Pole piece and preparation method thereof, diaphragm-free battery and solid-state battery

Abstract

The invention belongs to the technical field of batteries, and discloses a pole piece and a preparation method thereof, a diaphragm-free battery and a solid-state battery. The pole piece comprises a current collector and an active substance layer, the active substance layer is arranged on at least one side of the current collector, the active substance layer comprises a mixed ion electron conductor material and an active substance, the mixed ion electron conductor material comprises an aggregate formed by reaction of a monomer, an initiator, a solid electrolyte and a conductive agent, a polymer formed by the monomer has cohesiveness and ion conductivity. According to the pole piece provided by the invention, the cycle performance, the safety performance and the rate capability of the battery can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a pole piece and a preparation method thereof, a diaphragm-free battery and a solid-state battery. Background Art

[0002] Solid-state lithium batteries based on solid electrolytes do not contain flammable or volatile components, and completely eliminate safety hazards such as battery smoking and fire caused by leakage and high temperature. They are known as the safest battery system.

[0003] Solid-state batteries generally construct ion and electron transmission channels inside the electrode by adding solid electrolytes and conductive agents during electrode preparation. However, this method often requires the addition of a large amount of solid electrolytes so that there is sufficient ionic conductivity inside the electrode to support the normal operation of the battery. However, this will have an adverse effect on the battery's cycle performance, safety performance and rate performance. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, one object of the present invention is to provide a pole piece and a preparation method thereof, a diaphragm-free battery and a solid-state battery. The pole piece provided in the present application can improve the cycle performance, safety performance and rate performance of the battery.

[0005] In the first aspect of the present invention, the present invention proposes a pole piece. According to an embodiment of the present invention, the pole piece includes a current collector and an active material layer. The active material layer is arranged on at least one side of the current collector. The active material layer includes a mixed ion-electronic conductor material and an active material. The mixed ion-electronic conductor material includes an agglomerate formed by reacting a monomer, an initiator, a solid electrolyte and a conductive agent. The polymer formed by the monomer has adhesion and ion conductivity.

[0006] According to the pole piece of the above embodiment of the present invention, the active material layer is composed of a mixed ion-electronic conductor material and an active material, and is arranged on one side of the current collector. The raw material components of the mixed ion-electronic conductor material include monomers, initiators, solid electrolytes and conductive agents. Under the action of the initiator, the polymer formed by the initiator monomer has adhesiveness and ion conductivity, and can bond the solid electrolyte and the conductive agent together by forming a bond. The solid electrolyte can conduct lithium ions, and the conductive agent can conduct electrons, so that the mixed ion-electronic conductor material has high ion conductivity, high electronic conductivity and strong adhesiveness at the same time, and can replace the use of conductive agents, solid electrolytes and adhesives in the original pole piece, which can reduce material costs and improve production efficiency. High ion conductivity and high electronic conductivity are also conducive to improving the charge and discharge efficiency and rate performance of the battery. Strong adhesiveness can bond the active material, prevent the internal contact failure of the active material and detachment from the current collector, and ensure the stability of the pole piece structure, thereby improving the cycle life and safety performance of the battery.

[0007] Furthermore, the oil-based monomers have different functional groups (such as O-, =O, -S-, =S, -N-, CF, CN, etc.), which can coordinate with high-valent ions (such as Ni, Co, Mn, etc.) in the electrode to provide compensation charge, inhibit metal ion dissolution and oxygen escape reaction under high voltage, reduce the structural changes and capacity decay of active substances during the cycle, thereby extending the cycle performance of the battery; and the monomers have high thermal stability after polymerization, which makes the battery more stable under extreme conditions such as high temperature and reduces the safety risks caused by problems such as thermal runaway; the functional groups of the water-based monomers (such as -OH, -COOH, -NH2, -CO-NH- and -SS-, etc.) show reversible bonding self-healing properties, which can repair the structural damage that may occur to the electrode during the charge and discharge process, maintain the stability of the electrode structure, enhance the adhesion between the electrode and other components, and at the same time improve the mechanical strength of the electrode, so that it can better withstand the volume change and stress during the charge and discharge process, further improving the cycle performance of the battery.

[0008] Although the polymer itself also has these functional groups (such as O-, =O, -S-, =S, -N-, CF, CN, -OH, -COOH, -NH2, -CO-NH-, -SS-, etc.), the polymer chain segment of the polymer itself has a low degree of disorder and a high degree of crystallinity, which results in a small number of functional groups that can play a role, and low ionic conductivity and adhesion. The monomers provided in the present application have a large number of functional groups that can play a role, and high ionic conductivity, adhesion, and interface isotropy, thereby improving the cycle performance and safety performance of the battery.

[0009] Furthermore, compared with the dual transmission routes of the original electrode in which the conductive agent conducts electrons and the solid electrolyte conducts ions, the mixed ion-electronic conductor material has the ability to conduct ions and electrons at the same time, thereby realizing a single transmission route and constructing a three-dimensional conductive lithium-conducting network of the internal transmission path of the electrode, reducing the tortuosity of ion and electron transmission, increasing the threshold flow rate, and improving the charge transfer efficiency, which is beneficial to improving the battery's rate performance; in addition, it can also reduce the porosity of the electrode, which is beneficial to improving the overall energy density of the battery.

[0010] Furthermore, the mixed ion-electronic conductor material can be filled in the pores between the active material particles, and the three major solid-solid interface problems can be improved through interface softening, such as: reducing the contact resistance between the active material layer and the solid electrolyte layer, enhancing the charge transfer efficiency, and increasing the diffusion rate of ions at the interface, thereby improving the performance of the battery; enhancing the peeling force between the active material layer and the current collector, ensuring that the charge can be effectively transferred from the current collector to the active material layer, reducing the resistance and energy loss at the interface; helping to optimize the contact and charge transfer between the three phases (active material, solid electrolyte and conductive agent) inside the active material layer, improving the stability and consistency of the interface, thereby improving the overall performance and cycle performance of the battery. In addition, the mixed ion-electronic conductor material can also effectively control the huge volume changes of the active material particles during the charge and discharge process, thereby avoiding the reduction or inactivation of the active material particles, avoiding the generation of depletion zones, and thereby improving the charge and discharge efficiency of the battery. The mixed ion-electronic conductor material can also give the active material layer flexibility, making it more flexible, which helps the active material layer better adapt to various changes during the charge and discharge process, reducing damage or performance degradation caused by material rigidity, thereby improving the cycle performance of the battery.

[0011] Therefore, the electrode provided in the present application can improve the cycle performance, safety performance and rate performance of the battery.

[0012] In addition, the pole piece according to the above embodiment of the present invention may also have the following additional technical features:

[0013] In some embodiments of the present invention, the mass ratio of the active material to the mixed ion-electron conductor material is (90-99):(1-10), preferably (93-99):(1-7). This is beneficial to improving the cycle performance, safety performance and rate performance of the battery.

[0014] In some embodiments of the present invention, based on the total mass of the active material layer, the mass proportion of the active material is 93%-99%, thereby improving the cycle performance and safety performance of the battery.

[0015] In some embodiments of the present invention, based on the total mass of the active material layer, the mass of the solid electrolyte accounts for 1%-5%, thereby improving the cycle performance and safety performance of the battery.

[0016] In some embodiments of the present invention, the Dv50 particle size of the mixed ionic and electronic conductor material is 50nm-300nm, thereby improving the cycle performance, safety performance and rate performance of the battery.

[0017] In some embodiments of the present invention, the peeling force between the active material layer and the current collector is 20 N / m-40 N / m. Thus, the cycle performance, safety performance and rate performance of the battery can be improved.

[0018] In some embodiments of the present invention, the cohesive force of the active material layer is 250 N / m-400 N / m, thereby improving the cycle performance, safety performance and rate performance of the battery.

[0019] In some embodiments of the present invention, the raw material components of the mixed ion electronic conductor material further include lithium salt and solvent, thereby further improving the ion conductivity of the mixed ion electronic conductor material.

[0020] In some embodiments of the present invention, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass of the monomer accounts for 0.5%-30%, thereby ensuring the conduction efficiency of ions in the active material layer and achieving an optimized balance of ion conduction capacity.

[0021] In some embodiments of the present invention, the mass of the initiator accounts for 0.1%-3% of the mass of the monomer, thereby providing sufficient initiation activity to ensure that the monomer undergoes polymerization under appropriate conditions, thereby helping to form a polymer with uniform structure and stable performance.

[0022] In some embodiments of the present invention, the Dv50 particle size of the solid electrolyte is 10nm-200nm, thereby improving the cycle performance, safety performance and rate performance of the battery.

[0023] In some embodiments of the present invention, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass of the solid electrolyte accounts for 5%-50%. As a result, lithium ions can migrate more smoothly between the pole pieces during the charge and discharge process, improving the ion conduction efficiency, thereby improving the charge and discharge performance and rate performance of the battery.

[0024] In some embodiments of the present invention, the Dv50 particle size of the conductive agent is 10 nm-200 nm, thereby improving the cycle performance, safety performance and rate performance of the battery.

[0025] In some embodiments of the present invention, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass proportion of the conductive agent is 5%-50%. Thus, electrons can migrate more smoothly between the pole pieces during the charge and discharge process, improving the electron conduction efficiency, thereby improving the charge and discharge performance and rate performance of the battery.

[0026] In some embodiments of the present invention, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass proportion of the lithium salt is 0.5%-30%. This helps to ensure efficient transmission of lithium ions between the pole pieces, improve ion conductivity, and thus improve the charge and discharge performance and rate performance of the battery.

[0027] In some embodiments of the present invention, the lithium salt includes at least one of lithium trifluoromethanesulfonate, lithium hexafluoroarsenate, lithium perchlorate, lithium difluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium tetrafluoroborate and lithium hexafluorophosphate.

[0028] In some embodiments of the present invention, the monomer includes one of an oil-based monomer and a water-based monomer.

[0029] In some embodiments of the present invention, the oil monomers include vinylidene fluoride, tetrafluoroethylene, ethylene oxide, vinylidene fluoride-hexafluoropropylene, hexafluoropropylene, 1,3,5-trioxane, 1,3-dioxane, 1,4-dioxane, 1,3-dioxolane, 1,4-dioxane, dithiolane, boroxane, vinylene carbonate, vinyl vinyl sulfite, vinylene trithiocarbonate, vinyl acetate, methyl vinyl sulfone, ethyl vinyl sulfone, phthalic acid diacrylate, pentaerythritol tetraacrylate, methacrylate, ethylene glycol methacrylate, ethylene glycol di ... At least one of diol acrylate, methyl methacrylate, propylene carbonate, acrylonitrile, lactam, lipoic acid, cyclopentane, alkyl disulfide, tetrakis(hydroxymethyl)phosphonium chloride, melamine, olefinated monophosphine ligand, bisphosphine ligand, arginine methyl ester, arginine ethyl ester, methoxypolyethylene glycol, isocyanate, quaternary ammonium salt monomer, trifluoromethylphenylboronic acid methyliminodiacetate, methacryloyloxyethyl ester, pentaerythrityl alcohol acrylate, N,N'-methylenebisacrylamide, 1,3-propylene-sultone and acrylamide, preferably at least one of methyl methacrylate, vinylene carbonate and N,N'-methylenebisacrylamide.

[0030] In some embodiments of the present invention, the aqueous monomer includes at least one of hydroxyethyl methacrylate, ethylene glycol methacrylate, N,N-(dimethylamine)ethyl methacrylate, ethylene glycol methacrylate, sodium methacrylate, N-isopropyl acrylamide, acrylate, methacrylate, acrylamide, sodium allyl sulfonate, sodium acrylate, methacrylamide, monomethacrylate glycerol, ethylenediaminetetraacetic acid, diethanolamine, acrylonitrile, methyl acrylate, itaconic acid, sulfobetaine, melamine, phenolic resin, diglycidyl glycerol ester, N,N′-methylenebisacrylamide, ethylene glycol, 1,3-propylene glycol, hydroxyethyl methacrylate, acrylic acid, acrylamide, vinyl alcohol, carboxymethyl cellulose, alginate, collagen, hyaluronic acid, alginic acid, cellulose, chitosan, chitin, and gelatin, preferably at least one of acrylic acid, acrylamide and alginate.

[0031] In some embodiments of the present invention, the initiator includes one of an oil-based initiator and a water-based initiator.

[0032] In some embodiments of the present invention, the solid electrolyte includes at least one of an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte, and a boride solid electrolyte.

[0033] In some embodiments of the present invention, the conductive agent includes at least one of conductive graphite, conductive carbon black, acetylene black, Ketjen black, vapor-grown carbon fiber, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, gallium-based metals, gallium-based alloys, bismuth-based metals, bismuth-based alloys, silicon carbide, boron carbide, silicon boride, vanadium boride, magnesium boride, titanium boride, polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene) and polyphenylene; preferably at least one of gallium-based metals, gallium-based alloys, bismuth-based metals, bismuth-based alloys, polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene) and polyphenylene.

[0034] In some embodiments of the present invention, the solvent includes at least one of an oil-based solvent and a water-based solvent.

[0035] In some embodiments of the present invention, the aqueous solvent includes water.

[0036] In some embodiments of the present invention, the aqueous solvent further includes an oil solvent.

[0037] In some embodiments of the present invention, the oil-based solvent includes at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, N-methylpyrrolidone, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide and N,N-dimethylacetamide, N,N-dimethylpropionamide, ethyl acetate, butyl butyrate, chloroform, dichloromethane, ethyl ether, toluene, acetone, tetrahydrofuran, fluoroethylene carbonate, methyl trifluoroethyl carbonate, difluoroethylene carbonate, tris(2,2,2-trifluoroethyl)phosphate, bis(2,2,2-trifluoroethyl) carbonate, 2,2,2-trifluoroethyl ether, ethyl trifluoroacetate, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0038] In some embodiments of the present invention, the pole piece includes a positive pole piece, and the raw material components of the mixed ion-electronic conductor material include the oil-based monomer, the oil-based initiator and the oil-based solvent.

[0039] In some embodiments of the present invention, the electrode sheet includes a negative electrode sheet, and the raw material components of the mixed ion-electronic conductor material include the water-based monomer, the water-based initiator and the water-based solvent.

[0040] In some embodiments of the present invention, the solid electrolyte comprises an ionic liquid.

[0041] In some embodiments of the present invention, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass of the ionic liquid accounts for 1%-3%. Thus, sufficient and suitable ion transmission channels can be formed in the active material layer, which is beneficial to improving the cycle performance and safety performance of the battery.

[0042] In some embodiments of the present invention, the ionic liquid includes lithium (triglyme), lithium (tetraglyme), 1-ethyl-3-methylimidazolium, 1-propyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1,2-dimethyl-3-butylimidazolium, 1-alkyl-3-methylimidazolium, 1-allyl-3-methylimidazolium, 1,3 -diallylimidazolium, 1-allyl-3-vinylimidazolium, 1-vinyl-3-ethylimidazolium, 1-cyanomethyl-3-methylimidazolium, 1,3-dicyanomethyl-imidazolium, 1-propyl-1-methylpiperidinium, 1-butyl-1-methylpiperidinium, 1-methyl-1-ethylpyrrolidinium, 1-benzyl-3-methylimidazolium, 1-propyl-1-methyl at least one of 1-[(trimethylsilyl)methyl]benzotriazolium, N-alkyl-N-methylpiperidinium, n-butyl-N-methylpyrrolidinium, tetramethylammonium, tetraethylammonium, tributylmethylammonium, diallyldimethylammonium, NN-diethyl-N-methyl-N-(2-methoxyethyl)ammonium, N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium, trimethylisobutylphosphonium, triisobutylmethylphosphonium, tributylmethylphosphonium, diethylmethylisobutylphosphonium, trihexadecylphosphonium, trihexyltetradecylphosphonium and tetrabutylphosphine.

[0043] In some embodiments of the present invention, the active material includes one of a positive electrode active material and a negative electrode active material.

[0044] In some embodiments of the present invention, the positive electrode active material includes at least one of a metal oxide positive electrode active material, a polyanion positive electrode active material, a transition metal positive electrode active material and an organic positive electrode active material.

[0045] In the second aspect of the present invention, the present invention proposes a method for preparing the above-mentioned pole piece. According to an embodiment of the present invention, an active material layer is prepared on at least one side of the current collector, and the active material layer is arranged on at least one side of the current collector. The active material layer includes a mixed ion-electronic conductor material and an active material. The mixed ion-electronic conductor material includes an aggregate formed by the reaction of a monomer, an initiator, a solid electrolyte and a conductive agent. The polymer formed by the monomer has adhesion and ion conductivity. In this way, the rate performance, cycle performance and safety performance of the battery can be improved.

[0046] In some embodiments of the present invention, the steps of preparing the active material layer include: mixing monomers, initiators, lithium salts, solid electrolytes, conductive agents and solvents, and polymerizing to obtain a mixed ion-electronic conductor material; mixing the mixed ion-electronic conductor material and active materials to obtain a mixed slurry; and coating the mixed slurry on at least one side of the current collector to obtain the active material layer. Thus, the rate performance, cycle performance and safety performance of the battery can be improved.

[0047] In some embodiments of the present invention, the step of preparing the mixed slurry includes: mixing monomers, initiators, lithium salts, solid electrolytes, conductive agents and solvents, and performing a first polymerization to obtain a mixed ion electronic conductor material precursor solution; and mixing the mixed ion electronic conductor material precursor solution and active materials for a second polymerization to obtain a mixed slurry. Thus, the rate performance, cycle performance and safety performance of the battery can be improved.

[0048] In some embodiments of the present invention, the monomer conversion rate of the first polymerization is 30%-45%, thereby improving the cycle performance, safety performance and rate performance of the battery.

[0049] In some embodiments of the present invention, the temperature of the first polymerization is 45°C-55°C.

[0050] In some embodiments of the present invention, the first polymerization time is 1 h-2 h.

[0051] In some embodiments of the present invention, the first polymerization method includes at least one of thermal polymerization, photopolymerization, ultrasonic polymerization and acid polymerization.

[0052] In some embodiments of the present invention, the viscosity of the mixed ion-electron conductor material precursor solution is 4000 mPa·S-8000 mPa·S. Thus, the cycle performance, safety performance and rate performance of the battery can be improved.

[0053] In some embodiments of the present invention, the monomer conversion rate of the second polymerization is 94%-98%, thereby improving the cycle performance, safety performance and rate performance of the battery.

[0054] In some embodiments of the present invention, the temperature of the second polymerization is 70°C-85°C.

[0055] In some embodiments of the present invention, the second polymerization time is 1h-20h.

[0056] In the third aspect of the present invention, the present invention provides a diaphragm-free battery. According to an embodiment of the present invention, the diaphragm-free battery comprises the pole piece of the first aspect or the pole piece prepared by the method of the second aspect. The diaphragm-free battery has excellent safety performance, cycle performance and rate performance.

[0057] In a fourth aspect of the present invention, the present invention provides a solid-state battery. According to an embodiment of the present invention, the solid-state battery comprises the pole piece of the first aspect or the pole piece prepared by the method of the second aspect. The solid-state battery has excellent safety performance, cycle performance and rate performance.

[0058] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. DETAILED DESCRIPTION

[0059] The embodiments of the present invention are described in detail below, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0060] In a first aspect of the present invention, the present invention provides a pole piece. According to an embodiment of the present invention, the pole piece includes a current collector and an active material layer.

[0061] The main function of the current collector is to carry active substances and collect the current generated by the electrochemical reaction to realize the conversion of chemical energy into electrical energy.

[0062] There is no particular limitation on the material of the current collector, and those skilled in the art can flexibly select it according to needs.

[0063] As an example, the current collector includes but is not limited to at least one of copper foil, aluminum foil, carbon-coated copper foil, carbon-coated aluminum foil, and a composite current collector.

[0064] As an example, the composite current collector includes, but is not limited to, an organic material substrate and an inorganic metal layer disposed on at least one side of the organic material substrate.

[0065] As an example, the material of the organic substrate includes, but is not limited to, at least one of polyethylene terephthalate, polybutylene terephthalate, polyimide, polystyrene, and polypropylene.

[0066] As an example, the metal material of the inorganic metal layer includes but is not limited to at least one of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, gold and gold alloy.

[0067] According to an embodiment of the present invention, the active material layer is arranged on at least one side of the current collector, and the active material layer includes a mixed ion electronic conductor material and an active material. The mixed ion electronic conductor material includes an agglomerate formed by the reaction of a monomer, an initiator, a solid electrolyte and a conductive agent, and the polymer formed by the monomer has adhesion and ion conductivity.

[0068] According to the pole piece of the above embodiment of the present invention, the active material layer is composed of a mixed ion-electronic conductor material and an active material, and is arranged on one side of the current collector. The raw material components of the mixed ion-electronic conductor material include monomers, initiators, solid electrolytes and conductive agents. Under the action of the initiator, the polymer formed by the initiator monomer has adhesiveness and ion conductivity, and can bond the solid electrolyte and the conductive agent together by forming a bond. The solid electrolyte can conduct lithium ions, and the conductive agent can conduct electrons, so that the mixed ion-electronic conductor material has high ion conductivity, high electronic conductivity and strong adhesiveness at the same time, and can replace the use of conductive agents, solid electrolytes and adhesives in the original pole piece, which can reduce material costs and improve production efficiency. High ion conductivity and high electronic conductivity are also conducive to improving the charge and discharge efficiency and rate performance of the battery. Strong adhesiveness can bond the active material, prevent the internal contact failure of the active material and detachment from the current collector, and ensure the stability of the pole piece structure, thereby improving the cycle life and safety performance of the battery.

[0069] Furthermore, the oil-based monomers have different functional groups (such as O-, =O, -S-, =S, -N-, CF, CN, etc.), which can coordinate with high-valent ions (such as Ni, Co, Mn, etc.) in the electrode to provide compensation charge, inhibit metal ion dissolution and oxygen escape reaction under high voltage, reduce the structural change and capacity decay of active substances during the cycle, thereby extending the cycle performance of the battery; and the monomers have high thermal stability after polymerization, which makes the battery more stable under extreme conditions such as high temperature and reduces the safety risks caused by problems such as thermal runaway; the functional groups of water-based monomers (such as -OH, -COOH, -NH2, -CO-NH- and -SS-, etc.) show reversible bonding self-healing properties, which can repair structural damage that may occur to the electrode during the charge and discharge process, maintain the stability of the electrode structure, enhance the adhesion between the electrode and other components, and at the same time improve the mechanical strength of the electrode, so that it can better withstand volume changes and stresses during the charge and discharge process, further improving the cycle performance of the battery.

[0070] Although the polymer itself also has these functional groups (such as O-, =O, -S-, =S, -N-, CF, CN, -OH, -COOH, -NH2, -CO-NH-, -SS-, etc.), the polymer chain segment of the polymer itself has a low degree of disorder and a high degree of crystallinity, which results in a small number of functional groups that can play a role, and low ionic conductivity and adhesion. The monomers provided in the present application have a large number of functional groups that can play a role, and high ionic conductivity and adhesion, thereby improving the cycle performance and safety performance of the battery.

[0071] Furthermore, compared with the dual transmission routes of the original electrode in which the conductive agent conducts electrons and the solid electrolyte conducts ions, the mixed ion-electronic conductor material has the ability to conduct ions and electrons at the same time, thereby realizing a single transmission route and constructing a three-dimensional conductive lithium-conducting network of the internal transmission path of the electrode, reducing the tortuosity of ion and electron transmission, increasing the threshold flow rate, and improving the charge transfer efficiency, which is beneficial to improving the battery's rate performance; in addition, it can also reduce the porosity of the electrode, which is beneficial to improving the overall energy density of the battery.

[0072] Furthermore, the mixed ion-electronic conductor material can be filled in the pores between the active material particles, and the three major solid-solid interface problems can be improved through interface softening, such as: reducing the contact resistance between the active material layer and the solid electrolyte layer, enhancing the charge transfer efficiency, and increasing the diffusion rate of ions at the interface, thereby improving the performance of the battery; enhancing the peeling force between the active material layer and the current collector, ensuring that the charge can be effectively transferred from the current collector to the active material layer, reducing the resistance and energy loss at the interface; helping to optimize the contact and charge transfer between the three phases (active material, solid electrolyte and conductive agent) inside the active material layer, improving the stability and consistency of the interface, thereby improving the overall performance and cycle performance of the battery. In addition, the mixed ion-electronic conductor material can also effectively control the huge volume changes of the active material particles during the charge and discharge process, thereby avoiding the reduction or inactivation of the active material particles, avoiding the generation of depletion zones, and thereby improving the charge and discharge efficiency of the battery. The mixed ion-electronic conductor material can also give the active material layer flexibility, making it more flexible, which helps the active material layer better adapt to various changes during the charge and discharge process, reducing damage or performance degradation caused by material rigidity, thereby improving the cycle performance of the battery.

[0073] Therefore, the electrode provided in the present application can improve the cycle performance, safety performance and rate performance of the battery.

[0074] It should be noted that mixed ionic and electronic conductor materials refer to materials in which solid electrolytes and conductive agents are connected together through monomer polymerization to form a stable overall structure.

[0075] According to some embodiments of the present invention, the mass ratio of the active substance to the mixed ionic electronic conductor material is (90-99): (1-10). For example, it can be 90:1, 99:1, 90:10, 99:10, 95:5, etc. By limiting the mass ratio of the active substance to the mixed ionic electronic conductor material within the above range, the addition of the mixed ionic electronic conductor material increases the mass proportion of the active substance in the pole piece, so that more energy can be stored in the pole piece, thereby improving the overall energy density of the battery. According to other embodiments of the present invention, the mass ratio of the active substance to the mixed ionic electronic conductor material can preferably be (93-99): (1-7).

[0076] It should be noted that there is no particular limitation on the type of active substance, and those skilled in the art can flexibly select it according to needs.

[0077] As an example, the active material includes one of a positive electrode active material and a negative electrode active material.

[0078] As an example, the positive electrode active material includes, but is not limited to, at least one of a metal oxide positive electrode active material, a polyanion positive electrode active material, a transition metal positive electrode active material, and an organic positive electrode active material.

[0079] As an example, the metal oxide positive electrode active material is not limited to lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), nickel cobalt manganese ternary material, nickel cobalt aluminum ternary material, lithium manganese-rich material, lithium manganese oxide (LiMn2O4), lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4), ferroferric oxide (Fe3O4) and lithium vanadate.

[0080] As an example, the polyanion positive electrode active material includes but is not limited to at least one of lithium iron phosphate (LiFePO4), lithium manganese phosphate (LiMnPO4), lithium iron manganese phosphate, lithium vanadium phosphate (Li3V2(PO4)3), lithium vanadium phosphate (LiVOPO4), lithium cobalt phosphate (LiCoPO4), lithium nickel phosphate (LiNiPO4), lithium iron silicate (Li2FeSiO4), lithium ferrous fluorosulfate (LiFeSO4F), lithium iron borate (LiFeBO3) and lithium iron titanate (Li2FeTiO4).

[0081] As an example, the transition metal positive electrode active material includes but is not limited to at least one of iron trifluoride (FeF3), cobalt trifluoride (CoF3), nickel trifluoride (NiF3), titanium disulfide (TiS2), iron disulfide (FeS2), molybdenum disulfide (MoS2) and niobium triselenide (NbSe3).

[0082] As an example, the organic positive electrode active material includes but is not limited to at least one of a quinone molecular organic material and a nitrogen-containing organic material.

[0083] As an example, the quinone-based molecular organic material includes at least one of benzoquinone, anthraquinone, phenanthrenequinone, dithienobenzoquinone, dipyridobenzoquinone, difuranobenzoquinone, 2,6-dicarboxylic acid lithium anthraquinone, 2,7-dicarboxylic acid lithium phenanthrenequinone and 2,7-dicarboxylic acid lithium pyrene-4,5,9,10-tetraone.

[0084] As an example, the nitrogen-containing organic material includes, but is not limited to, at least one of pteridine, phenoloxazine, a pteridine derivative, and a phenoloxazine derivative.

[0085] As an example, the negative electrode active material includes but is not limited to at least one of graphite, graphene, soft carbon, hard carbon, elemental silicon, silicon-oxygen materials, silicon-carbon materials, silicon-nitrogen composite materials, silicon-based alloys, elemental tin, tin oxide compounds, tin-based alloys, lithium metal, lithium alloys, lithium titanium oxides, transition metal oxides and transition metal sulfides.

[0086] According to some embodiments of the present invention, based on the total mass of the active material layer, the mass proportion of the active material is 93%-99%. For example, it can be 93%, 94%, 95%, 96%, 97%, 98%, 99%, etc. By limiting the mass proportion of the active material to the above range, more active materials participate in the reaction during the charge and discharge process, reducing the damage to the pole piece structure caused by the side reactions of inactive ingredients (such as solid electrolytes, conductive agents, etc.), helping to maintain the stability of the pole piece, reducing the volume change and structural degradation of the pole piece during the cycle, thereby improving the cycle performance and safety performance of the battery.

[0087] According to some embodiments of the present invention, based on the total mass of the active material layer, the mass proportion of the solid electrolyte is 1%-5%. For example, it can be 1%, 2%, 3%, 4%, 5%, etc. By limiting the mass proportion of the solid electrolyte to the above range, the amount of solid electrolyte is reduced, the contact area between the solid electrolyte and the conductive agent is reduced, and thus the possibility of decomposition of the solid electrolyte is reduced, which helps to maintain the stability of the internal chemical environment of the battery, reduce the adverse effects caused by the decomposition of the solid electrolyte, such as gas generation, electrode corrosion, etc., and is conducive to improving the cycle performance and safety performance of the battery. In addition, the mass ratio and volume ratio of the solid electrolyte and the conductive agent are reduced, so that the proportion of active materials is correspondingly increased, thereby being able to improve the energy density of the battery.

[0088] According to some embodiments of the present invention, the Dv50 particle size of the mixed ion electronic conductor material is 50nm-300nm. For example, it can be 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, etc. By limiting the Dv50 particle size of the mixed ion electronic conductor material to the above range, the contact area between the mixed ion electronic conductor material and the active material and the current collector is increased, the threshold flow of the ion electron transmission path is increased, and the polarization is reduced, which is conducive to improving the cycle performance and rate performance of the battery. As a result, the cycle performance and rate performance of the battery can be improved.

[0089] It should be noted that the Dv50 particle size refers to the particle size corresponding to when the cumulative volume distribution percentage reaches 50%, and is measured using a laser particle size analyzer (eg, Malvern Master Size 3000) with reference to the standard GB / T 19077-2016.

[0090] According to some embodiments of the present invention, the peeling force between the active material layer and the current collector is 20N / m-40N / m. For example, it can be 20N / m, 30N / m, 40N / m, etc. Thus, it can be ensured that the active material layer can be firmly attached to the current collector during normal use, which is beneficial to improving the cycle performance and safety performance of the battery.

[0091] According to some embodiments of the present invention, the cohesive force of the active material layer is 250N / m-400N / m. For example, it can be 250N / m, 300N / m, 350N / m, 400N / m, etc. Thus, the appropriate cohesive force can make the active material particles tightly bonded, prevent the particles from loosening and falling off, ensure the stable operation of the electrode, and help improve the cycle performance of the battery.

[0092] According to some embodiments of the present invention, the raw material components of the mixed ion electronic conductor material also include lithium salt and solvent. The addition of lithium salt can provide an additional lithium ion source for the mixed ion electronic conductor material, which can further improve the ionic conductivity of the mixed ion electronic conductor material. During the operation of the battery, lithium ions can migrate more quickly between the pole pieces, thereby improving the charge and discharge speed and rate performance of the battery. Secondly, the lithium salt can be decomposed with the highest priority to form a lithium-containing SEI or CEI layer on the surface of the active material and the conductive agent, avoiding the continuation of side reactions, thereby improving the cycle life of the battery. The addition of solvent can make the raw material components of different properties such as monomers, initiators, solid electrolytes, conductive agents, lithium salts, etc. evenly dissolved and dispersed in the system, which can avoid performance differences caused by local uneven components, so that the mixed ion electronic conductor material plays a consistent role in the entire active material layer.

[0093] It should be noted that there is no particular limitation on the types of lithium salt and solvent, and those skilled in the art can flexibly select them as needed.

[0094] As an example, the lithium salt includes, but is not limited to, at least one of lithium trifluoromethanesulfonate (LiCF3SO3), lithium hexafluoroarsenate (LiAsF6), lithium perchlorate (LiClO4), lithium difluorophosphate (LiDFP), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalatoborate) (LiBOB), lithium difluorooxalatoborate (LiDFOB), lithium tetrafluoroborate (LiBF4) and lithium hexafluorophosphate (LiPF6).

[0095] As an example, the solvent includes, but is not limited to, at least one of an oil-based solvent and a water-based solvent.

[0096] As an example, the aqueous solvent includes water.

[0097] As an example, the water-based solvent also includes the oil-based solvent.

[0098] As an example, the oil-based solvent includes, but is not limited to, at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, N-methylpyrrolidone, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide and N,N-dimethylacetamide, N,N-dimethylpropionamide, ethyl acetate, butyl butyrate, chloroform, dichloromethane, ethyl ether, toluene, acetone, tetrahydrofuran, fluoroethylene carbonate, methyl trifluoroethyl carbonate (FEMC), bisfluoroethylene carbonate (DFEC), tris(2,2,2-trifluoroethyl) phosphate (TFEP), bis(2,2,2-trifluoroethyl) carbonate (TFEC), 2,2,2-trifluoroethyl ether (BTFE), ethyl trifluoroacetate (ETFA), 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0099] According to some embodiments of the present invention, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass proportion of the monomer is 0.5%-30%. For example, it can be 0.5%, 1%, 5%, 10%, 20%, 30%, 50%, etc. By limiting the mass proportion of the monomer within the above range, the polymer formed by the monomer can provide appropriate adhesion, so that the active material layer is better attached to the current collector, ensuring that the active material will not fall off easily during the use of the battery, and will not affect the transmission of ions and electrons due to excessive adhesion. The polymer formed by the monomer can also be made to have ion conductivity. The appropriate monomer mass proportion can ensure the conduction efficiency of ions in the active material layer and achieve an optimized balance of ion conductivity.

[0100] According to some embodiments of the present invention, the monomer includes one of an oil-based monomer and a water-based monomer. The polymer formed by the above-mentioned monomer has high adhesion, which can ensure the stability of the pole piece structure, thereby improving the cycle life and safety performance of the battery. In addition, the monomer structure of the above-mentioned part contains functional groups such as -O-, =O, -S-, =S, -N-, CF, CN, etc., which can form a stable complex structure with lithium ions, which helps to improve the mobility of lithium ions in mixed ion electronic conductor materials, thereby improving ionic conductivity. Lithium ions can move more smoothly between pole pieces, improve the charge and discharge performance and rate performance of the battery, and these functional groups can form specific ion transmission channels in the material, guide the transmission path of lithium ions, reduce the resistance of ion diffusion, and can also interact with solid electrolytes to jointly build an efficient ion transmission network to further improve ionic conductivity. Aqueous monomers rich in hydrogen-bonding functional groups such as -OH, -COOH, -NH2, -CO-NH- and -SS- can form hydrogen-bonding networks in mixed ion-electronic conductor materials, which can enhance the structural stability of mixed ion-electronic conductor materials and improve the strength and toughness of the materials. During the charge and discharge process of the battery, the material can better withstand volume changes and stress, reduce the rupture and damage of the pole piece, and improve the cycle life of the battery. The conductive structural elements contained in the above monomers, such as -C4H4O2S-, -C 16 H9, -C 13 H8-and-C 12 Conjugated functional groups with electronic conductivity such as H8N- can improve the electronic conductivity of mixed ionic electronic conductor materials. Conjugated functional groups can form continuous electron transmission channels, allowing electrons to move more quickly in the electrode, reducing electron transmission resistance and improving battery power output and energy efficiency.

[0101] As an example, the oil monomers include, but are not limited to, vinylidene fluoride, tetrafluoroethylene, ethylene oxide, vinylidene fluoride-hexafluoropropylene, hexafluoropropylene, 1,3,5-trioxane, 1,3-dioxane, 1,4-dioxane, 1,3-dioxolane, 1,4-dioxane, dithiolane, boroxane, vinylene carbonate, vinyl vinyl sulfite, vinylene trithiocarbonate, vinyl acetate, methyl vinyl sulfone, ethyl vinyl sulfone, phthalic acid diacrylate, pentaerythritol tetraacrylate, methacrylate, ethylene glycol methacrylate, ethylene glycol methacrylate, etc. At least one of dimethacrylate, ethylene glycol diacrylate, ethylene glycol acrylate, methyl methacrylate, propylene carbonate, acrylonitrile, lactam, lipoic acid, cyclopentane, alkyl disulfide, tetrakis(hydroxymethyl)phosphonium chloride, melamine, olefinated monophosphine ligand, bisphosphine ligand, arginine methyl ester, arginine ethyl ester, methoxypolyethylene glycol, isocyanate, quaternary ammonium salt monomer, trifluoromethylphenylboronic acid methyliminodiacetate, methacryloyloxyethyl ester, pentaerythrityl acrylate, N,N'-methylenebisacrylamide, 1,3-propenyl-sultone and acrylamide.

[0102] Furthermore, the oil-based monomer is preferably at least one of methyl methacrylate, vinylene carbonate and N,N'-methylenebisacrylamide. Thus, the polymer formed by the above preferred monomers can provide a certain ion transmission channel, promote the migration of lithium ions, thereby improving ion conductivity; it also has high thermal stability, is not easy to decompose or produce harmful gases during the operation of the battery, and helps to improve the safety of the battery.

[0103] As an example, the aqueous monomer includes but is not limited to at least one of hydroxyethyl methacrylate, ethylene glycol methacrylate, N,N-(dimethylamine) ethyl methacrylate, ethylene glycol methacrylate, sodium methacrylate, N-isopropyl acrylamide, acrylate, methacrylate, acrylamide, sodium allyl sulfonate, sodium acrylate, methacrylamide, monomethacrylate glycerol, ethylenediaminetetraacetic acid, diethanolamine, acrylonitrile, methyl acrylate, itaconic acid, sulfobetaine, melamine, phenolic resin, glycerol diglycidyl ester, N,N′-methylenebisacrylamide, ethylene glycol, 1,3-propylene glycol, hydroxyethyl methacrylate, acrylic acid, acrylamide, vinyl alcohol, carboxymethyl cellulose, alginate, collagen, hyaluronic acid, alginic acid, cellulose, chitosan, chitin, and gelatin.

[0104] Further, the aqueous monomer is preferably at least one of acrylic acid, acrylamide and alginate. The polymer formed by selecting the above aqueous monomer has good flexibility, can adapt to the volume change of the pole piece during the battery charging and discharging process, reduce the rupture of the active material caused by stress concentration, and help to improve the cycle performance and safety performance of the battery. The formed polymer has high mechanical strength and can withstand certain external forces. It is not easy to be damaged during battery assembly and use, ensuring the stability of the battery structure. The formed polymer has high conductivity, can improve the conductivity of the mixed ion electronic conductor material, and help to improve the charge and discharge efficiency and rate performance of the battery. The formed polymer has good self-adhesion and self-healing properties. The self-adhesion property enables the polymer to better combine with the pole piece material and other components, improve the overall performance of the battery, and the self-healing property can automatically repair the mixed ion electronic conductor material after being damaged, and prolong the cycle performance of the battery. The formed polymer has excellent compatibility with negative electrode materials, can form a stable interface layer on the negative electrode surface, promote ion transmission, reduce the occurrence of side reactions, and is conducive to improving the safety performance and cycle performance of the battery.

[0105] According to some embodiments of the present invention, the mass of the initiator accounts for 0.1%-3% of the mass of the monomer. For example, it can be 0.1%, 0.5%, 1%, 2%, 3%, etc. By limiting the content of the initiator to the above range, sufficient initiation activity can be provided to ensure that the monomer undergoes polymerization reaction under appropriate conditions, which helps to form a polymer with uniform structure and stable performance.

[0106] It should be noted that there is no particular limitation on the type of initiator, and those skilled in the art can flexibly select the initiator according to their preferences.

[0107] As an example, the initiator includes one of an oil-based initiator and a water-based initiator.

[0108] As an example, the oil-based initiator includes, but is not limited to, at least one of an azo initiator, a peroxide initiator, a lithium salt initiator, and a Lewis acid initiator.

[0109] As an example, the azo initiator includes but is not limited to at least one of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile (ABVN), azobisisovaleronitrile (AMBN), dimethyl azobisisobutyrate (AIBME), azoisobutylcyanamide (CABN), diisopropyl azodicarboxylate (DIAD) and azobiscyclohexylcarbonitrile (ACCN).

[0110] As an example, the peroxide initiator includes, but is not limited to, at least one of benzoyl peroxide (BPO), di(2-ethylhexyl) peroxydicarbonate (EHP), tert-butyl perbenzoate (TBPB) and methyl ethyl ketone peroxide (MEKP).

[0111] As an example, the lithium salt initiator includes but is not limited to at least one of lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6) and lithium difluorooxalatoborate (LiDFOB).

[0112] As an example, the Lewis acid initiator is not limited to AB n1 , wherein A includes at least one of Fe, Al, Zn, Cn, B, In, Sb, V, Sc and Sn, B includes at least one of F, Cl, Br, I and trifluoromethanesulfonic acid, and 1<n1<6.

[0113] As an example, the water-based initiator includes but is not limited to ammonium persulfate, sulfuric acid, sulfuric acid, citric acid, formic acid, acetic acid, propionic acid, 2,2'-azoazole (2-(2-imidazolin-2-yl) propane) dihydrochloride, 3-((1-carboxyethyl (sulfur) carbonyl) sulfide) propionic acid, 4-((2-carboxyethyl (sulfur) carbonyl (sulfur) sulfide) sulfide)-4-cyanovaleric acid, 2-cyanopropan-2-yl N-methyl-N-(pyridin-4-yl) amino disulfate, At least one of methyl propionic dithiocarbamate (2-[methyl(4-pyridyl)carbamoylthio]propionic acid, 2-cyano-2-propylbenzodithiobenzoate, 2-((butylsulfonyl)carbonthiosulfonyl)propionic acid, azobisisobutyramidine hydrochloride (AIBA), azobisisopropylimidazoline hydrochloride (AIBI), azobiscyanovaleric acid (ACVA), azocyanovaleric acid, hydrogen peroxide, ammonium persulfate and potassium persulfate.

[0114] According to some embodiments of the present invention, the Dv50 particle size of the solid electrolyte is 10nm-200nm. For example, it can be 10nm, 50nm, 100nm, 150nm, 200nm, etc. By limiting the Dv50 particle size of the solid electrolyte to the above range, the contact with the active material can be maximized, and the ion migration in the active material can be improved; it can be effectively filled in the pores between the active material particles, reducing the porosity of the pole piece, and improving the cycle performance and energy density of the battery.

[0115] According to some embodiments of the present invention, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass proportion of the solid electrolyte is 5%-50%. For example, it can be 5%, 10%, 20%, 30%, 40%, 50%, etc. By limiting the mass proportion of the solid electrolyte to the above range, the solid electrolyte can form sufficient ion transmission channels in the mixed ion-electron conductor material, so that lithium ions can migrate more smoothly between the pole pieces during the charge and discharge process, improve the ion conduction efficiency, and thus improve the charge and discharge performance and rate performance of the battery.

[0116] As an example, the solid electrolyte includes, but is not limited to, at least one of an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte, and a boride solid electrolyte.

[0117] As an example, the oxide solid electrolyte includes but is not limited to at least one of a garnet-type solid electrolyte, a perovskite-type solid electrolyte, a NASICON-type solid electrolyte, and a lithium phosphorus oxygen nitrogen solid electrolyte.

[0118] Furthermore, the oxide solid electrolyte is preferably at least one of a garnet solid electrolyte and a NASICON solid electrolyte. Among them, the surface of the preferred solid electrolyte is rich in oxygen vacancies and hydroxyl groups, which can form a bond with the polymer formed by the monomer, so that the solid electrolyte and the polymer are tightly combined together. During the use of the battery, this strong combination can effectively prevent the separation of the solid electrolyte and the polymer layer, ensure the integrity of the pole piece structure, enhance the overall mechanical strength of the pole piece material, better resist external stress, and help improve the cycle performance and safety performance of the battery.

[0119] As an example, the garnet-type solid electrolyte includes Li a1 La b1 Zr c1 X1 d1 O 12 , wherein X comprises at least one of Ta, Al, Nb, Ca, Ti, Ga, Fe, Sr, Ce, Y, Sn, Sb, Te, Ba, Mo, Rb, Sc, Si and W, 6≤a1≤7, 2.5≤b1≤3, 1≤c1≤2, 0≤d1≤1; preferably Li 6.4 LqCy 1.4 Ta 0.6 O 12 (LLZTO).

[0120] As an example, the perovskite solid electrolyte includes Li 3a2 La 2 / 3-a2 TiO3, 0≤a2≤2 / 3.

[0121] As an example, the NASICON-type solid electrolyte includes Li a3 A' b2 B' c2 (PO4)3, wherein A' comprises at least one of Al, Cr, Ga, Fe, Sc, In, Lu, Y, Bi and La, B' comprises at least one of Ti, Ge and Si, 1.3≤a3≤1.5, 0.3≤b2≤0.5, 1.5≤c2≤1.7; preferably Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP).

[0122] As an example, the sulfide solid electrolyte includes but is not limited to at least one of an Argyrodite-type solid electrolyte, a Thio-LiSICON-type solid electrolyte, and a glass-ceramic Li2S-P2S5.

[0123] As an example, the Argyrodite-type solid electrolyte includes LiPSA"X2, wherein A" includes at least one of O, Cu, Zn, Bi, Sn, Al and In, and X2 includes at least one of F, Cl, Br and I.

[0124] As an example, the Thio-LiSICON type solid electrolyte includes Li 4-n2 A2 1-n2 B2 n2 S4, wherein A2 includes at least one of Si, Ge and Zr, B2 includes at least one of P, Al, Zn and Ga, and 0≤n2≤0.5.

[0125] As an example, the halide solid electrolyte includes but is not limited to LiX3, Li2MX44, Li3M'X56 and Li a4 M” b3 Ln c3 Cl3; wherein LiX3 satisfies: X3 includes at least one of F, Cl, Br and I; Li2MX44 satisfies: M includes at least one of Mg, Mn, Fe, Zn and Cd; Li3M'X56 satisfies: M' includes at least one of O, In, Y, Sc, Ho, Yb, Lu and Er; Li a4 M” b3 Ln c3 Cl3 satisfies: M" includes at least one of Ta, Zr, Ca and Al, Ln includes at least one of La, Ce, Pr, Nd and Sm, 0≤a4≤0.5, 0≤b3≤0.83, 0≤c3≤0.83.

[0126] As an example, the boride solid electrolyte is not limited to Li2B n3 X6 n3 、LiBH4、LiCB n4 H n4+1 , Li3BO3, Li2B4O7, Li2O-B2O3-P2O5, Li5B7S 13 、Li3BS3、Li9B 19 S3, Li2B2S5, Li 10 B 10 S 20 , Li 6+2n4 [B 10 S 18 ]S n5 At least one of; wherein Li2B n3 X6 n3 Satisfies: X6 includes at least one of Cl, Br, and H, n3 includes one of I0 and I2; LiCB n4 H n4+1 and Li 6+2n4 [B 10 S 18 ]S n5 Satisfies: n4 includes one of 9 and 11, and 0.8≤n5≤1.2.

[0127] It should be noted that NASICON-type active filler refers to active materials with a sodium superion conductor (Na Super Ionic Conductor, NASICON) structure, a three-dimensional open framework structure composed of metal ions and polyhedrons; LISICON-type active filler refers to a class of materials with a lithium superion conductor (Lithium Super Ionic Conductor, LISICON) structure; Argyrodite type has a unique crystal structure, generally composed of chalcogen elements (such as sulfur, selenium, tellurium, etc.) and metal elements, and its structure contains an open framework structure.

[0128] According to some embodiments of the present invention, the Dv50 particle size of the conductive agent is 10nm-200nm. For example, it can be 10nm, 50nm, 100nm, 150nm, 200nm, etc. By limiting the Dv50 particle size of the conductive agent to the above range, the contact with the active material can be maximized, and the electron migration in the active material can be improved; it can be effectively filled in the pores between the active material particles, reducing the porosity of the pole piece, and can improve the cycle performance and rate performance of the battery.

[0129] According to some embodiments of the present invention, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass proportion of the conductive agent is 5%-50%. For example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 40%, 50%, etc. By limiting the mass proportion of the conductive agent to the above range, the conductive agent can form sufficient electron transmission channels in the mixed ion-electron conductor material, so that electrons can migrate more smoothly between the pole pieces during the charge and discharge process, improve the electron conduction efficiency, and thus improve the charge and discharge performance and rate performance of the battery.

[0130] As an example, the conductive agent includes but is not limited to at least one of conductive graphite, conductive carbon black, acetylene black, Ketjen black, vapor-grown carbon fiber, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, gallium-based metals, gallium-based alloys, bismuth-based metals, bismuth-based alloys, silicon carbide, boron carbide, silicon boride, vanadium boride, magnesium boride, titanium boride, polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene) and polyphenylene.

[0131] Furthermore, the conductive agent is preferably at least one of gallium-based metals, gallium-based alloys, bismuth-based metals, bismuth-based alloys, polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene) and polyphenylene. The above-mentioned preferred conductive agent can effectively reduce the adverse effects of the carbon material in the positive electrode on the solid electrolyte, reduce the decomposition of the solid electrolyte, and then inhibit the side reaction between the positive electrode material and the solid electrolyte during the charge and discharge process of the battery, reduce the heat generation and gas release inside the battery, reduce the risk of thermal runaway and explosion of the battery, and improve the safety performance and cycle performance of the battery. The preferred conductive agent has good electrical conductivity and can achieve efficient electronic conduction without increasing too much volume, so that the battery can store more energy in a limited space and improve the volume energy density.

[0132] According to some embodiments of the present invention, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass proportion of the lithium salt is 0.5%-30%. For example, it can be 0.5%, 1%, 5%, 10%, 20%, 30%, etc. By limiting the mass proportion of the lithium salt to the above range, the lithium salt can provide a sufficient source of lithium ions for the battery, help ensure the efficient transmission of lithium ions between the pole pieces, improve the ionic conductivity, and thus improve the battery's charge and discharge performance and rate performance. Moreover, the lithium salt can also participate in the chemical reaction on the surface of the pole piece during the charge and discharge process to form a stable solid electrolyte interface (SEI) film. A good SEI film can protect the pole piece material, prevent the decomposition of the electrolyte and the occurrence of side reactions, improve the stability and cycle life of the pole piece, and thus help improve the safety performance and cycle performance of the battery.

[0133] According to some embodiments of the present invention, the pole piece includes a positive pole piece, and the raw material components of the mixed ion electronic conductor material include an oil-based monomer, an oil-based initiator, and an oil-based solvent. The positive pole piece will face the problems of metal dissolution and oxygen release. The mixed ion electronic conductor material formed by the oil-based monomer, the oil-based initiator, and the oil-based solvent can form a stable protective film on the surface of the positive pole piece to prevent the dissolution of metal ions and reduce the release of oxygen. The oil-based material usually has good oxidation resistance and stability, and can adapt to the higher potential environment of the positive pole piece. The oil-based material can also combine well with the positive active substance to improve the conductivity and ion transmission performance of the positive pole piece.

[0134] According to some embodiments of the present invention, the pole piece includes a negative pole piece, and the raw material components of the mixed ion electronic conductor material include an aqueous monomer, an aqueous initiator and an aqueous solvent. The main problem of the negative pole piece is volume expansion. The mixed ion electronic conductor material formed by the aqueous monomer, the aqueous initiator and the aqueous solvent has good flexibility and elasticity, can adapt to the volume change of the negative pole piece during the charging and discharging process, and reduce the damage to the pole piece structure caused by volume expansion. The aqueous material has a good affinity for the negative active material and can form a stable interface. The aqueous material can also promote the transmission of lithium ions in the negative pole piece, and improve the ion storage capacity and cycle performance of the negative pole piece.

[0135] According to some embodiments of the present invention, the solid electrolyte includes an ionic liquid. The ionic liquid has a high ionic conductivity and can provide a fast transmission channel for lithium ions and other ions. Adding an ionic liquid to the solid electrolyte can significantly increase the migration speed of ions in the electrode, which is beneficial to improving the charge and discharge performance and rate performance of the battery.

[0136] According to some embodiments of the present invention, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass proportion of the ionic liquid is 1%-3%. For example, it can be 1%, 2%, 3%, etc. By limiting the mass proportion of the ionic liquid to the above range, on the one hand, sufficient and suitable ion transmission channels can be formed in the active material layer, and on the other hand, excessive ionic liquid is prevented from affecting the toughness of the pole piece, thereby improving the stability of the pole piece, which is beneficial to improving the cycle performance and safety performance of the battery.

[0137] As an example, the ionic liquid includes, but is not limited to, lithium (triglyme), lithium (tetraglyme), 1-ethyl-3-methylimidazolium, 1-propyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1,2-dimethyl-3-butylimidazolium, 1-alkyl-3-methylimidazolium, 1-allyl-3-methylimidazolium, 1,3-diene Propyl imidazolium, 1-allyl-3-vinyl imidazolium, 1-vinyl-3-ethyl imidazolium, 1-cyanomethyl-3-methyl imidazolium, 1,3-dicyanomethyl-imidazolium, 1-propyl-1-methylpiperidinium, 1-butyl-1-methylpiperidinium, 1-methyl-1-ethylpyrrolidinium, 1-benzyl-3-methylimidazolium, 1-propyl-1-methylpyrrolidinium At least one of pyrrolidinium, 1-butyl-1-methylpyrrolidinium, 3-methyl-1-ethoxycarbonylmethylimidazolium, 1-alkyl-3-methylimidazolium, methyl-methylcarboxymethyl-pyrrolidinium, 1-[(trimethylsilyl)methyl]benzotriazolium, N-alkyl-N-methylpiperidinium, n-butyl-N-methylpyrrolidinium, tetramethylammonium, tetraethylammonium, tributylmethylammonium, diallyldimethylammonium, NN-diethyl-N-methyl-N-(2-methoxyethyl)ammonium, N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium, trimethylisobutylphosphonium, triisobutylmethylphosphonium, tributylmethylphosphonium, diethylmethylisobutylphosphonium, tri(hexadecyl)phosphonium, trihexyltetradecylphosphonium and tetrabutylphosphine.

[0138] In a second aspect, the present invention provides a method for preparing the pole piece of the first aspect. According to an embodiment of the present application, the method comprises: preparing an active material layer on at least one side of a current collector, wherein the active material layer is arranged on at least one side of the current collector, wherein the active material layer comprises a mixed ion-electronic conductor material and an active material, wherein the mixed ion-electronic conductor material comprises an agglomerate formed by reacting a monomer, an initiator, a solid electrolyte and a conductive agent, wherein the polymer formed by the monomer has adhesion and ion conductivity.

[0139] According to the method of the embodiment of the present application, under the action of the initiator, the monomer undergoes a polymerization reaction to form a polymer, and the polymer can bond with the solid electrolyte and the conductive agent to closely combine the three key components of the polymer, the solid electrolyte and the conductive agent. When the particle size of the conductive agent is smaller than the solid electrolyte, the conductive agent is uniformly constructed on the surface of the solid electrolyte with the solid electrolyte as the core; when the particle size of the conductive agent is larger than the solid electrolyte, the solid electrolyte is uniformly constructed on the surface of the conductive agent with the conductive agent as the core, and a mixed ion electronic conductor material can be obtained. Among them, the polymer formed by the monomer has adhesion and ion conductivity, and can bond the solid electrolyte and the conductive agent together by forming a bond. The solid electrolyte can conduct lithium ions, and the conductive agent can conduct electrons, so that the mixed ion electronic conductor material has high ionic conductivity, high electronic conductivity and strong adhesion at the same time, and can replace the use of conductive agents, solid electrolytes and adhesives in the original pole pieces, which can reduce material costs and improve production efficiency. High ionic conductivity and high electronic conductivity are also beneficial to improving the battery's charge and discharge efficiency and rate performance. Strong adhesion can bond active materials, prevent internal contact failure of active materials and detachment from the current collector, ensure the stability of the electrode structure, and thus improve the battery's cycle life and safety performance.

[0140] Furthermore, the oil-based monomers have different functional groups (such as O-, =O, -S-, =S, -N-, CF, CN, etc.), which can coordinate with high-valent ions (such as Ni, Co, Mn, etc.) in the electrode to provide compensation charge, inhibit metal ion dissolution and oxygen escape reaction under high voltage, reduce the structural changes and capacity decay of active substances during the cycle, thereby extending the cycle performance of the battery; and the monomers have high thermal stability after polymerization, which makes the battery more stable under extreme conditions such as high temperature and reduces the safety risks caused by problems such as thermal runaway; the functional groups of the water-based monomers (such as -OH, -COOH, -NH2, -CO-NH- and -SS-, etc.) show reversible bonding self-healing properties, which can repair the structural damage that may occur to the electrode during the charge and discharge process, maintain the stability of the electrode structure, enhance the adhesion between the electrode and other components, and at the same time improve the mechanical strength of the electrode, so that it can better withstand the volume change and stress during the charge and discharge process, further improving the cycle performance of the battery.

[0141] Although the polymer itself also has these functional groups (such as O-, =O, -S-, =S, -N-, CF, CN, -OH, -COOH, -NH2, -CO-NH-, -SS-, etc.), the polymer chain segment of the polymer itself has a low degree of disorder and a high degree of crystallinity, which results in a small number of functional groups that can play a role, and low ionic conductivity and adhesion. The monomers provided in the present application have a large number of functional groups that can play a role, and high ionic conductivity and adhesion, thereby improving the cycle performance and safety performance of the battery.

[0142] Furthermore, compared with the dual transmission routes of the original electrode in which the conductive agent conducts electrons and the solid electrolyte conducts ions, the mixed ion-electronic conductor material has the ability to conduct ions and electrons at the same time, thereby realizing a single transmission route and constructing a three-dimensional conductive lithium-conducting network of the internal transmission path of the electrode, reducing the tortuosity of ion and electron transmission, increasing the threshold flow rate, and improving the charge transfer efficiency, which is beneficial to improving the battery's rate performance; in addition, it can also reduce the porosity of the electrode, which is beneficial to improving the overall energy density of the battery.

[0143] Furthermore, the mixed ion-electronic conductor material can be filled in the pores between the active material particles, and the three major solid-solid interface problems can be improved through interface softening, such as: reducing the contact resistance between the active material layer and the solid electrolyte layer, enhancing the charge transfer efficiency, and increasing the diffusion rate of ions at the interface, thereby improving the performance of the battery; enhancing the peeling force between the active material layer and the current collector, ensuring that the charge can be effectively transferred from the current collector to the active material layer, reducing the resistance and energy loss at the interface; helping to optimize the contact and charge transfer between the three phases (active material, solid electrolyte and conductive agent) inside the active material layer, improving the stability and consistency of the interface, thereby improving the overall performance and cycle performance of the battery. In addition, the mixed ion-electronic conductor material can also effectively control the huge volume changes of the active material particles during the charge and discharge process, thereby avoiding the reduction or inactivation of the active material particles, avoiding the generation of depletion zones, and thereby improving the charge and discharge efficiency of the battery. The mixed ion-electronic conductor material can also give the active material layer flexibility, making it more flexible, which helps the active material layer better adapt to various changes during the charge and discharge process, reducing damage or performance degradation caused by material rigidity, thereby improving the cycle performance of the battery.

[0144] According to some embodiments of the present invention, the step of preparing the active material layer includes:

[0145] S10, mixing monomers, initiators, lithium salts, solid electrolytes, conductive agents and solvents, and polymerizing them to obtain mixed ion-electronic conductor materials.

[0146] In this step, a monomer, an initiator, a lithium salt, a solid electrolyte, a conductive agent and a solvent are mixed by a high dispersion process to obtain a uniform dispersion, and then a polymerization reaction is carried out. Under the action of the initiator, the monomer undergoes a polymerization reaction to form a polymer, and the polymer can perform a bonding reaction with the solid electrolyte and the conductive agent, and the three key components of the polymer, the solid electrolyte and the conductive agent are tightly combined together, thereby obtaining a mixed ion electronic conductor material. Among them, the polymer formed by the monomer has adhesion and ion conductivity, the solid electrolyte can conduct lithium ions, and the conductive agent can conduct electrons, so that the mixed ion electronic conductor material has high ion conductivity, high electronic conductivity and strong adhesion at the same time, and can replace the use of conductive agents, solid electrolytes and adhesives in the original pole pieces, and can reduce material costs and improve production efficiency. High ion conductivity and high electronic conductivity are also conducive to improving the charge and discharge efficiency and rate performance of the battery. Strong adhesion can bond the active material, prevent the internal contact failure of the active material and detachment from the current collector, and ensure the stability of the pole piece structure, thereby improving the cycle life and safety performance of the battery.

[0147] It should be noted that there is no special limitation on the high dispersion process, and those skilled in the art can flexibly select it according to needs.

[0148] As an example, the high dispersion process includes, but is not limited to, mechanical ball milling, ultrasonic dispersion, spray drying, sol-gel method, chemical co-precipitation method, and the like.

[0149] S20, mixing the mixed ion-electron conductor material and the active material to obtain a mixed slurry.

[0150] In this step, by mixing the mixed ion electronic conductor material and the active material, the mixed ion electronic conductor material has strong bonding properties and can wrap and bond the active material particles together, thereby obtaining a mixed slurry.

[0151] According to some embodiments of the present invention, the step of preparing the mixed slurry includes step S11 and step S21:

[0152] S11. After mixing the monomer, initiator, lithium salt, solid electrolyte, conductive agent and solvent, a first polymerization is carried out to obtain a precursor solution of a mixed ion-electronic conductor material.

[0153] In this step, a high dispersion process is used to mix monomers, initiators, lithium salts, solid electrolytes, conductive agents and solvents to obtain a uniform dispersion, and then a first polymerization reaction is carried out. During the first polymerization reaction, the initiator can induce a polymerization reaction in the monomers to form a polymer with adhesion that can bond the solid electrolyte and the conductive agent together to obtain a precursor solution of a mixed ion-electronic conductor material.

[0154] According to some embodiments of the present invention, the step of preparing a precursor solution of a mixed ionic electronic conductor material also includes adding an ionic liquid. The addition of the ionic liquid during the first polymerization process can form interconnected ion channels in the formed polymer domain crystalline region, thereby separating ion relaxation from polymer relaxation. The accelerated transmission of ions in the polymer matrix can significantly increase the migration speed of ions in the electrode, thereby improving the charge and discharge performance and rate performance of the battery.

[0155] According to some embodiments of the present invention, the monomer conversion rate of the first polymerization is 30%-45%. For example, it can be 30%, 35%, 40%, 45%, etc. By limiting the monomer conversion rate of the first polymerization to the above range, it is helpful to form a stable bond between the solid electrolyte and the conductive agent, and it can also help the formed mixed ion electronic conductor material to be stably dispersed in the slurry; and most of the unreacted monomers can form a bond between the active material and the mixed ion electronic conductor material during the secondary polymerization process. In this way, the cycle performance, safety performance and rate performance of the battery can be improved.

[0156] It should be noted that the monomer conversion rate refers to the ratio of the amount of monomer converted into polymer to the initial amount of monomer in the polymerization reaction, usually expressed as a percentage. The calculation formula is: monomer conversion rate = (amount of converted monomer / initial monomer) × 100%.

[0157] According to a specific embodiment of the present invention, the temperature of the first polymerization is 45° C.-55° C. For example, it can be 45° C., 50° C., 55° C., etc. By limiting the temperature of the first polymerization to the above range, it is beneficial to control the monomer conversion rate to be within the range of 30%-45%.

[0158] According to a specific embodiment of the present invention, the first polymerization time is 1h-2h. For example, it can be 1h, 1.5h, 5h, etc. By limiting the first polymerization time to the above range, it is beneficial to control the monomer conversion rate within the range of 30%-45%.

[0159] According to a specific embodiment of the present invention, the viscosity of the mixed ion-electron conductor material precursor solution is 4000mPa·S-8000mPa·S. For example, it can be 4000mPa·S, 5000mPa·S, 6000mPa·S, 7000mPa·S, 8000mPa·S, etc. By limiting the viscosity of the mixed ion electronic conductor material precursor solution within the above range, the mixed ion electronic conductor material precursor solution has a certain fluidity, which enables the mixed ion electronic conductor material to be filled in the pores between the active material particles. The three major solid-solid interface problems can be improved through interface softening, such as: reducing the contact resistance between the active material layer and the solid electrolyte layer, enhancing the charge transfer efficiency, and increasing the diffusion rate of ions at the interface, thereby improving the performance of the battery; enhancing the adhesion between the active material layer and the current collector, ensuring that the charge can be effectively transferred from the current collector to the active material layer, reducing the resistance and energy loss at the interface; helping to optimize the contact and charge transfer between the three phases (active material, solid electrolyte and conductive agent) inside the active material layer, improving the stability and consistency of the interface, thereby improving the overall performance and cycle performance of the battery.

[0160] It should be noted that there is no particular limitation on the method of the first polymerization, and those skilled in the art can flexibly select it according to needs.

[0161] As an example, the first polymerization method includes but is not limited to at least one of thermal polymerization, photopolymerization, ultrasonic polymerization and acid polymerization.

[0162] S21, mixing the mixed ion-electron conductor material precursor solution and the active material for a second polymerization to obtain a mixed slurry.

[0163] In this step, the mixed ionic electronic conductor material precursor solution and the active substance are mixed and then subjected to a second polymerization reaction. During the second polymerization process, not only the mixed ionic electronic conductor material can be obtained, but also a bridge relationship (such as a bonding relationship, etc.) between the mixed ionic electronic conductor material and the active substance can be constructed, and the mixed ionic electronic conductor material and the active substance are bonded together to obtain a mixed slurry.

[0164] According to some embodiments of the present invention, the monomer conversion rate of the second polymerization is 94%-98%. For example, it can be 94%, 95%, 96%, 97%, 98%, etc. By limiting the monomer conversion rate of the second polymerization to the above range, so that the monomer is polymerized as completely as possible, the side reaction of the residual monomer in the electrochemical cycle can be avoided, and the formation of the polymer helps to improve the battery safety. As a result, the battery cycle performance, safety performance and rate performance can be improved.

[0165] According to some embodiments of the present invention, the temperature of the second polymerization is 70° C.-85° C. For example, it can be 70° C., 75° C., 80° C., 85° C., etc. By limiting the temperature of the second polymerization to the above range, most of the unreacted monomers can form bonds between the active material and the mixed ion-electronic conductor material during the secondary polymerization process.

[0166] According to some embodiments of the present invention, the second polymerization time is 1 hour to 20 hours. For example, it can be 1 hour, 5 hours, 10 hours, 15 hours, 20 hours, etc. By limiting the second polymerization time to the above range, most of the unreacted monomers can form bonds between the active material and the mixed ion-electronic conductor material during the secondary polymerization process.

[0167] S30, coating the mixed slurry on at least one side of the current collector to obtain the active material layer.

[0168] In this step, by coating the mixed slurry on at least one side of the current collector, an active material layer can be obtained on at least one side of the current collector, and further a pole piece can be obtained.

[0169] It should be noted that there is no particular limitation on the coating method, and those skilled in the art can flexibly select it according to needs.

[0170] In the third aspect of the present invention, the present invention provides a diaphragm-free battery. According to an embodiment of the present invention, the diaphragm-free battery comprises the pole piece of the first aspect or the pole piece prepared by the method of the second aspect. The diaphragm-free battery has excellent safety performance, cycle performance and rate performance.

[0171] In a fourth aspect of the present invention, the present invention provides a solid-state battery. According to an embodiment of the present invention, the solid-state battery comprises the pole piece of the first aspect or the pole piece prepared by the method of the second aspect. The solid-state battery has excellent safety performance, cycle performance and rate performance.

[0172] The scheme of the present disclosure will be explained below in conjunction with the examples. Those skilled in the art will appreciate that the following examples are only used to illustrate the present disclosure and should not be considered to limit the scope of the present disclosure. Where specific techniques or conditions are not indicated in the examples, the techniques or conditions described in the literature in this area or the product instructions are used. Where the manufacturers of reagents or instruments are not indicated, they are all conventional products that can be obtained commercially.

[0173] Example 1

[0174] 1. Preparation of positive electrode sheet:

[0175] 1) Dissolve the monomer, lithium salt, solid electrolyte, conductive agent and initiator in a solvent to form a uniform dispersion by a high dispersion process, wherein the Dv50 particle size of the conductive agent is 30 nm, the monomer is methyl methacrylate, the lithium salt is LiTFSI, the solid electrolyte includes LLZTO and an ionic liquid, the Dv50 particle size of LLZTO is 100 nm, the conductive agent is GaIn liquid metal (Ga and In mass ratio is 8:2), the initiator is azobisisobutyronitrile, the ionic liquid is lithium (triethylene glycol dimethyl ether), and the solvent is NMP; the mass of the initiator is 1.5% of the mass of the monomer; in addition, based on the total mass of the monomer, lithium salt, solid electrolyte and conductive agent: the mass of the monomer accounts for 25%, the mass of the lithium salt accounts for 25%, the mass of the solid electrolyte accounts for 25% (wherein the mass of LLZTO accounts for 24% and the mass of the ionic liquid accounts for 1%), and the mass of the conductive agent accounts for 25%;

[0176] 2) subjecting the dispersion prepared in step 1) to a first polymerization reaction at 50° C. for 1 h to obtain a precursor solution of a mixed ionic electronic conductor material, wherein the monomer conversion rate of the first polymerization is 40%;

[0177] 3) adding the mixed ion electronic conductor material precursor solution prepared in step 2) to the positive electrode active material, wherein the positive electrode active material is NCM, forming a stable slurry through a high dispersion process, and then performing a second polymerization reaction at a temperature of 70° C. for 12 hours to obtain a mixed slurry containing a mixed ion electronic conductor material, wherein the Dv50 particle size of the mixed ion electronic conductor material is 150 nm, and the monomer conversion rate of the second polymerization is 95%;

[0178] 4) coating the mixed slurry on a copper foil current collector, drying it, and rolling it to obtain a positive electrode sheet, wherein the mass ratio of the positive electrode active material is 96%, and the mass ratio of the mixed ion-electronic conductor material is 4%.

[0179] 2. Preparation of negative electrode sheet:

[0180] 1) dissolving a monomer, a lithium salt, a solid electrolyte, a conductive agent and an initiator in a solvent, and forming a uniform dispersion by a high dispersion process, wherein the Dv50 particle size of the conductive agent is 30 nm, the monomer is acrylic acid, the lithium salt is lithium difluorophosphate, the solid electrolyte includes LATP and an ionic liquid, the Dv50 particle size of LATP is 100 nm, the conductive agent is a gallium-based metal, the initiator is ammonium persulfate, the solvent is water, and the ionic liquid is lithium (triethylene glycol dimethyl ether); wherein the mass of the initiator is 1.5% of the mass of the monomer; in addition, based on the total mass of the monomer, the lithium salt, the solid electrolyte and the conductive agent: the mass of the monomer accounts for 30%, the mass of the lithium salt accounts for 20%, the mass of the solid electrolyte accounts for 45% (wherein the mass of LATP accounts for 44% and the mass of the ionic liquid accounts for 1%), and the mass of the conductive agent accounts for 5%;

[0181] 2) subjecting the dispersion prepared in step 1) to a first polymerization reaction at 55° C. for 2 h to obtain a precursor solution of a mixed ionic electronic conductor material, wherein the monomer conversion rate of the first polymerization is 40%;

[0182] 3) adding negative electrode active material to the mixed ion electronic conductor material precursor solution prepared in step 2), wherein the negative electrode active material is graphite, forming a stable slurry through a high dispersion process, and then performing a second polymerization reaction at a temperature of 70° C. for 12 hours to obtain a mixed slurry containing a mixed ion electronic conductor material, wherein the Dv50 particle size of the mixed ion electronic conductor material is 170 nm, and the monomer conversion rate of the second polymerization is 95%;

[0183] 4) coating the mixed slurry on a copper foil current collector, drying it, and rolling it to obtain a negative electrode sheet, wherein the mass ratio of the negative electrode active material is 95%, and the mass ratio of the active material to the mixed ion-electronic conductor material is 5%.

[0184] 3. Preparation of solid-state battery: Lithium aluminum titanium phosphate (LATP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and polyvinylidene fluoride (PVDF) are dissolved in dimethylformamide (DMF) at a mass ratio of 40%:30%:30%, coated on a polytetrafluoroethylene (PTFE) substrate and vacuum baked to obtain a solid electrolyte. The positive electrode sheet, the solid electrolyte and the negative electrode sheet are stacked in sequence and assembled into a solid-state battery.

[0185] Embodiment 32

[0186] The difference between Example 32 and Example 1 is that:

[0187] Preparation of negative electrode sheets: Disperse negative electrode active material graphite, conductive carbon black (SP), adhesive sodium carboxymethyl cellulose (CMC) and polyacrylic acid (PAA) in water and mix them evenly to obtain negative electrode slurry, wherein the mass ratio of graphite, conductive carbon black (SP), adhesive CMC and PAA is 96:2:1.5:0.5, and coat the negative electrode slurry on the negative electrode collector copper foil, and obtain the negative electrode sheet after drying, cold pressing, slitting and cutting.

[0188] Embodiment 33

[0189] The difference between Example 33 and Example 1 is that:

[0190] Preparation of positive electrode sheets: The positive electrode active material lithium nickel cobalt manganese oxide (NCM), conductive carbon black (SP), and adhesive polyvinylidene fluoride (PVDF) are dispersed in a solvent N-methylpyrrolidone (NMP) and mixed evenly to obtain a positive electrode slurry, wherein the mass ratio of lithium nickel cobalt manganese oxide, PVDF, and conductive carbon black is 96:2:2. The positive electrode slurry is coated on the positive electrode current collector aluminum foil, and after drying, cold pressing, slitting, and cutting, the positive electrode sheets are obtained.

[0191] Embodiment 34

[0192] Except that no ionic liquid is added, the rest is the same as Example 1.

[0193] Embodiment 35

[0194] Except that no ionic liquid is added in step 1) and ionic liquid is added in step 3), the rest is the same as Example 1.

[0195] The pole piece of Example 2-31 is the same as that of Example 1 except for different experimental parameters (see Table 1).

[0196] Some experimental parameters of the pole pieces of Examples 1-34 are shown in Table 1.

[0197] Table 1

[0198]

[0199]

[0200]

[0201] Comparative Example 1

[0202] The difference between Comparative Example 1 and Example 1 is that:

[0203] 1. Preparation of positive electrode sheet: Mix monomer, initiator, lithium salt, solid electrolyte, conductive agent, solvent, positive electrode active material and ionic liquid to form slurry, apply the slurry on at least one side of the current collector, perform in-situ polymerization, and obtain positive electrode sheet;

[0204] 2. Preparation of negative electrode sheet: Mix monomers, initiators, lithium salts, solid electrolytes, conductive agents, solvents, negative electrode active materials and ionic liquids to form a slurry, apply the slurry on at least one side of the current collector, and perform in-situ polymerization to obtain a negative electrode sheet.

[0205] Comparative Example 2

[0206] The difference between Comparative Example 1 and Example 1 is that in the preparation process of the positive electrode sheet and the negative electrode sheet, in the steps of forming the mixed ion-electronic conductor material, no initiator and monomer are added, and polymethyl methacrylate is directly added.

[0207] Comparative Example 3

[0208] The difference between Comparative Example 1 and Example 1 is that in the process of preparing the positive electrode sheet and the negative electrode sheet, in the step of forming the mixed ion-electronic conductor material, no solid electrolyte is added.

[0209] Comparative Example 4

[0210] The difference between Comparative Example 1 and Example 1 is that in the process of preparing the positive electrode sheet and the negative electrode sheet, in the steps of forming the mixed ionic and electronic conductor materials respectively, no conductive agent is added.

[0211] Testing and analysis

[0212] Under the same conditions, the batteries prepared in the above Examples 1-35 and Comparative Examples 1-4 were tested for cycle performance, safety performance, rate performance, etc. The specific testing methods are as follows:

[0213] Rate performance test: Constant current and constant voltage charging is performed at 2C current, the voltage range is 4.25V-2.7V, the cut-off current is 0.05C, and the discharge capacity tested at 0.1C is taken as the benchmark 100%.

[0214] Cycle performance test: Constant current and constant voltage charging is carried out at 25°C, the cycle rate is 1C, the cut-off current is 0.05C, and after 200 cycles, the ratio of the current capacity to the initial capacity is calculated.

[0215] Hot box test: Charge the battery cell to 4.25V at a constant current and voltage of 0.33C, then heat the battery cell to 100℃, observe the sample for 0.5h, continue to increase the temperature by 5℃, and observe the sample for 0.5h after the battery cell temperature reaches the ambient temperature, until the battery cell shows thermal runaway.

[0216] The test results are shown in Table 2.

[0217] Table 2

[0218]

[0219]

[0220] Combining Table 1 and Table 2, it can be seen that compared with the batteries of Comparative Examples 1-4, the batteries of Examples 1-35 have better cycle performance, safety performance and rate performance.

[0221] In the prior art, traditional PVDF mainly relies on the van der Waals force between high molecular weights to bond active materials. This bonding method has insufficient peel strength. As the number of cycles of the battery cell increases, insufficient bonding force will lead to failure of bonding between the active material layer and the current collector foil, and the pole piece will fall off and fall off, causing the internal resistance of the battery cell to increase, and even the battery cell will fail due to water diving. The active material layer in the pole piece provided by the present application is composed of a mixed ion electronic conductor material and an active material, and the raw material components of the mixed ion electronic conductor material include monomers, initiators, solid electrolytes and conductive agents. Under the action of the initiator, the polymer formed by the initiator monomer has adhesiveness and ion conductivity, and can bond the solid electrolyte and the conductive agent together by forming a bond. The solid electrolyte can conduct lithium ions, and the conductive agent can conduct electrons, so that the mixed ion electronic conductor material has high ionic conductivity, high electronic conductivity and strong bonding at the same time, and can replace the use of conductive agents, solid electrolytes and binders in the original pole piece, and can reduce material costs and improve production efficiency. High ionic conductivity and high electronic conductivity are also beneficial to improving the charging and discharging efficiency and rate performance of the battery. Strong adhesion can bond the active materials, prevent the internal contact failure of the active materials and detachment from the current collector, ensure the stability of the pole piece structure, and thus improve the cycle life and safety performance of the battery. Compared with the dual transmission routes of the conductive agent conducting electrons and the solid electrolyte conducting ions in the original pole piece, the mixed ion-electron conductor material has the ability to conduct ions and electrons at the same time, thus realizing a single transmission route, constructing a three-dimensional conductive lithium-conducting network of the transmission path inside the pole piece, reducing the tortuosity of ion-electron transmission, and improving the threshold flow rate. It can improve the charge transfer efficiency and help improve the rate performance of the battery; in addition, it can also reduce the porosity of the pole piece, which is beneficial to the improvement of the overall energy density of the battery.

[0222] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", "some implementation schemes" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0223] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A pole piece, characterized in that: include: current collector; An active material layer, wherein the active material layer is disposed on at least one side of the current collector, and the active material layer comprises a mixed ion-electronic conductor material and an active material, wherein the mixed ion-electronic conductor material comprises an aggregate formed by reacting a monomer, an initiator, a solid electrolyte and a conductive agent, and the polymer formed by the monomer has adhesion and ion conductivity.

2. The pole piece according to claim 1, characterized in that: The mass ratio of the active material to the mixed ion-electron conductor material is (90-99):(1-10), preferably (93-99):(1-7); Preferably, based on the total mass of the active material layer, the mass proportion of the active material is 93%-99%; Preferably, based on the total mass of the active material layer, the mass proportion of the solid electrolyte is 1%-5%.

3. The pole piece according to claim 1, characterized in that: The Dv50 particle size of the mixed ion-electron conductor material is 50nm-300nm; Preferably, the peeling force between the active material layer and the current collector is 20N / m-40N / m; Preferably, the cohesive force of the active material layer is 250 N / m-400 N / m.

4. The pole piece according to claim 1, characterized in that: The raw material components of the mixed ion-electron conductor material also include lithium salt and solvent; Preferably, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass of the monomer accounts for 0.5%-30%; Preferably, the mass of the initiator accounts for 0.1%-3% of the mass of the monomer; Preferably, the Dv50 particle size of the solid electrolyte is 10nm-200nm; Preferably, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass of the solid electrolyte accounts for 5%-50%; Preferably, the Dv50 particle size of the conductive agent is 10nm-200nm; Preferably, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass proportion of the conductive agent is 5%-50%; Preferably, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass proportion of the lithium salt is 0.5%-30%; Preferably, the lithium salt includes at least one of lithium trifluoromethanesulfonate, lithium hexafluoroarsenate, lithium perchlorate, lithium difluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium tetrafluoroborate and lithium hexafluorophosphate.

5. The pole piece according to any one of claims 1 to 4, characterized in that: The monomer includes one of an oil-based monomer and a water-based monomer; Preferably, the oil monomers include vinylidene fluoride, tetrafluoroethylene, ethylene oxide, vinylidene fluoride-hexafluoropropylene, hexafluoropropylene, 1,3,5-trioxane, 1,3-dioxane, 1,4-dioxane, 1,3-dioxolane, 1,4-dioxane, dithiolane, boroxane, vinylene carbonate, vinyl vinyl sulfite, vinylene trithiocarbonate, vinyl acetate, methyl vinyl sulfone, ethyl vinyl sulfone, phthalic acid diacrylate, pentaerythritol tetraacrylate, methacrylate, ethylene glycol methacrylate, ethylene glycol dimethacrylate, ethylene glycol diacrylate, ethylene glycol propylene At least one of esters, methyl methacrylate, propylene carbonate, acrylonitrile, lactam, lipoic acid, cyclosulfide, alkyl disulfide, tetrakis(hydroxymethyl)phosphonium chloride, melamine, olefinated monophosphine ligands, bisphosphine ligands, arginine methyl ester, arginine ethyl ester, methoxy polyethylene glycol, isocyanate, quaternary ammonium salt monomer, trifluoromethylphenylboronic acid methyliminodiacetate, methacryloyloxyethyl ester, pentaerythrityl alcohol acrylate, N,N'-methylenebisacrylamide, 1,3-propylene-sultone and acrylamide, preferably at least one of methyl methacrylate, vinylene carbonate and N,N'-methylenebisacrylamide; Preferably, the aqueous monomer includes at least one of hydroxyethyl methacrylate, ethylene glycol methacrylate, N,N-(dimethylamine) ethyl methacrylate, ethylene glycol methacrylate, sodium methacrylate, N-isopropyl acrylamide, acrylate, methacrylate, acrylamide, sodium allyl sulfonate, sodium acrylate, methacrylamide, glycerol monomethacrylate, ethylenediaminetetraacetic acid, diethanolamine, acrylonitrile, methyl acrylate, itaconic acid, sulfobetaine, melamine, phenolic resin, glycerol diglycidyl ester, N,N′-methylenebisacrylamide, ethylene glycol, 1,3-propylene glycol, hydroxyethyl methacrylate, acrylic acid, acrylamide, vinyl alcohol, carboxymethyl cellulose, alginate, collagen, hyaluronic acid, alginic acid, cellulose, chitosan, chitin, and gelatin, preferably at least one of acrylic acid, acrylamide and alginate; Preferably, the initiator comprises one of an oil-based initiator and a water-based initiator; Preferably, the solid electrolyte includes at least one of an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte and a boride solid electrolyte; Preferably, the conductive agent includes at least one of conductive graphite, conductive carbon black, acetylene black, Ketjen black, vapor-grown carbon fiber, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, gallium-based metals, gallium-based alloys, bismuth-based metals, bismuth-based alloys, silicon carbide, boron carbide, silicon boride, vanadium boride, magnesium boride, titanium boride, polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene) and polyphenylene; preferably at least one of gallium-based metals, gallium-based alloys, bismuth-based metals, bismuth-based alloys, polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene) and polyphenylene; Preferably, the solvent includes at least one of an oil-based solvent and an aqueous solvent; Preferably, the aqueous solvent comprises water; Preferably, the water-based solvent also includes the oil-based solvent; Preferably, the oil-based solvent includes at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, N-methylpyrrolidone, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide and N,N-dimethylacetamide, N,N-dimethylpropionamide, ethyl acetate, butyl butyrate, chloroform, dichloromethane, ethyl ether, toluene, acetone, tetrahydrofuran, fluoroethylene carbonate, methyl trifluoroethyl carbonate, difluoroethylene carbonate, tris(2,2,2-trifluoroethyl)phosphate, bis(2,2,2-trifluoroethyl) carbonate, 2,2,2-trifluoroethyl ether, ethyl trifluoroacetate, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

6. The pole piece according to claim 5, characterized in that: The pole piece includes a positive pole piece, and the raw material components of the mixed ion-electron conductor material include the oil-based monomer, the oil-based initiator and the oil-based solvent; and / or, The pole piece includes a negative pole piece, and the raw material components of the mixed ion-electron conductor material include the water-based monomer, the water-based initiator and the water-based solvent.

7. The pole piece according to claim 5, characterized in that: The solid electrolyte includes an ionic liquid; Preferably, based on the total mass of the monomer, the solid electrolyte, the conductive agent and the lithium salt, the mass of the ionic liquid accounts for 1%-3%; Preferably, the ionic liquid comprises lithium (triglyme), lithium (tetraglyme), 1-ethyl-3-methylimidazolium, 1-propyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1,2-dimethyl-3-butylimidazolium, 1-alkyl-3-methylimidazolium, 1-allyl-3-methylimidazolium, 1,3-diallylimidazolium, imidazolium, 1-allyl-3-vinylimidazolium, 1-vinyl-3-ethylimidazolium, 1-cyanomethyl-3-methylimidazolium, 1,3-dicyanomethyl-imidazolium, 1-propyl-1-methylpiperidinium, 1-butyl-1-methylpiperidinium, 1-methyl-1-ethylpyrrolidinium, 1-benzyl-3-methylimidazolium, 1-propyl-1-methylpyrrolidinium At least one of 1-[(trimethylsilyl)methyl]benzotriazolium, N-alkyl-N-methylpiperidinium, n-butyl-N-methylpyrrolidinium, tetramethylammonium, tetraethylammonium, tributylmethylammonium, diallyldimethylammonium, NN-diethyl-N-methyl-N-(2-methoxyethyl)ammonium, N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium, trimethylisobutylphosphonium, triisobutylmethylphosphonium, tributylmethylphosphonium, diethylmethylisobutylphosphonium, trihexadecylphosphonium, trihexyltetradecylphosphonium and tetrabutylphosphine.

8. The pole piece according to any one of claims 1 to 4, characterized in that: The active material includes one of a positive electrode active material and a negative electrode active material; Preferably, the positive electrode active material includes at least one of a metal oxide positive electrode active material, a polyanion positive electrode active material, a transition metal positive electrode active material and an organic positive electrode active material.

9. A method for preparing a pole piece according to any one of claims 1 to 8, characterized in that: include: An active material layer is prepared on at least one side of a current collector, wherein the active material layer is arranged on at least one side of the current collector, wherein the active material layer includes a mixed ion-electronic conductor material and an active material, wherein the mixed ion-electronic conductor material includes an aggregate formed by reacting a monomer, an initiator, a solid electrolyte and a conductive agent, and wherein the polymer formed by the monomer has adhesion and ion conductivity.

10. The method according to claim 9, characterized in that The steps of preparing the active material layer include: The monomer, initiator, lithium salt, solid electrolyte, conductive agent and solvent are mixed and polymerized to obtain a mixed ion-electron conductor material; Mixing the mixed ion-electron conductor material and the active material to obtain a mixed slurry; The mixed slurry is coated on at least one side of the current collector to obtain the active material layer.

11. The method according to claim 10, characterized in that The steps of preparing the mixed slurry include: After mixing the monomer, initiator, lithium salt, solid electrolyte, conductive agent and solvent, a first polymerization is performed to obtain a precursor solution of a mixed ion-electron conductor material; The mixed ion-electron conductor material precursor solution and the active material are mixed and polymerized for the second time to obtain a mixed slurry.

12. The method according to claim 11, characterized in that The monomer conversion rate of the first polymerization is 30%-45%; Preferably, the temperature of the first polymerization is 45°C-55°C; Preferably, the first polymerization time is 1h-2h; Preferably, the first polymerization method includes at least one of thermal polymerization, photopolymerization, ultrasonic polymerization and acid polymerization; Preferably, the viscosity of the mixed ion-electron conductor material precursor solution is 4000 mPa·S-8000 mPa·S.

13. The method according to claim 11, characterized in that The monomer conversion rate of the second polymerization is 94%-98%; Preferably, the temperature of the second polymerization is 70°C-85°C; Preferably, the second polymerization time is 1 h-20 h.

14. A diaphragm-free battery, characterized in that: The diaphragm-free battery comprises the pole piece according to any one of claims 1 to 8 or the pole piece prepared by the method according to any one of claims 9 to 13.

15. A battery, characterized in that: The battery comprises the pole piece according to any one of claims 1 to 8 or the pole piece prepared by the method according to any one of claims 9 to 13.

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