Composite positive pole piece, preparation method thereof and solid-state battery

Abstract

The invention provides a composite positive pole piece, a preparation method thereof and a solid-state battery. The composite positive pole piece comprises a positive pole current collector and a positive pole diaphragm arranged on the surface of the positive pole current collector, the positive pole diaphragm comprises a positive pole active material, a conductive agent and a first binder, a three-dimensional pore of the positive pole diaphragm comprises a halide solid electrolyte and a second binder, the three-dimensional pore is the positive pole active material, and the second binder is a second binder. And a gap between the conductive agent and the first binder. According to the composite positive pole piece provided by the invention, the halide solid electrolyte is contained in the three-dimensional pores of the positive pole piece, so that the contact area between the positive pole active material and the electrolyte is maximized, and the diffusion length of ions in the positive pole piece is shortened; the method is used for reducing the interface impedance between a positive electrode active material and an electrolyte in the battery so as to improve the rate capability and the cycling stability of the battery.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a composite positive electrode sheet and a preparation method thereof, and a solid-state battery. Background Art

[0002] Driven by the demand for high energy density, high safety and long life batteries, all-solid-state batteries are seen as an innovative technology to accelerate the popularization of electric vehicles.

[0003] At present, in all-solid-state batteries, since the positive electrode sheet and the solid electrolyte layer are in contact through a solid-solid interface, the contact area between the positive electrode active material and the electrolyte is small, resulting in a large interfacial impedance between the positive electrode active material and the electrolyte in the battery, thereby affecting the battery's rate performance and cycle stability.

[0004] Therefore, it is urgent to solve the problem of large interfacial impedance in all-solid-state batteries. Summary of the Invention

[0005] The present invention provides a composite positive electrode sheet and a preparation method thereof, and a solid-state battery, which are used to reduce the interfacial impedance between the positive electrode active material and the electrolyte in the battery, thereby improving the rate performance and cycle stability of the battery.

[0006] In a first aspect of the present invention, a composite positive electrode sheet is provided, comprising: a positive electrode current collector and a positive electrode membrane disposed on a surface of the positive electrode current collector; the positive electrode membrane comprises a positive electrode active material, a conductive agent, and a first binder; and the three-dimensional pores of the positive electrode membrane comprise a halide solid electrolyte and a second binder;

[0007] The three-dimensional pores are gaps between the positive electrode active material, the conductive agent and the first binder.

[0008] According to one embodiment of the present invention, the halide solid electrolyte includes at least one of the Li3MX6 electrolytes;

[0009] Wherein, M is any one of scandium, yttrium, lanthanide elements, aluminum, gallium or indium, and / or X is any one of fluorine, chlorine, bromine or iodine.

[0010] According to one embodiment of the present invention, the first binder includes at least one of polyisobutylene, ethyl cellulose, nitrile rubber, styrene-butadiene rubber, and styrene-ethylene-butylene-styrene copolymer;

[0011] And / or, the second binder includes at least one of butadiene rubber, polyisobutylene, polycyanoacrylate, ethyl cellulose, nitrile rubber, styrene-butadiene rubber, and styrene-ethylene-butylene-styrene copolymer.

[0012] A second aspect of the present invention provides a method for preparing the composite positive electrode sheet according to the first aspect, comprising:

[0013] Mixing a positive electrode active material, a conductive agent, a first binder, and a first solvent to obtain a positive electrode slurry;

[0014] The positive electrode slurry is applied to the surface of the positive electrode current collector and dried to form a positive electrode film having three-dimensional pores, thereby obtaining a positive electrode sheet; the three-dimensional pores are the gaps between the positive electrode active material, the conductive agent, and the first binder;

[0015] mixing a halide solid electrolyte, a second binder, and a second solvent to obtain a halide electrolyte solution;

[0016] The halide electrolyte solution is poured onto the positive electrode membrane of the positive electrode plate so that the halide electrolyte solution is immersed into the three-dimensional pores, and then dried to obtain the composite positive electrode plate.

[0017] According to one embodiment of the present invention, the halide solid electrolyte includes at least one of the Li3MX6 electrolytes;

[0018] Wherein, M is any one of scandium, yttrium, lanthanide elements, aluminum, gallium or indium, and / or X is any one of fluorine, chlorine, bromine or iodine.

[0019] According to one embodiment of the present invention, the first binder includes at least one of polyisobutylene, ethyl cellulose, nitrile rubber, styrene-butadiene rubber, and styrene-ethylene-butylene-styrene copolymer;

[0020] And / or, the second binder includes at least one of butadiene rubber, polyisobutylene, polycyanoacrylate, ethyl cellulose, nitrile rubber, styrene-butadiene rubber, and styrene-ethylene-butylene-styrene copolymer.

[0021] According to one embodiment of the present invention, the first solvent comprises at least one of ethyl acetate, butyl butyrate, p-xylene, isobutyl isobutyrate, n-hexane, anisole, isopentyl isovalerate, and dodecyl;

[0022] And / or, the second solvent includes at least one of ethyl acetate, butyl butyrate, p-xylene, isobutyl isobutyrate, n-hexane, anisole, isopentyl isovalerate, and dodecyl.

[0023] According to one embodiment of the present invention, the solid content of the halide electrolyte solution is 45-50%.

[0024] According to one embodiment of the present invention, in the halide electrolyte solution, the mass ratio between the halide solid electrolyte and the second binder is (1-5): (99-95).

[0025] According to one embodiment of the present invention, the drying process is performed at a temperature of 60-90° C. and / or for a time of 5-10 hours.

[0026] According to one embodiment of the present invention, the positive electrode active material includes at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide and ternary nickel cobalt lithium manganese oxide;

[0027] and / or,

[0028] The conductive agent includes at least one of acetylene black, carbon black, graphite, metal fiber, nano-carbon fiber, carbon nanotube and graphene.

[0029] According to one embodiment of the present invention, in the positive electrode slurry, the mass ratio of the positive electrode active material, the conductive agent, and the first binder is (80-90): (1.5-5): (1-3).

[0030] According to one embodiment of the present invention, the process of mixing the positive electrode active material, the conductive agent, the first binder and the first solvent includes at least one of magnetic stirring, slurry mixing and wet ball milling;

[0031] And / or, the process of mixing the halide solid electrolyte, the second binder and the second solvent includes at least one of magnetic stirring, slurry mixing and wet ball milling.

[0032] A third aspect of the present invention provides a solid-state battery comprising a positive electrode sheet, an electrolyte, and a negative electrode sheet;

[0033] Wherein, the positive electrode sheet is the composite positive electrode sheet described in the first aspect, or the composite positive electrode sheet prepared by the method described in the second aspect.

[0034] A fourth aspect of the present invention provides an electrical device comprising an electrical device body and the solid-state battery described in the third aspect.

[0035] The implementation of the present invention has at least the following beneficial effects:

[0036] In the composite positive electrode sheet provided by the present invention, the halide solid electrolyte in the three-dimensional pores of the positive electrode membrane forms a continuous Li + The channel is formed and the contact area between the positive electrode active material and the electrolyte is maximized, which effectively shortens the diffusion length of ions in the positive electrode sheet, thereby reducing the interface impedance between the positive electrode active material and the electrolyte in the battery, thereby improving the battery's rate performance and cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0038] Figure 1 Schematic diagram of the structure of the three-dimensional pores of the positive electrode membrane provided by the present invention

[0039] Figure 2 This is a top-view SEM image of the positive electrode membrane provided by the present invention;

[0040] Figure 3 A schematic flow chart of a method for preparing a composite positive electrode sheet is provided for the second embodiment of the present invention;

[0041] Figure 4 Schematic diagram of the operation of pouring the halide electrolyte solution onto the positive electrode membrane.

[0042] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific embodiments listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present invention.

[0044] Based on the introduction of the above technical background, embodiment 1 of the present invention provides a composite positive electrode sheet, including a positive electrode current collector and a positive electrode membrane arranged on the surface of the positive electrode current collector, the positive electrode membrane including a positive electrode active material, a conductive agent and a first binder, and the three-dimensional pores of the positive electrode membrane include a halide solid electrolyte and a second binder.

[0045] The three-dimensional pores are the spaces between the positive electrode active material, the conductive agent and the first binder.

[0046] It should be noted that the second binder is a binder compatible with the solid electrolyte and is used to embed the solid electrolyte into the three-dimensional pores of the positive electrode membrane during the preparation of the composite positive electrode sheet. The above-mentioned halide solid electrolyte can be a halide solid electrolyte commonly used in the art, and the present invention does not impose specific limitations on this.

[0047] Figure 1 This is a schematic diagram of the structure of the three-dimensional pores of the positive electrode membrane provided by the present invention (the halide solid electrolyte is not shown). Figure 1 As shown, the positive electrode membrane includes a conductive agent, a binder (including a first binder and a second binder), and a positive electrode active material. The spaces between the conductive agent, binder, and positive electrode active material are the three-dimensional pores of the positive electrode membrane. Specifically, the spaces between the conductive agent, binder, and positive electrode active material refer to the unfilled spaces within the three-dimensional structure of the positive electrode membrane.

[0048] Further, Figure 2 The SEM image of the positive electrode membrane provided by the present invention in a top view is used to intuitively show the filling state of the halide electrolyte in the three-dimensional pores of the positive electrode membrane in the composite positive electrode sheet provided by the present invention, as shown in FIG. Figure 1 As shown in the top view of the scanning electron microscope (SEM), it can be observed that the gaps between the positive electrode active material particles in the positive electrode membrane provided by the present invention are filled with halide solid electrolytes, forming a continuous Li + It should be noted that since the conductive agent and the binder (including the first binder and the second binder) are small in size and mostly distributed inside the positive electrode membrane, they are difficult to be clearly identified in the SEM image when viewed from above. Figure 1 Only the positive electrode active material and the halide solid electrolyte are marked.

[0049] According to the inventors' research, by filling the three-dimensional pores of the positive electrode membrane with a halide solid electrolyte, a continuous Li-ion battery that runs through the entire positive electrode membrane can be formed in the positive electrode sheet. + The channel is formed and the contact area between the positive electrode active material and the electrolyte is maximized, which effectively shortens the diffusion length of ions in the positive electrode sheet, thereby reducing the interface impedance between the positive electrode active material and the electrolyte in the battery, thereby improving the battery's rate performance and cycle stability.

[0050] In addition, according to further research by the inventors, halide solid electrolytes have advantages over other electrolytes, such as excellent electrochemical window, high positive electrode stability and acceptable room-temperature ionic conductivity, and can be successfully used in sulfide all-solid-state battery systems.

[0051] In one possible implementation, the halide solid electrolyte includes at least one of the Li3MX6 series electrolytes, wherein M is any element of scandium, yttrium, lanthanide elements, aluminum, gallium or indium, and / or X is any element of fluorine, chlorine, bromine or iodine.

[0052] Among them, the Lanxi elements include lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.

[0053] Specifically, in the Li3MX6 electrolyte, M can be any element selected from scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, aluminum, gallium, or indium; and / or X can be any element selected from fluorine, chlorine, bromine, or iodine. Exemplary halide solid electrolytes include Li3YCl6, Li3InCl6, and Li3YbCl6.

[0054] Optionally, the first binder includes at least one of polyisobutylene (PIB), ethyl cellulose, nitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), and styrene-ethylene-butylene-styrene block copolymer (SEBS).

[0055] The first binder is a binder compatible with the positive electrode active material and the conductive agent system.

[0056] Optionally, the second binder includes at least one of butadiene rubber (BR), PIB, poly vinyl cyanoacrylate (PVACN), ethyl cellulose, NBR, SBR, and SEBS.

[0057] The second binder is a binder compatible with the halide solid electrolyte.

[0058] In the composite positive electrode sheet provided by the present invention, the halide solid electrolyte in the three-dimensional pores of the positive electrode membrane forms a continuous Li + The channel is formed and the contact area between the positive electrode active material and the electrolyte is maximized, which effectively shortens the diffusion length of ions in the positive electrode sheet, thereby reducing the interface impedance between the positive electrode active material and the electrolyte in the battery, thereby improving the battery's rate performance and cycle stability.

[0059] Figure 3 A schematic flow chart of a method for preparing a composite positive electrode sheet is provided for the second embodiment of the present invention, as shown in FIG. Figure 3 As shown, the preparation method is used to prepare the above-mentioned composite positive electrode sheet, comprising:

[0060] S101 , mixing a positive electrode active material, a conductive agent, a first binder, and a first solvent to obtain a positive electrode slurry.

[0061] In this step, the first binder refers to a binder compatible with the positive electrode active material and conductive agent system; the first solvent refers to a binder compatible with the positive electrode active material and conductive agent system. In this step, the positive electrode slurry can be prepared using a common positive electrode active material, conductive agent, first binder, and first solvent in the art.

[0062] Optionally, the positive electrode active material includes at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide and ternary nickel cobalt manganese oxide (NCM).

[0063] Specifically, the positive electrode active material can be any one of lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide and ternary nickel cobalt manganese oxide (NCM), or it can be a combination of any multiple of the above substances. For example, it can be a combination of two, three or more substances. This embodiment of the present invention does not make specific limitations. Such a setting can effectively improve the versatility of the composite positive electrode sheet, so that the composite positive electrode sheet can meet various different application scenarios.

[0064] Optionally, the conductive agent includes at least one of acetylene black, carbon black (SP), graphite, metal fiber, nanofiber, carbon nanotube (CNT) and graphene.

[0065] Specifically, the conductive agent can be any one of acetylene black, carbon black, graphite, metal fiber, nanocarbon fiber, carbon nanotube and graphene, or it can be a combination of any multiple of the above substances. For example, it can be a combination of two, three or more substances. This embodiment of the present invention does not make specific limitations. Such a setting can effectively improve the versatility of the composite positive electrode sheet, so that the composite positive electrode sheet can meet various different application scenarios.

[0066] Optionally, the first binder includes at least one of PIB, ethyl cellulose, NBR, SBR, and SEBS.

[0067] Specifically, the first binder can be any one of PIB, ethyl cellulose, NBR, SBR, and SEBS, or a combination of any multiple of the above substances. For example, it can be a combination of two, three or more substances. The embodiment of the present invention does not make specific limitations on this. Such a setting can effectively improve the versatility of the composite positive electrode sheet, so that the composite positive electrode sheet can meet various application scenarios.

[0068] Optionally, the first solvent includes at least one of ethyl acetate, butyl butyrate, p-xylene, isobutyl isobutyrate, n-hexane, anisole, isopentyl isovalerate, and dodecyl.

[0069] Specifically, the first solvent can be any one of ethyl acetate, butyl butyrate, p-xylene, isobutyl isobutyrate, n-hexane, anisole, isoamyl isovalerate, and dodecyl, or it can be composed of any multiple of the above substances. For example, it can be composed of two, three or more substances. This embodiment of the present invention does not make specific limitations. Such a setting can effectively improve the versatility of the composite positive electrode sheet, so that the composite positive electrode sheet can meet various different application scenarios.

[0070] In a possible implementation, the mass ratio of the positive electrode active material, the conductive agent, and the first binder in the positive electrode slurry is (80-90):(1.5-5):(1-3).

[0071] Specifically, in the positive electrode slurry, the mass ratio of the positive electrode active material is 80-90%, the mass ratio of the conductive agent is 1.5-5%, and the mass ratio of the first binder is 1-3%. Exemplarily, the mass ratio of the positive electrode active material, the conductive agent, and the first binder in the positive electrode slurry is 80:1.5:1, or 90:5:3, or any ratio within the range of (80-90):(1.5-5):(1-3).

[0072] In a possible implementation, the process of mixing the positive electrode active material, the conductive agent, the first binder, and the first solvent includes at least one of magnetic stirring, slurry mixing, and wet ball milling.

[0073] Specifically, the positive electrode active material, the conductive agent, the first binder and the first solvent may be mixed by using one process among magnetic stirring, slurry mixing and wet ball milling, or any two or three of the processes.

[0074] S102, coating the positive electrode slurry on the surface of the positive electrode current collector and drying it to form a positive electrode membrane with three-dimensional pores, thereby obtaining a positive electrode sheet.

[0075] The three-dimensional pores are the spaces between the positive electrode active material, the conductive agent and the first binder;

[0076] In this step, a coating process is used to coat the positive electrode slurry on the positive electrode current collector and then naturally dry it. During the drying process, the first solvent in the positive electrode slurry is evaporated, and a positive electrode membrane with three-dimensional pores is formed on the surface of the positive electrode current collector.

[0077] Optionally, the positive electrode slurry may be coated on one surface or both surfaces of the positive electrode current collector.

[0078] S103 , mixing the halide solid electrolyte, the second binder, and the second solvent to obtain a halide electrolyte solution.

[0079] In this step, the halide solid electrolyte, the second binder and the second solvent are mixed to dissolve the halide solid electrolyte and the second binder in the second solvent to obtain a halide electrolyte solution.

[0080] The second binder is a binder compatible with the halide solid electrolyte; and the second solvent is a solvent compatible with the halide solid electrolyte.

[0081] Optionally, the halide solid electrolyte includes at least one of the Li3MX6 series electrolytes; wherein M is any element of scandium, yttrium, lanthanide elements, aluminum, gallium or indium, and / or X is any element of fluorine, chlorine, bromine or iodine.

[0082] Optionally, the second binder includes at least one of BR, PIB, PVACN, ethyl cellulose, NBR, SBR, and SEBS.

[0083] Specifically, the second binder can be any one of BR, PIB, PVACN, ethyl cellulose, NBR, SBR, and SEBS, or it can be a combination of any multiple of the above substances. For example, it can be a combination of two, three or more substances. This embodiment of the present invention does not specifically limit this.

[0084] Optionally, the second solvent includes at least one of ethyl acetate, butyl butyrate, p-xylene, isobutyl isobutyrate, n-hexane, anisole, isopentyl isovalerate, and dodecyl.

[0085] Specifically, the second solvent can be any one of ethyl acetate, butyl butyrate, p-xylene, isobutyl isobutyrate, n-hexane, anisole, isopentyl isovalerate, and dodecyl, or it can be composed of any multiple of the above substances. For example, it can be composed of two, three or more substances. This embodiment of the present invention does not specifically limit this.

[0086] It should be understood that when preparing a composite positive electrode sheet, the above-mentioned first solvent and the second solvent may be the same or different, and the above-mentioned first binder and the second binder may be the same or different, which can be determined according to the specific implementation scenario of the scheme. This application does not impose specific restrictions on this.

[0087] In one possible implementation, the solid content of the halide electrolyte solution is 45-50%.

[0088] Specifically, the solid content of the halide electrolyte solution refers to the content of the second binder and the halide solid electrolyte in the halide electrolyte solution. Exemplary solid content of the halide electrolyte solution is, for example, 45%, 45.5%, 46%, 46.5%, 47%, 47.5%, 48%, 48.5%, 49%, 49.5%, 50%, or a value within a new range formed by selecting any two of the foregoing values.

[0089] It should be understood that the halide electrolyte solution should have strong fluidity so that when the halide electrolyte solution is subsequently cast on the positive electrode membrane, it can naturally flow into the three-dimensional pores of the positive electrode membrane.

[0090] In a possible implementation, in the halide electrolyte solution, the mass ratio between the halide solid electrolyte and the second binder is (1-5):(99-95).

[0091] Illustratively, the mass ratio of the halide solid electrolyte to the second binder is, for example, 1:99, 2:98, 3:97, 4:96, 5:95, or any ratio within the range of (1-5): (99-95).

[0092] In a possible implementation, the process of mixing the halide solid electrolyte, the second binder, and the second solvent includes at least one of magnetic stirring, slurry mixing, and wet ball milling.

[0093] Specifically, the halide solid electrolyte, the second binder, and the second solvent may be mixed by using one of magnetic stirring, slurry mixing, and wet ball milling, or any two or three of the above processes.

[0094] S104, pouring the halide electrolyte solution on the positive electrode membrane of the positive electrode sheet so that the halide electrolyte solution is immersed into the three-dimensional pores, and performing drying treatment to obtain a composite positive electrode sheet.

[0095] Figure 4 This is a schematic diagram of the operation of pouring the halide electrolyte solution onto the positive electrode membrane, as shown in Figure 4 As shown, a positive electrode membrane is coated on one side of the positive electrode current collector. After the configured halide electrolyte solution is poured on the positive electrode membrane, the halide electrolyte solution will penetrate into the three-dimensional pores of the positive electrode membrane.

[0096] In this step, after the halide electrolyte solution is poured onto the positive electrode membrane of the positive electrode sheet, a drying process is required. During the drying process, the second solvent will be evaporated, thereby obtaining a composite positive electrode sheet.

[0097] In a possible implementation manner, the drying process is performed at a temperature of 60-90° C. and / or for a time of 5-10 hours.

[0098] Specifically, the temperature of the drying treatment is, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or any two of the aforementioned values ​​are selected to form a new range, and the value taken within the new range; and / or the time of the drying treatment is, for example, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, 9.5 h, 10 h, or any two of the aforementioned values ​​are selected to form a new range, and the value taken within the new range.

[0099] The present invention provides a method for preparing a composite positive electrode sheet, wherein a halide electrolyte solution is poured into a prefabricated positive electrode membrane to produce a composite positive electrode sheet containing a halide solid electrolyte within the three-dimensional pores of the positive electrode membrane. This method not only simplifies the preparation process but also does not affect the performance of the positive electrode active material when the halide solid electrolyte is added to the positive electrode membrane. This method increases the contact area between the positive electrode active material and the electrolyte in the positive electrode sheet while ensuring that the performance of the positive electrode active material in the positive electrode sheet is not affected, thereby shortening the diffusion length of ions in the positive electrode sheet.

[0100] A third embodiment of the present invention provides a solid-state battery, comprising a positive electrode sheet, an electrolyte, and a negative electrode sheet; wherein the positive electrode sheet is the composite positive electrode sheet in the first embodiment, or the composite positive electrode sheet prepared by the method in the second embodiment.

[0101] The negative electrode sheet specifically includes a negative electrode current collector and a negative electrode active layer formed of a negative electrode active material disposed on the surface of the negative electrode current collector. It should be understood that the present invention is not strictly limited to the negative electrode active material in the negative electrode sheet; it can be at least one of the negative electrode active materials commonly used in lithium-ion batteries, such as graphite, hard carbon, soft carbon, mesocarbon microbeads, silicon-based negative electrode materials (primarily including silicon monoxide and silicon-carbon negative electrodes), and tin-based negative electrode materials (primarily including tin and tin alloys).

[0102] In addition, the present invention does not strictly limit the selection of the electrolyte, and the electrolyte can be a solid electrolyte commonly used in the art. For example, the electrolyte can be a sulfide electrolyte, a halide electrolyte, etc.

[0103] As an example, the method for preparing the above-mentioned solid-state battery includes: pressurizing sulfide electrolyte powder to form an electrolyte layer; stacking the composite positive electrode plate, electrolyte layer and negative electrode plate provided by the present invention in sequence, and pressurizing and assembling them to obtain the solid-state battery.

[0104] As another example, the method for preparing the above-mentioned solid-state battery includes: loading the composite positive electrode sheet, separator and positive electrode sheet provided by the present invention into a traditional soft-pack battery; injecting the halide electrolyte solution provided by the present invention into the soft-pack battery; evaporating the solvent in the soft-pack battery to obtain the solid-state battery provided by the present invention.

[0105] Among them, the diaphragm can be a diaphragm material commonly used in current lithium-ion batteries. The present invention does not strictly limit the selection of diaphragm materials, such as polypropylene diaphragm (PP), polyethylene diaphragm (PE), polypropylene / polyethylene double-layer composite film (PP / PE), polyimide electrospun diaphragm (PI), polypropylene / polyethylene / polypropylene three-layer composite film (PP / PE / PP), cellulose non-woven fabric diaphragm, and one of the diaphragms with ceramic coating.

[0106] It should be understood that the solid-state battery provided by the present invention can be prepared based on the traditional liquid battery preparation process, and can also be prepared using the conventional process for preparing solid-state batteries.

[0107] The solid-state battery provided by the present invention uses a positive electrode separator in which the three-dimensional pores include a halide solid electrolyte, so that the interface impedance between the positive electrode active material and the electrolyte in the battery is small, thereby enabling the battery to have excellent rate performance and cycle stability.

[0108] A fourth embodiment of the present invention provides an electrical device, comprising an electrical device body and the all-solid-state battery provided by the present invention.

[0109] It should be noted that the present invention does not specifically limit the type of electrical device, which can be any electrical device that includes the battery, including but not limited to electric vehicles, mobile phones, portable devices, laptops, electric bicycles, electric toys, energy storage devices, etc.

[0110] The present invention is further described below through specific examples.

[0111] Example 1

[0112] 1) Preparation of positive electrode:

[0113] In an inert gas atmosphere, a homogenous mixing method is used to sequentially add 85% by mass of the positive electrode active material lithium nickel cobalt manganese oxide LiNi into the tank. 0.8 Co 0.1 Mn 0.1 O2, 3% by weight of a conductive agent vapor-grown carbon fiber (VGCF), 2% by weight of a first binder PIB, and a first solvent isobutyl isobutyrate to obtain a positive electrode slurry; wherein the solid content of the positive electrode slurry is 70%, the slurry mixing speed is 1200 rpm, and the time is 1 hour;

[0114] The positive electrode slurry is coated on the surface of the carbon-coated aluminum foil using a coating machine and dried to form a positive electrode film for coating to obtain a positive electrode sheet;

[0115] A second binder, SEBS, accounting for 2% by weight, and a second solvent, p-xylene, were sequentially added to a magnetic stirring bottle and stirred. After the second binder was dissolved, a halide solid electrolyte, Li3InCl6, accounting for 98% by weight, was evenly added to the magnetic stirring bottle and stirred again. After the halide solid electrolyte was evenly dispersed, a halide electrolyte solution was obtained, wherein the solid content of the halide electrolyte solution was 50%.

[0116] After the halide electrolyte solution is evenly poured on the positive electrode film of the positive electrode sheet, it is transferred to a vacuum oven for baking to obtain a composite positive electrode sheet. The baking temperature is 70°C and the time is 10 hours;

[0117] The composite positive electrode sheet was cut into discs with a diameter of 12 mm to obtain positive electrode discs.

[0118] 2) Preparation of negative electrode

[0119] In an inert gas atmosphere, silicon-carbon material, conductive agent SP, CNT, and binder polyvinylidene fluoride (PVDF) were weighed in a mass ratio of 89.6:8:0.2:0.4 and added to solvent N-methylpyrrolidone (NMP). The mixture was uniformly mixed by ball milling to obtain a negative electrode slurry. The solid content of the negative electrode slurry was 30%, and the ball milling speed was 500 rpm for 3 hours.

[0120] The negative electrode slurry was coated on a flat carbon-coated copper foil and then dried in a vacuum oven at 80°C for 10 h to obtain a negative electrode sheet.

[0121] The negative electrode sheet was cut into 12 mm discs to obtain negative electrode discs.

[0122] 3) Assembly of solid-state batteries:

[0123] In an inert gas atmosphere, the positive electrode disc was placed in a mold with a diameter of 12 mm, and 120 mg of solid electrolyte Li6PS5Cl powder was added;

[0124] The mold was placed in a powder tablet press for pressurization, wherein the pressing pressure was 3T and the holding time was 1 min;

[0125] After placing the negative electrode disc in the mold battery, the mold is placed in a powder tablet press for pressurization treatment, wherein the pressing pressure is 4T and the holding time is 1min;

[0126] Tighten the sealing kit and screws of the mold to obtain the mold battery.

[0127] Example 2

[0128] 1) Preparation of positive electrode:

[0129] In an inert gas atmosphere, 84% by weight of the positive electrode active material LiCoO2, 4% by weight of the conductive agent SP, 2% by weight of the first binder SEBS, and the first solvent p-xylene were sequentially added to a tank by wet ball milling to obtain a positive electrode slurry. The solid content of the positive electrode slurry was 75%, and the ball milling mixing speed was 500 rpm for 2 hours.

[0130] Using a coating machine, the positive electrode slurry is applied to the flat surface of the carbon-coated aluminum foil and dried to form a positive electrode film for coating to obtain a positive electrode sheet;

[0131] A second binder NBR (1.5% by weight) and a second solvent anisole were sequentially added to a magnetic stirring bottle and stirred. After the second binder was dissolved, a halide electrolyte Li3YCl6 (98.5% by weight) was evenly added to the magnetic stirring bottle and stirred again. After the halide electrolyte was evenly dispersed, a halide electrolyte solution was obtained, wherein the solid content of the halide electrolyte solution was 50%.

[0132] After the halide electrolyte solution is evenly poured on the positive electrode film of the positive electrode sheet, it is transferred to a vacuum oven for baking to obtain a composite positive electrode sheet. The baking temperature is 90°C and the time is 5 hours;

[0133] The composite positive electrode sheet was cut into discs with a diameter of 12 mm to obtain positive electrode discs.

[0134] 2) Preparation of negative electrode:

[0135] Same as Example 1.

[0136] 3) Assembly of solid-state batteries:

[0137] Same as Example 1.

[0138] Comparative Example

[0139] 1) Preparation of positive electrode:

[0140] In an inert gas atmosphere, the positive electrode active material lithium nickel cobalt manganese oxide LiNi 0.8 Co 0.1 Mn 0.1O2, sulfide solid electrolyte Li6PS5Cl, conductive agent VGCF and binder PIB were weighed in a mass ratio of 80:16:2.5:1.5, added to solvent isobutyl isobutyrate, and mixed uniformly by ball milling to obtain a positive electrode slurry. The solid content of the positive electrode slurry was 70%, and the ball milling mixing speed was 500 rpm for 4 hours.

[0141] The positive electrode slurry was coated on the flat surface of carbon-coated aluminum foil and then dried in a vacuum oven at 80°C for 10 hours to obtain a positive electrode sheet;

[0142] The positive electrode sheet was cut into 12 mm discs to obtain positive electrode discs.

[0143] 2) Preparation of negative electrode:

[0144] Same as Example 1.

[0145] 3) Assembly of solid-state batteries:

[0146] Same as Example 1.

[0147] The solid-state batteries prepared in the above examples and comparative examples were subjected to performance tests, and the test contents specifically included:

[0148] (1) Rate performance test. The test results are shown in Table 1. The test method is:

[0149] The mold battery was charged to 4.2V at a constant current of 0.1C, charged to a cut-off charge of 0.05C at a constant voltage, and then discharged to 2.8V at a constant current of 0.1C. The 0.1C discharge specific capacity of the battery was calculated based on the test data.

[0150] Similar to the above test method, the battery was charged and charged at constant current at 0.3C, 0.5C and 1C respectively, and the corresponding 0.3C discharge specific capacity, 0.5C discharge specific capacity and 1C discharge specific capacity of the battery were calculated based on the test data.

[0151] Table 1: Rate performance test results

[0152]

[0153] (2) Impedance test. The test results are shown in Table 2. The test method is:

[0154] Before the cycle test and after 50 cycles, the impedance of the solid-state battery was tested using electrochemical impedance spectroscopy (EIS) testing equipment to obtain the battery's pre-cycle impedance and the impedance after 50 cycles.

[0155] Table 2: Impedance test results

[0156]

[0157] From the test results in Table 1, it can be seen that the discharge specific capacities of the batteries corresponding to Examples 1 and 2 at 0.1C, 0.3C, 0.5C, and 1C are all higher than those of the comparative example; from the test results in Table 2, it can be seen that the impedance of the batteries corresponding to Examples 1 and 2 before and after 50 cycles is significantly lower than that of the comparative example. This shows that the composite positive electrode provided by the present invention can reduce the interfacial impedance of the battery, thereby effectively improving the rate performance and cycle stability of the battery.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite positive electrode sheet, characterized in that: The composite positive electrode sheet includes a positive electrode current collector and a positive electrode membrane disposed on the surface of the positive electrode current collector; the positive electrode membrane includes a positive electrode active material, a conductive agent, and a first binder; the three-dimensional pores of the positive electrode membrane include a halide solid electrolyte and a second binder; The three-dimensional pores are gaps between the positive electrode active material, the conductive agent and the first binder.

2. The composite positive electrode sheet according to claim 1, characterized in that: The halide solid electrolyte includes at least one of Li3MX6 electrolytes; Wherein, M is any one of scandium, yttrium, lanthanide elements, aluminum, gallium or indium, and / or X is any one of fluorine, chlorine, bromine or iodine.

3. The composite positive electrode sheet according to claim 1 or 2, characterized in that: The first binder comprises at least one of polyisobutylene, ethyl cellulose, nitrile rubber, styrene-butadiene rubber, and styrene-ethylene-butylene-styrene copolymer; And / or, the second binder includes at least one of butadiene rubber, polyisobutylene, polycyanoacrylate, ethyl cellulose, nitrile rubber, styrene-butadiene rubber, and styrene-ethylene-butylene-styrene copolymer.

4. A method for preparing a composite positive electrode sheet according to any one of claims 1 to 3, characterized in that: include: Mixing a positive electrode active material, a conductive agent, a first binder, and a first solvent to obtain a positive electrode slurry; The positive electrode slurry is applied to the surface of the positive electrode current collector and dried to form a positive electrode film having three-dimensional pores, thereby obtaining a positive electrode sheet; the three-dimensional pores are the gaps between the positive electrode active material, the conductive agent, and the first binder; mixing a halide solid electrolyte, a second binder, and a second solvent to obtain a halide electrolyte solution; The halide electrolyte solution is poured onto the positive electrode membrane of the positive electrode plate so that the halide electrolyte solution is immersed into the three-dimensional pores, and then dried to obtain the composite positive electrode plate.

5. The method according to claim 4, characterized in that The halide solid electrolyte includes at least one of Li3MX6 electrolytes; Wherein, M is any one of scandium, yttrium, lanthanide elements, aluminum, gallium or indium, and / or X is any one of fluorine, chlorine, bromine or iodine.

6. The method according to claim 4, characterized in that The first binder comprises at least one of polyisobutylene, ethyl cellulose, nitrile rubber, styrene-butadiene rubber, and styrene-ethylene-butylene-styrene copolymer; And / or, the second binder includes at least one of butadiene rubber, polyisobutylene, polycyanoacrylate, ethyl cellulose, nitrile rubber, styrene-butadiene rubber, and styrene-ethylene-butylene-styrene copolymer.

7. The method according to claim 4, characterized in that The first solvent comprises at least one of ethyl acetate, butyl butyrate, p-xylene, isobutyl isobutyrate, n-hexane, anisole, isopentyl isovalerate, and dodecyl; And / or, the second solvent includes at least one of ethyl acetate, butyl butyrate, p-xylene, isobutyl isobutyrate, n-hexane, anisole, isopentyl isovalerate, and dodecyl.

8. The method according to claim 4, characterized in that The solid content of the halide electrolyte solution is 45-50%.

9. The method according to claim 8, characterized in that In the halide electrolyte solution, the mass ratio of the halide solid electrolyte to the second binder is (1-5):(99-95).

10. The method according to any one of claims 4 to 9, characterized in that The drying process is performed at a temperature of 60-90° C. and / or for a time of 5-10 hours.

11. The method according to any one of claims 4 to 9, characterized in that The positive electrode active material includes at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide and ternary nickel cobalt lithium manganese oxide; and / or, The conductive agent includes at least one of acetylene black, carbon black, graphite, metal fiber, nano-carbon fiber, carbon nanotube and graphene.

12. The method according to any one of claims 4 to 9, characterized in that In the positive electrode slurry, the mass ratio of the positive electrode active material, the conductive agent, and the first binder is (80-90):(1.5-5):(1-3).

13. The method according to any one of claims 4 to 9, characterized in that The process of mixing the positive electrode active material, the conductive agent, the first binder and the first solvent comprises at least one of magnetic stirring, slurry mixing and wet ball milling; And / or, the process of mixing the halide solid electrolyte, the second binder and the second solvent includes at least one of magnetic stirring, slurry mixing and wet ball milling.

14. A solid-state battery, characterized in that: Including positive electrode sheet, electrolyte and negative electrode sheet; Wherein, the positive electrode sheet is the composite positive electrode sheet according to any one of claims 1 to 3, or the positive electrode sheet is the composite positive electrode sheet prepared by the method according to any one of claims 4 to 13.

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