Preparation method for composite electrode sheet containing solid-state electrolyte layer, and composite electrode sheet, preparation method for solid-state battery, and solid-state battery

Abstract

A preparation method for a composite electrode sheet containing a solid-state electrolyte layer. A solid-state electrolyte is uniformly introduced into a solid-state battery by means of wet electrostatic atomizing spraying, so that a continuous and compact interface of a solid-state electrolyte layer can be constructed on an electrode sheet, enhancing flexible interfacial contact between the electrode sheet and the solid-state electrolyte layer, thereby reducing interface impedance, and improving the electrochemical performance of the solid-state battery.

Description

Preparation method of composite pole piece containing solid electrolyte layer, composite pole piece, preparation method of solid-state battery, and solid-state battery

[0001] This application is based on the Chinese patent application with application number 202311005639.4 and application date August 10, 2023, and claims the priority of the Chinese patent application. The entire content of the Chinese application is hereby introduced into this application as a reference. Technical Field

[0002] The present invention belongs to the field of solid-state batteries and relates to a method for preparing a composite pole piece containing a solid electrolyte layer, a method for preparing the composite pole piece, a solid-state battery, and the solid-state battery. Background Art

[0003] The current research and development trend of lithium-ion batteries in the field of new energy storage is to simultaneously improve their energy density and safety. However, the liquid battery system used in traditional lithium-ion batteries has many defects, which lead to a series of problems. For example, the SEI film of the liquid electrolyte partially dissolves at high temperatures, the SEI film continues to grow on the surface of the positive and negative electrode materials, causing a decrease in active lithium and an increase in the internal resistance of the battery, the problem of oxygen evolution of the positive electrode material in the liquid electrolyte under high pressure, and the volume expansion of some negative electrode materials in the liquid system. In view of the above problems, the existing technology uses thermodynamically stable solid electrolytes to replace the flammable liquid electrolyte and separator, which can effectively improve the safety and energy density of lithium-ion batteries.

[0004] Solid-state electrolytes, one of the core materials in solid-state batteries, currently primarily consist of high-conductivity inorganic solid electrolytes, flexible polymer solid electrolytes, and inorganic-organic composite solid electrolytes with improved mechanical properties. Unlike liquid electrolytes, the interface between solid electrolytes and the battery cell electrodes is solid-solid. Therefore, establishing a stable interface, increasing the contact area between the active material and the solid electrolyte, and further reducing the interfacial impedance of the solid-state battery system are key to improving solid-state battery performance.

[0005] The existing method of introducing solid electrolytes is to prepare solid-state battery pole pieces through coating or chemical vapor deposition. Methods such as coating or chemical vapor deposition have low material utilization, high process costs and low production efficiency, making it difficult to achieve large-scale and uniform introduction of solid electrolytes. Battery pole pieces containing solid electrolytes can be prepared through traditional wet coating methods, or inorganic solid electrolyte ceramic sheets obtained by mold assembly and sintering can be used to assemble solid-state batteries. However, there are process problems such as powder loss and material jamming, which make it impossible to achieve flexible interface contact between the solid electrolyte and the battery pole piece. In addition, the existing methods are limited by the process requirements of mass production of solid-state batteries, and cannot achieve industrial production of solid-state batteries with uniform thickness and firm interface contact.

[0006] Summary of the Invention

[0007] Problems to be solved by the invention

[0008] Considering the current situation that the above methods cannot achieve flexible interface contact between solid electrolytes and battery electrodes, there is an urgent need to develop a solid electrolyte introduction method that can increase the contact area between electrode active materials and solid electrolytes, achieve close contact between electrodes and solid electrolytes, reduce the interfacial impedance of solid-state battery systems, and is suitable for industrial production. By constructing a stable solid-state battery interface, the efficiency of mass production can be improved, and problems such as active material agglomeration, powder loss, and material jamming that occur in existing methods can be prevented.

[0009] Solutions for solving problems

[0010] To address the above issues, the present invention proposes a wet electrostatic atomization spraying method to address the mass production of battery pole pieces and solid-state batteries containing solid-state electrolytes. The present invention introduces a solid-state electrolyte into the method by adjusting the process parameters of the spraying equipment to ensure that the slurry containing the solid-state electrolyte meets the spraying requirements. This allows for the construction of a continuous, dense solid-state electrolyte layer interface on the pole piece, enhancing the interfacial contact between the pole piece and the solid-state electrolyte layer, thereby reducing interfacial impedance and improving the electrochemical performance of the solid-state battery.

[0011] Specifically, the present invention provides a method for preparing a composite electrode sheet containing a solid electrolyte layer, which comprises the following steps:

[0012] Step S1: preparing a solid electrolyte slurry containing a solid electrolyte composition, and

[0013] Step S2: introducing the solid electrolyte slurry onto the positive electrode sheet or the negative electrode sheet by electrostatic atomization spraying and drying, thereby obtaining a positive electrode sheet or a negative electrode sheet containing a solid electrolyte layer.

[0014] The spraying pressure during the electrostatic atomization spraying is 0.2-0.8 MPa.

[0015] According to the preparation method described above, the electrostatic atomization spraying in step S2 further includes a step of heating the positive electrode sheet or the negative electrode sheet, and the heating temperature is 50-210°C, preferably 70-160°C.

[0016] According to the above preparation method, the solid content of the solid electrolyte slurry is 20% by mass to 85% by mass.

[0017] According to the preparation method described above, in the electrostatic atomization spraying, the electrostatic voltage is 45-100kV, the electrostatic current is 10μA-30μA, and the compressed gas pressure is 2.5-8.5kg / cm 2, the spraying distance is 10 - 210 mm, the spraying angle is 85 - 90°, and the spraying flow rate is 1 - 35 mL / min.

[0018] According to the preparation method described above, the drying temperature is 50 - 160°C and the drying time is 5 - 20 h.

[0019] According to the preparation method described above, the solid electrolyte is selected from one or more of inorganic solid electrolytes and organic polymer solid electrolytes;

[0020] Preferably, the inorganic solid electrolyte is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes.

[0021] According to the preparation method described above, the oxide solid electrolyte is selected from one or more of perovskite-type oxide solid electrolytes, garnet-type oxide solid electrolytes, and NASICON-type oxide solid electrolytes; [[ID=1३]]

[0022] The sulfide solid electrolyte is selected from one or more of lithium germanium phosphorus sulfur, lithium phosphorus sulfur chlorine, lithium silicon phosphorus sulfur chlorine, lithium phosphorus sulfur bromine, lithium phosphorus sulfur iodine, lithium thiophosphate, and vitreous sulfide;

[0023] The halide solid electrolyte is selected from Li3OCl, LiI, Li5ZnI4, Li3OCl <००००००२>Br <००००००३>(where 0 < x < 1), Li2XCl4 (X is selected from Cd and / or Mg), Li2X'I4 (X' is selected from Cd and / or Zn), LiMCl5X'' (M is selected from one or more of La, Ta, Nb, X'' is selected from O, Cl, F or OH), Li <००००००४>Zr <००००००५>M’ <००००००६>Cl6 (M' is selected from one or more of Y, Er, Yb, Ho, Lu, 0 < y < 1);

[0024] The lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, and lithium difluorooxalate borate;

[0025] The organic polymer solid electrolyte is selected from one or more of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene, polyvinylidene fluoride - chlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, poly(ethylene succinate), polyvinyl chloride, poly(vinylidene carbonate), polyvinylpyrrolidone, polyimide, polyacrylate, and polyurethane;

[0026] Preferably, the perovskite-type oxide solid electrolyte is selected from lithium lanthanum titanate;

[0027] The garnet-type oxide solid electrolyte is selected from one or more of lithium lanthanum zirconium oxide, niobium-doped lithium lanthanum zirconium oxide, tantalum-doped lithium lanthanum zirconium oxide, and niobium-tantalum dual-doped lithium lanthanum zirconium oxide;

[0028] The NASICON type oxide solid electrolyte is selected from one or more of lithium titanium aluminum phosphate, lithium yttrium titanium phosphate, and lithium germanium aluminum phosphate.

[0029] According to the preparation method described above, the preparation method further comprises the following steps before step S2:

[0030] Step S0: spraying the positive electrode material composition or the negative electrode material composition onto the surface of the positive electrode collector or the negative electrode collector by dry electrostatic spraying, or spraying the positive electrode slurry or the negative electrode slurry onto the surface of the positive electrode collector or the negative electrode collector by wet electrostatic spraying, and then drying and rolling to obtain the positive electrode sheet or the negative electrode sheet.

[0031] According to the preparation method described above, in the dry electrostatic spraying, the electrostatic voltage is 50-90 kV, the electrostatic current is 15-25 μA, and the compressed gas pressure is 2.5-7.5 kg / cm 2 , the spraying pressure is 0.2-0.8MPa, the spraying distance is 5-200mm, and the spraying angle is 80-90°.

[0032] According to the preparation method described above, in the wet electrostatic spraying, the electrostatic voltage is 45-100kV, the electrostatic current is 10μA~30μA, the compressed gas pressure is 2.5~8.5kg / cm2, the spraying pressure is 0.2-0.8MPa, the spraying distance is 10~210mm, and the spraying angle is 85~90°; the temperature of the positive electrode collector or the negative electrode collector is 60-200℃.

[0033] According to the preparation method described above, the positive electrode slurry or the negative electrode slurry is prepared by slurrying the positive electrode active material composition or the negative electrode active material composition in a solvent; the solid content of the positive electrode slurry or the negative electrode slurry is 30-80% by mass, preferably 40-60% by mass.

[0034] According to the preparation method described above, the positive electrode active material composition or the negative electrode active material composition includes a positive electrode active material or a negative electrode active material, a conductive agent, and a binder.

[0035] According to the preparation method described above, the positive electrode active material is selected from one or more of nickel-cobalt-manganese ternary material, nickel-cobalt-aluminum ternary material, lithium iron phosphate, lithium cobaltate, lithium manganese oxide, and lithium vanadium phosphate; the negative electrode active material is selected from one or more of graphite, graphene, carbon nanotubes, silicon-based alloys, silicon-oxygen negative electrode, silicon-carbon negative electrode, lithium metal, lithium alloy negative electrode, lithium titanium oxide, transition metal oxide, and transition metal sulfide.

[0036] The present invention also provides a composite electrode piece containing a solid electrolyte layer, which comprises at least one of the composite electrode pieces containing a solid electrolyte layer prepared according to the preparation method described above.

[0037] According to the composite electrode sheet containing a solid electrolyte layer described above, it includes a positive electrode sheet or a negative electrode sheet and a solid electrolyte layer provided on the positive electrode sheet or the negative electrode sheet.

[0038] According to the composite pole piece containing a solid electrolyte layer described above, the thickness of the solid electrolyte layer is 5-55 μm.

[0039] The present invention also provides a method for preparing a solid-state battery, which includes the steps of preparing a positive electrode sheet containing a solid electrolyte layer and / or a negative electrode sheet containing a solid electrolyte layer by the preparation method described above.

[0040] The present invention further provides a solid-state battery, which includes at least one of the solid-state batteries prepared according to the preparation method described above.

[0041] Effects of the Invention

[0042] The above technical solution of the present invention has the following beneficial effects:

[0043] (1) The present invention uses a wet electrostatic atomization spraying method to introduce the solid electrolyte into the solid-state battery, which can achieve the construction of a continuous and dense solid electrolyte layer interface on the electrode, and realize flexible interface contact between the solid electrolyte and the battery electrode;

[0044] (2) The solid electrolyte introduction method of the present invention can improve the process problems such as powder loss and material sticking in the existing process, improve production efficiency, and increase the interface stability between the solid electrolyte and the active material;

[0045] (3) In the electrode piece containing the solid electrolyte layer obtained by the preparation method of the present invention, the flexible interface contact between the electrode piece and the solid electrolyte layer is enhanced, thereby reducing the interface impedance and improving the electrochemical performance of the solid-state battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG1 is a schematic diagram showing the structure of a composite electrode including a solid electrolyte layer according to the present invention.

[0047] FIG2 shows the first charge and discharge curve of the composite electrode prepared in Example 2 of the present invention.

[0048] FIG3 is a diagram showing a scanning electron microscope characterization of the composite electrode prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0049] The following describes embodiments of the present invention, but the present invention is not limited thereto. The present invention is not limited to the various configurations described below; various modifications may be made within the scope of the invention claims, and embodiments obtained by appropriately combining different embodiments and appropriately combining the technical means disclosed in the examples are also included in the technical scope of the present invention. In addition, all documents listed in this specification are cited as references in this specification.

[0050] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0051] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0052] In this specification, unless otherwise specified, "multiple" in "multiple", "multiple", "many" and the like means a numerical value of 2 or more.

[0053] In this specification, the term “substantially”, “generally” or “essentially” means that the error is less than 5%, or less than 3%, or less than 1% compared with the relevant perfect standard or theoretical standard.

[0054] In this specification, unless otherwise specified, "%" means percentage by mass.

[0055] In this specification, when "room temperature" or "normal temperature" appears, the temperature may generally be 10-37°C, or 15-35°C.

[0056] In this specification, the meanings of “may” or “can” include both existence and non-existence, and both performing a certain process and not performing a certain process.

[0057] Throughout this specification, “optional” and “optionally” mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

[0058] The term "comprises" and any variations thereof in the specification and claims of the present invention and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0059] In this specification, references to "some / certain / preferred embodiments," "embodiments," etc., mean that the specific elements (e.g., features, structures, properties, and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it should be understood that the elements may be combined in any suitable manner in various embodiments.

[0060] <First Aspect>

[0061] A first aspect of the present invention provides a method for preparing a composite electrode sheet containing a solid electrolyte layer. The preparation method of this aspect comprises the following steps:

[0062] Step S1: preparing a solid electrolyte slurry containing a solid electrolyte composition, and

[0063] Step S2: introducing the solid electrolyte slurry onto the positive electrode sheet or the negative electrode sheet by electrostatic atomization spraying and drying the resulting mixture, thereby obtaining a positive electrode sheet or a negative electrode sheet containing a solid electrolyte layer.

[0064] In the present invention, the positive electrode sheet or the negative electrode sheet can be purchased from an existing supplier or can be prepared.

[0065] In some embodiments of the present invention, when preparing a positive electrode sheet or a negative electrode sheet, the preparation method of the present invention further includes the following steps before step S2:

[0066] Step S0: spraying the positive electrode material composition or the negative electrode material composition onto the surface of the positive electrode collector or the negative electrode collector by dry electrostatic spraying, or spraying the positive electrode slurry or the negative electrode slurry onto the surface of the positive electrode collector or the negative electrode collector by wet electrostatic spraying, and then drying to obtain the positive electrode sheet or the negative electrode sheet.

[0067] It should be noted that the expression "electrostatic atomization spraying" used in the present invention can also be called "wet atomization electrostatic spraying". The two have the same meaning, indicating a method of electrostatic spraying in which the slurry needs to be atomized during spraying; and the expression "wet electrostatic spraying" used in the present invention indicates a method of electrostatic spraying in which the slurry is not atomized during spraying.

[0068] The following describes each step in detail.

[0069] Step S0

[0070] In step S0 , a positive electrode sheet having a positive electrode active material layer or a negative electrode sheet having a negative electrode active material layer is prepared by applying a positive electrode active material or a negative electrode active material to the surface of a positive electrode collector or a negative electrode collector by dry electrostatic spraying or wet electrostatic spraying.

[0071] In dry electrostatic spraying, the positive electrode active material composition or the negative electrode active material composition is sprayed onto the surface of the current collector and then dried.

[0072] In wet electrostatic spraying, the positive electrode active material composition or the negative electrode active material composition is slurried in a solvent to prepare a positive electrode slurry or a negative electrode slurry, which is then sprayed onto the surface of a current collector and dried.

[0073] The solid content of the positive electrode slurry or the negative electrode slurry may be 30-80 mass %, preferably 40-60 mass %, for example, 30 mass %, 40 mass %, 50 mass %, 60 mass %, 70 mass %, 80 mass %, etc.

[0074] In some embodiments of the present invention, the positive electrode active material composition or the negative electrode active material composition may include a positive electrode active material or a negative electrode active material, as well as a conductive agent, a binder, and the like.

[0075] In the present invention, there is no particular limitation on the positive electrode active material or the negative electrode active material, the conductive agent, and the binder, and those commonly used in the art can be used.

[0076] In some embodiments of the present invention, examples of the positive electrode active material may include one or more of nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate, lithium cobaltate, lithium manganate, and lithium vanadium phosphate.

[0077] In some embodiments of the present invention, examples of negative electrode active materials may include one or more of graphite (natural graphite or artificial graphite), graphene, carbon nanotubes, silicon-based alloys, silicon-oxygen negative electrodes, silicon-carbon negative electrodes, lithium metal, lithium alloy negative electrodes, lithium titanium oxides, transition metal oxides, and transition metal sulfides.

[0078] In some embodiments of the present invention, examples of the conductive agent may include one or more of conductive graphite, conductive carbon black, acetylene black, carbon nanotubes, Ketjen black, graphene, carbon nanofibers, polyethylene dioxythiophene, polystyrene sulfonic acid, and sodium polystyrene sulfonate. Examples of the binder may include one or more of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium hydroxymethyl cellulose, styrene-butadiene rubber, and polyacrylic acid.

[0079] Examples of the solvent used in the homogenization may include one or more of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, butyrate, toluene, xylene, anisole, hexane, heptane, dibromomethane, dichloroethane, ethanol, and glycol ether.

[0080] There is no particular limitation on the mass ratio of the positive electrode active material or negative electrode active material to the conductive agent and binder, and a mass ratio commonly used in the art can be used. In some embodiments of the present invention, the mass ratio of the positive electrode active material or negative electrode active material to the conductive agent and binder can be 90-95:2-6:1-4.

[0081] In some specific embodiments of wet electrostatic spraying, the positive electrode active material or the negative electrode active material is fully mixed with the conductive agent and the binder in batches according to a certain mass ratio in an appropriate amount of solvent to be homogenized, thereby preparing a slurry.

[0082] In the present invention, there is no particular limitation on the positive electrode current collector or the negative electrode current collector, and any positive electrode current collector or negative electrode current collector commonly used in the art can be used.

[0083] In dry electrostatic spraying, spraying conditions may include the following:

[0084] The electrostatic voltage may be 50-90 kV, preferably 60-80 kV, for example, 50 kV, 60 kV, 70 kV, 80 kV, 90 kV, etc.;

[0085] The electrostatic current may be 15 to 25 μA, preferably 18 to 22 μA, for example, 15 μA, 18 μA, 20 μA, 22 μA, 25 μA, etc.;

[0086] The compressed gas pressure can be 2.5~7.5kg / cm 2 , for example, 2.5 kg / cm 2 、3.0kg / cm 2 、 3.5kg / cm 2 , 4.0kg / cm 2 , 4.5kg / cm 2 , 5.0kg / cm 2 , 5.5kg / cm 2 、6.0kg / cm 2 , 6.5kg / cm 2 , 7.0kg / cm 2 wait;

[0087] The spraying pressure may be 0.2-0.8 MPa, preferably 0.3-0.8 MPa, for example, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, etc.;

[0088] The spraying distance can be 5 to 200 mm, preferably 50 to 150 mm, for example, 5 mm, 10 mm, 20 mm, 30 mm, 50 mm, 60 mm, 80 mm, 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, etc.

[0089] The spraying angle may be 80 to 90°, for example, 80°, 85°, 88°, 90°, etc.

[0090] In wet electrostatic spraying, spraying conditions may include the following:

[0091] The electrostatic voltage may be 45-100 kV, preferably 50-90 kV, for example, 45 kV, 50 kV, 55 kV, 60 kV, 65 kV, 70 kV, 75 kV, 80 kV, 85 kV, 90 kV, 95 kV, 100 kV, etc.

[0092] The electrostatic current may be 10 to 30 μA, for example, 10 μA, 15 μA, 20 μA, 25 μA, 30 μA, etc.;

[0093] The compressed gas pressure can be 2.5~8.5kg / cm 2 , for example, 2.5 kg / cm 2 、3.0kg / cm 2 、3.5kg / cm 2 , 4.0kg / cm 2 , 4.5kg / cm 2 , 5.0kg / cm 2 , 5.5kg / cm 2 、6.0kg / cm 2 , 6.5kg / cm 2 , 7.0kg / cm 2 , 7.5kg / cm 2 、8.0kg / cm 2 ,8.5kg / cm 2 wait;

[0094] The spraying pressure may be 0.2-0.8 MPa, for example, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, etc.;

[0095] The spraying distance can be 10 to 210 mm, preferably 30 to 180 mm, for example, 10 mm, 20 mm, 30 mm, 50 mm, 60 mm, 80 mm, 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, 210 mm, etc.

[0096] The spraying angle may be 85° to 90°, for example, 85°, 86°, 88°, 90°, etc.

[0097] In addition, the dry electrostatic spraying and wet electrostatic spraying of the present invention are preferably carried out in a dry environment with a moisture content of less than 10 ppm, preferably 5 ppm, and more preferably less than 1 ppm.

[0098] In the above-mentioned dry electrostatic spraying and wet electrostatic spraying, the electrostatic voltage affects the adhesion rate of the active material on the current collector. Too low an electrostatic voltage is not conducive to the adhesion of the active material on the current collector, resulting in loose interface contact. Too high an electrostatic voltage makes it difficult to control the thickness of the sprayed active material layer.

[0099] In the above-mentioned dry electrostatic spraying and wet electrostatic spraying, appropriate spraying pressure can make the material sprayed evenly on the surface of the current collector, improve the adhesion rate and increase the effective adsorption rate of the active material, build a stable flexible interface, and reduce the problems of active material agglomeration and material waste in the process of preparing battery electrodes. Too low spraying pressure will lead to uneven distribution of active materials sprayed on the surface of the current collector, and too high spraying pressure will cause waste of materials and uneven distribution of active materials on the electrode surface.

[0100] In some preferred embodiments of wet electrostatic spraying, the positive electrode collector or the negative electrode collector can be heated. The heating temperature can be 60-200°C, preferably 80-150°C, for example, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, etc. By heating the current collector, the slurry can be evenly distributed on the surface of the current collector, reducing the agglomeration of active materials during the spraying process, allowing the solid electrolyte to be in close contact with the electrode active material, reducing the interfacial impedance, and improving the cycle stability of the battery. In some embodiments, the positive electrode collector or the negative electrode collector is placed on a work plate for operation. Thus, the heating of the positive electrode collector or the negative electrode collector and the drying after spraying can be achieved through the work plate, thereby reducing the process flow while achieving mass production.

[0101] In some specific embodiments of wet electrostatic spraying, the positive electrode current collector or the negative electrode current collector is placed on a work plate, which is then heated and set to electrostatic spraying conditions. The positive electrode slurry or the negative electrode slurry is sprayed onto the surface of the current collector to the desired thickness. After standing for a period of time, the electrostatic spraying equipment is turned off, and then dried and naturally cooled to obtain a positive electrode sheet with a positive electrode slurry layer or a negative electrode sheet with a negative electrode slurry layer. In some embodiments, during the standing period, the temperature of the work plate can be raised to a temperature slightly higher than the heating temperature during spraying, such as 10 to 30°C higher. The standing time can be, for example, 20 to 120 minutes.

[0102] In step S0, the drying is carried out at 50-180° C., preferably 60-150° C., under vacuum for 8-16 h, preferably 9-12 h.

[0103] In the present invention, the thickness of the positive electrode active material layer or the negative electrode active material layer may be 10 to 200 μm, preferably 30 to 150 μm, for example, 10 μm, 30 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, etc.

[0104] After the positive electrode active material or the negative electrode active material is applied to the current collector by dry electrostatic spraying or wet electrostatic spraying, it can be dried, rolled, or processed by one or more processes for standby use.

[0105] Both the dry electrostatic spraying and the wet electrostatic spraying in step S0 utilize the principle of corona discharge, and adjust the process conditions of the electrostatic spraying to achieve uniform introduction of the active material layer. They can also increase the interface stability between the active material and the current collector, reduce the interface impedance, and improve the electrochemical performance of the solid-state battery.

[0106] Step S1

[0107] In step S1, a solid electrolyte slurry comprising a solid electrolyte composition is prepared. The solid electrolyte slurry of the present invention can be purchased as an existing slurry or can also be prepared. Therefore, the preparation of the solid electrolyte slurry in step S1 includes purchasing an existing commercially available slurry or preparing the slurry.

[0108] When preparing the slurry, the solid electrolyte composition is dispersed in a solvent to prepare the solid electrolyte slurry.

[0109] In the present invention, there is no particular limitation on the solid electrolyte, and those commonly used in the art can be used.

[0110] In some embodiments of the present invention, the solid electrolyte may be selected from one or more of an inorganic solid electrolyte and an organic polymer solid electrolyte. The inorganic solid electrolyte may be selected from one or more of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte. When two or more solid electrolytes are used, the ratio between them is not particularly limited and can be adjusted according to actual needs.

[0111] The oxide solid electrolyte may be selected from one or more of a perovskite-type oxide solid electrolyte, a garnet-type oxide solid electrolyte, and a NASICON-type oxide solid electrolyte.

[0112] Among them, the perovskite-type oxide solid electrolyte can be selected from lithium lanthanum titanium oxide. The garnet-type oxide solid electrolyte can be selected from one or more of lithium lanthanum zirconium oxide, niobium-doped lithium lanthanum zirconium oxide, tantalum-doped lithium lanthanum zirconium oxide, and niobium-tantalum co-doped lithium lanthanum zirconium oxide. The NASICON-type oxide solid electrolyte can be selected from one or more of lithium aluminum titanium phosphate, lithium yttrium titanium phosphate, and lithium germanium aluminum phosphate.

[0113] The sulfide solid electrolyte can be selected from one or more of lithium germanium phosphorus sulfur (LGPS), lithium phosphorus sulfur chlorine (LPSCl), lithium silicon phosphorus sulfur, lithium silicon phosphorus sulfur chlorine, lithium phosphorus sulfur bromine (LPSBr), lithium phosphorus sulfur iodine (LPSI), lithium thiophosphate (LPS), and vitreous sulfides (such as Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, etc.).

[0114] The halide solid electrolyte can be selected from Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1), Li₂XCl₄ (X = Cd and / or Mg), Li₂X′I₄ (X′ = Cd and / or Zn), LiMCl₅X″ (M is selected from one or more of La, Ta, Nb, and X″ is selected from O, Cl, F, or OH), Li 3-y Zr y M’ 1-y Cl₆ (M’ is selected from one or more of Y, Er, Yb, Ho, Lu, and 0 < y < 1).

[0115] The organic polymer solid electrolyte can be selected from one or more of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyvinylidene fluoride - hexafluoropropylene (PVDF - HFP), polyvinylidene fluoride - chlorotrifluoroethylene (PVDF - CTFE), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polypropylene carbonate (PPC), polyphenylene sulfide (PPS), polyethyl cyanoacrylate (PCA), poly(ethylene succinate), polyvinyl chloride (PVC), poly(vinylidene carbonate), polyvinylpyrrolidone (PVP), polyimide (PI), polyacrylate, and polyurethane.

[0116] In the solid electrolyte composition, in addition to the solid electrolyte, it is preferably to contain one or more of a lithium salt, a binder, and a dispersant. When the solid electrolyte is only an organic polymer solid electrolyte, the composition must contain a lithium salt. When the composition containing the solid electrolyte contains a lithium salt, the mass ratio of the solid electrolyte to the lithium salt can be 8:1 to 2:1, for example, it can be 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, etc.

[0117] There is no particular limitation on the lithium salt, binder, and dispersant, and those commonly used in the art can be used. In some embodiments of the present invention, examples of lithium salts can be any one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and lithium difluorooxalatoborate. Examples of binders can be one or more of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium hydroxymethylcellulose, styrene-butadiene rubber, and polyacrylic acid.

[0118] In the present invention, the solvent used to disperse the composition containing the solid electrolyte can be selected from one or more of N-methylpyrrolidone, dimethylformamide, dimethylacetamide, butyrate, toluene, xylene, anisole, hexane, heptane, dibromomethane, dichloroethane, ethanol and glycol ether.

[0119] In the present invention, the solid content of the solid electrolyte slurry can be 20% to 85% by mass, preferably 40% to 60% by mass, for example, 20%, 30%, 40%, 50%, 60%, 70%, 75%, 85% by mass, etc. A solid content within the above range is conducive to the spraying and uniform distribution of the solid electrolyte, preventing the process problem of material sticking during electrostatic spraying caused by too high a concentration and preventing the process problem of powder falling during electrostatic spraying caused by too low a concentration, which affects the distribution of the solid electrolyte on the battery electrode.

[0120] Step S2

[0121] The solid electrolyte slurry prepared in step S1 is introduced onto the positive electrode sheet or the negative electrode sheet by electrostatic atomization spraying and dried, thereby obtaining a positive electrode sheet or a negative electrode sheet containing a solid electrolyte layer.

[0122] In the present invention, during the electrostatic atomization spraying in step S2, the spraying pressure can be 0.2-0.8 MPa, preferably 0.3-0.8 MPa, for example, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, etc. When the spraying pressure is within the above range, the material can be evenly sprayed on the surface of the current collector, thereby improving the adhesion rate and increasing the effective adsorption rate of the solid electrolyte, thereby reducing the problems of solid electrolyte agglomeration and material waste during the preparation of battery pole pieces; if the spraying pressure is too low, the solid electrolyte sprayed on the pole piece surface will be unevenly distributed, and if the spraying pressure is too high, it will cause material waste and uneven distribution of the solid electrolyte on the pole piece surface.

[0123] In the electrostatic atomization spraying of the present invention, the electrostatic voltage during spraying can be 45-100kV, preferably 50-90kV, for example, 45kV, 50kV, 55kV, 60kV, 65kV, 70kV, 75kV, 80kV, 85kV, 90kV, 95kV, 100kV, etc. The electrostatic voltage affects the adhesion rate of the solid electrolyte on the electrode. Too low a voltage is not conducive to the adhesion of the solid electrolyte to the electrode, resulting in a weak interface contact. Too high a voltage makes it difficult to control the thickness of the sprayed solid electrolyte layer.

[0124] In addition, the spraying conditions in the electrostatic atomization spraying of the present invention also include the following:

[0125] The electrostatic current may be 10 to 30 μA, for example, 10 μA, 15 μA, 20 μA, 25 μA, 30 μA, etc.;

[0126] The compressed gas pressure can be 2.5~8.5kg / cm 2 , for example, 2.5 kg / cm 2 、3.0kg / cm 2 、3.5kg / cm 2 , 4.0kg / cm 2 , 4.5kg / cm 2 , 5.0kg / cm 2 , 5.5kg / cm 2 、6.0kg / cm 2 , 6.5kg / cm 2 , 7.0kg / cm 2 , 7.5kg / cm 2 、8.0kg / cm 2 ,8.5kg / cm 2 wait;

[0127] The spraying distance can be 10 to 210 mm, preferably 30 to 180 mm, for example, 10 mm, 20 mm, 30 mm, 50 mm, 60 mm, 80 mm, 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, 210 mm, etc.

[0128] The spraying flow rate is 1-35mL / min, for example, it can be 1mL / min, 5mL / min, 10mL / min, 15mL / min, 20mL / min, 25mL / min, 30mL / min, 35mL / min; controlling the spraying flow rate can control the thickness of the solid electrolyte layer. Too high will lead to uneven thickness, and too low will easily cause uneven distribution.

[0129] The spraying angle may be 85° to 90°, for example, 85°, 86°, 88°, 90°, etc.

[0130] In addition, the electrostatic atomization spraying of the present invention is preferably carried out in a dry environment with a moisture content of less than 10 ppm, preferably 5 ppm, and more preferably less than 1 ppm.

[0131] In some preferred embodiments of the present invention, the preparation method of the present invention further comprises the step of heating the positive electrode sheet or the negative electrode sheet before the electrostatic atomization spraying in step S2. The heating temperature may be 50-210°C, preferably 70-160°C, for example, 50°C, 55°C, 60°C, 70°C, 75°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 155°C, 160°C, 170°C, 180°C, 190°C, 200°C, 205°C, 210°C, etc. By heating the electrode sheet, the electrolyte slurry can be evenly distributed on the surface of the electrode sheet, the agglomeration of the solid electrolyte during the mixing process can be reduced, and the cycle stability of the battery can be improved.

[0132] In some embodiments, the positive electrode sheet or the negative electrode sheet is placed on a work plate for operation. Thus, both the heating of the positive electrode sheet or the negative electrode sheet and the drying after spraying can be achieved by the work plate, thereby reducing the process flow and achieving mass production.

[0133] In some specific embodiments, the positive electrode sheet or the negative electrode sheet is placed on a working plate, which is then heated and sprayed under the conditions. The electrolyte slurry is sprayed onto the surface of the sheet to the desired thickness. After standing for a period of time, the static coating equipment is turned off, and the sheet is dried and cooled naturally to obtain a positive electrode sheet or a negative electrode sheet containing a solid electrolyte layer.

[0134] In some embodiments, during the standing period, the temperature of the working plate may be raised to a temperature slightly higher than the heating temperature during spraying, for example, 10 to 30° C. higher. The standing period may be, for example, 20 to 120 minutes.

[0135] After the solid electrolyte slurry is evenly sprayed onto the surface of the positive electrode sheet or the negative electrode sheet by electrostatic atomization spraying, vacuum drying and one or more of hot pressing or isostatic pressing are performed. In some embodiments of the present invention, the above-mentioned drying includes vacuum drying at 50-160°C, preferably 60-150°C, for 5-20 hours, preferably 9-12 hours.

[0136] After drying, hot pressing can be performed. In some embodiments of the present invention, the temperature of hot pressing can be 50-80°C, preferably 60-80°C, the time of hot pressing can be 10-60 minutes, 20-40 minutes, and the pressure of hot pressing can be 0.2-1.0 MPa, preferably 0.3-0.6 MPa.

[0137] After hot pressing, the product is naturally cooled to obtain a positive electrode sheet or a negative electrode sheet having a solid electrolyte layer.

[0138] In some embodiments of the present invention, the thickness of the solid electrolyte layer may be 5 to 55 μm, for example, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, etc. Within this range, the positive and negative electrodes can be effectively separated, and the cycle stability of the solid-state battery can be guaranteed while ensuring the battery energy density. If the thickness of the solid electrolyte layer is too low, it will lead to interface failure during the cycle and short circuit caused by contact between the positive and negative electrodes; if the thickness is too high, the internal resistance of the battery will increase, which is not conducive to the design of high energy density battery cells.

[0139] The wet electrostatic atomization spraying adopted in the present invention utilizes the principle of corona discharge, adjusts the process conditions of the wet electrostatic atomization spraying to achieve uniform introduction of the solid electrolyte layer, and improves process problems such as powder loss and material sticking during the electrostatic spraying process by adjusting the solid content in the slurry. It can increase the interface stability between the solid electrolyte and the active material and improve the electrochemical performance of the solid-state battery.

[0140] <Second Aspect>

[0141] The second aspect of the present invention relates to a composite electrode sheet containing a solid electrolyte layer, which comprises at least one of the composite electrode sheets containing a solid electrolyte layer obtained by the preparation method described in the above <first aspect>.

[0142] The composite electrode sheet containing a solid electrolyte layer of the present invention comprises a positive electrode sheet or a negative electrode sheet and a solid electrolyte layer disposed on the positive electrode sheet or the negative electrode sheet. The thickness of the solid electrolyte layer can be 5-55 μm.

[0143] FIG1 is a schematic structural diagram of a pole piece containing a solid electrolyte layer according to the present invention.

[0144] The pole piece containing the solid electrolyte layer of the present invention has a peel strength of 15.0 to 45.0 N / m, preferably 19.0 to 43.0 N / m, at a peel speed of 60 mm / min and a peel angle of 180°. For example, the peel strength may be 15.0 N / m, 17.0 N / m, 19.0 N / m, 20.0 N / m, 22.0 N / m, 25.0 N / m, 28.0 N / m, 30.0 N / m, 32.0 N / m, 35.0 N / m, 38.0 N / m, 40.0 N / m, 42.0 N / m, 43.0 N / m, 45.0 N / m, etc. The specific test method for the peel strength can be found in the method described in the examples below.

[0145] The peel strength in the present invention refers to the peel strength between the current collector and the layer on the current collector.

[0146] <Third Aspect>

[0147] The third aspect of the present invention relates to a method for preparing a solid-state battery, which includes the steps of preparing a positive electrode sheet containing a solid electrolyte layer and / or a negative electrode sheet containing a solid electrolyte layer by the preparation method described in the above <first aspect>.

[0148] Subsequent steps in the preparation of solid-state batteries can be performed using conventional operations in the art. For example, the positive and / or negative electrode sheets containing solid electrolytes prepared by the preparation method described above can be processed by one or more of roll pressing, cold isostatic pressing, and hot isostatic pressing, and the resulting battery sheets can then be assembled into a solid-state battery.

[0149] Example

[0150] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be obtained commercially.

[0151] Example 1

[0152] This embodiment provides a method for preparing a composite electrode sheet containing an oxide solid electrolyte by a wet process. The specific preparation process is as follows:

[0153] (1) Prepare slurry containing solid electrolyte: grind Li7La3Zr2O 12 The solid electrolyte was dispersed in DMF solvent, stirred thoroughly and added with dispersant (purchased from Aladdin S-17650, the same below). The resulting solution was sand-milled to obtain Li7La3Zr2O 12 The mass ratio of the solid electrolyte to polypentylene succinate was 20:1, and polypentylene succinate was added and stirred thoroughly to prepare a slurry with a solid content of 40%;

[0154] (2) Heat the working plate to 70°C and spray the slurry by electrostatic atomization spraying in a dry environment with a moisture content of less than 1 ppm. Set the electrostatic spraying voltage to 90 kV, the electrostatic current to 30 μA, and the compressed gas pressure to 5.5 kg / cm 2 The spraying pressure was 0.5 MPa, the spraying distance was 60 mm, the spraying flow rate was 15 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the positive electrode sheet prepared in Example 6 described below to obtain a solid electrolyte layer with a thickness of 30 μm.

[0155] (3) The obtained composite positive electrode sheet was vacuum dried at 80°C for 12 hours, and then hot-pressed at 65°C for 30 minutes at a pressure of 0.5 MPa. After natural cooling, a positive electrode sheet containing a solid electrolyte was obtained.

[0156] Example 2

[0157] This embodiment provides a method for preparing a composite electrode containing a composite solid electrolyte by a wet process. The specific preparation process is as follows:

[0158] (1) Prepare slurry containing composite solid electrolyte: Li 6.75 La3Zr 1.75 Nb 0.25 O 12 Solid electrolyte, polyvinylidene fluoride-hexafluoropropylene, polypentanediol succinate, and lithium bis(trifluoromethanesulfonyl)imide were dissolved in DMF solvent in a mass ratio of 5:3:1:2, and a dispersant was added and stirred for 12 hours to obtain a slurry with a solid content of 60% by mass;

[0159] (2) Heat the working plate to 60°C and spray the slurry by electrostatic atomization spraying in a dry environment with a moisture content of less than 1 ppm. Set the electrostatic spraying voltage to 90 kV, the electrostatic current to 30 μA, and the compressed gas pressure to 5.5 kg / cm 2 The spraying pressure was 0.5 MPa, the spraying distance was 80 mm, the spraying flow rate was 10 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the positive electrode sheet prepared in Example 7 described below to obtain a solid electrolyte layer with a thickness of 30 μm.

[0160] (3) The obtained composite positive electrode sheet was vacuum dried at 60°C for 12 hours, and then hot-pressed at 60°C for 30 minutes at a pressure of 0.5 MPa. After natural cooling, a positive electrode sheet containing a composite solid electrolyte was obtained.

[0161] Example 3

[0162] This embodiment provides a method for preparing a composite electrode containing a solid electrolyte by a wet process. The specific preparation process is as follows:

[0163] (1) preparing a slurry containing a solid electrolyte: dispersing the ground lithium titanium aluminum phosphate solid electrolyte in a DMF solvent, stirring it thoroughly, and adding a dispersant; sand-milling the resulting solution; and adding polypentylene succinate at a mass ratio of lithium titanium aluminum phosphate solid electrolyte to polypentylene succinate of 20:1, stirring it thoroughly, to prepare a slurry with a solid content of 70%;

[0164] (2) Heat the working plate to 65°C and spray the slurry by electrostatic atomization in a dry environment with a moisture content of less than 1 ppm. Set the electrostatic spraying voltage to 80 kV, the electrostatic current to 25 μA, and the compressed gas pressure to 5.0 kg / cm 2 The spraying pressure was 0.6 MPa, the spraying distance was 50 mm, the spraying flow rate was 25 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the positive electrode sheet prepared in Example 8 described below to obtain a solid electrolyte layer with a thickness of 35 μm.

[0165] (3) The obtained composite positive electrode sheet was vacuum dried at 80°C for 12 hours, and then hot-pressed at 60°C for 30 minutes at a pressure of 0.4 MPa. After natural cooling, a positive electrode sheet containing a solid electrolyte was obtained.

[0166] Example 4

[0167] This embodiment provides a method for preparing a composite electrode containing a solid electrolyte by a wet process. The specific preparation process is as follows:

[0168] (1) preparing a slurry containing a solid electrolyte: uniformly dispersing polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate, polypentanediol succinate, and lithium bis(trifluoromethanesulfonyl)imide in a DMF solvent at a mass ratio of 4:2:1:3 and stirring thoroughly to obtain a slurry with a solid content of 40%;

[0169] (2) Heat the working plate to 60°C and apply the slurry by electrostatic atomization spraying in a dry environment with a moisture content of less than 1 ppm. Set the electrostatic spraying voltage to 70 kV, the electrostatic current to 20 μA, and the compressed gas pressure to 4.0 kg / cm 2 The spraying pressure was 0.3 MPa, the spraying distance was 30 mm, the spraying flow rate was 20 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the positive electrode sheet prepared in Example 9 described below to obtain a solid electrolyte layer with a thickness of 40 μm.

[0170] (3) The obtained composite positive electrode sheet was vacuum dried at 60° C. for 12 hours and then naturally cooled to obtain a positive electrode sheet containing a polymer solid electrolyte.

[0171] Example 5

[0172] This embodiment provides a method for preparing a composite electrode containing a solid electrolyte by a wet process. The specific preparation process is as follows:

[0173] (1) preparing a slurry containing a solid electrolyte: uniformly dispersing polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate, and lithium bis(trifluoromethanesulfonyl)imide in a DMF solvent at a mass ratio of 5:2:3 and stirring thoroughly to obtain a slurry with a solid content of 50%;

[0174] (2) Heat the working plate to 60°C and apply the slurry by electrostatic atomization spraying in a dry environment with a moisture content of less than 1 ppm. Set the electrostatic spraying voltage to 70 kV, the electrostatic current to 30 μA, and the compressed gas pressure to 4.0 kg / cm 2 The spraying pressure was 0.3 MPa, the spraying distance was 30 mm, the spraying flow rate was 15 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the negative electrode sheet prepared in Example 10 described below to obtain a solid electrolyte layer with a thickness of 35 μm.

[0175] (3) The obtained composite negative electrode sheet was vacuum dried at 60° C. for 12 hours and then naturally cooled to obtain a negative electrode sheet containing a polymer solid electrolyte.

[0176] Example 6

[0177] This embodiment provides a method for preparing a positive electrode sheet by wet electrostatic spraying. The specific preparation process is as follows:

[0178] 1) Lithium iron phosphate cathode material, polyvinylidene fluoride, and carbon nanotubes were homogenized in batches in an appropriate amount of NMP according to a mass ratio of 93:3:4 to prepare a slurry with a solid content of 65% by mass;

[0179] 2) Place the positive electrode current collector aluminum foil on the working plate, heat it to 70°C, set the electrostatic spraying voltage to 80KV, the electrostatic current to 25μA, and the compressed gas pressure to 6.5kg / cm 2 , the spraying pressure is 0.7 MPa, the spraying distance is 60 mm, and the spraying angle is 87°, and the positive electrode active material slurry is sprayed onto the surface of the current collector to obtain a positive electrode active material layer with a thickness of 80 μm;

[0180] 3) The working plate was heated to 90° C. and allowed to stand for 90 minutes. The electrostatic device was turned off. The sprayed positive electrode sheet was vacuum-dried at 100° C. for 720 minutes after roller pressing and then naturally cooled to obtain a positive electrode sheet.

[0181] Example 7

[0182] This embodiment provides a method for preparing a positive electrode sheet by wet electrostatic spraying. The specific preparation process is as follows:

[0183] (1) Lithium cobalt oxide positive electrode active material, polyvinylidene fluoride, and conductive carbon black are homogenized in an appropriate amount of NMP at a mass ratio of 95:3:2 to prepare a slurry with a solid content of 60% by mass;

[0184] (2) Place the positive electrode current collector aluminum foil on the working plate, heat it to 80°C, set the electrostatic spraying voltage to 70KV, the electrostatic current to 15μA, and the compressed gas pressure to 6.5kg / cm 2 , spraying pressure is 0.6MPa, spraying distance is 20mm, spraying flow rate is 25mL / min, spraying angle is 87°, spraying the positive electrode active material slurry onto the surface of the current collector to obtain a positive electrode active material layer with a thickness of 80μm;

[0185] (3) The working plate was heated to 100°C and allowed to stand for 90 minutes. The electrostatic equipment was turned off. The positive electrode sheet obtained by spraying was vacuum-dried at 120°C for 720 minutes after roller pressing and then naturally cooled to obtain the positive electrode sheet.

[0186] Example 8

[0187] This embodiment provides a method for preparing a positive electrode sheet by wet electrostatic spraying. The specific preparation process is as follows:

[0188] (1) NCM811 ternary positive electrode active material, polyvinylidene fluoride, and conductive carbon black were homogenized in batches in an appropriate amount of NMP according to a mass ratio of 94:3:3 to prepare a slurry with a solid content of 75% by mass;

[0189] (2) Place the positive electrode current collector aluminum foil on the working plate, heat it to 80°C, set the electrostatic spraying voltage to 80KV, the electrostatic current to 25μA, and the compressed gas pressure to 5.5kg / cm 2 , spraying pressure is 0.5MPa, spraying distance is 40mm, spraying flow rate is 12mL / min, spraying angle is 87°, spraying the positive electrode active material slurry onto the surface of the current collector to obtain a positive electrode active material layer with a thickness of 70μm;

[0190] (3) The working plate was heated to 100°C and allowed to stand for 90 minutes. The electrostatic equipment was turned off. The positive electrode sheet obtained by spraying was vacuum-dried at 120°C for 720 minutes after roller pressing and then naturally cooled to obtain the positive electrode sheet.

[0191] Example 9

[0192] This embodiment provides a method for preparing a positive electrode sheet by wet electrostatic spraying. The specific preparation process is as follows:

[0193] (1) Lithium manganate positive electrode active material, polyvinylidene fluoride, and carbon nanotubes were homogenized in batches in an appropriate amount of NMP according to a mass ratio of 96:2:2 to prepare a slurry with a solid content of 75% by mass;

[0194] (2) Place the positive electrode current collector aluminum foil on the working plate, heat it to 75°C, set the electrostatic spraying voltage to 60KV, the electrostatic current to 20μA, and the compressed gas pressure to 5.0kg / cm 2 , spraying pressure is 0.4MPa, spraying distance is 25mm, spraying flow rate is 18mL / min, spraying angle is 87°, spraying the positive electrode active material slurry onto the surface of the current collector to obtain a positive electrode active material layer with a thickness of 80μm;

[0195] (3) The working plate was heated to 100°C and allowed to stand for 90 minutes. The electrostatic equipment was turned off. The positive electrode sheet obtained by spraying was vacuum-dried at 120°C for 720 minutes after roller pressing and then naturally cooled to obtain the positive electrode sheet.

[0196] Example 10

[0197] This embodiment provides a method for preparing a negative electrode sheet by wet electrostatic spraying. The specific preparation process is as follows:

[0198] (1) slurrying the graphite negative electrode active material, styrene-butadiene rubber, sodium hydroxymethyl cellulose and conductive carbon black in a mass ratio of 94:2:1:3 in an appropriate amount of deionized water to prepare a slurry with a solid content of 60% by mass;

[0199] (2) Place the negative electrode current collector copper foil on the working plate, heat it to 80°C, set the electrostatic spraying voltage to 65KV, the electrostatic current to 30μA, and the compressed gas pressure to 5.0kg / cm 2 , spraying pressure is 0.6MPa, spraying distance is 30mm, spraying flow rate is 23mL / min, spraying angle is 87°, spraying the negative electrode active material slurry onto the surface of the current collector to obtain a negative electrode active material layer with a thickness of 90μm;

[0200] (3) The working plate was heated to 100°C and allowed to stand for 90 minutes. The electrostatic equipment was turned off. The negative electrode sheet obtained by spraying was vacuum-dried at 120°C for 720 minutes after roller pressing and then naturally cooled to obtain the negative electrode sheet.

[0201] Comparative Example 1

[0202] This comparative example provides a method for preparing a composite electrode by a wet process. The difference from Example 1 is that the applied voltage is different. The specific preparation process is as follows:

[0203] (1) Prepare slurry containing solid electrolyte: grind Li7La3Zr2O 12 Solid electrolyte was dispersed in DMF solvent, stirred thoroughly and added with dispersant, and the obtained solution was sand-milled to obtain Li7La3Zr2O 12The mass ratio of the solid electrolyte to polypentylene succinate was 20:1, and polypentylene succinate was added and stirred thoroughly to prepare a slurry with a solid content of 40%;

[0204] (2) Heat the working plate to 70°C and spray the mixture in a dry environment with a moisture content of less than 1 ppm using electrostatic atomization spraying. Set the electrostatic spraying voltage to 30 kV, the electrostatic current to 30 μA, and the compressed gas pressure to 5.5 kg / cm 2 The spraying pressure was 0.5 MPa, the spraying distance was 60 mm, the spraying flow rate was 15 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the positive electrode sheet prepared in Example 6 to obtain a solid electrolyte layer with a thickness of 30 μm.

[0205] (3) The obtained composite positive electrode sheet was vacuum dried at 80°C for 12 hours, and then hot-pressed at 65°C for 30 minutes at a pressure of 0.5 MPa. After natural cooling, a positive electrode sheet containing a solid electrolyte was obtained.

[0206] Comparative Example 2

[0207] This comparative example provides a method for preparing a composite electrode by a wet process. The difference from Example 1 is that the spraying pressure applied is different. The specific preparation process is as follows:

[0208] (1) Prepare slurry containing solid electrolyte: grind Li7La3Zr2O 12 Solid electrolyte was dispersed in DMF solvent, stirred thoroughly and added with dispersant, and the obtained solution was sand-milled to obtain Li7La3Zr2O 12 The mass ratio of the solid electrolyte to polypentylene succinate was 20:1, and polypentylene succinate was added and stirred thoroughly to prepare a slurry with a solid content of 40%;

[0209] (2) Heat the working plate to 70°C and spray the mixture in a dry environment with a moisture content of less than 1 ppm using electrostatic atomization spraying. Set the electrostatic spraying voltage to 90 kV, the electrostatic current to 30 μA, and the compressed gas pressure to 5.5 kg / cm 2 The spraying pressure was 0.1 MPa, the spraying distance was 60 mm, the spraying flow rate was 15 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the positive electrode sheet prepared in Example 6 to obtain a solid electrolyte layer with a thickness of 30 μm.

[0210] (3) The obtained composite positive electrode sheet was vacuum dried at 80°C for 12 hours, and then hot-pressed at 65°C for 30 minutes at a pressure of 0.5 MPa. After natural cooling, a positive electrode sheet containing a solid electrolyte was obtained.

[0211] Comparative Example 3

[0212] This comparative example provides a method for preparing a composite electrode by a wet process. The difference from Example 1 is that the spray flow rate applied is different. The specific preparation process is as follows:

[0213] (1) Prepare slurry containing solid electrolyte: grind Li7La3Zr2O 12 Solid electrolyte was dispersed in DMF solvent, stirred thoroughly and added with dispersant, and the obtained solution was sand-milled to obtain Li7La3Zr2O 12 The mass ratio of the solid electrolyte to polypentylene succinate was 20:1, and polypentylene succinate was added and stirred thoroughly to prepare a slurry with a solid content of 40%;

[0214] (2) Heat the working plate to 70°C and spray the mixture in a dry environment with a moisture content of less than 1 ppm using electrostatic atomization spraying. Set the electrostatic spraying voltage to 90 kV, the electrostatic current to 30 μA, and the compressed gas pressure to 5.5 kg / cm 2 The spraying pressure was 0.5 MPa, the spraying distance was 60 mm, the spraying flow rate was 0.5 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the positive electrode sheet prepared in Example 6 to obtain a solid electrolyte layer with a thickness of 30 μm.

[0215] (3) The obtained composite positive electrode sheet was vacuum dried at 80°C for 12 hours, and then hot-pressed at 65°C for 30 minutes at a pressure of 0.5 MPa. After natural cooling, a positive electrode sheet containing a solid electrolyte was obtained.

[0216] Comparative Example 4

[0217] This comparative example provides a method for preparing a composite electrode by a wet process. The difference from Example 1 is that the working plate is not heated. The specific preparation process is as follows:

[0218] (1) Prepare slurry containing solid electrolyte: grind Li7La3Zr2O 12 Solid electrolyte was dispersed in DMF solvent, stirred thoroughly and added with dispersant, and the obtained solution was sand-milled to obtain Li7La3Zr2O 12 The mass ratio of the solid electrolyte to polypentylene succinate was 20:1, and polypentylene succinate was added and stirred thoroughly to prepare a slurry with a solid content of 40%;

[0219] (2) The slurry was sprayed by electrostatic atomization in a dry environment with a moisture content of less than 1 ppm. The voltage of the electrostatic spray was set to 90 kV, the electrostatic current to 30 μA, and the compressed gas pressure to 5.5 kg / cm 2The spraying pressure was 0.5 MPa, the spraying distance was 60 mm, the spraying flow rate was 15 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the positive electrode sheet prepared in Example 6 to obtain a solid electrolyte layer with a thickness of 30 μm.

[0220] (3) The obtained composite positive electrode sheet was vacuum dried at 80°C for 12 hours, and then hot-pressed at 65°C for 30 minutes at a pressure of 0.5 MPa. After natural cooling, a positive electrode sheet containing a solid electrolyte was obtained.

[0221] Comparative Example 5

[0222] This comparative example provides a method for preparing a positive electrode sheet by wet electrostatic spraying. The difference from Example 6 is that the slurry has a lower solid content. The specific preparation process is as follows:

[0223] 1) Lithium iron phosphate cathode material, polyvinylidene fluoride, and carbon nanotubes were homogenized in batches in an appropriate amount of NMP according to a mass ratio of 93:3:4 to prepare a slurry with a solid content of 6% by mass;

[0224] 2) Place the positive electrode current collector aluminum foil on the working plate, heat it to 70°C, set the electrostatic spraying voltage to 80KV, the electrostatic current to 25μA, and the compressed gas pressure to 6.5kg / cm 2 , the spraying pressure is 0.7 MPa, the spraying distance is 60 mm, and the spraying angle is 87°, and the positive electrode active material slurry is sprayed onto the surface of the current collector to obtain a positive electrode active material layer with a thickness of 80 μm;

[0225] 3) The working plate was heated to 90° C. and allowed to stand for 90 minutes. The electrostatic device was turned off. The positive electrode sheet obtained by spraying was vacuum-dried at 100° C. for 720 minutes after roller pressing and then naturally cooled to obtain a positive electrode sheet.

[0226] Comparative Example 6

[0227] This comparative example provides a method for preparing a positive electrode sheet by wet electrostatic spraying. The difference from Example 6 is that the slurry has a higher solid content. The specific preparation process is as follows:

[0228] 1) Lithium iron phosphate cathode material, polyvinylidene fluoride, and carbon nanotubes were homogenized in batches in an appropriate amount of NMP according to a mass ratio of 93:3:4 to prepare a slurry with a solid content of 90% by mass;

[0229] 2) Place the positive electrode current collector aluminum foil on the working plate, heat it to 70°C, set the electrostatic spraying voltage to 80KV, the electrostatic current to 25μA, and the compressed gas pressure to 6.5kg / cm 2, the spraying pressure is 0.7 MPa, the spraying distance is 60 mm, and the spraying angle is 87°, and the positive electrode active material slurry is sprayed onto the surface of the current collector to obtain a positive electrode active material layer with a thickness of 80 μm;

[0230] 3) The working plate was heated to 90° C. and allowed to stand for 90 minutes. The electrostatic device was turned off. The sprayed positive electrode sheet was vacuum-dried at 100° C. for 720 minutes after roller pressing and then naturally cooled to obtain a positive electrode sheet.

[0231] Comparative Example 7

[0232] This comparative example provides a method for preparing a composite electrode by a wet process. The difference from Example 1 is that the spraying pressure applied is different. The specific preparation process is as follows:

[0233] (1) Prepare slurry containing solid electrolyte: grind Li7La3Zr2O 12 Solid electrolyte was dispersed in DMF solvent, stirred thoroughly and added with dispersant, and the obtained solution was sand-milled to obtain Li7La3Zr2O 12 The mass ratio of the solid electrolyte to polypentylene succinate was 20:1, and polypentylene succinate was added and stirred thoroughly to prepare a slurry with a solid content of 40%;

[0234] (2) Heat the working plate to 70°C and spray the mixture in a dry environment with a moisture content of less than 1 ppm using electrostatic atomization spraying. Set the electrostatic spraying voltage to 90 kV, the electrostatic current to 30 μA, and the compressed gas pressure to 5.5 kg / cm 2 The spraying pressure was 0.9 MPa, the spraying distance was 60 mm, the spraying flow rate was 15 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the positive electrode sheet prepared in Example 6 to obtain a solid electrolyte layer with a thickness of 30 μm.

[0235] (3) The obtained composite positive electrode sheet was vacuum dried at 80°C for 12 hours, and then hot-pressed at 65°C for 30 minutes at a pressure of 0.5 MPa. After natural cooling, a positive electrode sheet containing a solid electrolyte was obtained.

[0236] Comparative Example 8

[0237] This comparative example provides a method for preparing a composite electrode by a wet process. The difference from Example 1 is that the solid content of the slurry used is different. The specific preparation process is as follows:

[0238] (1) Prepare slurry containing solid electrolyte: grind Li7La3Zr2O 12 Solid electrolyte was dispersed in DMF solvent, stirred thoroughly and added with dispersant, and the obtained solution was sand-milled to obtain Li7La3Zr2O12 The mass ratio of the solid electrolyte to polypentylene succinate was 20:1, and polypentylene succinate was added and stirred thoroughly to prepare a slurry with a solid content of 5%;

[0239] (2) Heat the working plate to 70°C and spray the mixture in a dry environment with a moisture content of less than 1 ppm using electrostatic atomization spraying. Set the electrostatic spraying voltage to 90 kV, the electrostatic current to 30 μA, and the compressed gas pressure to 5.5 kg / cm 2 The spraying pressure was 0.5 MPa, the spraying distance was 60 mm, the spraying flow rate was 15 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the positive electrode sheet prepared in Example 6 to obtain a solid electrolyte layer with a thickness of 30 μm.

[0240] (3) The obtained composite positive electrode sheet was vacuum dried at 80°C for 12 hours, and then hot-pressed at 65°C for 30 minutes at a pressure of 0.5 MPa. After natural cooling, a positive electrode sheet containing a solid electrolyte was obtained.

[0241] Comparative Example 9

[0242] This comparative example provides a method for preparing a composite electrode by a wet process. The difference from Example 1 is that the solid content of the slurry used is different. The specific preparation process is as follows:

[0243] (1) Prepare slurry containing solid electrolyte: grind Li7La3Zr2O 12 Solid electrolyte was dispersed in DMF solvent, stirred thoroughly and added with dispersant, and the obtained solution was sand-milled to obtain Li7La3Zr2O 12 The mass ratio of the solid electrolyte to polypentylene succinate is 20:1, and polypentylene succinate is added and stirred thoroughly to prepare a slurry with a solid content of 90%;

[0244] (2) Heat the working plate to 70°C and spray the mixture in a dry environment with a moisture content of less than 1 ppm using electrostatic atomization spraying. Set the electrostatic spraying voltage to 90 kV, the electrostatic current to 30 μA, and the compressed gas pressure to 5.5 kg / cm 2 The spraying pressure was 0.5 MPa, the spraying distance was 60 mm, the spraying flow rate was 15 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the positive electrode sheet prepared in Example 6 to obtain a solid electrolyte layer with a thickness of 30 μm.

[0245] (3) The obtained composite positive electrode sheet was vacuum dried at 80°C for 12 hours, and then hot-pressed at 65°C for 30 minutes at a pressure of 0.5 MPa. After natural cooling, a positive electrode sheet containing a solid electrolyte was obtained.

[0246] Comparative Example 10

[0247] This comparative example provides a method for preparing a composite electrode by a wet process. The difference from Example 1 is that the applied voltage is different. The specific preparation process is as follows:

[0248] (1) Prepare slurry containing solid electrolyte: grind Li7La3Zr2O 12 Solid electrolyte is dispersed in DMF solvent, stirred thoroughly and added with dispersant, and the obtained solution is sand-milled to obtain Li7La3Zr2O 12 The mass ratio of the solid electrolyte to polypentylene succinate was 20:1, and polypentylene succinate was added and stirred thoroughly to prepare a slurry with a solid content of 40%;

[0249] (2) Heat the working plate to 70°C and spray the mixture in a dry environment with a moisture content of less than 1 ppm using electrostatic atomization spraying. Set the electrostatic spraying voltage to 110 kV, the electrostatic current to 30 μA, and the compressed gas pressure to 5.5 kg / cm 2 The spraying pressure was 0.5 MPa, the spraying distance was 60 mm, the spraying flow rate was 15 mL / min, and the spraying angle was 87°. The slurry containing the solid electrolyte was introduced onto the positive electrode sheet prepared in Example 6 to obtain a solid electrolyte layer with a thickness of 30 μm.

[0250] (3) The obtained composite positive electrode sheet was vacuum dried at 80°C for 12 hours, and then hot-pressed at 65°C for 30 minutes at a pressure of 0.5 MPa. After natural cooling, a positive electrode sheet containing a solid electrolyte was obtained.

[0251] Performance testing:

[0252] Interfacial impedance testing: The prepared composite electrode and lithium metal sheet were assembled into a button cell. The AC impedance was measured using an electrochemical workstation with a voltage amplitude of 5 mV and a frequency range of 0.1 Hz to 1 MHz. The results are shown in Table 1.

[0253] Cycling stability test: Positive and negative electrode sheets, or cut pieces of positive or negative electrode sheets containing solid electrolytes, were assembled into button cells. Each example was charged and discharged at a rate of 0.2C at 30°C for 100 cycles. The battery capacity before and after each cycle was recorded. The initial charge and discharge capacity was also recorded, and the initial coulombic efficiency was calculated. The results are shown in Table 1.

[0254] Table 1

[0255] By analyzing the test results of Examples 1-5 and Comparative Examples 1-4 and Comparative Examples 7-10, the wet electrostatic atomization spraying method is used to prepare composite electrodes containing solid electrolytes, which can effectively reduce the interface impedance. Among them, the impedance of Example 2 is only 23.79Ω, which increases the interface contact between the solid electrolyte and the electrode, and solves the key problem of large impedance caused by solid-solid interface contact. By comparing Examples 6-10 with Comparative Examples 5 and 6, the battery electrodes prepared within the preferred electrostatic atomization spraying process parameter range have a high first coulomb efficiency and good cycle stability. The cycle capacity retention rate of the composite electrode of the embodiment during 100 cycles is better than that of the comparative example, indicating that the preparation of battery electrodes by electrostatic atomization spraying can achieve the construction of a continuous and dense solid electrolyte layer interface on the electrode, enhance the flexible interface contact between the electrode and the solid electrolyte layer, and effectively improve the cycle stability of the battery.

[0256] Peel strength testing was conducted in a peel tester at 25°C (room temperature) and a -40°C (dew point) humidity. One side of the prepared battery electrode current collector was adhered to a work surface using double-sided adhesive tape. Test tape was then used to connect the active material surface to the peel tester. The test was performed at a speed of 60 mm / min and a peel angle of 180°. The peel force was recorded. The results are shown in Table 2.

[0257] Table 2

[0258] By analyzing the peel strength test results of Examples 1-5 and Comparative Examples 1-4 and 7-10, it can be seen that the peel strength of the composite electrode sheets containing solid electrolytes prepared using electrostatic atomization spraying within the preferred process parameter range is significantly higher than that of the comparative examples. The peel strength in Example 2 is 39.43 N / m, indicating that the mechanical properties of the electrode sheets have been improved. By comparing Examples 6-10 with Comparative Examples 4 and 5, the adhesion between the active material and the current collector is stronger, and the close contact between the interfaces further reduces the interfacial impedance, enhancing the electrochemical performance of the solid-state battery.

[0259] FIG2 is the first charge and discharge curve of the composite electrode prepared in Example 2 of the present invention, and its first charge and discharge efficiency is as high as 96.41%.

[0260] FIG3 is a SEM representation of a composite electrode containing a solid electrolyte prepared by wet electrostatic atomization spraying in Example 2 of the present invention. The solid electrolyte is evenly dispersed on the surface of the electrode without obvious agglomeration.

[0261] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

[0262] Industrial applicability

[0263] The present invention uses wet electrostatic spraying to introduce solid electrolytes into battery pole pieces, which can achieve the construction of a continuous and dense solid electrolyte layer interface on the pole piece, enhance the interfacial contact between the pole piece and the solid electrolyte layer, thereby reducing the interfacial impedance and improving the electrochemical performance of the solid-state battery. The solid electrolyte introduction method of the present invention can improve the process problems such as active material agglomeration, powder loss, and material sticking that exist in the electrostatic spraying process, and can increase the interfacial stability between the solid electrolyte and the active material, thereby improving the electrochemical performance of the solid-state battery.

Claims

1. A method for preparing a composite electrode sheet containing a solid electrolyte layer, characterized in that: It includes the following steps: Step S1: preparing a solid electrolyte slurry containing a solid electrolyte composition, and Step S2: introducing the solid electrolyte slurry onto the positive electrode sheet or the negative electrode sheet by electrostatic atomization spraying and drying, thereby obtaining a positive electrode sheet or a negative electrode sheet containing a solid electrolyte layer. The spraying pressure during the electrostatic atomization spraying is 0.2-0.8Mpa.

2. The preparation method according to claim 1 further comprises a step of heating the positive electrode sheet or the negative electrode sheet before the electrostatic atomization spraying in step S2, wherein the heating temperature is 50-210°C, preferably 70-160°C.

3. The preparation method according to claim 1 or 2, wherein the solid content of the solid electrolyte slurry is 20% to 85% by mass.

4. The preparation method according to any one of claims 1 to 3, wherein in the electrostatic atomization spraying, the electrostatic voltage is 45-100 kV, the electrostatic current is 10 μA to 30 μA, and the compressed gas pressure is 2.5 to 8.5 kg / cm 2 , the spraying distance is 10-210mm, the spraying angle is 85-90°, and the spraying flow rate is 1-35mL / min.

5. The preparation method according to any one of claims 1 to 4, wherein the drying temperature is 50-160°C and the drying time is 5-20 hours.

6. The preparation method according to any one of claims 1 to 5, wherein the solid electrolyte is selected from one or more of an inorganic solid electrolyte and an organic polymer solid electrolyte; Preferably, the inorganic solid electrolyte is selected from one or more of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte.

7. The preparation method according to any one of claims 1 to 6, wherein the oxide solid electrolyte is selected from one or more of a perovskite oxide solid electrolyte, a garnet oxide solid electrolyte, and a NASICON oxide solid electrolyte; The sulfide solid electrolyte is selected from one or more of lithium germanium phosphosulfur, lithium phosphosulfuryl chloride, lithium silicon phosphosulfuryl chloride, lithium phosphosulfuryl bromine, lithium phosphosulfuryl iodide, lithium thiophosphate, and glassy sulfide; The halide solid electrolyte is selected from Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1), Li2XCl4 (X is selected from Cd and / or Mg), Li2X′I4 (X′ is selected from Cd and / or Zn), LiMCl5X″ (M is selected from one or more of La, Ta, Nb, and X″ is selected from O, Cl, F, or OH), Li 3-y Zr y M’ 1-y Cl6 (M’ is selected from one or more of Y, Er, Yb, Ho, Lu, 0 < y < 1); The lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide and lithium difluorooxalatoborate; The organic polymer solid electrolyte is selected from one or more of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, polypentylene succinate, polyvinyl chloride, polyvinyl carbonate, polyvinyl pyrrolidone, polyimide, polyacrylate, and polyurethane; Preferably, the perovskite-type oxide solid electrolyte is selected from lithium lanthanum titanium oxide; The garnet-type oxide solid electrolyte is selected from one or more of lithium lanthanum zirconium oxide, niobium-doped lithium lanthanum zirconium oxide, tantalum-doped lithium lanthanum zirconium oxide, and niobium-tantalum dual-doped lithium lanthanum zirconium oxide; The NASICON type oxide solid electrolyte is selected from one or more of lithium aluminum titanium phosphate, lithium yttrium titanium phosphate, and lithium aluminum germanium phosphate.

8. The preparation method according to any one of claims 1 to 7, wherein the preparation method further comprises the following steps before step S2: Step S0: spraying the positive electrode material composition or the negative electrode material composition onto the surface of the positive electrode collector or the negative electrode collector by dry electrostatic spraying, or spraying the positive electrode slurry or the negative electrode slurry onto the surface of the positive electrode collector or the negative electrode collector by wet electrostatic spraying, and then drying and rolling to obtain the positive electrode sheet or the negative electrode sheet.

9. The preparation method according to claim 8, wherein in the dry electrostatic spraying, the electrostatic voltage is 50-90 kV, the electrostatic current is 15-25 μA, and the compressed gas pressure is 2.5-7.5 kg / cm 2 , the spraying pressure is 0.2-0.8MPa, the spraying distance is 5-200mm, and the spraying angle is 80-90°.

10. The preparation method according to claim 8, wherein in the wet electrostatic spraying, the electrostatic voltage is 45-100 kV, the electrostatic current is 10 μA-30 μA, the compressed gas pressure is 2.5-8.5 kg / cm2, the spraying pressure is 0.2-0.8 MPa, the spraying distance is 10-210 mm, and the spraying angle is 85-90°; the temperature of the positive electrode collector or the negative electrode collector is 60-200°C.

11. The preparation method according to claim 8, wherein the positive electrode slurry or the negative electrode slurry is prepared by slurrying the positive electrode active material composition or the negative electrode active material composition in a solvent; the solid content of the positive electrode slurry or the negative electrode slurry is 30-80% by mass, preferably 40-60% by mass. 12 . The preparation method according to claim 8 , wherein the positive electrode active material composition or the negative electrode active material composition comprises a positive electrode active material or a negative electrode active material, a conductive agent, and a binder.

13. The preparation method according to claim 12, wherein the positive electrode active material is selected from one or more of nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate, lithium cobaltate, lithium manganate, and lithium vanadium phosphate; and the negative electrode active material is selected from one or more of graphite, graphene, carbon nanotubes, silicon-based alloys, silicon-oxygen negative electrodes, silicon-carbon negative electrodes, lithium metal, lithium alloy negative electrodes, lithium titanium oxides, transition metal oxides, and transition metal sulfides.

14. A composite electrode having a solid electrolyte layer, characterized in that: The composite pole piece containing a solid electrolyte layer comprises at least one of the composite pole pieces containing a solid electrolyte layer prepared by the preparation method according to any one of claims 1 to 13. 15 . The composite electrode sheet containing a solid electrolyte layer according to claim 14 , wherein the composite electrode sheet containing a solid electrolyte layer comprises a positive electrode sheet or a negative electrode sheet and a solid electrolyte layer arranged on the positive electrode sheet or the negative electrode sheet. 16 . The composite pole piece containing a solid electrolyte layer according to claim 15 , wherein the thickness of the solid electrolyte layer is 5-55 μm.

17. A method for preparing a solid-state battery, comprising the step of preparing a positive electrode sheet containing a solid electrolyte layer and / or a negative electrode sheet containing a solid electrolyte layer by the preparation method according to any one of claims 1 to 13.

18. A solid-state battery, comprising at least one of the solid-state batteries prepared according to the preparation method according to claim 17.

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