second region 2312 is the portion of the first part 231 disposed on the connecting surface 2244. The first region 2311 and the second region 2312 are arranged along the width direction of the positive electrode plate 224 and are connected to each other.

[0214] Please refer to Figure 11 To facilitate the distinction between Zone 1 (2311) and Zone 2312, the boundary between Zone 1 (2311) and Zone 2312 is shown by a dashed line in the diagram. It should be noted that the dashed line is only for ease of distinction and does not represent any other meaning.

[0215] "The thickness of the first zone 2311 is greater than the thickness of the second zone 2312" means that the minimum thickness of the first zone 2311 is greater than the maximum thickness of the second zone 2312, that is, the thickness of any position in the first zone 2311 is greater than the thickness of any position in the second zone 2312.

[0216] When the positive electrode current collector 2241 comes into contact with lithium dendrites and a short circuit occurs, a large amount of heat is generated, which can easily cause fire or explosion, representing the most severe short circuit mode. By setting the first region 2311 on the first surface 22411 and making the thickness of the first region 2311 greater than the thickness of the second region 2312, the blocking effect on lithium dendrites is better, which helps to further reduce the risk of short circuit and improve the reliability of the battery cell 20.

[0217] Please refer to Figure 11 In some embodiments, the electrode assembly 22 includes a positive electrode tab 2245 disposed at one end of the positive current collector 2241 along the width direction, and a first region 2311 covers a portion of the positive electrode tab 2245.

[0218] Please refer to Figure 11 The electrode assembly 22 includes a positive electrode tab 2245. The portion of the positive current collector 2241 that is not covered by the positive active material layer 2242 constitutes the positive electrode tab 2245. The positive electrode tab 2245 is disposed at one end of the positive current collector 2241 along the width direction of the positive electrode sheet 224.

[0219] By covering a portion of the positive electrode tab 2245 with the first region 2311, it is beneficial to reduce the risk of short circuit caused by burrs on the tab 222 piercing the insulating element 225 and coming into contact with the negative electrode plate 223 when the tab 222 is folded.

[0220] Please refer to Figure 11 In some embodiments, the thickness of the first region 2311 is H3, satisfying: 3μm≤H3≤50μm.

[0221] H3 represents the thickness of the first region 2311. The thickness of the first region 2311 can be uniform, in which case the thickness at any position of the first region 2311 can be measured as H3. The thickness of the first region 2311 can also be variable, in which case the minimum thickness of the first region 2311 is greater than or equal to 3 μm, and the maximum thickness of the first region 2311 is less than or equal to 50 μm.

[0222] H3 can be in the following sizes: 3μm, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, etc.

[0223] When H3 ≥ 3 μm, the thickness of the first region 2311 is relatively large, which is beneficial for covering the burrs on the tab 222 and reducing the risk of short circuit caused by the burrs on the tab 222 piercing the separator 225 and coming into contact with the negative electrode plate 223 when the tab 222 is folded. When H3 ≤ 50 μm, the thickness of the first region 2311 is not too large, which facilitates the cutting of the tab 222.

[0224] Optionally, 3μm≤H3≤30μm.

[0225] H3 can be in the following sizes: 3μm, 5μm, 8μm, 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm, 30μm, etc.

[0226] When H3 ≥ 3 μm, the thickness of the first region 2311 is relatively large, which is beneficial for covering the burrs on the tab 222 and reducing the risk of short circuit caused by the burrs on the tab 222 piercing the separator 225 and coming into contact with the negative electrode plate 223 when the tab 222 is folded. When H3 ≤ 30 μm, the thickness of the first region 2311 is not too large, which facilitates the cutting of the tab 222.

[0227] Please refer to Figure 10 and Figure 11 In some embodiments, in a cross section perpendicular to the length direction of the positive electrode 224, the cross-sectional area of ​​the second region 2312 is A1, and the cross-sectional area of ​​the portion of the thinned region 22422 located between the second region 2312 and the positive current collector 2241 is A2, satisfying: 0.01≤A2 / (A1+A2)<1.

[0228] Please refer to Figure 10 The length direction of the positive electrode 224 is the Z direction as shown in the figure.

[0229] A1 represents the cross-sectional area of ​​the second region 2312 in the section perpendicular to the length direction of the positive electrode plate 224.

[0230] A2 represents the cross-sectional area of ​​the thinned region 22422 located between the second region 2312 and the positive current collector 2241, within a section perpendicular to the length of the positive electrode sheet 224. Please refer to... Figure 11 To facilitate the distinction between the portion of the thinned region 22422 located between the second region 2312 and the positive current collector 2241, and the other portions of the thinned region 22422, the boundary between this portion and the other portions of the thinned region 22422 is indicated by a dashed line in the figure. It should be noted that the dashed line is only for the purpose of distinguishing between the portion of the thinned region 22422 located between the second region 2312 and the positive current collector 2241, and does not represent any other meaning.

[0231] A2 / (A1+A2) can take values ​​of: 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, etc.

[0232] When 0.01≤A2 / (A1+A2)<1, it not only provides good protection for the thinned area 22422, but also reduces the waste of capacity in the thinned area 22422, which is conducive to giving the battery cell 20 a higher energy density, thus giving the battery cell 20 higher reliability and energy density.

[0233] Optionally, 0.2 ≤ A2 / (A1+A2) ≤ 0.8.

[0234] A2 / (A1+A2) can take the following values: 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, etc.

[0235] When 0.2≤A2 / (A1+A2)≤0.8, the reliability and energy density of the battery cell 20 can be better balanced.

[0236] This application embodiment also provides a battery device 100, which includes the aforementioned battery cell 20.

[0237] This application embodiment also provides an electrical device, which includes the aforementioned battery cell 20, and the battery cell 20 is used to provide electrical energy to the electrical device.

[0238] According to some embodiments of this application, please refer to Figures 3-11 .

[0239] This application provides a battery cell 20, which includes an electrode assembly 22. The electrode assembly 22 includes a positive electrode 224, which includes a positive current collector 2241 and a positive active material layer 2242. Along the thickness direction of the positive current collector 2241, the positive current collector 2241 has a first surface 22411, and the positive active material layer 2242 is disposed on the first surface 22411. The positive active material layer 2242 includes a main region 22421 and a thinned region 22422 arranged along the width direction of the positive electrode 224. The thickness of the main region 22421 is greater than the thickness of the thinned region 22422, and at least one end of the main region 22421 along the width direction is connected to the thinned region 22422. The main body region 22421 has a second surface 2243 facing away from the positive electrode current collector 2241, and the thinned region 22422 has a connecting surface 2244, which connects the first surface 22411 and the second surface 2243. The positive electrode sheet 224 further includes an insulating layer 23, which includes a first portion 231 and a second portion 232. The first portion 231 is disposed on the first surface 22411 and covers a portion of the connecting surface 2244, while the second portion 232 is disposed on the connecting surface 2244 and spaced apart from the first portion 231, so that active ions can be transported from the region between the first portion 231 and the second portion 232. The first part 231 covers a portion of the connecting surface 2244, and the second part 232 is disposed on the connecting surface 2244 and spaced apart from the first part 231. On the one hand, both the first part 231 and the second part 232 can protect the thinned area 22422. When lithium plating occurs on the negative electrode 223, they can prevent lithium dendrites from contacting the thinned area 22422 to a certain extent, reducing the risk of short circuit and improving the reliability of the battery cell 20. On the other hand, the spaced arrangement of the first part 231 and the second part 232 facilitates the transport of active ions from the area between the first part 231 and the second part 232 to the negative electrode 223, reducing the waste of capacity in the thinned area 22422 and enabling the battery cell 20 to have a higher energy density.

[0240] The positive electrode 224 also includes a transition layer 24, which is disposed on the connection surface 2244 and located between the first portion 231 and the second portion 232. The material of the transition layer 24 includes the material of the insulating layer 23 and the active material of the positive electrode active material layer 2242. By disposing the transition layer 24 between the first portion 231 and the second portion 232 and covering the connection surface 2244, the transition layer 24 can protect the thinned region 22422. When lithium plating occurs on the negative electrode 223, it can prevent lithium dendrites from contacting the thinned region 22422 to a certain extent, reducing the risk of short circuit and improving the reliability of the battery cell 20. Furthermore, active ions can also be transported from the transition layer 24 to the negative electrode 223, which helps to reduce the waste of capacity in the thinned region 22422 and helps the battery cell 20 to have a higher energy density.

[0241] In some embodiments, the transition layer 24 connects the first portion 231 and the second portion 232. The connection between the first portion 231 and the second portion 232 via the transition layer 24 is beneficial for improving the protection of the thinned area 22422 and for improving the reliability of the battery cell 20.

[0242] In other embodiments, the transition layer 24 is connected to the first portion 231, and the connection surface 2244 forms an exposed area 22441 between the transition layer 24 and the second portion 232. This connection between the transition layer 24 and the first portion 231, with the exposed area 22441 between the transition layer 24 and the second portion 232, results in a closer distance between the exposed area 22441 and the negative electrode 223, which helps shorten the ion path and reduce the risk of lithium plating. Furthermore, the presence of the exposed area 22441 facilitates the determination of the boundary position of the positive electrode active material layer 2242 during manufacturing.

[0243] In some embodiments, the transition layer 24 is connected to the second portion 232, and the connection surface 2244 forms an exposed area 22441 between the transition layer 24 and the first portion 231. The exposed area 22441 is closer to the edge of the thinned region 22422, allowing for more accurate determination of the boundary position of the positive electrode active material layer 2242 during manufacturing. Furthermore, active ions can also be transported from the exposed area 22441 to the negative electrode sheet 223, which helps reduce the wasted capacity of the thinned region 22422 and contributes to a higher energy density in the battery cell 20.

[0244] In some embodiments, the positive electrode 224 includes multiple transition layers 24, each including a first transition layer 241 and a second transition layer 242. The first transition layer 241 is connected to a first portion 231, and the second transition layer 242 is connected to a second portion 232. A connection surface 2244 forms an exposed area 22441 between the first transition layer 241 and the second transition layer 242. The connection between the first transition layer 241 and the first portion 231, and the connection between the second transition layer 242 and the second portion 232, results in a larger area covered by the transition layers 24, which improves the protection of the thinned area 22422 and enhances the reliability of the battery cell 20. The exposed area 22441 formed between the first transition layer 241 and the second transition layer 242 allows the boundary position of the positive electrode active material layer 2242 to be determined during manufacturing. In addition, active ions can also be transported from the exposed area 22441 to the negative electrode 223, which helps to reduce the waste of capacity in the thinned area 22422 and helps to make the battery cell 20 have a higher energy density.

[0245] In some embodiments, the connecting surface 2244 forms an exposed area 22441 between the first portion 231 and the second portion 232. By forming an exposed area 22441 between the first portion 231 and the second portion 232, the boundary position of the positive electrode active material layer 2242 can be more accurately determined during manufacturing by the position of the exposed area 22441. In addition, active ions can also be transported from the exposed area 22441 to the negative electrode sheet 223, which helps to reduce the waste of capacity in the thinned area 22422 and helps to enable the battery cell 20 to have a higher energy density.

[0246] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized in that, include: An electrode assembly includes a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active material layer. Along the thickness direction of the positive current collector, the positive current collector has a first surface, the first surface being disposed of the positive active material layer. The positive active material layer includes a main body region and a thinned region arranged along the width direction of the positive electrode sheet. The thickness of the main body region is greater than the thickness of the thinned region. At least one end of the main body region along the width direction is connected to the thinned region. The main body region has a second surface facing away from the positive current collector. The thinned region has a connecting surface, the connecting surface connecting the first surface and the second surface. The positive electrode further includes an insulating layer, which comprises a first part and a second part. The first part is disposed on the first surface and covers a portion of the connection surface, and the second part is disposed on the connection surface and spaced apart from the first part, so that active ions can be transported from the region between the first part and the second part.

2. The battery cell according to claim 1, characterized in that, The positive electrode sheet further includes a transition layer, which is disposed on the connection surface and located between the first part and the second part. The material of the transition layer includes the material of the insulating layer and the active material of the positive electrode active material layer.

3. The battery cell according to claim 2, characterized in that, The transition layer connects the first part and the second part.

4. The battery cell according to claim 2, characterized in that, The transition layer is connected to the first part, and the connection surface forms an exposed area between the transition layer and the second part.

5. The battery cell according to claim 2, characterized in that, The transition layer is connected to the second part, and the connection surface forms an exposed area between the transition layer and the first part.

6. The battery cell according to claim 2, characterized in that, The positive electrode sheet includes a plurality of transition layers, the plurality of transition layers including a first transition layer and a second transition layer, the first transition layer being connected to the first portion, the second transition layer being connected to the second portion, and the connection surface forming an exposed area between the first transition layer and the second transition layer.

7. The battery cell according to claim 6, characterized in that, Along the width direction, the size of the first transition layer is X1, the size of the exposed area is X2, and the size of the second transition layer is X3, satisfying: X1+X2+X3≤10mm.

8. The battery cell according to claim 7, characterized in that, X1+X2+X3≤2mm.

9. The battery cell according to claim 7, characterized in that, X1≤3mm.

10. The battery cell according to claim 7, characterized in that, X2≤2mm.

11. The battery cell according to claim 7, characterized in that, X3≤3mm.

12. The battery cell according to claim 6, characterized in that, The minimum distance between the exposed area and the first surface is H1, and the thickness of the main body area is H2, satisfying: 0.4≤H1 / H2≤0.

6.

13. The battery cell according to claim 2, characterized in that, Along the direction from the positive current collector to the positive active material layer, the first portion, the transition layer, and the second portion do not extend beyond the second surface.

14. The battery cell according to claim 1, characterized in that, The connecting surface forms an exposed area between the first part and the second part.

15. The battery cell according to any one of claims 1-14, characterized in that, Along the width direction, the width of the second part is X4, which satisfies: X4≤3mm.

16. The battery cell according to claim 15, characterized in that, X4≤1mm.

17. The battery cell according to any one of claims 1-14, characterized in that, The battery cell also includes an electrolyte, a portion of which is contained within the first portion and / or the second portion.

18. The battery cell according to any one of claims 1-14, characterized in that, The connecting surface includes a first arc surface, a first plane, and a second arc surface connected in sequence. The first arc surface is connected to the first surface, and the second arc surface is connected to the second surface. The first part covers at least a portion of the first arc surface, and the second part is disposed on the second arc surface.

19. The battery cell according to any one of claims 1-14, characterized in that, The first part includes a first region disposed on the first surface and a second region disposed on the connecting surface. The first region and the second region are connected and arranged along the width direction. The thickness of the first region is greater than the thickness of the second region.

20. The battery cell according to claim 19, characterized in that, The electrode assembly includes a positive electrode tab, which is disposed at one end of the positive current collector along the width direction, and the first region covers a portion of the positive electrode tab.

21. The battery cell according to claim 19, characterized in that, The thickness of the first region is H3, which satisfies: 3μm≤H3≤50μm.

22. The battery cell according to claim 21, characterized in that, 3μm≤H3≤30μm.

23. The battery cell according to claim 19, characterized in that, In a cross section perpendicular to the length of the positive electrode sheet, the cross-sectional area of ​​the second region is A1, and the cross-sectional area of ​​the portion of the thinned region located between the second region and the positive current collector is A2, satisfying: 0.01≤A2 / (A1+A2)<1.

24. The battery cell according to claim 23, characterized in that, 0.2≤A2 / (A1+A2)≤0.

8.

25. A battery device, characterized in that, Includes the battery cell according to any one of claims 1-24.

26. An electrical appliance, characterized in that, Includes a battery cell according to any one of claims 1-24, the battery cell being used to provide electrical energy to the electrical device.

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