Negative electrode sheet, battery, and method for manufacturing negative electrode sheet

Abstract

The application discloses a negative plate, a battery and a negative plate manufacturing method. The negative plate comprises a foil material, a first active material layer, a second active material layer and a barrier piece. The foil material, the first active material layer, the barrier piece and the second active material layer are sequentially stacked along the thickness direction of the foil material, and the barrier piece is used for blocking the expansion of the first active material layer. The negative plate disclosed by the application can have better performance.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a negative electrode, a battery, and a method for manufacturing the negative electrode. Background Technology

[0002] In related technologies, the negative electrode sheet includes a foil and an active material layer. Specifically, the foil can be copper foil, and the active material layer includes graphite, with graphite coated on the copper foil to form the negative electrode sheet. To further improve the energy density of the battery, silicon material can be added to the active material layer of the negative electrode sheet. Specifically, silicon material is coated on the foil, and then graphite is coated on the silicon material. While coating the active material layer formed by silicon material and graphite on the copper foil can improve the energy density of the battery, silicon undergoes significant volume changes during lithium-ion insertion and extraction, leading to poor performance of the negative electrode sheet. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a negative electrode sheet that can have better performance.

[0004] The present invention also proposes a battery.

[0005] This invention also proposes a method for manufacturing a negative electrode sheet.

[0006] According to a first aspect of the present invention, a negative electrode sheet comprises: Foil; First active substance layer; Second active substance layer; A blocking element is provided, wherein the foil, the first active material layer, the blocking element and the second active material layer are stacked sequentially along the thickness direction of the foil, wherein the blocking element is used to prevent the expansion of the first active material layer.

[0007] The negative electrode sheet according to embodiments of the present invention has at least the following beneficial effects: a blocking member is disposed between the first active material layer and the second active material layer, wherein the blocking member is used to prevent the expansion of the first active material layer. In the prior art, silicon material is coated on a foil, and graphite material is coated on the silicon material. The silicon material will undergo significant expansion, resulting in poor performance of the negative electrode sheet. However, in this application, the blocking member can effectively prevent the expansion of the first active material layer, thereby effectively improving the performance of the negative electrode sheet. Specifically, the negative electrode sheet can have better performance.

[0008] According to some embodiments of the present invention, the blocking element of the negative electrode sheet is a mesh structure.

[0009] According to some embodiments of the present invention, the negative electrode sheet has a plurality of through holes provided, wherein the diameter of the through holes is L, and 100nm≤L≤180nm.

[0010] According to some embodiments of the present invention, the negative electrode sheet has a plurality of through holes provided in the blocking member, and the porosity of the blocking member is W, 60%≤W≤90%.

[0011] According to some embodiments of the present invention, the thickness of the blocking element in the negative electrode sheet is A, where 45um ≤ A ≤ 90um.

[0012] According to some embodiments of the present invention, the negative electrode sheet includes two blank areas and a coating area. The two blank areas are respectively connected to the two ends of the coating area. The first active material layer is connected to the coating area. The blocking member includes a body portion and two protrusions. The two protrusions are respectively connected to the two ends of the body portion and protrude relative to the body portion in the same direction. The two protrusions are respectively welded to the two blank areas. The body portion covers the first active material layer.

[0013] According to some embodiments of the present invention, the negative electrode body has a mesh structure.

[0014] According to some embodiments of the present invention, the first active material layer includes a plurality of sub-active material layers, and a plurality of blocking members are provided, wherein the plurality of sub-active material layers and the plurality of blocking members are alternately arranged along the thickness direction of the foil.

[0015] The battery according to a second aspect embodiment of the present invention includes the negative electrode sheet as described in any one of the first aspect embodiments.

[0016] The battery according to embodiments of the present invention has at least the following beneficial effects: a blocking member is disposed between the first active material layer and the second active material layer, wherein the blocking member is used to prevent the expansion of the first active material layer. In the prior art, silicon material is coated on a foil, and graphite material is coated on the silicon material. The silicon material will undergo significant expansion, resulting in poor performance of the negative electrode. In this application, the blocking member can effectively prevent the expansion of the first active material layer, thereby effectively improving the performance of the negative electrode. Specifically, the negative electrode can have better performance. Furthermore, the battery having this negative electrode has better performance.

[0017] A method for manufacturing a negative electrode according to a third aspect embodiment of the present invention includes the following steps: Foil material is produced; A first active material layer is coated onto the foil. A blocking element is placed and fixed on the first active material layer; A second active material layer is coated on the blocking element.

[0018] The negative electrode manufacturing method according to embodiments of the present invention has at least the following beneficial effects: In the prior art, when silicon material is coated on a foil and graphite material is coated on the silicon material, the silicon material undergoes significant expansion, resulting in poor performance of the negative electrode. In this application, a blocking element can be disposed between the first active material layer and the second active material layer, wherein the blocking element is used to prevent the expansion of the first active material layer, thereby effectively improving the performance of the negative electrode. Specifically, the negative electrode obtained by the negative electrode manufacturing method can have better performance.

[0019] Additional aspects and advantages of the 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

[0020] 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 negative electrode sheet according to the first embodiment of the present invention; Figure 2 This is a schematic diagram of a blocking element in the negative electrode sheet according to some embodiments of the present invention; Figure 3 This is a schematic diagram of the negative electrode sheet according to the second embodiment of the present invention; Figure 4 This is a schematic diagram of the negative electrode sheet according to the third embodiment of the present invention.

[0021] Figure label: The components include: negative electrode 100, foil 200, blank area 210, coating area 220, first active material layer 300, sub-active material layer 310, second active material layer 400, blocking element 500, through hole 510, body part 520, and protrusion 530. Detailed Implementation

[0022] Embodiments of the present invention 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 the present invention, and should not be construed as limiting the present invention.

[0023] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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 limiting this invention.

[0024] In the description of this invention, "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.

[0025] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0026] In the description of this invention, 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 the invention. 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.).

[0032] 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.

[0033] 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.

[0034] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0035] 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.).

[0036] 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.

[0037] 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.

[0038] 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.

[0039] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0040] In some implementations, the battery cell also includes an isolation element disposed between the positive and negative terminals.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0048] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0049] 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.

[0050] 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.

[0051] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0052] In some implementations, the battery cell has a wound structure. The positive and negative electrode plates are wound into a wound structure.

[0053] In some implementations, the battery cell has a laminated structure.

[0054] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0055] 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.

[0056] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0057] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0058] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0059] In some implementations, the battery cell can be cylindrical, flat, or polygonal, etc.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] In related technologies, the negative electrode sheet includes a foil and an active material layer. Specifically, the foil can be a copper foil, and the active material layer includes graphite, with graphite coated on the copper foil to form the negative electrode sheet. To further improve the energy density of the battery, silicon material can be added to the active material layer of the negative electrode sheet. Specifically, silicon material is coated on the foil, and then graphite is coated on the silicon material. While coating the active material layer formed by silicon material and graphite on the copper foil can improve the energy density of the battery, silicon undergoes significant volume changes during lithium-ion insertion and extraction, leading to poor performance of the negative electrode sheet. Therefore, this application proposes a negative electrode sheet.

[0069] Please refer to Figures 1 to 2In some embodiments, the negative electrode 100 includes: a foil 200, a first active material layer 300, a second active material layer 400, and a blocking member 500. The foil 200 can be copper foil, which is inexpensive and can reduce the manufacturing cost of the negative electrode 100. The first active material layer 300 can be silicon, and the second active material layer 400 can be graphite. The binder content of the second active material layer 400 is greater than that of the first active material layer 300. Along the thickness direction of the foil 200, the foil 200, the first active material layer 300, the blocking member 500, and the second active material layer 400 are sequentially stacked. That is, the two sides of the first active material layer 300 are respectively connected to the foil 200 and the blocking member 500, and the two sides of the blocking member 500 are respectively connected to the first active material layer 300 and the second active material layer 400. The blocking member 500 is used to prevent the first active material layer 300 from expanding. Specifically, a blocking element 500 is disposed between the first active material layer 300 and the second active material layer 400. The blocking element 500 is used to prevent the first active material layer 300 from expanding. In the prior art, silicon material is coated on the foil 200, and graphite material is coated on the silicon material. The silicon material undergoes significant expansion, resulting in poor performance of the negative electrode 100. In this application, however, the blocking element 500 can effectively prevent the expansion of the first active material layer 300, thereby effectively improving the performance of the negative electrode 100. Specifically, the negative electrode 100 can exhibit better performance.

[0070] Furthermore, the blocking element 500 can be a metal part or a sheet structure made of other conductive materials. These other conductive materials can be conductive inorganic materials. When the blocking element 500 is a sheet structure, such as a copper sheet, the blocking element 500 can effectively block the expansion of the first active material layer 300. In addition to being a sheet structure, the blocking element 500 can also be a mesh structure. Therefore, please refer to... Figure 2 In some embodiments, the blocking element 500 has a mesh structure. Specifically, the mesh structure refers to the blocking element 500 having multiple through holes 510. When the blocking element 500 is made of metal, such as copper, it can be a copper mesh. When the first active material layer 300 expands, the copper mesh can prevent the silicon particles from expanding excessively, thereby effectively improving the expansion degree of the silicon-carbon anode and effectively preventing the anode sheet 100 from expanding excessively. At the same time, the presence of the second active material layer 400 can ensure that the silicon particles are always inside the graphite anode, effectively preventing the silicon particles from losing electrical contact due to expansion and pulverization, which can effectively improve the performance of the anode sheet 100.

[0071] Furthermore, in some embodiments, the blocking member 500 has a mesh structure and has a first state and a second state. It is conceivable that when the first active material layer 300 is not expanded, the blocking member 500 is located between the first active material layer 300 and the second active material layer 400. When the first active material layer 300 expands, the mesh structure design of the blocking member 500 may cause at least a portion of the blocking member 500 to be pushed into the second active material layer 400 by the first active material layer 300. That is, when the blocking member 500 is in the first state, the blocking member 500 is located between the first active material layer 300 and the second active material layer 400; when the blocking member 500 is in the second state, at least a portion of the blocking member 500 is located within the second active material layer 400.

[0072] Furthermore, the manufacturing method of the negative electrode 100 can be as follows: a first active material slurry is coated onto the foil 200 according to technical requirements to form a first active material layer 300. Then, a copper mesh is fixed onto the first active material layer 300 using a dispensing technique. After the copper mesh is fixed, a second active material is coated onto the surface of the first active material layer to form a second active material layer 400. After coating, the material is further compacted using a roller press to ensure good flatness of the negative electrode 100. The first active material layer 300 is made of silicon carbon. The second active material layer 400 can be made of graphite, including but not limited to graphene, carbon fiber, and graphite particles. The conductive agent is including but not limited to conductive carbon black, acetylene black, and metal powder. The binder includes one of polyacrylic acid (PAA), lithium polyacrylate (PAA-Li), sodium polyacrylate (PAA-Na), polyvinyl alcohol (PVA), and polyacrylonitrile (PAN). The first active material layer 300 contains 95%–97% silicon-carbon, 1%–4% conductive agent, and 0.2%–1% binder. The second active material layer 400 contains 92%–94% graphite, 1%–4% conductive agent, and 2%–6% binder.

[0073] The following experiments illustrate the beneficial effects of the negative electrode 100 in this application.

[0074] Example 1: The preparation method of negative electrode 100 includes the following steps: S1: The first active material layer 300 is prepared with 96% silicon-carbon anode, 3% conductive carbon black, and 1% polyvinyl alcohol. S2: The second active material layer 400 is prepared with 92% graphene, 3% conductive carbon black and 5% polyvinyl alcohol. S3: Prepare a copper mesh with a thickness of 50μm; S4: The first active material layer 300, the copper mesh, and the second active material layer 400 are respectively coated on the foil 200; S5: Roll-press the coated negative electrode sheet 100. The thickness of the rolled negative electrode sheet 100 is 400μm. S6: To manufacture a soft-pack battery, the battery is injected with electrolyte and formed.

[0075] Example 2: S1: The first active material layer 300 is prepared with 97% silicon-carbon anode, 2% conductive carbon black, and 1% polyvinyl alcohol. S2: The second active material layer 400 is prepared by using 93% graphene, 2% conductive carbon black and 5% polyvinyl alcohol. S3: Prepare a copper mesh with a thickness of 50μm; S4: The first active material layer 300, the copper mesh, and the second active material layer 400 are respectively coated on the foil 200; S5: Roll-press the coated negative electrode sheet 100. The thickness of the rolled negative electrode sheet 100 is 450μm. S6: To manufacture a soft-pack battery, the battery is injected with electrolyte and formed.

[0076] Example 3: S1: The first active material layer 300 is prepared with 96% silicon-carbon anode, 3% conductive carbon black, and 1% polyvinyl alcohol. S2: The second active material layer 400 is prepared with 92% graphene, 3% conductive carbon black and 5% polyvinyl alcohol. S3: The first active material layer 300 and the second active material layer 400 are respectively coated on the foil 200; S4: Roll the coated negative electrode sheet 100, and the thickness of the rolled negative electrode sheet 100 is 400μm; S5: To manufacture a soft-pack battery, the battery is injected with electrolyte and formed.

[0077] Specifically, after the negative electrode 100 is made into a battery, the battery is tested. The first discharge capacity test refers to the constant current discharge test of the battery at room temperature, with a charge-discharge range of 1.0 to 3V and a current density range of 400 to 5000 mA / g.

[0078] Capacity retention testing refers to the ratio of the discharge specific capacity after 500 cycles to the initial discharge specific capacity when the batteries of each embodiment and comparative example are operating at a current density of 0.2C at room temperature. Cycle capacity retention rate = (500th cycle discharge capacity / first cycle discharge capacity) * 100%.

[0079] Thermal shock performance refers to the following: under 25℃ environmental conditions, the battery is discharged to 3.0V at a given current of 0.2C; left to stand for 5 minutes; charged to 4.45V at a charging current of 0.2C; when the battery voltage reaches 4.45V, it is switched to constant voltage charging at 4.45V until the charging current is less than or equal to the given cutoff current of 0.05C; after standing for 1 hour, the battery is placed in an oven, and the oven temperature is increased to 135±2℃ at a rate of 5±2℃ / min and maintained for 30 minutes before stopping. The judgment criterion is that the battery does not catch fire or explode.

[0080] The 60℃ high-temperature storage test refers to the following steps: The battery is placed at room temperature and charged / discharged once at 0.5C (4.45V~3.0V). The discharge capacity C0 before storage is recorded. Then, the battery is charged to a full charge state of 4.45V using a constant current and constant voltage method. The battery thickness d1 before high-temperature storage is measured using a PPG battery thickness gauge (500g). The battery is then stored in a 60℃ constant temperature chamber for 14 days. After storage, the battery is removed and its thermal thickness d2 after storage is measured. The battery thickness expansion rate after 14 days of storage at 60℃ is calculated. After the battery cools at room temperature for 24 hours, it is discharged again at 0.5C to 3.0V using a constant current method, and then charged to 4.45V at 0.5C using a constant current and constant voltage method. The discharge capacity C1 and charge capacity C2 after storage are recorded. The remaining capacity and recovery rate after 14 days of storage at 60℃ are calculated using the following formula: Thickness expansion rate after 14 days of storage at 60℃ = (d2-d1) / d1*100%. The experimental results are shown in the table below.

[0081]

[0082] As can be seen from the table above, Examples 1 and 2 adopted the setting of the blocking member 500. Compared with Example 3, which did not adopt the setting of the blocking member 500, the battery made with the blocking member 500 has a smaller expansion rate, a higher probability of passing thermal shock, a higher capacity retention rate, and a higher first discharge specific capacity.

[0083] Further, please refer to Figure 2 In some embodiments, the blocking element 500 is provided with multiple through holes 510, the diameter of which is L, 100nm≤L≤180nm. The diameter of the through holes 510 can be 100nm, 110nm, 120nm, 150nm, or 180nm. When the diameter of the through holes 510 is less than 100nm, the silicon material particles may not be able to pass through due to the small diameter, resulting in greater stress on the blocking element 500, and the blocking element 500 may not be able to effectively prevent the expansion of the first active material layer 300. When the diameter of the through holes 510 is greater than 180nm, most of the silicon material particles will pass through the through holes 510 due to the large diameter, resulting in excessive expansion of the negative electrode 100.

[0084] Furthermore, in some embodiments, the blocking member 500 is provided with multiple through holes 510, and the porosity W of the blocking member 500 is 60% ≤ W ≤ 90%. Specifically, the porosity of the blocking member 500 can be 60%, 70%, 80%, or 90%. The porosity reflects the number and distribution of pores in the blocking member 500. That is, the higher the porosity, the more through holes 510 are provided on the blocking member 500, and the smaller the gap between two adjacent through holes 510. When the porosity of the blocking member 500 is greater than 90%, there are many through holes 510 provided on the blocking member 500, which may lead to greater manufacturing difficulty in setting the through holes 510, resulting in excessively high costs for the blocking member 500. When the porosity of the blocking component 500 is less than 60%, the number of through holes 510 provided on the blocking component 500 is small. This may result in the blocking component 500 not being effective in restricting the expansion of the silicon material. The silicon material will push up the blocking component 500, resulting in a low flatness of the negative electrode sheet 100.

[0085] Furthermore, in some embodiments, the thickness of the barrier 500 is A, where 45µm ≤ A ≤ 90µm. Specifically, the thickness of the barrier 500 can be 45µm, 50µm, 60µm, 80µm, or 90µm. When the thickness of the barrier 500 is large, since the main function of the barrier 500 is to restrict the expansion of the silicon layer, a larger thickness of the barrier 500 will result in less active material in the negative electrode 100 at a fixed size, thus lowering the energy density of the negative electrode 100. Therefore, the thickness of the barrier 500 cannot exceed 90µm. When the thickness of the barrier 500 is less than 45µm, the smaller thickness of the barrier 500 will increase the difficulty of punching holes in the barrier 500, and the lower strength of the barrier 500 will result in a poorer effect in restricting the expansion of the silicon material.

[0086] Furthermore, the specific methods by which the blocking element 500 effectively restricts the expansion of silicon material are described below. Please refer to [link / reference]. Figure 3In some embodiments, the foil 200 includes two blank areas 210 and a coating area 220. The two blank areas 210 are respectively connected to both ends of the coating area 220. Specifically, along the length of the foil 200, the blank areas 210, the coating area 220, and the blank areas 210 are arranged sequentially. The first active material layer 300 is connected to the coating area 220. The blocking member 500 includes a body portion 520 and two protrusions 530. The two protrusions 530 are respectively connected to both ends of the body portion 520, and the two protrusions 530 protrude relative to the body portion 520 in the same direction. The two protrusions 530 are respectively welded to the two blank areas 210, and the body portion 520 covers the first active material layer 300. Specifically, the two protrusions 530 are welded to the blank area 210 respectively. This allows the blocking member 500 to be fixed to the foil 200. After the body part 520 covers the first active material layer 300, when the silicon material expands, the silicon material will abut against the body part 520. The protrusions 530 can hold the body part 520, and the body part 520 can effectively abut against the silicon material, thereby preventing the silicon material from expanding.

[0087] Further, please refer to Figure 3 In some embodiments, the body portion 520 has a mesh structure. Specifically, the body portion 520 is configured as a mesh structure, meaning that the body portion 520 has multiple through holes 510, and the blocking member 500 is made of metal, such as copper, in which case the body portion 520 can be a copper mesh. When the first active material layer 300 expands, the copper mesh can prevent the silicon particles from expanding too much, thereby effectively improving the expansion degree of the silicon-carbon anode and effectively preventing the anode sheet 100 from expanding too much. At the same time, the presence of the second active material layer 400 can ensure that the silicon particles are always inside the graphite anode, effectively preventing the silicon particles from losing electrical contact due to expansion and pulverization, which can effectively improve the performance of the anode sheet 100.

[0088] Further, please refer to Figure 4In some embodiments, the first active material layer 300 includes multiple sub-active material layers 310, and multiple blocking members 500 are provided, with the multiple sub-active material layers 310 and multiple blocking members 500 alternately arranged along the thickness direction of the foil 200. For example, taking a first active material layer 300 including two sub-active material layers 310 and two blocking members 500 as an example, the alternating arrangement of the multiple sub-active material layers 310 and multiple blocking members 500 along the thickness direction of the foil 200 specifically involves a sub-active material layer 310-blocking member 500-sub-active material layer 310-blocking member 500. This arrangement allows for the layering of the first active material layer 300, and then the blocking members 500 are placed between two adjacent sub-active material layers 310. After layering, the expansion degree of each sub-active material layer 310 is relatively low, and the blocking members 500 can effectively limit it, thereby further improving the performance of the negative electrode 100. That is, the arrangement of multiple blocking members 500 can improve the effect of limiting the expansion of silicon material.

[0089] In some embodiments, the battery includes a negative electrode 100 as described in any of the above embodiments. Specifically, a blocking member 500 is disposed between the first active material layer 300 and the second active material layer 400. The blocking member 500 is used to prevent the first active material layer 300 from expanding. In the prior art, silicon material is coated on the foil 200, and graphite material is coated on the silicon material. The silicon material will expand significantly, resulting in poor performance of the negative electrode 100. In this application, the blocking member 500 can effectively prevent the expansion of the first active material layer 300, thereby effectively improving the performance of the negative electrode 100. Specifically, the negative electrode 100 can have better performance. Furthermore, the battery with this negative electrode 100 has better performance.

[0090] In some embodiments, the method for manufacturing the negative electrode 100 includes the following steps: S100, 200 foil materials are obtained; S200, A first active material layer 300 is coated on the foil 200; S300: Place and fix the blocking member 500 on the first active material layer 300; S400, A second active material layer 400 is applied to the barrier 500.

[0091] Specifically, in the prior art, silicon material is coated on foil 200, and graphite material is coated on silicon material. The silicon material undergoes significant expansion, resulting in poor performance of the negative electrode 100. In this application, a blocking member 500 can be disposed between the first active material layer 300 and the second active material layer 400. The blocking member 500 is used to prevent the expansion of the first active material layer 300, thereby effectively improving the performance of the negative electrode 100. Specifically, the negative electrode 100 manufactured by this method exhibits better performance.

[0092] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A negative electrode, characterized in that, include: Foil; First active substance layer; Second active substance layer; A blocking element is provided, wherein the foil, the first active material layer, the blocking element and the second active material layer are sequentially stacked along the thickness direction of the foil, wherein the blocking element is used to prevent the expansion of the first active material layer; The foil includes two blank areas and one coating area. The two blank areas are respectively connected to the two ends of the coating area. The first active material layer is connected to the coating area. The blocking member includes a body and two protrusions. The two protrusions are respectively connected to the two ends of the body and protrude relative to the body in the same direction. The two protrusions are respectively welded to the two blank areas. The body covers the first active material layer.

2. The negative electrode sheet according to claim 1, characterized in that, The blocking component has a mesh structure.

3. The negative electrode sheet according to claim 2, characterized in that, The blocking component is provided with multiple through holes, and the diameter of the through holes is L, where 100nm≤L≤180nm.

4. The negative electrode sheet according to claim 2, characterized in that, The blocking member is provided with multiple through holes, and the porosity of the blocking member is W, where 60%≤W≤90%.

5. The negative electrode sheet according to claim 1, characterized in that, The thickness of the blocking element is A, where 45um ≤ A ≤ 90um.

6. The negative electrode sheet according to claim 1, characterized in that, The main body has a mesh structure.

7. The negative electrode sheet according to claim 1, characterized in that, The first active material layer includes multiple sub-active material layers, and multiple blocking elements are provided. Along the thickness direction of the foil, the multiple sub-active material layers and the multiple blocking elements are alternately arranged.

8. A battery, characterized in that, Includes the negative electrode sheet as described in any one of claims 1 to 7.

9. A method for manufacturing a negative electrode sheet, used to manufacture the negative electrode sheet according to any one of claims 1 to 7, characterized in that, The method for manufacturing the negative electrode includes the following steps: Foil material is produced; A first active material layer is coated onto the foil. A blocking element is placed and fixed on the first active material layer; A second active material layer is coated on the blocking element.

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