All-solid-state battery, preparation method thereof and battery module

Abstract

The invention discloses an all-solid-state battery, a preparation method thereof and a battery module. The all-solid-state battery comprises a positive pole piece, a negative pole piece and a sulfide solid electrolyte layer located between the positive pole piece and the negative pole piece, wherein the positive pole piece and the negative pole piece are stacked; the positive pole piece comprises a positive pole current collector and a composite positive pole layer positioned on at least one side of the positive pole current collector; wherein the composite positive electrode layer comprises a high-voltage oxide positive electrode main material, an oxide solid electrolyte, a conductive oxide and a sintering aid; the high-voltage oxide positive electrode main material, the oxide solid electrolyte and particles of the conductive oxide are combined through a sintering neck based on the sintering aid; the sintering aid comprises at least one of a metal simple substance, an inorganic oxide, a metal fluoride, a metal nitride and a lithium-containing compound; the problems of poor physical contact and unstable chemical interface between the oxide positive electrode and the sulfide solid electrolyte are solved, and the safety performance of the battery is greatly improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to all-solid-state batteries and their preparation methods, as well as battery modules containing the all-solid-state batteries. Background Technology

[0002] All-solid-state lithium batteries use non-flammable solid electrolytes instead of traditional liquid electrolytes, which is expected to fundamentally solve battery safety issues and achieve higher energy density. Among them, sulfide solid electrolytes have extremely high room-temperature ionic conductivity (up to 10⁻⁶). -3 -10 -2 With a flux ratio (S / cm), approaching or even exceeding that of liquid electrolytes, it is one of the systems with the greatest potential for industrialization.

[0003] However, especially when sulfide electrolytes are matched with high-capacity, high-voltage (charging voltage > 4.2V (vs. Li+ / Li)) oxide cathode materials (such as lithium cobalt oxide, high-nickel ternary materials, etc.), their inherent chemical and electrochemical incompatibility leads to severe interfacial instability. On the one hand, residual lithium compounds (such as Li2CO3, LiOH) commonly found on the surface of oxide cathodes can undergo violent acid-base reactions with sulfide electrolytes, generating high-resistivity sulfur / oxygen-containing species and lithium salts, and may be accompanied by the release of harmful gases, thereby drastically deteriorating interfacial ion transport and increasing the battery's internal resistance. On the other hand, when charged to high voltage, active oxygen species released from the cathode lattice oxidize the sulfide electrolyte, causing its continuous decomposition and the accumulation of insulating products at the interface, further exacerbating electrochemical polarization. In addition, the composite cathode, which is simply constructed by mixing active materials, solid electrolytes, and conductive agents, has only loose solid-solid point contacts inside. Volume deformation during cycling can easily lead to particle contact failure and transport network breakage, severely restricting the battery's kinetic performance and cycle life. Summary of the Invention

[0004] To address the aforementioned issues, this application discloses an all-solid-state battery, its fabrication method, and a battery module. The all-solid-state battery includes a composite cathode layer, which can directly circumvent or significantly suppress harmful interfacial reactions between the high-voltage oxide cathode and the sulfide electrolyte at the material level. Furthermore, it can construct a robust and continuous ion / electron dual-pathway network at the electrode scale, thereby achieving a synergistic improvement in energy density, rate performance, and long-cycle stability of the all-solid-state battery.

[0005] A first aspect of this application provides an all-solid-state battery, comprising: a positive electrode, a negative electrode, and a sulfide solid electrolyte layer disposed therebetween the positive and negative electrode; the positive electrode includes a positive current collector and a composite positive electrode layer disposed on at least one side of the positive current collector; wherein the composite positive electrode layer includes a high-voltage oxide positive electrode material, an oxide solid electrolyte, a conductive oxide, and a sintering aid; the particles of the high-voltage oxide positive electrode material, the oxide solid electrolyte, and the conductive oxide are bonded together by a sintering neck based on the sintering aid; the sintering aid includes at least one selected from elemental metals, inorganic oxides, metal fluorides, metal nitrides, and lithium-containing compounds.

[0006] According to some embodiments of this application, the high-voltage oxide cathode material includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, lithium-rich manganese-based layered oxide, and lithium nickel manganese oxide; the oxide solid electrolyte includes Li 0.5 La 0.5 TiO3, LiSr 1.5 Zr 0.5 Ta 1.5 O8, Li7La3Zr2O 12 Li 1.3 Al 0.3 Ti 1.7 (PO4)3, Li 1.4 Al 0.4 Ge 1.6 (PO4)3, LiZr2(PO4)3, LiTi2(PO4)3, Li 3.5 Si 0.5 P 0.5 At least one of O4, Li2SO4-Li2O-B2O3; the conductive oxide includes SnO2, ZnO, In2O3:Sn, SnO2:F, ZnO:Al, RuO2, La 1-x Sr x At least one of MnO3, CuAlO2, and SrCu2O2.

[0007] According to some embodiments of this application, the sintering aid includes at least one selected from Li3BO3, LiF, SiO2, P2O5, MgO, CaO, TiO2, Y2O3, V2O5, Ni2O3, SeO2, Sb2O3, La2O3, AlF3, CaF2, BN, Ni, Cu, and Ag.

[0008] According to some embodiments of this application, the sulfide solid electrolyte layer includes a sulfide solid electrolyte, which includes Li6PS5Cl, Li3PS4, and Li 10 GeP2S12 Li7P3S 11 At least one of its halogenated or oxygen-doped modified materials.

[0009] According to some embodiments of this application, the thickness of the composite positive electrode layer is 50 μm-300 μm.

[0010] A second aspect of this application provides a method for preparing an all-solid-state battery, including a step of preparing the composite cathode layer, the preparation step comprising: S1. mechanically fusing and mixing a high-voltage oxide cathode material with a conductive oxide to obtain a composite mixture; S2. mixing the composite mixture, the oxide solid electrolyte, a binder, and the sintering aid and forming a film to obtain a composite cathode precursor layer; S3. heat-treating the composite cathode precursor layer to obtain the composite cathode layer; wherein the sintering aid forms a sintering neck during the heat treatment process.

[0011] According to some embodiments of this application, the film formation in step S2 is achieved by wet coating, including: mixing the composite mixture, the oxide solid electrolyte, the sintering aid and the binder in a solvent to obtain a composite slurry; coating the composite slurry onto a polymer substrate to form a wet film, and drying it to obtain the composite positive electrode precursor layer; wherein, the above process satisfies at least one of the following (1)-(3): (1) the polymer substrate includes at least one of polyester film, polycarbonate film, polyamide film and modified cellulose film; (2) the thickness of the polymer substrate is 5μm-250μm; (3) the drying temperature is 80℃-180℃ and the drying time is 6h-24h.

[0012] According to some embodiments of this application, the preparation steps satisfy at least one of the following (1)-(3): (1) the mass ratio of the high voltage oxide positive electrode material, the oxide solid electrolyte, the conductive oxide, the binder and the sintering aid is (60-80):(10-30):(1-10):(0.5-5):(1-10); (2) the rotation speed of the mechanical fusion is 1000rpm-2000rpm and the fusion time is 5min-10min; (3) the atmosphere of the heat treatment process is an oxygen atmosphere or an air atmosphere, the heat treatment temperature is 300℃-1000℃ and the time is 0.5h-5h.

[0013] According to some embodiments of this application, the method for preparing the all-solid-state battery further includes: providing a positive electrode current collector, and pressing the composite positive electrode layer and the positive electrode current collector together under flat pressure to obtain a positive electrode sheet; sequentially stacking the positive electrode sheet, the sulfide solid electrolyte layer, and the negative electrode sheet, followed by isostatic pressing to obtain the all-solid-state battery; wherein the pressure of the flat pressing is 5MPa-200MPa; the pressure of the isostatic pressing is 300MPa-500MPa, the processing time is 5min-20min, and the processing temperature is 25℃-90℃.

[0014] A third aspect of this application provides a battery module, including the all-solid-state battery described in the first aspect.

[0015] 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

[0016] 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: Figure 1 These are exemplary structural diagrams of an all-solid-state battery according to some embodiments of this application; Figure 2 This is an exemplary flowchart of a method for preparing a composite cathode layer according to some embodiments of this application; Figure 1 In the diagram, 100 is the positive electrode, 110 is the positive current collector, 120 is the composite positive electrode layer, 200 is the sulfide solid electrolyte layer, and 300 is the negative electrode. Detailed Implementation

[0017] 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.

[0018] 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.

[0019] 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.

[0020] This application discloses an all-solid-state battery, including a positive electrode with a composite positive electrode layer. The composite positive electrode layer contains a high-voltage oxide positive electrode material and an oxide solid electrolyte. A conductive oxide is used instead of a carbon-based conductive agent to avoid reaction between the positive electrode surface and the carbon-based conductive agent, thus preventing damage to electrochemical activity. A sintering aid is used to react with residual lithium on the positive electrode surface to form a stable passivation layer, and after diffusion, a robust "ceramic-ceramic" sintering neck connection is formed between the particles of the composite positive electrode layer. This structure not only provides an excellent electronic conductivity network but also establishes a fast ion transport path throughout the composite positive electrode, thereby achieving superior rate performance and low overall internal resistance.

[0021] refer to Figure 1 , Figure 1 These are exemplary configuration diagrams of an all-solid-state battery according to some embodiments of this application. Figure 1 As shown, the all-solid-state battery includes a positive electrode 100, a sulfide solid electrolyte layer 200, and a negative electrode 300 stacked sequentially.

[0022] The positive electrode 100 may include a positive current collector 110 and a composite positive electrode layer 120 located on one side of the positive current collector 110. The positive current collector 110 may be made of a material with electronic conductivity. For example, the positive current collector 110 may be aluminum foil, aluminum alloy foil, titanium foil, titanium alloy foil, stainless steel foil, carbon-based current collector, aluminum-polymer-aluminum composite foil, carbon-coated aluminum foil, etc.

[0023] The composite cathode layer 120 may include a high-voltage oxide cathode material, an oxide solid electrolyte, a conductive oxide, and a sintering aid. The particles of the high-voltage oxide cathode material, the oxide solid electrolyte, and the conductive oxide are bonded together through sintering necks based on the sintering aid.

[0024] The high-voltage oxide cathode material (or cathode active material) may include lithium cobalt oxide (LCO, LiCoO2) and lithium nickel cobalt manganese oxide (NCM, LiNi). x Co y Mn 1-x-y O2, such as in high-nickel ternary materials LiN 0.8 Co 0.1 Mn 0.1 O2), lithium manganese oxide (LMO, LiMn2O4), lithium nickel manganese oxide (LNMO, LiNi 0.5 Mn 1.5 At least one of the following: O4), lithium-rich manganese base oxide (LRLO,xLi2MnO3·(1-x)LiMO2, where M is at least one of Ni, Co, and Mn).

[0025] The oxide solid electrolyte can be used to construct lithium-ion conductive pathways that penetrate the bulk phase surrounding the oxide cathode substrate. For example, the oxide solid electrolyte may include Li... 0.5 La 0.5 TiO3, LiSr 1.5 Zr 0.5 Ta 1.5 O8, Li7La3Zr2O 12 Li 1.3 Al 0.3 Ti 1.7 (PO4)3, Li 1.4 Al 0.4 Ge 1.6 (PO4)3, LiZr2(PO4)3, LiTi2(PO4)3, Li 3.5 Si 0.5 P 0.5 At least one of O4, Li2SO4-Li2O-B2O3.

[0026] The conductive oxide may include electronic conductive pathways that can be used to construct the bulk phase surrounding the oxide cathode substrate. For example, the conductive oxide may include SnO2, ZnO, In2O3:Sn, SnO2:F, ZnO:Al, RuO2, La, etc. 1-x Sr xAt least one of MnO3, CuAlO2, and SrCu2O2. In some implementations, the conductive oxide may be coated on the surface of the high-voltage oxide cathode substrate. For example, the conductive oxide is first mixed with the high-voltage oxide cathode substrate before participating in the construction of the composite cathode layer. This application uses conductive oxides instead of carbon-based conductive agents, avoiding the problem of carbon-based conductive agents reacting with lattice oxygen or even bulk oxygen on the surface of the oxide cathode, leading to oxygen deficiency on the cathode material surface, irreversible phase transition, and severe damage to its electrochemical activity. It also avoids the problem of carbon-based conductive agents reducing the oxide solid electrolyte, destroying its crystal structure, and causing a decrease in ionic conductivity.

[0027] The composite cathode material formed by mixing the high-voltage oxide cathode material, the oxide solid electrolyte, and the conductive oxide can be carried out with the addition of a binder. Since the surface structure of the high-voltage oxide cathode material will be damaged after absorbing moisture, the binder may include an oil-based binder, including at least one of polyvinylidene fluoride (PVDF), polyvinyl butyral (PVB), polyimide (PI), polyamide-imide (PAI), fluororubber (FKM / FVPM), polybutyl methacrylate (PBMA), and ethyl cellulose (EC). Using oil-based binders not only completely avoids harmful reactions with sulfide components in the subsequent solid electrolyte layer and residual alkali on the cathode surface, but also ensures the chemical stability and safety of the slurry (if the composite cathode layer 120 is prepared by wet film formation) during the preparation process: the surface of high-nickel ternary and other oxide cathode materials is rich in residual alkali, which will dissolve in water, making the slurry strongly alkaline; many low-melting-point oxides or their precursors (such as boric acid H3BO3, some lithium salts) are water-soluble or hygroscopic, and in aqueous slurries, they may dissolve and migrate in advance, resulting in uneven distribution after drying.

[0028] For example, the mixture of the high-voltage oxide positive electrode material and the conductive oxide is first mixed with the oxide solid electrolyte and the binder in an organic solvent, then thoroughly mixed, stirred, and dispersed to obtain a composite positive electrode slurry. This slurry is coated onto a substrate and dried to obtain a film, which is composed of composite positive electrode particles "connected" by the binder. Alternatively, the mixture of the high-voltage oxide positive electrode material and the conductive oxide can be fed into a high-speed shearing machine for fiberization, where the composite positive electrode particles are "connected" by the binder.

[0029] The sintering aid can be used to strengthen the interfacial bonding between composite cathode materials (i.e., high-voltage oxide cathode material, oxide solid electrolyte, and conductive oxide) and reduce interfacial impedance. Elements such as metallic elements (e.g., Li, Al, Mg, Zn, In, Ag, Cu, Co, Bi, Ni, Fe, etc.), inorganic oxides (e.g., aluminum oxide Al₂O₃, calcium oxide CaO, magnesium oxide MgO, zinc oxide ZnO, titanium dioxide TiO₂, zirconium dioxide ZrO₂, yttrium oxide Y₂O₃, lanthanum oxide La₂O₃, cerium oxide CeO₂, yttrium oxide Y₂O₃, vanadium pentoxide V₂O₅, nickel trioxide Ni₂O₃, antimony trioxide Sb₂O₃, indium oxide In₂O₃, gallium oxide Ga₂O₃, tin dioxide SnO₂, silicon dioxide SiO₂, phosphorus pentoxide P₂O₅, boron oxide B₂O₃, silicon monoxide SiO, germanium dioxide GeO₂, tellurium dioxide TeO₂, selenium dioxide SeO₂, etc.), and metals Fluorides (e.g., lithium fluoride LiF, magnesium fluoride MgF2, aluminum fluoride AlF3, zinc fluoride ZnF2, calcium fluoride CaF2, yttrium fluoride YF3, lanthanum fluoride LaF3, cerium fluoride CeF3, zirconium fluoride ZrF4, bismuth fluoride BiF3, etc.), metal nitrides (e.g., boron nitride BN, aluminum nitride AlN, silicon nitride Si3N4, titanium nitride TiN, vanadium nitride VN, gallium nitride GaN, lithium nitride Li3N, indium nitride InN, etc.), lithium-containing compounds (e.g., lithium oxide Li2O, lithium aluminate LiAlO2, lithium zirconate Li2ZrO3, lithium silicate Li2SiO3, lithium borate Li3BO3, lithium indium oxide LiInO2, lithium lanthanum titanate LaLiTiO3, etc.) at least one or any combination thereof can be used as the sintering aid. For example, the sintering aid may include at least one selected from Li3BO3, LiF, SiO2, P2O5, MgO, CaO, TiO2, Y2O3, V2O5, Ni2O3, SeO2, Sb2O3, La2O3, AlF3, CaF2, BN, Ni, Cu, and Ag. The sintering aid may be added during the aforementioned blending / shearing process and melted or softened during subsequent heat treatment (e.g., heat treatment after drying to remove solvent and forming a film, or heat treatment after pressing into a film), thereby forming sintering necks between the composite cathode particles.

[0030] In some implementations, the diffusion temperature (i.e., melting or softening temperature) of the sintering aid can be 300-1000°C. While this temperature is lower than the densification temperature required for the oxide solid electrolyte itself, the sintering aid forms a robust "ceramic-ceramic" sintering neck connection between the high-voltage oxide cathode material, the oxide solid electrolyte, and the conductive oxidant. This structure not only provides an excellent electronic conductivity network but also establishes a fast ion transport path throughout the composite cathode, thereby achieving superior rate performance and low overall internal resistance. Furthermore, the diffusion temperature of the sintering aid does not prevent the conductive oxide from undergoing reduction or phase transition at heat treatment temperatures, and it does not compete with the high-voltage oxide cathode material and the oxide solid electrolyte for oxygen, thus fully preserving the interface modification effect and ion network construction of the sintering aid. Simultaneously, the effective sintering neck connection also enhances the mechanical strength of the composite cathode layer 120.

[0031] In some implementations, the thickness of the composite cathode layer 120 can be between 50 μm and 300 μm. For example, the thickness of the composite cathode layer 120 can be 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, or any increment or decrease of any of the above values. This application does not impose any specific limitation on this.

[0032] The solid electrolyte layer 200 may include a sulfide solid electrolyte layer, and the sulfide solid electrolyte material may include, but is not limited to, Li2S–P2S5 and Li2S–P2S5–MS. x (M=Si, Ge, Sn, 0≤x≤2), Li 9.6 P3S 12 Li7P3S 11 Li7P2S8I, Li 10 SnP2S 12 Li 10 SiP2S 12 , Li3PS4, Li9P3S9O3, LGPS (Li 10 GeP2S 12 Thio-LISICON (Li 3.25 Ge 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 Ge 0.25 P 0.75 S4, Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2S11.7 O 0.3 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 10.35 Ge 1.35 P 1.65 S 12 Li 10.35 Si 1.35 P 1.65 S 12 Li 9.81 Sn 0.81 P 2.19 S 12 Li 10 (Si 0.5 Ge 0.5 P2S 12 Li 10 (Ge 0.5 Sn 0.5 P2S 12 Li 10 (Si 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 Li6PS5I 0.2 Cl 0.8 Li5SnS2C l3 Li 10 P3S 12 Cl2, Li7P2S 8.5 Cl 0.5 Derivatives produced by doping or coating with materials such as, or any combination thereof, or related materials. Optionally or preferably, the sulfide solid electrolyte material of the solid electrolyte layer 200 can be Li6PS5Cl, Li3PS4, Li 10 GeP2S 12 Or Li7P3S 11 One or more of the halogen / oxygen doped modified materials, or the above materials.

[0033] The negative electrode 300 may include a negative electrode current collector and a negative electrode active material located on one side of the negative electrode current collector. The negative electrode current collector can be implemented using a metal plate with electronic conductivity. Currently known negative electrode current collectors can all be used in this application. For example, the negative electrode current collector is a copper foil. The negative electrode active material can be a metallic material (such as Li, Ag, Al, Bi, Cu, Ga, Ge, In, Ni, Pb, Sb, Si, Sn, Sr, Zn, etc., or alloys or compounds of the above metals, such as Li–Sn alloys, Li–Sn–O alloys, Sn, SnO, SnO2, TiO2–Li4Ti5O). 12 Li Al alloys, Ag–C alloys, etc., carbon materials (such as graphite including natural / artificial graphite, carbon fibers, soft carbon, hard carbon, crystalline carbon, amorphous carbon, etc.), silicon compounds (such as silicon, silicon-oxygen compounds, silicon-carbon compounds), or composite materials formed by metals and carbon / silicon. In some implementations, the negative electrode 300 can be a silicon-containing negative electrode (Si / SiO). x / Si-C), lithium metal anode, lithium alloy anode (Li-Mg, Li-Al, Li-Sn, Li-In, Li-Zn), silver-carbon anode (Ag-C), lithium titanate anode (LTO, Li4Ti5O) 12 One of the following. When the negative electrode 300 is a lithium metal negative electrode or a lithium alloy negative electrode, if a lithium foil or alloy foil is used for self-support, the negative electrode 300 may not require a negative current collector.

[0034] The composite cathode layer in the all-solid-state battery disclosed in this application introduces oxide solid electrolyte and conductive oxide, and introduces specific sintering aids. Under low melting point sintering conditions, a stable "ceramic-ceramic" sintering neck connection is formed inside the composite cathode layer, and the surface of the high-voltage oxide cathode material particles is locally modified / passivated at the same time. This solves the problems of poor physical contact and unstable chemical interface, and greatly increases the safety performance of the battery.

[0035] This application discloses, in another aspect, a method for preparing an all-solid-state battery, including a step for preparing a composite cathode. This is provided as an exemplary but not limiting illustration, with reference to... Figure 2 As shown, the preparation steps include: S1. A composite mixture is obtained by mechanically fusing high-voltage oxide cathode material with conductive oxide. S2. The composite cathode precursor layer is obtained by mixing the composite mixture, the oxide solid electrolyte, the binder and the sintering aid and forming a film. S3. Heat-treat the composite cathode precursor layer to obtain the composite cathode layer; wherein the sintering aid forms a sintering neck during the heat treatment process.

[0036] In step S1, the mechanical fusion allows the conductive oxide to coat the surface of the high-voltage oxide cathode active material. For example, micron / nano-sized conductive oxide particles ("guest particles") and high-voltage oxide cathode active material particles ("host particles") are fed into a mechanical fusion machine. Through the synergistic action of centrifugal force, extrusion force, shear force, and friction, a core-shell structured composite mixture is formed. The "core" is the high-voltage oxide cathode active material particle, and the "shell" is the conductive oxide. The resulting composite mixture can further improve conductivity and cycle stability. For the above mechanical fusion process, the rotation speed can be 1000 rpm-2000 rpm, for example, 1000 rpm, 1300 rpm, 1500 rpm, 1800 rpm, 2000 rpm, or any value within this range. The fusion time can be 5 min-15 min, for example, 5 min, 10 min, 15 min, or any increment or decrease within this range.

[0037] For step S2, the film formation can be achieved based on wet coating. For example, the composite mixture, the oxide solid electrolyte, the sintering aid, and the binder are added to a solvent and mixed to obtain a composite slurry. This solvent can be an organic solvent, including but not limited to N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), γ-butyrolactone (GBL), dimethyl sulfoxide (DMSO), butanone (MEK), tetrahydrofuran (THF), diethyl ether / methyl tert-butyl ether (MTBE), diethylene glycol dimethyl ether (DGM), etc. 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 uniform composite slurry. This composite slurry can be coated onto a polymer substrate using blade coating, slot extrusion coating, or cast coating to form a wet film, and then dried to obtain the composite cathode precursor. The polymer substrate is made of a thermally decomposable polymer material and serves as a temporary adhesive / support layer, capable of complete decomposition and vaporization at relatively low temperatures (e.g., 200-500°C) during subsequent heat treatment. For example, the polymer substrate may include at least one of polyester film, polycarbonate film, polyamide film, and modified cellulose film. A polymer substrate with a thickness of 5-250 μm can be used here to provide good support.

[0038] The drying of the wet film described above can be carried out at 80℃-180℃, for example, vacuum drying or oven drying at 100℃. The drying time can be 6h-24h, and can be adjusted according to the actual situation to achieve complete removal of the solvent.

[0039] The mass ratio of all the raw materials forming the composite cathode precursor layer, the high-voltage oxide cathode material, the oxide solid electrolyte, the conductive oxide, the binder and the sintering aid can be (60-80):(10-30):(1-10):(0.5-5):(1-10).

[0040] For step S3, the heat treatment can be performed in an oxygen atmosphere or an air atmosphere. The composite cathode precursor layer obtained by drying in step S2 can be held at 300℃-1000℃ for 0.5h-5h to complete the heat treatment process. In some examples, the composite cathode precursor layer can be placed in an air furnace and subjected to gradient heating, for example, at a rate of 5℃ / min, 10℃ / min, to a target temperature, such as 700℃, 800℃, and then held at that temperature. Subsequently, it is cooled in the furnace to obtain the composite cathode layer. The sintering aid will melt or soften during the heat treatment process, thereby forming a strong sintering neck between the composite cathode particles.

[0041] The above method for preparing an all-solid-state battery may further include: providing a positive electrode current collector, and pressing the composite positive electrode layer and the positive electrode current collector together under flat pressure to obtain a positive electrode sheet; and sequentially stacking the positive electrode sheet, the sulfide solid electrolyte layer, and the negative electrode sheet, followed by isostatic pressing to obtain the all-solid-state battery. The positive electrode current collector can be the positive electrode current collector described above, such as aluminum foil. The composite positive electrode layer and the positive electrode current collector are stacked and then pressed, for example, under flat pressure, at a pressure between 5 MPa and 200 MPa. After pressing, the positive electrode sheet, the sulfide solid electrolyte layer, and the negative electrode sheet can be sequentially stacked and pressed to obtain the all-solid-state battery. This process can be achieved using isostatic pressing. The isostatic pressing pressure can be 300 MPa-500 MPa, the time can be 5 min-20 min, and the temperature can be 25℃-90℃. Using flat pressure followed by isostatic pressing can improve density and ionic conductivity.

[0042] The all-solid-state battery and its fabrication method provided in this application utilize conductive oxides instead of carbon-based conductive agents. During heat treatment, sintering aids preferentially react with residual lithium on the surface of the high-voltage oxide cathode material, forming a stable passivation layer. This physically isolates the direct contact between the sulfide electrolyte and the oxide cathode material, significantly reducing active lithium loss and interfacial impedance growth caused by interfacial side reactions. Simultaneously, mechanical fusion pre-coating ensures electronic pathways, and the melting / softening effect of sintering aids at lower temperatures forms a robust "ceramic-ceramic" sintering neck connection between the high-voltage oxide cathode material, the oxide solid electrolyte, and the conductive oxide particles. This structure not only provides an excellent electronic conductivity network but also establishes a rapid ion transport path throughout the composite cathode, achieving superior rate performance and low overall internal resistance. The aforementioned interface stabilization and structural integration design enable all-solid-state batteries using high-ionic-conductivity sulfide electrolytes to simultaneously achieve high energy density, high power density, and long cycle life.

[0043] This application also discloses a battery module 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.

[0044] 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.

[0045] Example 1 1. Preparation of positive electrode sheet 1.1 Using LiNi oxide cathode material 0.8 Co 0.1 Mn 0.1 O2 and In2O3:Sn nanoparticles (ITO, 20nm) were premixed at a ratio of 70:2 in a high-speed fusion machine at 600 rpm for 5 minutes, and then the speed was increased to 1500 rpm for high-speed fusion for 10 minutes. 1.2 LiNi 0.8 Co 0.1 Mn 0.1 O2 and In2O3:Sn nanoparticles (ITO, 20nm), Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The low-melting-point oxide (sintering aid) Li3BO3 and the binder PVDF were mixed in a mass ratio of 70:2:22:4:2, and an appropriate amount of NMP was added. The mixture was ball-milled for 24 hours to obtain a uniform slurry. 1.3 The slurry was cast onto the modified cellulose membrane, with a wet film thickness of approximately 100 µm, and then dried at 100 °C. 1.4 The dried positive electrode film was heated to 800°C in an air furnace at a rate of 5°C / min and held at that temperature for 2 hours, and then cooled in the furnace. 1.5 The heat-treated positive electrode film is pressed and composited with a carbon-coated aluminum foil current collector at a pressing pressure of 20 MPa and a pressing temperature of 60 °C to obtain the positive electrode sheet.

[0046] 2. Fabrication of all-solid-state batteries The composite positive electrode film, Li6PS5Cl sulfide electrolyte layer, and Ag-C negative electrode are stacked and packaged in sequence, and then subjected to isostatic pressing at a pressure of 400 MPa for a time of 12 minutes and a temperature of 60°C to obtain an all-solid-state battery.

[0047] Example 2 1. Preparation of positive electrode sheet 1.1 Using LiNi oxide cathode material 0.8 Co 0.1 Mn 0.1 O2 and In2O3:Sn nanoparticles (ITO, 20nm) were premixed at a ratio of 74:1.5 in a high-speed fusion machine at 600 rpm for 5 minutes, and then the speed was increased to 1500 rpm for high-speed fusion for 10 minutes. 1.2 LiNi 0.8 Co 0.1 Mn 0.1 O2 and In2O3:Sn nanoparticles (ITO, 20nm), Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The low-melting-point oxide Li3BO3 and binder PVDF were mixed in a mass ratio of 74:1.5:20:4:0.5, and an appropriate amount of NMP was added. The mixture was ball-milled for 24 hours to obtain a uniform slurry. 1.3 The slurry was cast onto the modified cellulose membrane, with a wet film thickness of approximately 100 µm, and then dried at 100 °C. 1.4 The dried positive electrode film was heated to 700°C in an air furnace at a rate of 5°C / min and held at that temperature for 2 hours, and then cooled in the furnace. 1.5 The heat-treated positive electrode film is pressed and laminated with a carbon-coated aluminum foil current collector at a pressing pressure of 20 MPa and a pressing temperature of 60 ℃.

[0048] 2. Fabrication of all-solid-state batteries The composite positive electrode film, Li6PS5Cl sulfide electrolyte layer, and Ag-C negative electrode are stacked and packaged in sequence, and then subjected to isostatic pressing at a pressure of 400 MPa for a time of 12 minutes and a temperature of 60°C to obtain an all-solid-state battery.

[0049] Example 3 1. Preparation of positive electrode sheet 1.1 The oxide cathode material LiCoO2 and SnO2:F nanoparticles were premixed at a ratio of 65:2.5 in a high-speed fusion machine at 600 rpm for 5 minutes, and then the speed was increased to 1800 rpm for high-speed fusion for 10 minutes. 1.2 LiCoO2, SnO2:F, Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The low-melting-point oxide Li3BO3 and binder PVDF were mixed in a mass ratio of 65:2.5:25:5:2.5, and an appropriate amount of NMP was added. The mixture was ball-milled for 24 hours to obtain a uniform slurry. 1.3 The slurry was cast onto the modified cellulose membrane, with a wet film thickness of approximately 100 µm, and then dried at 100 °C. 1.4 Place the dried positive electrode film in an oxygen atmosphere furnace, heat it to 700℃ at a rate of 5℃ / min, hold it at that temperature for 1.5 hours, and then cool it with the furnace. 1.5 The heat-treated positive electrode film is pressed and composited with a carbon-coated aluminum foil current collector at a pressing pressure of 20 MPa and a pressing temperature of 60 ℃.

[0050] 2. Fabrication of all-solid-state batteries The composite positive electrode film, Li6PS5Cl sulfide electrolyte layer, and Ag-C negative electrode are stacked and packaged in sequence, and then subjected to isostatic pressing at a pressure of 400 MPa for a time of 12 minutes and a temperature of 60°C to obtain an all-solid-state battery.

[0051] Example 4 1. Preparation of positive electrode sheet 1.1 The oxide cathode material LiCoO2 and SnO2:F nanoparticles were premixed at a ratio of 70:2 in a high-speed fusion machine at 600 rpm for 5 minutes, and then the speed was increased to 1800 rpm for high-speed fusion for 10 minutes. 1.2 LiCoO2, SnO2:F, Li 6.4 La3Zr 1.4 Ta 0.6 O 12 The low-melting-point oxide V2O5 and binder PVDF were mixed in a mass ratio of 70:2:22:4:2, and an appropriate amount of NMP was added. The mixture was ball-milled for 24 hours to obtain a uniform slurry. 1.3 The slurry was cast onto the modified cellulose membrane, with a wet film thickness of approximately 100 µm, and then dried at 100 °C. 1.4 Place the dried positive electrode film in an oxygen atmosphere furnace, heat it to 700°C at a rate of 5°C / min, hold it at that temperature for 2 hours, and then cool it with the furnace.

[0052] 2. Fabrication of all-solid-state batteries An aluminum foil current collector, the aforementioned composite positive electrode film, a Li6PS5Cl sulfide electrolyte layer, and an Ag-C negative electrode are sequentially stacked and packaged. Then, an isostatic pressing process is performed at a pressure of 400 MPa for a time preferably of 12 minutes and a temperature of 60°C to obtain an all-solid-state battery.

[0053] Example 5 1. Preparation of positive electrode sheet 1.1 Using LiNi oxide cathode material 0.9 Co 0.05 Mn 0.05 O2 and ZnO:Al are premixed at a ratio of 70:2 in a high-speed fusion machine at 600 rpm for 5 minutes, and then the speed is increased to 1800 rpm for high-speed fusion for 15 minutes. 1.2 LiNi 0.9 Co 0.05 Mn 0.05 O2, ZnO:Al, Li 1.3 Al 0.3 Ti 1.7 (PO4)3, low-melting-point oxide AlF3 and binder PVDF are mixed in a mass ratio of 70:2:22:4:2, with an appropriate amount of NMP added, and ball-milled for 24 hours to obtain a uniform slurry. 1.3 The slurry was cast onto the modified cellulose membrane, with a wet film thickness of approximately 100 µm, and then dried at 100 °C. 1.4 Place the dried positive electrode film in an oxygen atmosphere furnace, heat it to 800°C at a rate of 5°C / min, hold it at that temperature for 1 hour, and then cool it with the furnace.

[0054] 2. Fabrication of all-solid-state batteries An aluminum foil current collector, the aforementioned composite positive electrode film, a Li6PS5Cl sulfide electrolyte layer, and an Ag-C alloy negative electrode are sequentially stacked and packaged. Then, an isostatic pressing process is performed at a pressure of 400 MPa for a time preferably of 12 minutes and a temperature of 60°C to obtain an all-solid-state battery.

[0055] Example 6 1. Preparation of positive electrode sheet 1.1 Using LiNi oxide cathode material 0.9 Co 0.05 Mn 0.05O2 and RuO2 nanoparticles were premixed at a ratio of 70:2 in a high-speed fusion machine at 600 rpm for 5 minutes, and then the speed was increased to 1800 rpm for high-speed fusion for 15 minutes. 1.2 LiNi 0.9 Co 0.05 Mn 0.05 O2, RuO2 nanoparticles, Li2SO4-Li2O-B2O3, low-melting-point oxide Li3BO3 and binder PVDF are mixed in a mass ratio of 70:2:22:4:2, and an appropriate amount of NMP is added. The mixture is ball-milled for 24 hours to obtain a uniform slurry. 1.3 The slurry was cast onto the modified cellulose membrane, with a wet film thickness of approximately 100 µm, and then dried at 100 °C. 1.4 Place the dried positive electrode film in an oxygen-protected tube furnace, heat it to 500°C at a rate of 5°C / min, hold it at that temperature for 1.5 hours, and then cool it with the furnace.

[0056] 2. Fabrication of all-solid-state batteries An aluminum foil current collector, the aforementioned composite positive electrode film, a Li6PS5Cl sulfide electrolyte layer, and an Ag-C alloy negative electrode are sequentially stacked and packaged. Then, an isostatic pressing process is performed at a pressure of 400 MPa for a time preferably of 12 minutes and a temperature of 60°C to obtain an all-solid-state battery.

[0057] Comparative Example 1 Comparative Example 1 did not add low-melting-point oxides (sintering aids) and did not undergo calcination. The specific steps are as follows.

[0058] 1. LiNi 0.8 Co 0.1 Mn 0.1 O2, Li 6.4 La3Zr 1.4 Ta 0.6 O 12 Super P and binder PVDF are mixed in a mass ratio of 70:26:2:2, with an appropriate amount of NMP added, and ball milled for 24 hours to obtain a uniform slurry; 2. The slurry is cast onto a modified cellulose membrane, with a wet film thickness of approximately 100 µm, and then dried at 100°C to obtain a composite positive electrode membrane. 3. The aluminum foil current collector, the above-mentioned composite positive electrode film, the Li6PS5Cl sulfide electrolyte layer, and the Li-Mg alloy negative electrode are stacked and packaged in sequence, and then subjected to isostatic pressing treatment at a pressure of 400MPa, a time preferably of 12 minutes, and a temperature of 60℃ to obtain an all-solid-state battery.

[0059] Comparative Example 2 Comparative Example 2 did not add low-melting-point oxides (sintering aids). The specific steps are as follows.

[0060] 1. LiNi 0.8 Co 0.1 Mn 0.1 O2, Li 6.4 La3Zr 1.4 Ta 0.6 O 12 In2O3:Sn nanoparticles (ITO, 20nm) and binder PVDF were mixed in a mass ratio of 70:26:2:2, and an appropriate amount of NMP was added. The mixture was ball-milled for 24 hours to obtain a uniform slurry. 2. Cast the slurry onto the modified cellulose membrane, with a wet film thickness of approximately 100 µm, and then dry it at 100°C. 3. Place the dried positive electrode film in an argon-protected tube furnace, heat it to 500℃ at a rate of 5℃ / min, hold it at that temperature for 1.5 hours, and then cool it with the furnace. 4. The aluminum foil current collector, the above-mentioned composite positive electrode film, the Li6PS5Cl sulfide electrolyte layer, and the Li-Mg alloy negative electrode are stacked and packaged in sequence, and then subjected to isostatic pressing treatment at a pressure of 400MPa, a time preferably of 12 minutes, and a temperature of 60℃ to obtain an all-solid-state battery.

[0061] Although Comparative Example 2 underwent heat treatment, due to the absence of sintering aids, effective sintered neck connections failed to form between the positive electrode particles at the heat treatment temperature, and its internal structure remained primarily loose physical contact. This comparative example illustrates that, in the absence of sintering aids, simple heat treatment cannot achieve the interfacial bonding and network construction effects achieved in this application.

[0062] Comparative Example 3 Comparative Example 3 uses a solid electrolyte without oxides. The specific steps are as follows.

[0063] 1. LiNi 0.8 Co 0.1 Mn 0.1 O2, In2O3:Sn nanoparticles (ITO, 20nm), low-melting-point oxide Li3BO3 and binder PVDF were added in a mass ratio of 92:2:4:2 with an appropriate amount of NMP, and ball-milled for 24 hours to obtain a uniform slurry. 2. Cast the slurry onto the modified cellulose membrane, with a wet film thickness of approximately 100 µm, and then dry it at 100°C. 3. Place the dried positive electrode film in an argon-protected tube furnace, heat it to 500℃ at a rate of 5℃ / min, hold it at that temperature for 1.5 hours, and then cool it with the furnace. 4. The aluminum foil current collector, the above-mentioned composite positive electrode film, the Li6PS5Cl sulfide electrolyte layer, and the Li-Mg alloy negative electrode are stacked and packaged in sequence, and then subjected to isostatic pressing treatment at a pressure of 400MPa, a time preferably of 12 minutes, and a temperature of 60℃ to obtain an all-solid-state battery.

[0064] Test case Evaluation of rate retention and reversibility: The all-solid-state batteries obtained in the examples and comparative examples were charged and discharged starting from a low rate of 0.1C, gradually increasing to 0.5C, 1C, 2C, and then returning to the low rate. The initial coulombic efficiency was recorded, which directly reflects the severity of the consumption of active lithium by interfacial side reactions. The specific test results are shown in Table 1.

[0065] Table 1 Test Results As shown in Table 1, compared with Comparative Examples 1-6 and Comparative Examples 1-3, Examples 1-6, by using an oxide solid electrolyte and a conductive oxidant, and adding a sintering aid, achieve a higher discharge specific capacity, thus exhibiting a higher energy density. Furthermore, they demonstrate excellent first-cycle coulombic efficiency, retaining more reversible lithium in the all-solid-state battery. The all-solid-state batteries of these examples exhibit superior electrical performance.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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: A positive electrode, a negative electrode, and a sulfide solid electrolyte layer are stacked together. The positive electrode includes a positive current collector and a composite positive electrode layer located on at least one side of the positive current collector; wherein, The composite cathode layer includes a high-voltage oxide cathode material, an oxide solid electrolyte, a conductive oxide, and a sintering aid. The high-voltage oxide cathode material, the oxide solid electrolyte, and the conductive oxide particles are bonded together through a sintering neck based on the sintering aid. The sintering aid includes at least one of the following: elemental metal, inorganic oxide, metal fluoride, metal nitride, and lithium-containing compound.

2. The all-solid-state battery according to claim 1, characterized in that, The high-voltage oxide cathode material includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, lithium-rich manganese base oxide, and lithium nickel manganese oxide. The oxide solid electrolyte includes Li 0.5 La 0.5 TiO3, LiSr 1.5 Zr 0.5 Ta 1.5 O8, Li7La3Zr2O 12 Li 1.3 Al 0.3 Ti 1.7 (PO4)3, Li 1.4 Al 0.4 Ge 1.6 (PO4)3, LiZr2(PO4)3, LiTi2(PO4)3, Li 3.5 Si 0.5 P 0.5 At least one of O4, Li2SO4-Li2O-B2O3; The conductive oxides include SnO2, ZnO, In2O3:Sn, SnO2:F, ZnO:Al, RuO2, and La. 1-x Sr x At least one of MnO3, CuAlO2, and SrCu2O2.

3. The all-solid-state battery according to claim 1, characterized in that, The sintering aid includes at least one of Li3BO3, LiF, SiO2, P2O5, MgO, CaO, TiO2, Y2O3, V2O5, Ni2O3, SeO2, Sb2O3, La2O3, AlF3, CaF2, BN, Ni, Cu, and Ag.

4. The all-solid-state battery according to claim 1, characterized in that, The sulfide solid electrolyte layer includes a sulfide solid electrolyte, which comprises Li6PS5Cl, Li3PS4, and Li 10 GeP2S 12 Li7P3S 11 At least one of its halogenated or oxygen-doped modified materials.

5. The all-solid-state battery according to claim 1, characterized in that, The thickness of the composite cathode layer is 50μm-300μm.

6. A method for preparing an all-solid-state battery as described in any one of claims 1-5, characterized in that, The preparation steps include the following: S1. A composite mixture is obtained by mechanically fusing high-voltage oxide cathode material with conductive oxide. S2. The composite cathode precursor layer is obtained by mixing the composite mixture, the oxide solid electrolyte, the binder and the sintering aid and forming a film. S3. Heat-treat the composite cathode precursor layer to obtain the composite cathode layer; wherein... The sintering aid forms a sintering neck during the heat treatment process.

7. The method for preparing an all-solid-state battery according to claim 6, characterized in that, The film formation in step S2 is achieved based on wet coating, including: The composite mixture, the oxide solid electrolyte, the sintering aid, and the binder are mixed and homogenized in a solvent to obtain a composite slurry; The composite slurry is coated onto a polymer substrate to form a wet film, and after drying, the composite positive electrode precursor layer is obtained; wherein... The above process satisfies at least one of the following (1)-(3): (1) The polymer substrate includes at least one of polyester film, polycarbonate film, polyamide film, and modified cellulose film; (2) The thickness of the polymer substrate is 5μm-250μm; (3) The drying temperature is 80℃-180℃ and the drying time is 6h-24h.

8. The method for preparing an all-solid-state battery according to claim 6, characterized in that, The preparation steps satisfy at least one of the following (1)-(3): (1) The mass ratio of the high-voltage oxide positive electrode material, the oxide solid electrolyte, the conductive oxide, the binder and the sintering aid is (60-80):(10-30):(1-10):(0.5-5):(1-10); (2) The rotation speed of the mechanical fusion is 1000rpm-2000rpm, and the fusion time is 5min-10min; (3) The atmosphere of the heat treatment process is an oxygen atmosphere or an air atmosphere, the heat treatment temperature is 300℃-1000℃, and the time is 0.5h-5h.

9. The method for preparing an all-solid-state battery according to claim 6, characterized in that, The method for preparing the all-solid-state battery also includes: A positive electrode current collector is provided, and the composite positive electrode layer and the positive electrode current collector are pressed together to obtain a positive electrode sheet; The positive electrode, sulfide solid electrolyte layer, and negative electrode are sequentially stacked and then subjected to isostatic pressing to obtain the all-solid-state battery; wherein... The pressure of the flat pressing is 5MPa-200MPa; The isostatic pressing process is performed at a pressure of 300MPa-500MPa, a processing time of 5min-20min, and a processing temperature of 25℃-90℃.

10. A battery module, characterized in that, Including all-solid-state batteries as described in any one of claims 1 to 5.

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