Electrochemical device and electronic equipment

Abstract

The utility model discloses an electrochemical device and electronic equipment, electrochemical device includes electrode subassembly, and electrode subassembly is formed through positive sheet, diaphragm and negative sheet and is sequentially laminated and is coiled, its characterized in that, the positive sheet includes current collector and active material layer, and the current collector includes first surface and second surface along the positive sheet thickness direction, and the active material layer is established at the first surface and / or second surface of the current collector, and the active material layer is provided with a plurality of recess and a plurality of thinning groove, and the recess has an opening, and the groove wall of thinning groove extends along the first direction, and the first direction is the length direction of the positive sheet or the width direction of the positive sheet, not only can effectively avoid the sheet fracture, and can effectively avoid appearing lithium precipitation.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to an electrochemical device and electronic device. Background Technology

[0002] In related technologies, as market demand for battery capacity continues to rise, people's requirements for battery performance are becoming increasingly stringent, and the electrochemical device is the core component of lithium-ion batteries. The electrochemical device includes a positive electrode, a negative electrode, and a separator positioned between the positive and negative electrodes. Since the negative electrode's active material is a silicon-containing active layer, the silicon content affects the expansion of the negative electrode during charging and discharging. A higher silicon content in the active layer results in greater expansion of the negative electrode, leading to more severe compression between the positive and negative electrodes, which can easily cause problems such as electrode breakage and lithium plating, affecting the normal operation of the electrochemical device. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an electrochemical device that can not only effectively prevent electrode breakage but also effectively prevent lithium plating.

[0004] This utility model also proposes an electronic device.

[0005] An electrochemical device according to a first aspect of the present invention includes an electrode assembly formed by sequentially stacking and winding a positive electrode, a separator, and a negative electrode. The positive electrode includes a current collector and an active material layer. The current collector includes a first surface and a second surface along the thickness direction of the positive electrode. The active material layer is disposed on the first surface and / or the second surface of the current collector. The active material layer is provided with a plurality of grooves and a plurality of thinning grooves. The grooves have openings, and the walls of the thinning grooves extend along a first direction, which is either the length direction of the positive electrode or the width direction of the positive electrode.

[0006] The electrochemical device according to embodiments of this utility model has at least the following beneficial effects: Multiple grooves are provided on the positive electrode sheet. After the positive and negative electrode sheets are stacked, the groove design increases the supporting force of the positive electrode sheet, thereby effectively preventing electrode breakage. Furthermore, after the positive electrode sheet is thinned, the amount of positive active material on the positive electrode sheet is reduced, thereby effectively preventing lithium plating in the electrochemical device. Specifically, the electrochemical device not only effectively prevents electrode breakage but also effectively prevents lithium plating.

[0007] According to some embodiments of the present invention, in an electrochemical device, the first direction is the width direction of the positive electrode sheet, the electrode assembly includes a straight section and a corner section, the thinning groove is disposed in the corner section, and in the corner section, along the thickness direction of the positive electrode sheet, the thinning groove and the groove at least partially overlap.

[0008] According to some embodiments of the present invention, in an electrochemical device, the openings of the plurality of grooves are oriented in the same direction.

[0009] According to some embodiments of the electrochemical device of the present invention, the depth of the thinning groove is L, where 5μm≤L≤50μm.

[0010] According to some embodiments of the present invention, the electrochemical device has multiple thinning grooves, and the distance between two adjacent thinning grooves is A, where 0.3 mm ≤ A ≤ 3 mm.

[0011] According to some embodiments of the electrochemical device of the present invention, the width of the thinning groove is H, 30μm≤H≤150μm.

[0012] According to some embodiments of the present invention, in an electrochemical device, the depth of the thinning groove in each corner segment gradually decreases along the winding direction of the positive electrode.

[0013] According to some embodiments of the electrochemical device of the present invention, the depth of the groove is B, where 3μm≤B≤20μm.

[0014] According to some embodiments of the electrochemical device of the present invention, the distance between two adjacent grooves is G, where 0.1mm≤G≤5mm.

[0015] An electronic device according to a second aspect embodiment of the present invention includes the electrochemical device described in any one of the first aspect embodiments.

[0016] The battery according to the embodiments of this utility model has at least the following beneficial effects: The positive electrode sheet has multiple grooves, each groove having an opening. After the positive and negative electrode sheets are stacked, the groove design increases the supporting force of the positive electrode sheet, thereby effectively preventing electrode breakage. Furthermore, after the positive electrode sheet is thinned, the amount of positive active material on the positive electrode sheet is reduced, thereby effectively preventing lithium plating in the electrochemical device. Specifically, the electrochemical device not only effectively prevents electrode breakage but also effectively prevents lithium plating. Furthermore, electronic devices equipped with this electrochemical device have better quality.

[0017] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of the positive electrode plate in the electrochemical device of the first embodiment of this utility model; Figure 2 This is a schematic diagram of the positive electrode plate in the electrochemical device of the second embodiment of this utility model; Figure 3 This is a schematic diagram of the positive electrode in the electrochemical device of the third embodiment of this utility model.

[0019] Figure label: Positive electrode 100, groove 200, thinning groove 300, tab 400. Detailed Implementation

[0020] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0021] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not 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 this utility model.

[0022] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0023] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0024] In the description of this utility model, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0025] The battery 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.

[0026] A battery typically consists of a cell. The cell includes a positive electrode, a negative electrode, and a separator. During charging and discharging, active ions (such as lithium ions) move back and forth between the positive and negative electrodes, inserting and releasing. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0027] 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.

[0028] 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.

[0029] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal 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, nickel, 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.).

[0030] 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 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 oxides 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 NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), 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.

[0031] 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.

[0032] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0033] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, nickel, or titanium, etc. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, 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 (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.).

[0034] 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.

[0035] 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.

[0036] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. 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 batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0037] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0038] In some implementations, the battery cell also includes an isolation element disposed between the positive and negative terminals.

[0039] In some embodiments, the separator is a separator membrane. The separator membrane can be of various types, and any known porous separator membrane with good chemical and mechanical stability can be selected.

[0040] 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.

[0041] 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.

[0042] In some embodiments, the battery also includes an electrolyte that acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or solid. Liquid electrolytes include an electrolyte salt and a solvent.

[0043] 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.

[0044] 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.

[0045] Among them, gel electrolytes include a polymer-based electrolyte backbone network combined with an ionic liquid-lithium salt.

[0046] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0047] 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.

[0048] 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.

[0049] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0050] In some implementations, the battery cell has a wound structure. The positive and negative electrode plates are wound into a wound structure.

[0051] In some implementations, the battery cell has a laminated structure.

[0052] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0053] 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.

[0054] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0055] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0056] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0057] In some implementations, the battery cell can be cylindrical, flat, or polygonal, etc.

[0058] In some implementations, the battery cell is provided with tabs that allow current to be drawn out of the cell. The tabs include a positive tab and a negative tab.

[0059] In some embodiments, the battery may include a casing. The casing is used to encapsulate components such as the battery cell and electrolyte. The casing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0060] As an example, the battery can be a cylindrical battery, a prismatic battery, a pouch battery, or a battery of other shapes. Prismatic batteries include, but are not limited to, square-shell batteries, blade-shaped batteries, and multi-prismatic batteries, such as hexagonal prismatic batteries.

[0061] The battery mentioned in the embodiments of this application refers to a single physical module that includes one or more batteries to provide higher voltage and capacity.

[0062] In some embodiments, the battery can be a battery module, and when there are multiple batteries, the multiple batteries are arranged and fixed to form a battery module.

[0063] In some embodiments, the battery may be a battery pack, which includes a housing and a battery, with the battery or battery module housed within the housing.

[0064] 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.

[0065] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0066] In related technologies, as market demand for battery capacity continues to rise, people's requirements for battery performance are becoming increasingly stringent, and electrochemical devices are the core components of lithium-ion batteries. An electrochemical device includes a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes. Since the negative electrode's active material is a silicon-containing active layer, the silicon content affects the expansion of the negative electrode during charging and discharging. The higher the silicon content in the active layer, the greater the expansion of the negative electrode, and the more severe the compression between the positive and negative electrodes, which can easily cause problems such as electrode breakage and lithium plating, affecting the normal use of the electrochemical device. Therefore, this application proposes an electrochemical device.

[0067] Please refer to Figures 1 to 3 In some embodiments, the electrochemical device is formed by sequentially stacking and winding a positive electrode 100, a separator, and a negative electrode. The positive electrode 100 includes a current collector and an active material layer. The current collector has a first surface and a second surface along the thickness direction of the positive electrode 100. The active material layer is disposed on the first surface and / or the second surface of the current collector. The active material layer is provided with a plurality of grooves 200 and a plurality of thinning grooves 300. The grooves 200 have openings, and the groove walls of the thinning grooves 300 extend along a first direction, which is either the length direction or the width direction of the positive electrode 100. The positive electrode 100 has multiple grooves 200, each groove 200 having an opening. After the positive and negative electrode sheets are stacked, the grooves 200 increase the support force of the positive electrode 100, effectively preventing electrode breakage. Furthermore, the thinning grooves 300 on the positive electrode 100 reduce the amount of positive active material, effectively preventing lithium plating in the electrochemical device. Specifically, the electrochemical device not only effectively prevents electrode breakage but also effectively prevents lithium plating.

[0068] It should be added that after setting the grooves 200 on the positive electrode 100, more space can be provided for expansion in the electrochemical device, which can further reduce the expansion force between the electrodes, and reduce electrode breakage and interface lithium deposition. The grooves 200 are formed by rolling with a roller with protrusions; the thinning grooves 300 are formed by laser or physical mechanical scraping. In addition, the space of the grooves 200 can also accommodate electrolyte, thereby increasing the degree of wetting. The thinning grooves 300 can extend along the width direction of the positive electrode 100, or they can extend along the length direction of the positive electrode 100. The thinning grooves 300 can be formed on the active material of the positive electrode 100 by laser processing. Multiple grooves 200 means that there are many grooves 200, such as tens, hundreds, or even thousands or tens of thousands. Multiple grooves 200 can be arrayed on the positive electrode 100. Among them, the area on the positive electrode 100 connected to the tab 400 does not have grooves 200, but other areas can have grooves 200. In addition, in some other embodiments, multiple grooves 200 may be provided on the negative electrode sheet.

[0069] Furthermore, in some embodiments, the first direction is the width direction of the positive electrode 100, and the electrochemical device includes a straight section and a corner section, with a thinning groove 300 disposed in the corner section. Specifically, the positive electrode 100 and the negative electrode are wound to form an electrochemical device, which includes a straight section and a corner section. In the corner section, along the thickness direction of the positive electrode 100, the thinning groove 300 and the groove 200 at least partially overlap. The thinning groove 300 is disposed in the corner section, which can further effectively prevent lithium plating at the corner of the electrochemical device. That is, embossing the groove 200 on the thinning groove 300 in the corner section can solve the problem of corner breakage while improving the wetting of the electrolyte. This is because stress is concentrated at the corner, making it easy for the electrode to break. Therefore, after setting the thinning groove 300 and the groove 200, stress can be released, and space for electrode expansion can be reserved.

[0070] Furthermore, in some embodiments, the openings of multiple grooves 200 face the same direction. Specifically, this uniform orientation design facilitates a more uniform stress distribution during the winding and operation of the electrochemical device. When the openings of the grooves 200 face the same direction, the flow path of the electrolyte inside the electrochemical device is more regular, allowing it to fill each groove 200 area more smoothly. It also facilitates the deformation of the grooves 200 in a predetermined direction during electrode expansion, avoiding localized stress concentration caused by disordered opening orientations, thereby enhancing the structural reliability of the electrochemical device.

[0071] Furthermore, in some embodiments, the depth of the thinning groove 300 is L, where 5μm ≤ L ≤ 50μm. Specifically, the dimension of L can be 5μm, 6μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, or 50μm. If the depth of the thinning groove 300 is less than 5μm, the thinning groove 300 will not thin enough of the positive electrode active material from the positive electrode sheet 100, which may easily lead to lithium plating in the electrochemical device. When the depth of the thinning groove 300 is greater than 50μm, this may excessively weaken the structural strength of the positive electrode sheet 100, affecting the overall performance and safety of the electrochemical device.

[0072] Further, please refer to Figures 1 to 3 In some embodiments, there are multiple thinning grooves 300 along the length or width direction of the positive electrode 100, with a distance A between two adjacent thinning grooves 300, where 0.3 mm ≤ A ≤ 3 mm. Specifically, the number of thinning grooves 300 can be ten, twenty, thirty, forty, fifty, one hundred, two hundred, etc. When the distance between two adjacent thinning grooves 300 is too small (less than 0.3 mm), it may cause excessive segmentation of the local structure of the positive electrode 100, resulting in less active material and low energy density of the electrochemical device. When the distance between two adjacent thinning grooves 300 is too large (greater than 3 mm), the distribution of the thinning grooves 300 will be too sparse, failing to fully cover the positive electrode 100, and may increase the probability of lithium plating in the electrochemical device.

[0073] Further, please refer to Figures 1 to 3 In some embodiments, the width of the thinning groove 300 is H, where 30 μm ≤ H ≤ 150 μm. The width of the thinning groove 300 can be 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, or 150 μm. When the width of the thinning groove 300 is less than 30 μm, the width is too small, which increases manufacturing difficulty and cost. When the width of the thinning groove 300 is greater than 150 μm, this results in a high mass of positive electrode active material being removed, reducing the energy density of the electrochemical device.

[0074] Furthermore, in some embodiments, there are multiple thinning grooves 300, and the depth of each thinning groove 300 gradually decreases along the winding direction of the positive electrode 100. Specifically, the gradual decrease in the depth of each thinning groove 300 can be achieved by gradually decreasing the depth of each thinning groove 300 from the beginning of winding the positive electrode 100 to the end of winding the positive electrode 100. Wherein, the closer to the inner layer of the electrochemical device, the greater the pressure and the easier it is for lithium plating to occur; in this position, the depth of the thinning groove 300 can be made larger, and then the depth of the thinning groove 300 can be gradually reduced.

[0075] Further, please refer to Figures 1 to 3 In some embodiments, the depth of the groove 200 is B, where 3μm ≤ B ≤ 20μm. Specifically, the depth of the groove 200 can be 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, or 20μm. When the depth of the groove 200 is less than 3μm, the groove 200 has insufficient capacity to accommodate the expansion of the positive electrode 100, and cannot effectively reduce the compression between the positive electrode 100s. When the depth of the groove 200 is greater than 20μm, the structure of the positive electrode 100 may be significantly affected, and may even lead to problems such as breakage of the positive electrode 100 during processing or use. In other embodiments, the diameter of the groove 200 can be from 1μm to 5μm. The shape of the groove 200 is not specifically limited; the shape of the groove 200 can be cylindrical, rectangular, spherical, or square, etc.

[0076] Further, please refer to Figures 1 to 3 In some embodiments, the distance between two adjacent grooves 200 is G, where 0.1mm ≤ G ≤ 5mm. Specifically, the distance between two adjacent grooves 200 can be 0.1mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, or 5mm. When the distance between two adjacent grooves 200 is too small, the process of machining the grooves 200 becomes more complex, increasing the manufacturing difficulty. When the distance between two adjacent grooves 200 is too large, the effect of the grooves 200 in reducing expansion force is not significant, and the risk of breakage of the electrochemical device cannot be effectively reduced.

[0077] In some embodiments, the electronic device includes the electrochemical device of any of the above embodiments. Specifically, a plurality of grooves 200 are provided on the positive electrode 100, wherein each groove 200 has an opening. After the positive electrode 100 and the negative electrode are stacked, the design of the grooves 200 can increase the supporting force of the positive electrode 100, thereby effectively preventing the electrode from breaking. In addition, after the thinning grooves 300 are provided on the positive electrode 100, the amount of positive active material on the positive electrode 100 can be reduced, thereby effectively preventing lithium plating in the electrochemical device. Specifically, the electrochemical device can not only effectively prevent electrode breakage, but also effectively prevent lithium plating. Furthermore, the electronic device with this electrochemical device has better quality.

[0078] The embodiments of this utility model have been described in detail above with reference to the accompanying drawings. However, this utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this utility model. Furthermore, unless otherwise specified, the embodiments of this utility model and the features thereof can be combined with each other.

Claims

1. An electrochemical device, comprising an electrode assembly formed by sequentially stacking and winding a positive electrode, a separator, and a negative electrode, characterized in that, The positive electrode includes a current collector and an active material layer. The current collector includes a first surface and a second surface along the thickness direction of the positive electrode. The active material layer is disposed on the first surface and / or the second surface of the current collector. The active material layer is provided with a plurality of grooves and a plurality of thinning grooves. The grooves have openings. The groove walls of the thinning grooves extend along a first direction, which is the length direction of the positive electrode or the width direction of the positive electrode.

2. The electrochemical device according to claim 1, characterized in that, The first direction is the width direction of the positive electrode sheet. The electrode assembly includes a straight section and a corner section. The thinning groove is disposed in the corner section. In the corner section, along the thickness direction of the positive electrode sheet, the thinning groove and the groove at least partially overlap.

3. The electrochemical device according to claim 1, characterized in that, The openings of the plurality of grooves are oriented in the same direction.

4. The electrochemical device according to claim 1, characterized in that, The depth of the thinning groove is L, where 5μm≤L≤50μm.

5. The electrochemical device according to claim 2, characterized in that, The thinning groove has multiple grooves, and the distance between two adjacent thinning grooves is A, where 0.3mm≤A≤3mm.

6. The electrochemical device according to claim 2, characterized in that, The width of the thinning groove is H, where 30μm≤H≤150μm.

7. The electrochemical device according to claim 2, characterized in that, Along the winding direction of the positive electrode sheet, the depth of the thinning groove in each corner segment gradually decreases.

8. The electrochemical device according to claim 1, characterized in that, The depth of the groove is B, where 3μm≤B≤20μm.

9. The electrochemical device according to claim 1, characterized in that, The distance between two adjacent grooves is G, where 0.1mm ≤ G ≤ 5mm.

10. An electronic device, characterized in that, Includes the electrochemical device as described in any one of claims 1 to 9.

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