Battery monomer, battery device and electric equipment

Abstract

The utility model discloses a battery monomer, a battery device and electric equipment. The battery monomer comprises a shell and an electrode assembly, the shell is provided with a containing cavity, and the electrode assembly is arranged in the containing cavity. The electrode assembly comprises a first pole piece, the first pole piece comprises a first main body part and a first tab, and the first main body part comprises a first substrate connected to one side of the first tab along a first direction, and a first active material layer and a second active material layer which coat the surface of the first substrate; the second active material layer is arranged on one side of the first active material layer along the first direction, and the gram volume of the second active material layer is larger than that of the first active material layer. According to the technical scheme, the operation stability of the single battery can be improved.

Description

Technical Field

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

[0002] With the development of new energy technologies, batteries are being used more and more widely, such as in mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, and power tools.

[0003] The development of battery technology must take into account multiple design factors. Improving the stability of a single battery cell during operation is a research direction in the battery field. Utility Model Content

[0004] In view of the above problems, this application provides a battery cell, a battery device, and an electrical device that can improve the stability of battery cell operation.

[0005] In a first aspect, this application provides a battery cell, including a casing and an electrode assembly. The casing has a receiving cavity, and the electrode assembly is disposed within the receiving cavity. The electrode assembly includes a first electrode plate, the first electrode plate including a first body portion and a first tab, the first body portion including a first substrate connected to one side of the first tab along a first direction, a first active material layer coated on the surface of the first substrate, and a second active material layer, the second active material layer being disposed on one side of the first active material layer along the first direction, and the specific capacity of the second active material layer being greater than the specific capacity of the first active material layer.

[0006] In the technical solution of this application embodiment, the outer casing provides a sealed environment for the electrode assembly, reducing the impact of external impurities and moisture on the electrode assembly. In the electrode assembly, a layer of active material with a lower specific capacity is disposed in the region near the tab. This region near the tab is the main current channel; setting a low-specific-capacity region can reduce the current density in this region, avoiding localized overheating and current congestion, thereby optimizing the current distribution of the entire battery. Simultaneously, the first active material layer in the low-specific-capacity region helps reduce the resistance at the edge of the electrode sheet, thereby reducing the overall internal resistance of the battery, improving the battery's charge / discharge efficiency and power output, and thus improving the stability of the battery cell operation.

[0007] In some embodiments, the maximum thickness of the first active material layer is less than the minimum thickness of the second active material layer. The above structure reduces the thickness of the first active material layer, further reducing the current density at the edge of the first main body portion, lowering the overall internal resistance of the battery, improving the battery's charge / discharge efficiency and power output, and further enhancing the stability of the battery cell operation.

[0008] In some embodiments, the thickness of the first active material layer gradually decreases along the direction from the first body portion toward the first tab. In this structure, as the thickness of the first active material layer gradually decreases, the resistance to current transmission also decreases accordingly, allowing current to pass more smoothly through the electrode assembly, thereby optimizing the current distribution. The gradual reduction in thickness means a gradual decrease in the resistance of the first active material layer, which helps to reduce energy loss during battery charging and discharging, improving battery efficiency and performance.

[0009] In some embodiments, a first active material is coated on both opposite sides of the first main body, and a second active material is coated on both opposite sides of the first main body. The above structure, with active material layers on both sides of the first main body, improves the energy density and output power of the battery cell.

[0010] In some embodiments, the electrode assembly further includes a second electrode with a polarity opposite to that of the first electrode. The second electrode has a thinned region, and at least a portion of the first active material layer is disposed toward the thinned region. In the above structure, the second electrode has a thinned region, and the thinned region corresponds to the first active material layer at the edge of the first electrode. The second electrode can also reduce internal resistance and improve charge / discharge efficiency and power output.

[0011] In some embodiments, the first electrode is a positive electrode and the second electrode is a negative electrode. This structure increases the ratio of negative electrode capacity to positive electrode capacity per unit area, thereby reducing lithium deposition on the first active material layer of the positive electrode during charging and improving the charging performance and cycle life of the battery cell.

[0012] In some embodiments, the second electrode includes a second body portion and a second tab. The second body portion includes a second substrate, a third active material layer, and a fourth active material layer. The second substrate is disposed on one side of the second tab along a first direction. The third active material layer is coated on at least one surface of the second substrate, and at least a portion of the third active material layer is disposed opposite to the first active material layer. The fourth active material layer is coated on at least one surface of the second substrate and is connected to the third active material layer. The maximum thickness of the third active material layer is less than the minimum thickness of the fourth active material layer. In the above structure, the region corresponding to the third active material layer of the second electrode is a thinned region. The thinner third active material layer has lower dynamics, which matches the low dynamics of the low specific capacity region of the first active material layer, reducing the risk of lithium plating in this region and improving the charging performance and cycle life of the battery cell.

[0013] In some embodiments, the thickness of the third active material layer gradually decreases along the direction from the second substrate toward the second tab. This structure further reduces the internal resistance of the battery cell, decreases the risk of lithium plating on the electrode plates, and improves the operational stability of the battery cell.

[0014] In some embodiments, the orthographic projection of the third active material layer on the first substrate falls within the orthographic projection range of the first active material layer on the first substrate. In the above structure, the third active material layer and the first active material layer are correspondingly arranged, maximizing the matching of two regions with lower dynamics, reducing the risk of lithium plating and heat accumulation at the electrode edges, and improving the charging performance and cycle life of the battery cell.

[0015] In some embodiments, the first active material layer includes a first portion, a second portion, and a third portion sequentially distributed along a first direction. The first portion has a dimension W1 along the first direction of 4.5 mm < W1 ≤ 5.5 mm, and the thickness of the second active material layer is H. The thickness H1 of the first portion is 97% * H ≤ H1 ≤ 99% * H. The second portion has a dimension W2 along the first direction of 4.5 mm < W2 ≤ 5.5 mm, and the thickness H2 of the second portion is 92% * H ≤ H2 ≤ 97% * H. The third portion has a dimension W3 along the first direction of 2.5 mm < W3 ≤ 3.5 mm, and the thickness H3 of the third portion is 90% * H ≤ H3 ≤ 95% * H. This structure, by limiting the thickness and width of the first active material layer, reduces the risk of side reactions in the electrode thinning area, lowers the risk of lithium plating at the electrode edges, and improves the operational stability of the battery cell.

[0016] Secondly, this application provides a battery device that includes the battery cell described in the above embodiments.

[0017] Thirdly, this application provides an electrical device that includes the battery device described in the above embodiments, the battery device being used to provide electrical energy.

[0018] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0019] The features, advantages, and technical effects of exemplary embodiments of this application will now be described with reference to the accompanying drawings.

[0020] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0021] Figure 2 Explosion-proof diagrams of battery devices provided in some embodiments of this application;

[0022] Figure 3 This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0023] Figure 4This is a schematic diagram of the structure of the first electrode provided in some embodiments of this application;

[0024] Figure 5 This is a schematic diagram of the structure of the first electrode provided in other embodiments of this application;

[0025] Figure 6 This is a schematic diagram of the structure of the first electrode provided in other embodiments of this application;

[0026] Figure 7 This is a schematic diagram of the structure of the second electrode provided in some embodiments of this application;

[0027] Figure 8 This is a schematic diagram of the structure of the first electrode provided in other embodiments of this application;

[0028] Figure 9 This is a schematic diagram of the structure of the first electrode provided for other embodiments of this application.

[0029] Detailed Explanation of Reference Numerals

[0030] 1. Vehicle; 2. Battery assembly; 3. Controller; 4. Motor; 5. Housing; 5a. First housing section; 5b. Second housing section; 5c. Receiving space; 6. Battery cell; 10. Electrode assembly; 101. First electrode; 102. First main body section; 103. First tab; 104. First substrate; 105. First active material layer; 106. Second active material layer; 107. Thinned area; 108. Second electrode; 109. Second main body section; 110. Second tab; 111. Second substrate; 112. Third active material layer; 113. Fourth active material layer; 114. First part; 115. Second part; 116. Third part; 20. Outer shell; 50. Electrode terminal; X, First direction. Detailed Implementation

[0031] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein 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 specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0033] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0034] In this document, the term "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 throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0035] In the description of the embodiments 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, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0036] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0037] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0038] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0039] 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.

[0040] 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.

[0041] In the embodiments of this application, "parallel" includes not only the case of absolute parallelism, but also the case of approximate parallelism as commonly understood in engineering; similarly, "perpendicular" also includes not only the case of absolute perpendicularity, but also the case of approximate perpendicularity as commonly understood in engineering. For example, if the angle between two directions is 85°-95°, the two directions can be considered perpendicular; if the angle between two directions is 0°-5°, the two directions can be considered parallel.

[0042] In this application, "multiple" means two or more (including two).

[0043] 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.

[0044] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0045] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator, with the separator positioned between the positive and negative electrodes. 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, prevents short circuits while allowing active ions to pass through.

[0046] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0047] 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.

[0048] As an example, the positive current collector can be a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as a metal foil, pure metals, alloys, or surface-treated metals can be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0049] 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 battery positive electrode active materials 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 / 3 Mn 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) 0.8 Co 0.15 Al 0.05At least one of O2 and its modified compounds. Modified compounds refer to substances obtained by modification methods such as doping or coating based on the above-mentioned substances.

[0050] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0051] As an example, the negative electrode current collector can be a metal foil, a conductive polymer material, a carbon material, or a composite current collector. For example, as a metal foil, pure metals, alloys, or surface-treated metals can be used, including but not limited to stainless steel, copper, aluminum, nickel, titanium, or silver. The composite current collector may include a polymer material substrate and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0052] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0053] 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.

[0054] 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 for battery cells may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0055] In some embodiments, the negative electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. When foamed metal is used as the negative electrode sheet, the surface of the foamed metal may or may not have a negative electrode active material.

[0056] As an example, negative electrode active materials can be filled or / and deposited within the negative electrode current collector.

[0057] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0058] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

[0059] In some embodiments, the separator is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0060] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The separator can be a single component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes. An inorganic particle coating, an organic particle coating, or an organic / inorganic composite coating can also be applied to the surface of the separator.

[0061] 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.

[0062] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0063] Liquid electrolytes include electrolyte salts and solvents.

[0064] In some embodiments, the electrolyte salt may be selected from 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.

[0065] In some embodiments, the solvent may be selected from at least one of 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 of 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.

[0066] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell, such as additives that improve the overcharge / fast charge performance of the battery cell, additives that improve the high-temperature performance of the battery cell, and additives that improve the low-temperature performance of the battery cell.

[0067] The gel electrolyte includes a polymer as a backbone network and can be used in conjunction with an ionic liquid-lithium salt.

[0068] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0069] As an example, the polymers of polymeric solid electrolytes may include polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids, cellulose, etc.

[0070] As an example, inorganic solid electrolytes can be 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 phosphorus sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0071] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0072] The electrode assembly can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0073] In some implementations, the electrode assembly is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0074] In some implementations, the electrode assembly is a stacked structure.

[0075] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0076] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0077] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0078] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0079] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0080] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0081] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0082] In some embodiments, the battery cell may include a casing. The casing may be a steel casing, an aluminum casing, a plastic casing (such as a polypropylene casing), a composite metal casing (such as a copper-aluminum composite casing), or an aluminum-plastic film, etc. In some embodiments, the casing may be a sealed structure or a non-sealed structure. As an example, when the casing is a non-sealed structure, the casing serves to protect the electrode assembly, and a sealing bag is included between the casing and the electrode assembly to encapsulate the electrode assembly and electrolyte. Specifically, the sealing bag may be a bag-shaped insulating component or an aluminum-plastic film. When the casing is a sealed structure, it is used to encapsulate components such as the electrode assembly and electrolyte.

[0083] As an example, the 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 batteries, such as hexagonal prismatic batteries. This application does not have any particular limitations.

[0084] In some embodiments, the housing includes an end cap and a housing, the housing having an opening, and the end cap covering the opening. The housing may have one or more openings. The end cap may also have one or more.

[0085] In some embodiments, at least one electrode terminal is provided on the housing, and the electrode terminal is electrically connected to the tab. The electrode terminal can be directly connected to the tab, or it can be indirectly connected to the tab through a current collector. The electrode terminal can be provided on the end cap or on the housing.

[0086] During the operation of a single battery cell, the kinetic reaction efficiency of the electrode edge area is lower than that of the main body area, resulting in more side reactions and problems such as lithium plating.

[0087] Therefore, embodiments of this application provide a battery cell with a casing that provides a sealed environment for the electrode assembly, reducing the impact of external impurities and moisture on the electrode assembly. In the electrode assembly, a layer of active material with a lower specific capacity is disposed near the tabs. This region near the tabs is the main current channel; the low specific capacity region reduces the current density in this area, preventing localized overheating and current congestion, thereby optimizing the current distribution of the entire battery. Simultaneously, the first active material layer in the low specific capacity region helps reduce the resistance at the electrode edge, thereby reducing the overall internal resistance of the battery, improving the battery's charge / discharge efficiency and power output, and enhancing the stability of the battery cell operation.

[0088] 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.

[0089] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0090] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0091] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cell assemblies housed within the housing.

[0092] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0093] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0094] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0095] 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.

[0096] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0097] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0098] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical devices.

[0099] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0100] Figure 1 The diagram shows the structural features of a vehicle provided in some embodiments of this application.

[0101] like Figure 1 As shown, a battery 2 is installed inside the vehicle 1. The battery 2 can be located at the bottom, front, or rear of the vehicle 1. The battery device 2 can be used to power the vehicle 1; for example, the battery device 2 can serve as the operating power source for the vehicle 1.

[0102] The vehicle 1 may also include a controller 3 and a motor 4. The controller 3 is used to control the battery device 2 to supply power to the motor 4, for example, for the power needs of the vehicle 1 during starting, navigation and driving.

[0103] In some embodiments of this application, the battery device 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0104] Figure 2 This is a schematic diagram of a battery explosion provided for some embodiments of this application. For example... Figure 2 As shown, the battery device 2 includes a housing 5 and battery cells 6, with the battery cells 6 housed within the housing 5. The battery cell 6 can be the smallest unit that makes up a battery.

[0105] The housing 5 is used to house the battery cell 6, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a housing space 5c for housing the battery cell 6. The second housing portion 5b may be a hollow structure with one end open, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, with the open side of the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b can be various shapes, such as cylinders, cuboids, etc.

[0106] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

[0107] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be called the upper box cover, and the second box section 5b can also be called the lower box.

[0108] In the battery device 2, there can be one or more battery cells 6. If there are multiple battery cells 6, they can be connected in series, in parallel, or in a mixed manner. A mixed connection means that multiple battery cells 6 are connected in both series and parallel.

[0109] Multiple battery cells 6 can be directly connected in series, parallel, or in a mixed manner, and then the whole composed of multiple battery cells 6 can be housed in the housing 5; of course, multiple battery cells 6 can also be connected in series, parallel, or in a mixed manner to form a battery module, and multiple battery modules can then be connected in series, parallel, or in a mixed manner to form a whole, and housed in the housing 5.

[0110] Please refer to the reference. Figures 3 to 5 , Figure 3 This is a schematic diagram of the structure of a battery cell provided in some embodiments of this application. Figure 4 This is a schematic diagram of the structure of the first electrode provided in some embodiments of this application. Figure 5 This is a schematic diagram of the structure of the first electrode provided for other embodiments of this application.

[0111] As shown in the figure, the battery cell 6 provided in this embodiment includes a housing 20 and an electrode assembly 10. The housing 20 has a receiving cavity, and the electrode assembly 10 is disposed in the receiving cavity. The electrode assembly 10 includes a first electrode 101, the first electrode 101 includes a first body portion 102 and a first tab 103, the first body portion 102 includes a first substrate 104 connected to the first tab 103 along the first direction X, a first active material layer 105 coated on the surface of the first substrate 104, and a second active material layer 106, the second active material layer 106 is disposed on the first active material layer 105 along the first direction X, and the specific capacity of the second active material layer 106 is greater than the specific capacity of the first active material layer 105.

[0112] Specific capacity is the ratio of the electrical capacity that the active material inside a single battery cell can release to the mass of the active material, and is usually expressed in milliampere-hours per gram (mAh / g). A region with low specific capacity means that, for the same mass of active material, that region of the battery cell can release less electrical capacity.

[0113] Optionally, the type of active material in the second active material layer 106 may differ from that in the first active material layer 105. Different types of active materials have different specific capacities. For example, in lithium-ion batteries, the specific capacity of lithium iron phosphate is typically lower than that of high-performance materials such as lithium cobalt oxide and lithium nickel oxide. The first active material layer 105 may use materials such as lithium iron phosphate, while the second active material layer 106 may use materials such as lithium cobalt oxide and lithium nickel oxide.

[0114] Optionally, the types of active substances in the second active substance layer 106 are the same as those in the first active substance layer. However, for the same mass, the mass density of the active substances in the first active substance layer 105 is lower than that in the second active substance layer 106. Mass density refers to the proportion of the mass of a certain component to the total mass of the mixture; the higher the mass density, the greater the proportion of that component.

[0115] In the technical solution of this application embodiment, the outer casing 20 provides a sealed environment for the electrode assembly 10, reducing the impact of external impurities and moisture on the electrode assembly 10. In the electrode assembly 10, a layer of active material with a lower specific capacity is disposed in the region near the first tab 103. This region near the first tab 103 is the main current channel; disposing of a low-specific-capacity region can reduce the current density in this region, avoiding localized overheating and current congestion, thereby optimizing the current distribution of the entire battery. Simultaneously, the first active material layer 105 in the low-specific-capacity region helps reduce the resistance at the edge of the electrode sheet, thereby reducing the overall internal resistance of the battery, improving the battery's charge / discharge efficiency and power output, and enhancing the operational stability of the battery cell 6.

[0116] like Figure 5As shown, in some embodiments of this application, the maximum thickness of the first active material layer 105 is less than the minimum thickness of the second active material layer 106. This smaller maximum thickness means that in the region near the first electrode 103, i.e., the region where the first active material layer 105 is located, the amount of active material is relatively small. This design reduces the current density in this region because current tends to choose a path with lower resistance when passing through the electrode, and the thinner active material layer provides such a path. Reducing the thickness of the first active material layer 105 further reduces the current density at the edge of the first body portion 102. This helps avoid localized overheating and current congestion, thereby extending the lifespan of the battery cell 6.

[0117] The above structure reduces the thickness of the first active material layer 105, further reduces the current density at the edge of the first main body 102, reduces the overall internal resistance of the battery, improves the charging and discharging efficiency and power output of the battery, and further improves the operational stability of the battery cell 6.

[0118] In some embodiments of this application, the thickness of the first active material layer 105 gradually decreases along the direction from the first main body portion 102 toward the first tab 103.

[0119] The thickness of the first active material layer 105 gradually decreases from the end furthest from the tab to the end closest to the tab, thus gradually reducing the resistance to current transmission. Since current tends to choose the path of lower resistance, this gradual thickness design helps guide current more smoothly through the electrode assembly 10, thereby optimizing current distribution. The thinner active material layer can reach equilibrium more quickly during charge and discharge, reducing energy loss due to diffusion resistance within the active material. This contributes to improving the battery's charge and discharge efficiency and cycle stability.

[0120] In the aforementioned structure, as the thickness of the first active material layer 105 gradually decreases, the resistance to current transmission also decreases accordingly, allowing current to pass more smoothly through the electrode assembly 10, thereby optimizing the current distribution. The gradual reduction in thickness means a gradual decrease in the resistance of the first active material layer 105, which helps reduce energy loss during charging and discharging, improving battery efficiency and performance.

[0121] like Figure 6 As shown, in some embodiments of this application, a first active material is coated on both opposite sides of the first main body 102, and a second active material is coated on both opposite sides of the first main body 102.

[0122] By coating both sides of the first main body 102 with active material layers, the surface area of ​​the electrode can be fully utilized, the loading of active material can be increased, and the total amount of active material participating in the electrochemical reaction inside the battery can be increased, thereby improving the energy density of the battery.

[0123] like Figure 7 As shown, in some embodiments of this application, the electrode assembly 10 further includes a second electrode 108 with a polarity opposite to that of the first electrode 101, the second electrode 108 having a thinned region 107, and at least a portion of the first active material layer 105 being disposed toward the thinned region 107.

[0124] The aforementioned structure, with a thinning region 107 on the second electrode 108 and the battery electrode assembly 10 corresponding to the first active material layer 105 at the edge of the first electrode 101, indeed brings about multifaceted improvements in battery performance. This design not only reduces internal resistance and improves charge / discharge efficiency and power output, but also helps optimize the overall battery performance, extend service life, and improve cycle stability and safety.

[0125] In some embodiments of this application, the first electrode 101 is a positive electrode and the second electrode 108 is a negative electrode.

[0126] In battery design, the ratio of negative electrode capacity to positive electrode capacity (N / P ratio) is a crucial parameter. The N / P ratio can be increased by adjusting the electrode capacity and area. An increased N / P ratio means that during charging, the negative electrode has more capacity to accept lithium ions from the positive electrode, thereby reducing lithium plating on the first active material layer 105 of the positive electrode. The increased N / P ratio allows the negative electrode to more fully accept lithium ions during charging, thus improving the battery's charging efficiency and speed. This helps to shorten the battery's charging time and reduce lithium plating.

[0127] The above structure can increase the ratio of negative electrode capacity to positive electrode capacity per unit area, thereby reducing lithium deposition on the first active material layer 105 of the positive electrode during charging and improving the charging performance and cycle life of the battery cell 6.

[0128] In some embodiments of this application, the second electrode 108 includes a second main body 109 and a second tab 110. The second main body 109 includes a second substrate 111, a third active material layer 112, and a fourth active material layer 113. The second substrate 111 is disposed on one side of the second tab 110 along the first direction X. The third active material layer 112 is coated on at least one surface of the second substrate 111, and at least a portion of the third active material layer 112 is disposed opposite to the first active material layer 105. The fourth active material layer 113 is coated on at least one surface of the second substrate 111 and is connected to the third active material layer 112. The maximum thickness of the third active material layer 112 is less than the minimum thickness of the fourth active material layer 113.

[0129] In the above structure, the region corresponding to the third active material layer 112 of the second electrode 108 is the thinning region 107, and the fourth active material layer 113 is thinner and has lower dynamics, which matches the low dynamics of the low specific capacity region of the first active material layer 105, reducing the risk of lithium plating in this region and improving the charging performance and cycle life of the battery cell 6.

[0130] In some embodiments of this application, the thickness of the third active material layer 112 gradually decreases along the direction from the second substrate 111 toward the second tab 110. This structure further reduces the internal resistance of the battery cell 6, reduces the risk of lithium plating on the electrode plates, and improves the operational stability of the battery cell 6.

[0131] In some embodiments of this application, the orthographic projection of the third active material layer 112 onto the first substrate 104 falls within the orthographic projection range of the first active material layer 105 onto the first substrate 104. In the above structure, the third active material layer 112 and the first active material layer 105 are correspondingly arranged, maximizing the matching of two regions with lower dynamics, reducing the risk of lithium plating and heat accumulation at the electrode edges, and improving the charging performance and cycle life of the battery cell 6.

[0132] like Figure 8 as well as Figure 9 As shown, in some embodiments of this application, the first active material layer 105 includes a first portion 114, a second portion 115, and a third portion 116 sequentially distributed along a first direction X. The first portion 114 is connected to the second active material layer 106, and the third portion 116 is disposed on the side of the second portion 115 away from the first portion 114.

[0133] The first part 114 has a dimension W1 along the first direction X of 4.5mm < W1 ≤ 5.5mm, and the thickness of the second active material layer 106 is H. The thickness H1 of the first part 114 is 97% * H ≤ H1 ≤ 99% * H. The second part 115 has a dimension W2 along the first direction X of 4.5mm < W2 ≤ 5.5mm, and the thickness H2 of the second part 115 is 92% * H ≤ H2 ≤ 97% * H. The third part 116 has a dimension W3 along the first direction X of 2.5mm < W3 ≤ 3.5mm, and the thickness H3 of the third part 116 is 90% * H ≤ H3 ≤ 95% * H.

[0134] The above structure, by limiting the thickness and width of the first active material layer 105, reduces the risk of side reactions in the electrode thinning region 107, lowers the risk of lithium plating at the electrode edge, and improves the operational stability of the battery cell 6.

[0135] In some alternative embodiments, the battery cell 6 includes a housing 20 and an electrode assembly 10. The housing 20 has a receiving cavity, and the electrode assembly 10 is disposed within the receiving cavity. The electrode assembly 10 includes a first electrode 101, which includes a first body portion 102 and a first tab 103. The first body portion 102 includes a first substrate 104 connected to the first tab 103 along a first direction X, a first active material layer 105 coated on the surface of the first substrate 104, and a second active material layer 106. The second active material layer 106 is disposed on the first active material layer 105 along the first direction X, and the specific capacity of the second active material layer 106 is greater than that of the first active material layer 105. The thickness of the first active material layer 105 gradually decreases along the direction from the first body portion 102 toward the first tab 103. The first active material is coated on two opposite sides of the first body portion 102, and the second active material is coated on two opposite sides of the first body portion 102. The electrode assembly 10 further includes a second electrode 108 with the opposite polarity to the first electrode 101, wherein the first electrode 101 is a positive electrode and the second electrode 108 is a negative electrode. The second electrode 108 has a thinned region 107, and at least a portion of the first active material layer 105 is disposed facing the thinned region 107. The second electrode 108 includes a second body portion 109 and a second tab 110. The second body portion 109 includes a second substrate 111, a third active material layer 112, and a fourth active material layer 113. The second substrate 111 is disposed on one side of the second tab 110 along the first direction X. The third active material layer 112 is coated on at least one surface of the second substrate 111, and at least a portion of the third active material layer 112 is disposed opposite to the first active material layer 105. The fourth active material layer 113 is coated on at least one surface of the second substrate 111 and is connected to the third active material layer 112. The maximum thickness of the third active material layer 112 is less than the minimum thickness of the fourth active material layer 113.

[0136] This application provides a battery device 2, which includes the battery cell 6 described in the above embodiments. This application also provides an electrical device, which includes the battery device 2 described in the above embodiments. The battery device 2 is used to provide electrical energy. Both the battery device 2 and the electrical device include the battery cell 6 described in the above embodiments. A casing 20 is provided in the battery cell 6 to provide a sealed environment for the electrode assembly 10, reducing the impact of external impurities and moisture on the electrode assembly 10. In the electrode assembly 10, a layer of active material with a lower specific capacity is provided in the region near the electrode tab. This region is the main current channel; providing a low-specific-capacity region can reduce the current density in this region, avoiding local overheating and current congestion, thereby optimizing the current distribution of the entire battery. Simultaneously, the first active material layer 105 in the low-specific-capacity region helps reduce the resistance at the edge of the electrode plate, thereby reducing the overall internal resistance of the battery, improving the charging and discharging efficiency and power output of the battery, and improving the operational stability of the battery cell 6.

[0137] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized by, The battery cell comprises: a housing having a receiving cavity; an electrode assembly disposed in the receiving cavity, the electrode assembly comprising a first tab, the first tab comprising a first body portion and a first tab ear, the first body portion comprising a first base connected to a first side of the first tab ear in a first direction, a first active material layer coated on a surface of the first base, and a second active material layer, the second active material layer being disposed on a side of the first active material layer in the first direction, the second active material layer having a gram capacity greater than that of the first active material layer.

2. The battery cell of claim 1, wherein, A maximum thickness of the first active material layer is less than a minimum thickness of the second active material layer.

3. The battery cell of claim 2, wherein, In a direction of the first body portion towards the first tab ear, the thickness of the first active material layer gradually decreases.

4. The battery cell of any one of claims 1-3, wherein, The first active material is coated on two opposite side surfaces of the first body portion, and the second active material is coated on two opposite side surfaces of the first body portion.

5. The battery cell of claim 4, wherein, The electrode assembly further comprises a second tab having a polarity opposite to that of the first tab, the second tab having a thinned region, and at least part of the first active material layer is disposed towards the thinned region.

6. The battery cell of claim 5, wherein, The first tab is a positive electrode tab, and the second tab is a negative electrode tab.

7. The battery cell of claim 5, wherein, The second tab comprises a second body portion and a second tab ear, the second body portion comprising: a second base disposed on a side of the second tab ear in the first direction; a third active material layer coated on at least one surface of the second base, at least part of the third active material layer being disposed opposite to the first active material layer; a fourth active material layer coated on at least one surface of the second base and connected to the third active material layer, a maximum thickness of the third active material layer being less than a minimum thickness of the fourth active material layer.

8. The battery cell of claim 7, wherein, In a direction of the second base towards the second tab ear, the thickness of the third active material layer gradually decreases.

9. The battery cell of claim 7, wherein, A normal projection of the third active material layer on the first base falls within a normal projection range of the first active material layer on the first base.

10. The battery cell of any one of claims 5-9, wherein, The first active material layer comprises a first portion, a second portion, and a third portion sequentially distributed in the first direction, a size W1 of the first portion in the first direction is 4.5mm a size W2 of the second portion in the first direction is 4.5mm a size W3 of the third portion in the first direction is 2.5mm 11. A battery device characterized by comprising: The battery device comprises the battery cell as claimed in any one of claims 1-10.

12. An electrical device, characterized by The battery device is used to provide electric energy.

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