All-solid-state battery and method for manufacturing the same, and electric device

Abstract

The application discloses a kind of all-solid-state battery its preparation method, and electric device, including: with high-voltage positive active material positive pole piece, with lithium metal negative active material negative pole piece and solid electrolyte film, solid electrolyte film includes the first solid electrolyte layer in contact with negative pole piece, interface modification layer and the second solid electrolyte layer in contact with positive pole piece, the thickness of first solid electrolyte layer is greater than or equal to the thickness of second solid electrolyte layer;Interface modification layer is the interface buffer layer of electronic insulation and lithium ion conduction, and the thermal expansion coefficient is between the thermal expansion coefficient of first solid electrolyte layer and second solid electrolyte layer.The interface compatibility problem is solved by the layered structure of solid electrolyte film disclosed in the application, so as to improve battery safety and cycle life.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an all-solid-state battery with a layered design to achieve functional synergy of a solid electrolyte membrane, a method for preparing the same, and an electrical device comprising the all-solid-state battery. Background Technology

[0002] As the core of next-generation high-energy-density and high-safety energy storage technology, the development of all-solid-state batteries currently faces a major bottleneck: the interfacial stability between the solid electrolyte and the highly active electrode. On the negative electrode side, the extremely high reducibility of lithium metal and the risk of lithium dendrite penetration due to cycling volume changes easily lead to electrolyte reduction decomposition and lithium dendrite penetration. On the positive electrode side, the strong oxidizing properties of high-voltage positive electrode materials such as high-nickel lead to electrolyte interface oxidation failure and a surge in impedance. Existing solutions using a single-component electrolyte have limited intrinsic electrochemical windows, making it difficult to simultaneously meet the contradictory requirements of resistance to reduction at the negative electrode and resistance to oxidation at the positive electrode, resulting in a trade-off between battery performance and safety. Attempts have been made to use bilayer electrolyte membranes, but the problems of high interlayer interfacial impedance and easy peeling during long-term cycling have not been effectively solved. Therefore, how to obtain or prepare an all-solid-state battery that can effectively accommodate high-voltage positive electrodes and lithium metal negative electrodes, has low interfacial impedance, and is stable during long-term cycling has become a key technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0003] To address the aforementioned issues, this application discloses an all-solid-state battery, its fabrication method, and an electrical device thereof. The all-solid-state battery includes a solid electrolyte membrane with a layered design that achieves functional synergy, effectively resolving interface compatibility issues and thus significantly improving battery safety and cycle life.

[0004] This application provides an all-solid-state battery, comprising: a positive electrode sheet comprising a high-voltage positive active material; a negative electrode sheet comprising a lithium metal negative active material; and a solid electrolyte membrane comprising a first solid electrolyte layer in contact with the negative electrode sheet, a second solid electrolyte layer in contact with the positive electrode sheet, and an interface modification layer located between the first and second solid electrolyte layers; wherein the first solid electrolyte layer comprises a first solid electrolyte material including Li7La3Zr2O. 12 The second solid electrolyte layer comprises one or more of the following: (LLZO), Li3YCl6, Li3InCl6, Li3N, Li2O, and LiTaO3; the second solid electrolyte material includes Li6PS5Cl(LPSC) and Na3Zr2Si2PO4. 12 (NZSP), Li 1+x Al x Ti 2-x(PO4)3, where 0 < x < 1 (LATP) and one or more of LiF; the thickness of the first solid electrolyte layer is greater than or equal to the thickness of the second solid electrolyte layer; the interface modification layer is an interface buffer layer that is electronically insulating and lithium-ion conductive, and the thermal expansion coefficient of the interface modification layer is greater than the thermal expansion coefficient of the first solid electrolyte layer and less than the thermal expansion coefficient of the second solid electrolyte layer.

[0005] According to some embodiments of the present application, the high-voltage cathode active material includes one or more of lithium-rich manganese-based materials, spinel nickel manganese lithium oxide, or high-nickel ternary materials.

[0006] According to some embodiments of the present application, the first solid electrolyte material is LLZO, and the second solid electrolyte material is LPSC.

[0007] According to some embodiments of the present application, the interface modification layer includes one or more of metal oxygen salts, polymers, metal oxides, and metal alloys.

[0008] According to some embodiments of the present application, the interface modification layer includes lithium phosphate.

[0009] According to some embodiments of the present application, the thickness of the first solid electrolyte layer is 50 μm - 100 μm, the thickness of the second solid electrolyte layer is 20 μm - 50 μm, and the thickness of the interface modification layer is 1 μm - 10 μm.

[0010] A second aspect of the present application provides a method for manufacturing a all-solid-state battery, which includes the step of manufacturing the solid electrolyte membrane, and the step includes: S1. Mixing a first solid electrolyte material with a first binder and forming a film to obtain the first solid electrolyte layer; S2. Mixing a second solid electrolyte material with a second binder and a conductive agent and forming a film to obtain the second solid electrolyte layer; S3. Forming the interface modification layer on one side of the first solid electrolyte layer or one side of the second solid electrolyte layer; S4. Stacking and laminating the first solid electrolyte layer, the interface modification layer, and the second solid electrolyte layer to form a film, thereby obtaining the solid electrolyte membrane; wherein, the interface modification layer is located between the first solid electrolyte layer and the second solid electrolyte layer.

[0011] According to some embodiments of the present application, the film formation in S1 and S2 is achieved based on wet coating or dry pressing.

[0012] According to some embodiments of the present application, the formation of the interface modification layer in S3 is achieved by magnetron sputtering, pulsed laser deposition, or vacuum evaporation.

[0013] A third aspect of this application provides an electrical device comprising the all-solid-state battery as described above.

[0014] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0015] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the drawings are used to denote similar components, wherein:

[0016] Figure 1 These are exemplary structural diagrams of solid electrolyte membranes according to some embodiments of this application;

[0017] Figure 2 This is an exemplary flowchart of a method for preparing a solid electrolyte membrane according to some embodiments of this application. Detailed Implementation

[0018] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The terms “comprising” or “including” and similar terms used herein mean that an element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. The terms “and / or” or “and / or” as used herein include any and all combinations of one or more of the associated listed items.

[0020] The following describes some preferred embodiments of this application. It should be noted that the following description is for illustrative purposes only and is not intended to limit the scope of protection of this application. The steps involved in this application may be performed precisely in sequence, or various steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more steps may be removed from these processes.

[0021] This application discloses an all-solid-state battery, comprising a positive electrode with a high-voltage positive electrode active material, a negative electrode with a lithium metal negative electrode active material, and a solid electrolyte membrane. The solid electrolyte membrane is a multilayer membrane, with the solid electrolyte layers on opposite sides employing an anti-reduction electrolyte to suppress lithium dendrite growth on the negative electrode side and an anti-oxidation electrolyte to prevent oxidation failure under high voltage on the positive electrode side. Simultaneously, interface modification is used to match different coefficients of thermal expansion. By setting functional layers to achieve synergistic optimization of the solid electrolyte membrane, the interface compatibility problem between layers is effectively solved, significantly improving battery safety and cycle life.

[0022] refer to Figure 1 , Figure 1 These are exemplary configuration diagrams of solid electrolyte membranes according to some embodiments of this application. Figure 1 As shown, the solid electrolyte membrane in the all-solid-state battery includes a first solid electrolyte layer 100 that contacts the negative electrode, a second solid electrolyte layer 200 that contacts the positive electrode, and an interface modification layer 300 located between the first solid electrolyte layer 100 and the second solid electrolyte layer 200.

[0023] The thickness of the first solid electrolyte layer 100 is greater than or equal to the thickness of the second solid electrolyte layer 200; and the interface modification layer 300 is an electronically insulating and lithium-ion-conducting interface buffer layer. Furthermore, the thermal expansion coefficient of the interface modification layer 300 is greater than that of the first solid electrolyte layer 100 and less than that of the second solid electrolyte layer 200.

[0024] In some implementations, the high-voltage positive electrode active material includes lithium-rich manganese-based materials (xLi2MnO3·(1-x)LiMO2, where M is at least one of Ni, Co, and Mn), spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) or high-nickel ternary materials (LiN) 0.8 Co 0.1 Mn 0.1 One or more of the following (O2).

[0025] The first solid electrolyte layer 100 may include a first solid electrolyte material. The first solid electrolyte material may be one or more of reduction-resistant electrolyte materials. "Reduction resistance" can be understood as the stability of the electrolyte material in a low-potential environment on the negative electrode side, or its ability to resist reduction and decomposition. Since the negative electrode is an electron-rich region (low potential, lithium metal negative electrode potential is 0V), if the electrolyte material is easily reduced, it will react with the negative electrode to generate a high-resistivity interface phase, destroying interface stability. Based on this, the first solid electrolyte material used in this application is a reduction-resistant electrolyte material, which can effectively reduce reduction and decomposition on the negative electrode side, forming a uniform and stable interface phase. Furthermore, fewer interface side reactions (i.e., the aforementioned reduction and decomposition reactions) allow lithium ions to uniformly nucleate and deposit layered on the negative electrode surface, thereby avoiding the initial protrusions of lithium dendrite growth. Lithium ions can also pass through the uniform, dense, and low-resistivity interface phase to reach the negative electrode at a similar rate, avoiding uneven deposition caused by local ion enrichment, thus suppressing lithium dendrite growth. In addition, the interface phase formed by the anti-reduction electrolyte material has high thermodynamic / mechanical stability, can withstand the volume changes and mechanical stress during the charging and discharging process of lithium metal, and will not repeatedly break, which greatly reduces additional active deposition sites and prevents the "secondary germination" of dendrites.

[0026] In some implementations, the first solid electrolyte material includes Li7La3Zr2O 12The first solid electrolyte material is selected from one or more of LLZO, Li3YCl6, Li3InCl6, Li3N, Li2O, and LiTaO3. Optionally or preferably, the first solid electrolyte material may be LLZO. As a garnet-type oxide electrolyte, LLZO has excellent resistance to reduction and high mechanical strength, which can effectively suppress the formation and growth penetration of lithium dendrites in the negative electrode. At the same time, its wide electrochemical window gives it the potential to be compatible with high-voltage positive electrodes. The first solid electrolyte layer 100 can be prepared by weighing each component according to a predetermined mass ratio and then preparing it by wet coating or dry pressing. For example, the above components can be added to a solvent such as NMP or deionized water, stirred evenly to obtain a slurry of suitable viscosity, and then uniformly coated onto one side of a substrate (e.g., a rigid substrate such as glass or stainless steel plate, a flexible substrate such as PET film or PI film, or a porous substrate such as non-woven fabric or porous filter) using methods such as doctor blade coating, slot coating, gravure coating, or spin coating. After drying, curing, solvent removal, and peeling, a first solid electrolyte layer 100 can be obtained. In another example, the negative electrode sheet can be directly used as the above substrate, and the slurry can be directly coated onto the negative electrode sheet and dried and cured to obtain the first solid electrolyte layer 100. In yet another example, the above components can be fed into a mixer such as a high-speed mixer or an air-jet mixer for uniform mixing. The resulting mixture can be pressed into a film using molding, calendering, or rolling to finally obtain the first solid electrolyte layer 100. The thickness of the obtained first solid electrolyte layer 100 can be 50μm-100μm. For example, the thickness of the first solid electrolyte layer 100 can be 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, or any increment or decrease of any of the above values. This application does not make any specific limitation in this regard.

[0027] The second solid electrolyte layer 200 may include a second solid electrolyte material. The second solid electrolyte material may be selected from one or more antioxidant electrolyte materials. "Oxidation resistance" can be understood as the ability of the electrolyte material to resist oxidation and decomposition (i.e., loss of electrons) when in contact with a high-voltage positive electrode (e.g., NCM811 / lithium-rich manganese-based / lithium cobalt oxide). Since the positive electrode is an electron-deficient region (high potential, the conventional high-voltage positive electrode operating potential is 4.2-4.8V), if the electrolyte is easily oxidized, it will decompose and generate gas and impurity phases on the positive electrode surface, leading to electrolyte material oxidation failure and subsequent battery capacity decay. Based on this, the second solid electrolyte material used in this application is an antioxidant electrolyte material, which can effectively suppress side reactions at the positive electrode / electrolyte interface and construct a stable positive electrode interface phase. Without side reactions (i.e., the aforementioned oxidation and decomposition reactions), no impurities are generated, allowing for tight contact and uniform ionic conductivity distribution at the positive electrode / electrolyte interface, enabling rapid lithium-ion transport at the interface. Furthermore, because no gases or harmful products are generated, the risk of gas generation and harmful substances on the positive electrode side is eliminated, preventing battery bulging and short circuits. Furthermore, this cathode interface exhibits extremely high thermodynamic and electrochemical stability, capable of withstanding potential fluctuations, volume changes, and mechanical stresses during long-term charge-discharge of the high-voltage cathode, without repeated decomposition / regeneration. Additionally, during the charge-discharge process of the high-voltage cathode, the transition metal ions (Ni...) on the surface... 3+ / Co 3+ / Mn 4+ Transition metal ions are prone to dissolution, and the dissolved transition metal ions catalyze the oxidative decomposition of the electrolyte, forming a vicious cycle of "transition metal dissolution → accelerated electrolyte decomposition → more transition metal dissolution." Simultaneously, dissolution leads to cathode lattice collapse and rapid capacity decay. Antioxidant electrolytes, because they are not easily oxidized at high potentials, fundamentally eliminate the reaction basis for transition metal ion-catalyzed electrolyte decomposition, significantly reducing the amount of transition metal dissolution. A stable cathode / electrolyte interface phase also physically prevents transition metal ions from diffusing from the cathode surface into the electrolyte bulk phase, protecting the integrity of the cathode's crystal structure and preventing structural collapse of the electrolyte due to catalytic decomposition, achieving bidirectional stability of both the electrolyte and the cathode. Furthermore, antioxidant electrolytes can be directly matched with high-voltage cathodes without complex antioxidant coatings, thereby reducing production costs and efficiency.

[0028] In some implementations, the second solid electrolyte material includes one or more of LPSC, NZSP, LATP, and LiF. Optionally or preferably, the second solid electrolyte material may be LPSC. As a sulfide electrolyte, LPSC has extremely high ionic conductivity, which can meet the ion transport requirements of high-power scenarios (such as fast charging of electric vehicles). At the same time, it has good oxidation stability, making it suitable for matching high-voltage positive electrodes. The formation of the second solid electrolyte layer 200 can be the same as or similar to the formation of the first solid electrolyte layer 100. For example, it can be prepared by wet coating or dry pressing. The substrate used can be a positive electrode sheet, and the slurry is directly coated on the positive electrode sheet and dried and cured to obtain the second solid electrolyte layer 200. The thickness of the obtained second solid electrolyte layer 200 can be 20μm-50μm. For example, the thickness of the second solid electrolyte layer 200 can be 20μm, 30μm, 40μm, 50μm, etc., or any increment or decrease of any of the above values. This application does not specifically limit this.

[0029] The solid electrolyte membrane provided in this application, due to the use of different solid electrolyte layers, may exhibit excessive differences in the coefficients of thermal expansion between the different electrolytes, leading to stress and interfacial delamination during cycling. Furthermore, direct contact between two different electrolytes may cause side reactions, such as the interfacial reaction between LLZO and LPSC, which generates non-conductive products, thereby increasing impedance. Therefore, this application uses an interface modification layer 300, positioned between the first solid electrolyte layer 100 and the second solid electrolyte layer 200, to alleviate expansion differences, optimize ion transport paths, and reduce impedance.

[0030] The interface modification layer 300 may include one or more of the following: metal oxyacid salts, polymers, metal oxides, and metal alloys. The metal oxyacid salts exhibit strong chemical inertness, exhibiting no solid-phase side reactions with either the first solid electrolyte layer 100 or the second solid electrolyte layer 200, effectively isolating the two electrolyte layers. Furthermore, the metal oxyacid salts possess a wide electrochemical window, perfectly bridging the low reduction potential of the first solid electrolyte layer 100 and the high oxidation potential of the second solid electrolyte layer 200. Simultaneously, the metal oxyacid salts exhibit high thermal and chemical stability, showing no decomposition even after long-term cycling. In some examples, the metal oxyacid salts may include, but are not limited to, one or more of Li3PO4, LiTaO3, LiNbO3, Li2MoO4, LiBO2, and Li3BO3. The polymer exhibits strong adhesion, bonding the two solid electrolyte layers into a unified whole, significantly improving the structural stability of the stack. Moreover, the polymer's ion conduction mechanism is lithium-ion migration mediated by chain segment movement, enabling the construction of flexible ion conduction bridges and enhancing ion conductivity. In some examples, the polymer may include, but is not limited to, one or more of cross-linked PEO, fluorinated polycarbonate, PVDF-HFP, PEO-PPO block copolymer, polyimide PI-lithium salt complex, GPE gel polymer electrolyte, etc. The metal oxide exhibits extremely high chemical stability, with no side reactions with any solid electrolyte, and can completely suppress interfacial solid-phase reactions. Furthermore, the metal oxide possesses a high Young's modulus, effectively blocking the growth of lithium dendrites. In some examples, the metal oxide may include, but is not limited to, Al2O3, ZrO2, SiO2, TiO2, ZnO, CeO2, etc., or any combination thereof. The metal alloy, such as a lithium-based metal alloy, has a reduction potential similar to that of lithium metal, excellent electrochemical compatibility with the first solid electrolyte layer 100, does not undergo reduction decomposition, and can suppress the growth of lithium dendrites into the second solid electrolyte layer 200. Additionally, lithium ions diffuse in the lithium-based metal alloy in bulk, resulting in high ionic conductivity (10⁻⁶). -2 -10 -1 The lithium-based metal alloy (S / cm) can build highly efficient ion bridges, adapting to the high ionic conductivity of sulfides. Simultaneously, it can form an alloying interface with the lithium metal anode, suppressing the initiation and growth of lithium dendrites, thus achieving both interface modification and anode-side dendrite suppression. In some examples, the metal alloy may include Li-In alloys, Li-Sn alloys, Li-Zn alloys, Li-Al alloys, Li-B alloys, Li-SiO alloys, etc., or any combination thereof.

[0031] In some implementations, the interface modification layer 300 includes lithium phosphate. Lithium phosphate can prevent interfacial side reactions between the first solid electrolyte material in the first solid electrolyte layer 100 and the second solid electrolyte material in the second solid electrolyte layer 200, improve interfacial contact, suppress lithium dendrites, and has excellent long-term cycling stability.

[0032] The interface modification layer 300 can be prepared by methods such as sol-gel method, slurry coating method, solution spin coating method, magnetron sputtering method, pulsed laser deposition method, vacuum evaporation method, mechanical ball milling composite method, cold spraying method, melt quenching method, etc., and specific details can be found in existing related materials. The interface modification layer 300 can be formed on one side of the first solid electrolyte layer 100 or one side of the second solid electrolyte layer 200. Subsequently, the first solid electrolyte layer 100 or the second solid electrolyte layer 200 with the interface modification layer 300 is stacked and pressed, ensuring that the interface modification layer 300 is located between the two. After completion, the solid electrolyte membrane is obtained. In some examples, the interface modification layer 300 can be prepared by magnetron sputtering, laser deposition or vacuum evaporation method. For example, using a high-purity Li3PO4 ceramic target as the cathode and an electrolyte substrate (one side of the first solid electrolyte layer 100 or the second solid electrolyte layer 200) as the anode, in an inert gas (Ar) or Ar / O2 mixed atmosphere, Ar ions are bombarded on the target by a radio frequency / DC electric field. Atoms / ions are sputtered and deposited on the surface of the electrolyte substrate, forming a dense interface modification layer 300. Alternatively, a high-energy pulsed laser (KrF excimer laser) can be used to bombard the Li3PO4 ceramic target, causing the target surface to melt and vaporize instantaneously, forming a plasma plume. The plasma is deposited on the surface of the electrolyte substrate and crystallizes / amorphizes, forming the interface modification layer 300. Yet another example is placing a high-purity Li3PO4 evaporation source and an electrolyte substrate in an electron beam vacuum evaporation apparatus, where the interface modification layer 300 is deposited on the surface of the electrolyte substrate under vacuum. The thickness of the formed interface modification layer 300 is 1μm-10μm. For example, the thickness of the interface modification layer 300 can be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, or any increment or decrease of any of the above values. This application does not make any specific limitation in this regard.

[0033] The multi-layered solid electrolyte membrane in the all-solid-state battery disclosed in this application effectively suppresses lithium dendrite growth through an anti-reduction electrolyte, prevents oxidation failure under high voltage through an anti-oxidation electrolyte, and solves the problem of thermal expansion coefficient mismatch through an interface modification layer located in the middle. This application achieves synergistic optimization through functional layering, effectively solves interface compatibility issues, and significantly improves battery safety and cycle life.

[0034] This application discloses, in another aspect, a method for preparing an all-solid-state battery, including a step of preparing a solid electrolyte membrane. As an exemplary but not limiting illustration, the preparation step includes:

[0035] S1. The first solid electrolyte layer is obtained by mixing the first solid electrolyte material with the first binder and forming a film.

[0036] S2. The second solid electrolyte layer is obtained by mixing the second solid electrolyte material with the second binder and the conductive agent and forming a film.

[0037] S3. The interface modification layer is formed on one side of the first solid electrolyte layer or on one side of the second solid electrolyte layer;

[0038] S4. The first solid electrolyte layer, the interface modification layer, and the second solid electrolyte layer are stacked and then composited to form a film to obtain the solid electrolyte film; wherein, the interface modification layer is located between the first solid electrolyte layer and the second solid electrolyte layer.

[0039] For step S1, the first adhesive can be any known adhesive, including but not limited to polyvinylidene fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aromatic polyamide resin, polyamide, polyimide, polyamide-imide, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, polyhexafluoropropylene, styrene-butadiene rubber, carboxymethyl cellulose, etc., or any combination thereof, which can be used in this application. Copolymers can also be used as adhesives, exemplary of which are copolymers of two or more materials selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, trifluorochloroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, hexadiene, etc. Alternatively, mixtures of two or more materials in the above examples can also be used as adhesives. In some implementations, the first binder may include, but is not limited to, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC) and its derivatives such as sodium carboxymethyl cellulose (CMC-Na), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN0), polyvinyl alcohol (PVA), polyaniline (PANI), polypyrrole (PPy), seaweed nanofibers (CNF), sodium alginate (Alg), β-cyclodextrin polymer β-CDp, polypropylene emulsion LA132, etc., or any combination thereof, or functionalized derivatives of the above polymers or copolymers between monomers.

[0040] In some implementations, the first solid electrolyte material and the first binder (e.g., polyvinylidene fluoride PVDF) are weighed at a predetermined mass ratio of (94-96):(4-6) and then added to a solvent such as N-methylpyrrolidone (NMP) or deionized water. Homogenization is performed using equipment such as a mixer or disperser. After the mixture reaches a predetermined viscosity, it is degassed / filtered to obtain a first slurry. This first slurry can be coated onto at least one side of the substrate, such as the negative electrode sheet, using a doctor blade coating, slot extrusion coating, or cast coating. After coating, drying and curing are performed to remove the solvent and crosslink the first binder. Finally, the mixture is rolled to a target compaction density using a roller mill to obtain the first solid electrolyte layer.

[0041] In other implementations, the above components can be fed into a mixer, such as a high-speed mixer or an air-flow mixer, for uniform mixing. The resulting mixture can be pressed into a film using molding, calendering, rolling, or other methods to ultimately obtain the first solid electrolyte layer.

[0042] For step S2, the formation of the second solid electrolyte layer is similar to the formation process of the first solid electrolyte layer in step S1, except that a conductive agent is added and mixed together. The second binder is selected from the same or similar first binder. The conductive agent may include, but is not limited to, carbon-based materials such as graphite (natural or artificial graphite), carbon black (acetylene black, Ketjen black, Super P, etc.), carbon nanotubes, graphene, etc.; metal-based materials such as metal powders (aluminum powder, nickel powder, etc.), metal oxides (titanium oxide, etc.), metal whiskers (aluminum oxide, oxidizing agents, etc.); conductive polymers such as polyaniline, polypyrrole, polythiophene, etc.; conductive fibers such as carbon fibers, metal fibers, metal compound fibers, polymer fibers, etc.; or other known conductive agents.

[0043] In some implementations, the second solid electrolyte material can be weighed together with the second binder (e.g., PVDF) and a conductive agent (e.g., Super P) at a predetermined mass ratio of (85-95):(3-4):(1-12), and then sequentially added to a solvent, such as NMP, to form a second slurry (e.g., the second solid electrolyte material and the second conductive agent are first mixed and dispersed in NMP, and then the second binder is added). This second slurry can also be coated onto at least one side of a substrate, such as a positive electrode sheet, using the same coating process, dried, cured, and rolled to obtain the second solid electrolyte layer. Similarly, the second solid electrolyte layer can also be obtained by dry pressing.

[0044] In step S3, the interface modification layer can be formed using magnetron sputtering, pulsed laser deposition, or vacuum evaporation. The interface modification layer can be formed on one side of the first solid electrolyte layer or one side of the second solid electrolyte layer. During the composite film formation in step S4, the first solid electrolyte layer, the interface modification layer, and the second solid electrolyte layer are stacked with the interface modification layer "sandwiched" between them. Subsequently, densification is achieved through hot / cold pressing at a set temperature and pressure to obtain the solid electrolyte film.

[0045] In some implementations, the positive electrode and the negative electrode may include a current collector and an active material layer located on at least one side of the current collector.

[0046] The positive electrode includes a positive current collector and a high-voltage positive active material layer located on at least one side of the positive current collector. The positive current collector can be implemented using a metal plate with electronic conductivity. Currently known positive current collectors can all be used in this application. For example, the positive current collector is aluminum foil.

[0047] In some embodiments, the positive electrode active material layer may further include a solid electrolyte. For example, inorganic solid electrolytes, including but not limited to halide solid electrolytes, sulfide solid electrolytes, oxide solid electrolyte materials, nitride solid electrolytes, hydride solid electrolytes, borate solid electrolytes, etc.

[0048] Suitable, but not limited, halide solid electrolytes may include, but are not limited to, LaF3, LiCl, LiI, etc., or those with the chemical formula Li a MX b This refers to lithium halide solid electrolytes, where M represents a metallic element or metalloid element, including one or more of B, Si, Ge, As, Sb, Te, Al, Zn, Mg, Ca, Ba, Mn, Cd, Co, Yb, Y, Cr, In, Ga, Sr, Hf, Ti, Ta, Sn, Nb, Er, Sc, etc., and X represents a halogen element such as F, Cl, Br, I, etc. For example, derivatives produced by doping or coating Li₂CdCl₄, Li₂MgCl₄, Li₂CdI₄, Li₂ZnI₄, Li₂ZrCl₆, Li₃YCl₆, Li₃InCl₆, or related materials.

[0049] Suitable, but not limiting, sulfide solid electrolytes may include, but are not limited to, Li2S. P2S5, Li2S P2S5–MS x (M=Si, Ge, Sn, 0≤x≤2), Li 9.6 P3S 12 Li7P3S 11、Li7P2S8I、Li 10 SnP2S 12 、The 10 SiP2S 12 、Li9P3S9O3、LGPS(Li 10 GeP2S 12 )、Thio-LISICON(Li 3.25 Here 0.25 P 0.75 S4)、Li6PS5X(X=Cl、Br、I)、Li3PS4-X(X=Cl、Br、I)、Li4SnS4-X(X=Cl,Br)、Li 3.25 Here 0.25 P 0.75 S4、The 3.4 If 0.4 P 0.6 S4、The 10 GeP2S 11.7 O 0.3 、The 9.54 If 1.74 P 1.44 S 11.7 Cl 0.3 、The 10.35 Here 1.35 P 1.65 S 12 、The 10.35 If 1.35 P 1.65 S 12 、The 9.81 Sn 0.81 P 2.19 S 12 、The 10 (The 0.5 Here 0.5 )P2S 12 、The 10 (Here 0.5 Sn 0.5 )P2S 12 、The 10 (The 0.5 Sn 0.5 )P2S 12 、Li6(PS5) 0.7 (GeS4) 0.3 Cl、Li 7.5 P 2.5 Sn 0.5 S 10.5 Cl 1.5 、Li6PS5Cl 0.5 Br 0.5 、Li6PS5I0.2 Cl 0.8 、Li5SnS2C l3 、Li 10 P3S 12 Cl2、Li7P2S 8.5 Cl 0.5 and derivatives produced by doping or coating improvement with the like, any combination thereof or related materials.

[0050] Some suitable but non-limiting oxide solid electrolytes may include but are not limited to NASICON-type solid electrolytes such as LiTi2(PO4)3, LiGeTi(PO4)3, LiGe2(PO4)3, LiHf2(PO4)3, Li 1+x Al x Ge2 x (PO4)3 (LAGP, where 0 ≤ x ≤ 2), Li 1+x Al x Ti2 x (PO4)3 (LATP, where 0 ≤ x ≤ 2), Li 1+x Y x Zr2 x (PO4)3 (LYZP, where 0 ≤ x ≤ 2), Li 1.3 Al 0.3 Ti 1.7 (PO4)3, Na3Zr2Si2PO 13 (NZSP), etc., perovskite-type solid electrolytes such as Li 3x La( 2 / 3 x )TiO3 (LLTO, where 0 < x < 0.25), LiSr 1.65 Zr 1.3 Ta 1.7 O9, Li 2x y Sr1 x Ta y Zr1 y O3 (where x = 0.75y and 0.60 < y < 0.75), etc., LISICON-type solid electrolytes such as Li 14 ZnGe4O 16 、Li4SiO4、LiGeO4, etc., garnet-type solid electrolytes such as Li7La3Zr2O 12 (LLZO), Li 6.5 La3Zr1.75 Te 0.25 O 12 Li 6.25 Al 0.25 La3Zr2O 12 Li 6.2 Ga 0.3 La 2.95 Rb 0.05 Zr2O 12 Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 Li 6.75 La3Zr 1.75 Nb 0.25 O 12 Li 6.75 La3Zr 1.75 Nb 0.25 O 12 Derivatives produced by doping or coating with materials such as, etc., or any combination thereof or related materials.

[0051] Suitable, but not limited, nitride solid electrolytes may include, but are not limited to, Li3N, Li7PN4, LiSi2N3, and Li9N2Cl3. Suitable, but not limited, hydride solid electrolytes may include, but are not limited to, LiBH4 and LiBH4-Li X (X = Cl, Br, or I), LiNH2, Li2NH, LiBH4-LiNH2, Li3AlH6, etc. Some suitable but not limited borate solid electrolytes may include, but are not limited to, Li2B4O7, Li2O-B2O3-P2O5, Li2B... 10 H 10 -Li2B 12 H 12 Examples include Li7N2I-0.5LiOH. Derivatives of these electrolytes obtained through substitution, doping, modification, and compositing can also serve as the inorganic solid electrolytes described in this application. For instance, bromine-substituted or partially substituted Li2ZrCl6, such as Li2ZrCl... 6-x Br x Rare earth metals such as lanthanum or yttrium-doped Li6PS5Br, and LLZO deposited on indium (In) surfaces, etc. It should be noted that the above examples are for illustrative purposes only and are not intended to limit the scope of this application.

[0052] The negative electrode may include a negative current collector and a negative active layer located on at least one side of the negative current collector. The negative current collector can be implemented using a metal plate with electronic conductivity. Currently known negative current collectors can all be used in this application. For example, the negative current collector is copper foil.

[0053] The positive electrode and the negative electrode further include a binder and a conductive agent, respectively. The binder may be the same as or similar to the aforementioned first / second binder, and the conductive agent may be the same as or similar to the conductive agent used in the aforementioned second solid electrolyte; further details will not be provided here.

[0054] The positive and negative electrode sheets can be formed using a wet coating process. For example, active materials, binders, and conductive agents are weighed in a specific ratio and added to a solvent to form a slurry. This slurry is then coated onto a current collector and dried to obtain the corresponding electrode sheet.

[0055] The solid electrolyte membrane can be the solid electrolyte membrane described above. See the foregoing for details.

[0056] This application also discloses an electrical device comprising multiple all-solid-state batteries as described above, arranged in a folded, stacked, or combined manner. This solid-state battery module can be applied to electrically driven vehicles, including but not limited to electric vehicles, hybrid vehicles, and energy storage devices such as energy storage systems.

[0057] The present application will be further described in detail below with reference to embodiments. It should be noted that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection claimed in this application.

[0058] Example 1

[0059] 1. Preparation of positive electrode sheet

[0060] Positive electrode with LiN 0.8 Co 0.1 Mn 0.1 O2, conductive agent, and binder (PVDF) are mixed in a ratio of 97:2:1 and prepared by wet coating. Coating process: slurry viscosity 6000 (MPa·s), coating thickness 150 μm, roller compaction to 2.3 g / cm³. 3 The surface density is 30 mg / cm³. 2 .

[0061] 2. Preparation of negative electrode sheet

[0062] A lithium-copper composite strip with lithium metal as the negative electrode active material is selected as the negative electrode sheet, and the lithium-copper composite strip is cut to the required size.

[0063] 3. Preparation of solid electrolyte membranes

[0064] 3.1 Preparation of the first solid electrolyte layer

[0065] LLZO powder (95%) was dispersed in an NMP solution containing PVDF binder (5%) using a solution blending method. The mixture was stirred to form a homogeneous slurry, which was then coated onto the negative electrode surface using a casting coating process to form a first solid electrolyte layer with a thickness of 80 μm. The coefficient of thermal expansion of the first solid electrolyte layer was ~12 × 10⁻⁶. -6 / ℃.

[0066] 3.2 Preparation of the second solid electrolyte layer

[0067] LPSC powder (90%), SuperP (7%), and PVDF binder (3%) were mixed and dispersed in NMP solution and stirred to form a uniform slurry. This slurry was then coated onto the positive electrode surface using a casting coating process to form a second solid electrolyte layer with a thickness of 30 μm. The coefficient of thermal expansion of the second solid electrolyte layer was ~20 × 10⁻⁶. -6 / ℃.

[0068] 3.3 Preparation of the interface modification layer

[0069] A 5 μm thick Li3PO4 interface modification layer was deposited on the surface of the first or second solid electrolyte layer using magnetron sputtering. The thermal expansion coefficient of the interface modification layer was ~13 × 10⁻⁶. -6 / ℃.

[0070] 4. Solid-state battery fabrication

[0071] The positive electrode, solid electrolyte membrane and negative electrode prepared above are stacked in a cycle (29 positive electrode pieces), and then isostatically densified to assemble an all-solid-state pouch cell.

[0072] Example 2

[0073] The preparation method and thickness of Example 2 are the same as those of Example 1. The difference from Example 1 is that the first solid electrolyte material in the first solid electrolyte layer is Li3YCl6, and the second solid electrolyte material in the second solid electrolyte layer is Li 1.3 Al 0.3 Ti 1.7 The thermal expansion coefficient of the first solid electrolyte layer (PO4)3 is ~11×10⁻⁶. -6 At / ℃, the coefficient of thermal expansion of the second solid electrolyte is ~14×10⁻⁶. -6 / ℃.

[0074] Example 3

[0075] The materials and preparation methods of Example 3 are the same as those of Example 1. The difference from Example 1 is that the thickness of the first solid electrolyte layer is 60 μm.

[0076] Example 4

[0077] The materials and preparation methods of Example 4 are the same as those of Example 1. The difference from Example 1 is that the thickness of the first solid electrolyte layer is 50 μm.

[0078] Example 5

[0079] The materials and preparation methods of Example 5 are the same as those of Example 1. The difference from Example 1 is that the thickness of the first solid electrolyte layer is 100 μm.

[0080] Example 6

[0081] The materials and preparation methods of Example 6 are the same as those of Example 1. The difference from Example 1 is that the thickness of the first solid electrolyte layer is 30 μm.

[0082] Example 7

[0083] The materials and preparation methods of Example 7 are the same as those of Example 1. The difference from Example 1 is that the thickness of the first solid electrolyte layer is 120 μm.

[0084] Example 8

[0085] The materials and preparation methods of Example 8 are the same as those of Example 1. The difference from Example 1 is that the thickness of the second solid electrolyte layer is 40 μm.

[0086] Example 9

[0087] The materials and preparation methods of Example 9 are the same as those of Example 1. The difference from Example 1 is that the thickness of the second solid electrolyte layer is 20 μm.

[0088] Example 10

[0089] The materials and preparation methods of Example 10 are the same as those of Example 1. The difference from Example 1 is that the thickness of the second solid electrolyte layer is 50 μm.

[0090] Example 11

[0091] The materials and preparation methods of this Example 11 are the same as those of Example 1. The difference from Example 1 is that the thickness of the second solid electrolyte layer is 10 μm.

[0092] Example 12

[0093] The materials and preparation methods of Example 12 are the same as those of Example 1. The difference from Example 1 is that the thickness of the second solid electrolyte layer is 80 μm.

[0094] Example 13

[0095] The materials and preparation methods of Example 13 are the same as those of Example 1. The difference from Example 1 is that the thickness of the interface modification layer is 6 μm.

[0096] Example 14

[0097] The materials and preparation methods of Example 14 are the same as those of Example 1. The difference from Example 1 is that the thickness of the interface modification layer is 1 μm.

[0098] Example 15

[0099] The materials and preparation methods of Example 15 are the same as those of Example 1. The difference from Example 1 is that the thickness of the interface modification layer is 10 μm.

[0100] Example 16

[0101] The materials and preparation methods of Example 16 are the same as those of Example 1. The difference from Example 1 is that the thickness of the interface modification layer is 0.1 μm.

[0102] Example 17

[0103] The materials and preparation methods of Example 17 are the same as those of Example 1. The difference from Example 1 is that the thickness of the interface modification layer is 20 μm.

[0104] Comparative Example 1

[0105] Compared with Example 1, Comparative Example 1 differs in that only the second solid electrolyte layer is used as the solid electrolyte membrane, and the thickness is set to 115 μm.

[0106] Comparative Example 2

[0107] Compared with Example 1, Comparative Example 2 is different in that only the first solid electrolyte layer is used as the solid electrolyte membrane, with a thickness of 115 μm.

[0108] Comparative Example 3

[0109] Compared with Example 1, Comparative Example 3 is different in that it only uses a composite of the first solid electrolyte and the second solid electrolyte as a solid electrolyte membrane (without an interface modification layer), with thicknesses of 83 μm and 32 μm, respectively.

[0110] Comparative Example 4

[0111] Compared with Example 1, Comparative Example 4 differs in that the thickness of the first solid electrolyte layer is less than that of the second solid electrolyte layer. The thickness of the first solid electrolyte layer is set to 30 μm and the thickness of the second solid electrolyte layer is set to 80 μm.

[0112] Comparative Example 5

[0113] Comparative Example 5 differs from Example 1 in that the interface modification layer material is alumina, and the coefficient of thermal expansion of the interface modification layer is ~8.5×10⁻⁶. -6 / ℃.

[0114] Comparative Example 6

[0115] Comparative Example 6 differs from Example 1 in that the interface modification layer uses a conductive material, graphene, and the coefficient of thermal expansion of the interface modification layer is -7.5 × 10⁻⁶. -6 / ℃.

[0116] Test Example 1 - Thermal Expansion Coefficient Test

[0117] The linear thermal expansion coefficients of the first solid electrolyte layer, the interface modification layer, the second solid electrolyte layer, and the overall battery were measured using a thermomechanical analyzer (TMA) (temperature range: 25~200℃, heating rate: 5℃ / min).

[0118] Test Example 2 - Ionic Conductivity Test

[0119] Electrochemical impedance spectroscopy (EIS) was performed using an electrochemical workstation, and the ionic conductivity was calculated using the formula σ=L / (R×S).

[0120] Test Example 3 - Cyclic Performance Test

[0121] At an ambient temperature of 25±2℃, the device was charged at 0.33C constant current and constant voltage to the upper limit voltage of 4.4V, and the cutoff current was reduced to 0.05C; then left to stand for 30 minutes; followed by constant current discharge at 1C to 2.5V; then left to stand for 30 minutes; and the charge-discharge cycle was repeated 500 times while recording the data.

[0122] Test Example 4 - Rate Performance Test

[0123] At 25℃, it was charged to 4.4V at a constant current of 1C, then kept at a constant voltage of 0.05C and left to stand for 30 minutes; it was then discharged to 2.5V at a current of 5C, and the discharge rate was tested.

[0124] The test results are shown in Table 1.

[0125] Table 1 Test Results

[0126]

[0127] As shown in Table 1, the test results indicate that the solid electrolyte membrane employing the three-layer functional structure of this application (anti-reduction first layer / interface buffer layer with thermal expansion coefficient adaptation / anti-oxidation second layer) can synergistically optimize battery performance. Example 1 demonstrates the best overall performance (high ionic conductivity, long cycle life, and excellent rate performance). Comparative Examples 1-3 prove that no single or double-layer (without interface modification layer) structure can achieve the same effect; Comparative Example 4 shows that if the thickness of the first layer is less than the thickness of the second layer, it will lead to significant performance degradation; Comparative Examples 5-6 confirm that the interface modification layer must simultaneously meet the conditions of electronic insulation, ion conduction, and a thermal expansion coefficient between the two layers, otherwise the battery performance will severely degrade. These comparisons collectively verify that the various technical features in the overall technical solution of this application are interrelated and indispensable, and produce unexpected technical effects through synergistic effects. In summary, the all-solid-state battery using the three-layer functional structure solid electrolyte membrane of this application effectively improves interface stability, mitigates the difference in interlayer thermal expansion coefficients, and significantly improves battery electrical performance.

[0128] This application has described the basic concepts. Obviously, for those skilled in the art, the above detailed disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore such modifications, improvements, and corrections still fall within the spirit and scope of the exemplary embodiments of this application.

[0129] Furthermore, this application uses specific terms to describe its embodiments. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this application do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0130] Similarly, it should be noted that, in order to simplify the description of this application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of this application sometimes combines multiple features into one embodiment or its description. However, this disclosure method does not imply that the subject matter of this application requires more features than those mentioned in the claims. In fact, the embodiments have fewer features than all the features of the single embodiments disclosed above.

[0131] Finally, it should be understood that the embodiments described in this application are merely illustrative of the principles of the embodiments of this application. Other modifications may also fall within the scope of this application. Therefore, alternative configurations of the embodiments of this application are considered as examples and not limitations, and are regarded as consistent with the teachings of this application. Accordingly, the embodiments of this application are not limited to the embodiments explicitly described and illustrated in this application.

Claims

1. An all-solid-state battery, characterized in that, include: Positive electrode sheet, wherein the positive electrode sheet comprises a high-voltage positive electrode active material; The negative electrode sheet includes a lithium metal negative electrode active material; A solid electrolyte membrane, comprising a first solid electrolyte layer in contact with the negative electrode, a second solid electrolyte layer in contact with the positive electrode, and an interface modification layer located between the first and second solid electrolyte layers; wherein... The first solid electrolyte layer includes a first solid electrolyte material comprising Li7La3Zr2O. 12 One or more of (LLZO), Li3YCl6, Li3InCl6, Li3N, Li2O and LiTaO3; The second solid electrolyte layer includes a second solid electrolyte material including one or more of Li6PS5Cl (LPSC), Li 1+x Al x Ti 2-x (PO4)3, where 0 < x < 1 (LATP); The thickness of the first solid electrolyte layer is greater than or equal to the thickness of the second solid electrolyte layer; The interface modification layer is an electronically insulating and lithium-ion-conducting interface buffer layer. Furthermore, the thermal expansion coefficient of the interface modification layer is greater than that of the first solid electrolyte layer and less than that of the second solid electrolyte layer. The interface modification layer includes one or more of metal oxyacid salts, polymers, and metal oxides.

2. The all-solid-state battery according to claim 1, characterized in that, The high-voltage positive electrode active material includes one or more of lithium-rich manganese-based materials, spinel lithium nickel manganese oxide, or high-nickel ternary materials.

3. The all-solid-state battery according to claim 1, characterized in that, The first solid electrolyte material is LLZO, and the second solid electrolyte material is LPSC.

4. The all-solid-state battery according to claim 1, characterized in that, The interface modification layer includes lithium phosphate.

5. The all-solid-state battery according to claim 1, characterized in that, The thickness of the first solid electrolyte layer is 50μm-100μm, the thickness of the second solid electrolyte layer is 20μm-50μm, and the thickness of the interface modification layer is 1μm-10μm.

6. A method for preparing an all-solid-state battery as described in any one of claims 1-5, characterized in that, The preparation step of the solid electrolyte membrane includes: S1. The first solid electrolyte layer is obtained by mixing the first solid electrolyte material with the first binder and forming a film. S2. The second solid electrolyte layer is obtained by mixing the second solid electrolyte material with the second binder and the conductive agent and forming a film. S3. The interface modification layer is formed on one side of the first solid electrolyte layer or on one side of the second solid electrolyte layer; S4. The first solid electrolyte layer, the interface modification layer, and the second solid electrolyte layer are stacked and then composited to form a film to obtain the solid electrolyte film; wherein, the interface modification layer is located between the first solid electrolyte layer and the second solid electrolyte layer.

7. The method for preparing an all-solid-state battery according to claim 6, characterized in that, The film formation in S1 and S2 is achieved by wet coating or dry pressing.

8. The method for preparing an all-solid-state battery according to claim 6, characterized in that, The interface modification layer formed in S3 is achieved by magnetron sputtering, pulsed laser deposition, or vacuum evaporation.

9. An electrical device, characterized in that, Including all-solid-state batteries as described in any one of claims 1-5.

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