Sulfide-halide composite solid electrolyte and preparation method thereof, and solid-state battery

Abstract

The application provides a sulfide-halide composite solid electrolyte, a preparation method thereof and a solid-state battery. The method comprises the following steps: mixing ball milling a sulfide electrolyte, a halide electrolyte, a dopant and an interface modifier under inert gas protection to obtain a composite electrolyte powder; tabletting and forming the composite electrolyte powder under inert gas protection to obtain a composite solid electrolyte sheet; and annealing the composite solid electrolyte sheet under inert gas protection to obtain a sulfide-halide composite solid electrolyte. The sulfide-halide composite solid electrolyte can realize the synergistic improvement of multiple performances, has high room-temperature ionic conductivity and a wide electrochemical stability window, and has improved air stability and good mechanical performance.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery technology, specifically relating to a sulfide-halide composite solid electrolyte, its preparation method, and a solid-state battery. Background Technology

[0002] The escalating global energy crisis and heightened environmental awareness have driven a surge in demand for high-performance energy storage devices in fields such as new energy vehicles, energy storage systems, and consumer electronics. While traditional liquid lithium-ion batteries possess high energy density and ionic conductivity, the liquid electrolyte poses safety hazards such as leakage, flammability, and explosion, and exhibits poor stability under extreme conditions, making it difficult to meet the development requirements of next-generation battery technologies. Solid-state batteries, which replace liquid electrolytes with solid electrolytes, offer advantages such as high safety, high energy density, long cycle life, and wide environmental adaptability, becoming the core development direction in the energy storage field. As a core component, the performance of the solid electrolyte directly determines the overall performance of the solid-state battery.

[0003] Currently, solid electrolytes are mainly classified into four categories: oxides, sulfides, halides, and polymers. Among them, sulfide electrolytes and halide electrolytes have become research hotspots due to their unique properties, but each system has significant shortcomings. Sulfide electrolytes have the highest industrialization potential, with room temperature ionic conductivity approaching or even exceeding that of liquid electrolytes. They also exhibit excellent machinability, high lithium-ion transference numbers, and relatively mature preparation processes. However, they have extremely poor air stability, readily reacting with water vapor and oxygen in the air to generate toxic gases and damage the crystal structure, requiring a stringent inert environment for production, storage, and transportation. Furthermore, they have a narrow electrochemical stability window, making them unsuitable for high-voltage cathodes and lithium metal anodes. They also have poor compatibility with electrode interfaces, easily leading to side reactions and the formation of high-resistivity layers. Additionally, the high cost of core raw materials restricts their large-scale application.

[0004] On the other hand, halide electrolytes are an emerging research direction in recent years. They have a wide electrochemical stability window, are compatible with high-voltage cathode materials, and have better air stability and compatibility with lithium metal anodes than sulfide electrolytes, with lower raw material costs. However, the room temperature ionic conductivity of this system is still lower than that of high-performance sulfide electrolytes, making it difficult to meet the requirements of high-rate batteries. Furthermore, it is intrinsically brittle, with poor mechanical flexibility and compressibility, and easily forms interfacial gaps with the electrode. Some systems also suffer from poor cycle performance and moisture absorption and hydrolysis problems.

[0005] To combine the advantages of both, existing technologies propose a sulfide-halide composite solid electrolyte approach, hoping to improve performance through synergistic effects. Previous studies have attempted to construct this composite system, partially achieving a combination of high conductivity and high safety, but several drawbacks remain: the synergistic effect of sulfides and halides is difficult to fully realize; the preparation process is complex and prone to interphase interface reactions, leading to electrolyte performance degradation; and there are high interfacial impedances and poor long-term stability.

[0006] In summary, both existing single sulfide and halide electrolytes have performance limitations. Current composite systems have not yet resolved issues related to component synergy, interfacial reactions, and process compatibility, making it difficult to simultaneously meet the comprehensive requirements of solid-state batteries for high ionic conductivity, a wide electrochemical window, good air stability, interfacial compatibility, and mechanical properties. Therefore, developing a sulfide-halide composite solid-state electrolyte with a simple preparation process and synergistic performance improvement is of great significance. Summary of the Invention

[0007] Based on the technical problems described above, the purpose of this invention is to overcome the shortcomings of existing sulfide-halide composite solid electrolytes, such as poor performance synergy, poor air stability and interfacial compatibility, and complex preparation processes. This invention provides a new sulfide-halide composite solid electrolyte and a simple, low-energy-consumption preparation method suitable for large-scale production. It also provides solid-state batteries containing this electrolyte to meet the application needs of various fields for high-performance and high-safety energy storage batteries.

[0008] Specifically, according to one aspect of the present invention, a method for preparing a sulfide-halide composite solid electrolyte is provided, the method comprising the following steps:

[0009] (1) The sulfide electrolyte, halide electrolyte, dopant and interface modifier are mixed and ball-milled under inert gas protection to obtain composite electrolyte powder;

[0010] (2) The composite electrolyte powder is pressed into a sheet under inert gas protection to obtain a composite solid electrolyte sheet;

[0011] (3) The composite solid electrolyte sheet is annealed under inert gas protection to obtain a sulfide-halide composite solid electrolyte, wherein:

[0012] The sulfide electrolyte is one or more of Li6PS5Cl, Li6PS5Br and Li6PS5I;

[0013] The halide electrolyte is a mixture of Li2ZrCl6 and Li3InCl6;

[0014] The dopant is selected from one or more of MgBr2, Ga2S3, Al2O3, Y2S3, CaCl2, InCl3 and SiS2;

[0015] The interface modifier is silane coupling agent modified SiO2, and

[0016] Based on the total weight of the composite electrolyte powder as 100%, the sulfide electrolyte accounts for 40-80% by weight, the halide electrolyte accounts for 15-50% by weight, the dopant accounts for 0.5-8% by weight, and the interface modifier accounts for 0.1-5% by weight.

[0017] According to certain preferred embodiments of the present invention, the sulfide electrolyte is a mixture of Li6PS5Cl and Li6PS5Br in a weight ratio of 3:1 to 2:1.

[0018] According to certain preferred embodiments of the present invention, the halide electrolyte is a mixture of Li2ZrCl6 and Li3InCl6 in a weight ratio of 6:1 to 4:1.

[0019] According to certain preferred embodiments of the present invention, the dopant is a mixture of MgBr2 and Ga2S3 in a weight ratio of 3:1 to 1:1.

[0020] According to certain preferred embodiments of the present invention, the interface modifier is SiO2 modified with γ-aminopropyltriethoxysilane, wherein the degree of modification of γ-aminopropyltriethoxysilane is 5-30 by weight.

[0021] According to certain preferred embodiments of the present invention, the average particle size of the interface modifier is in the range of 20-100 nm.

[0022] According to certain preferred embodiments of the present invention, the preparation method further includes a step of drying the sulfide electrolyte, the halide electrolyte, the dopant and the interface modifier before step (1).

[0023] According to certain preferred embodiments of the present invention, in the drying process, the sulfide electrolyte, halide electrolyte and dopant are vacuum dried at 80-120°C for 8-12 hours, and the interface modifier is vacuum dried at 60-80°C for 4-6 hours.

[0024] According to certain preferred embodiments of the present invention, the preparation method further includes the step of ball milling the dried sulfide electrolyte and the dried halide electrolyte under inert gas protection.

[0025] According to certain preferred embodiments of the present invention, in the step of ball milling the dried sulfide electrolyte, the ball-to-material ratio is 10:1-20:1, the rotation speed is 200-400 r / min, and the ball milling time is 2-4 hours, to obtain sulfide electrolyte powder with a particle size of 100-500 nm.

[0026] According to certain preferred embodiments of the present invention, in the step of ball milling the dried halide electrolyte, the ball-to-material ratio is 8:1-15:1, the rotation speed is 150-300 r / min, and the ball milling time is 1-3 hours, to obtain halide electrolyte powder with a particle size of 200-600 nm.

[0027] According to certain preferred embodiments of the present invention, in step (1), the ball-to-material ratio of the ball mill is 12:1-25:1, the rotation speed is 250-450 r / min, and the milling time is 4-8 hours.

[0028] According to certain preferred embodiments of the present invention, in step (2), the pressure of the tablet forming is 50-150 MPa, the holding time is 5-15 minutes, and a composite solid electrolyte sheet with a thickness of 0.1-1 mm is obtained.

[0029] According to certain preferred embodiments of the present invention, in step (2), the mold used for tableting is preheated at 80-100°C.

[0030] According to certain preferred embodiments of the present invention, in step (3), the annealing treatment is performed at a temperature of 150-300°C for 2-6 hours.

[0031] According to certain preferred embodiments of the present invention, based on the total weight of the composite electrolyte powder as 100%, the sulfide electrolyte accounts for 55-70% by weight, the halide electrolyte accounts for 25-40% by weight, the dopant accounts for 2-4% by weight, and the interface modifier accounts for 1-2% by weight.

[0032] According to certain preferred embodiments of the present invention, in step (1), the sulfide electrolyte, halide electrolyte, dopant, interface modifier and antioxidant are mixed and ball-milled under inert gas protection to obtain composite electrolyte powder.

[0033] According to certain preferred embodiments of the present invention, the antioxidant is selected from one or more of di-tert-butyl-p-cresol, butylated hydroxyanisole, and sodium sulfite.

[0034] According to certain preferred embodiments of the present invention, the antioxidant accounts for 0.01-0.1% by weight, based on 100% of the total weight of the composite electrolyte powder.

[0035] According to certain preferred embodiments of the present invention, the inert gas is argon or nitrogen, and the flow rate of the inert gas is in the range of 8-25 mL / min.

[0036] According to another aspect of the present invention, a sulfide-halide composite solid electrolyte is provided, which is prepared according to the method described above.

[0037] According to certain preferred embodiments of the present invention, the room temperature ionic conductivity of the composite solid electrolyte is 5-15 mS·cm. -1 .

[0038] According to certain preferred embodiments of the present invention, the electrochemical window of the composite solid electrolyte is 0-5.0 V (vs. Li / Li). + ).

[0039] According to certain preferred embodiments of the present invention, after the composite solid electrolyte is exposed to an environment with a humidity of 5-10% for 72 hours, the ionic conductivity retention rate is greater than or equal to 81%.

[0040] According to certain preferred embodiments of the present invention, the composite solid electrolyte has a flexural strength greater than or equal to 15 MPa and a compressive strength greater than or equal to 30 MPa.

[0041] According to another aspect of the present invention, a solid-state battery is provided, comprising a positive electrode, a negative electrode, a solid electrolyte layer, and a casing, wherein the solid electrolyte layer is a sulfide-halide composite solid electrolyte as described above, the positive electrode and the negative electrode are respectively located on both sides of the solid electrolyte layer, and the casing is used to encapsulate the positive electrode, the negative electrode, and the solid electrolyte layer.

[0042] According to certain preferred embodiments of the present invention, the positive electrode comprises a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder, wherein, based on 100% by weight of the positive electrode, the positive electrode active material accounts for 80-95% by weight, the positive electrode conductive agent accounts for 3-10% by weight, and the positive electrode binder accounts for 2-10% by weight.

[0043] According to certain preferred embodiments of the present invention, the positive electrode active material is a high-voltage positive electrode material selected from LiCoO2 and LiNi. x Co y Mn 1-x-y O2, LiNi x Co y Al 1-x-y The positive electrode is a mixture of one or more of O2, LiMn2O4 and LiFePO4, wherein x = 0.6-0.9 and y = 0.05-0.2; the positive electrode conductive agent is selected from one or more of superconducting carbon black, acetylene black, Ketjen black, graphene and carbon nanotubes; the positive electrode binder is selected from one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyimide and sodium carboxymethyl cellulose.

[0044] According to certain preferred embodiments of the present invention, the negative electrode comprises a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder, wherein, based on 100% by weight of the negative electrode, the negative electrode active material accounts for 85-98% by weight, the negative electrode conductive agent accounts for 1-8% by weight, and the negative electrode binder accounts for 1-7% by weight.

[0045] According to certain preferred embodiments of the present invention, the negative electrode active material is selected from one or more of lithium foil, lithium alloy, graphite, hard carbon, soft carbon and silicon-based materials; the negative electrode conductive agent is selected from one or more of superconducting carbon black, acetylene black, Ketjen black, graphene and carbon nanotubes; and the negative electrode binder is selected from one or more of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose and styrene-butadiene rubber.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] (1) Through the synergistic effect of specific components and ratios, the composite solid electrolyte of the present invention possesses both the high room temperature ionic conductivity (5-15 mS·cm) of sulfide systems. -1 The wide electrochemical window (0-5.0 V) of the halogen system allows it to be adapted to high-voltage cathodes and lithium metal anodes.

[0048] (2) The introduction of halide electrolytes and interface modifiers makes the ionic conductivity retention rate of electrolytes reach more than 81% after exposure to humidity environment, which solves the industry problem of poor air stability of sulfide electrolytes.

[0049] (3) The interface modifier effectively reduced the internal impedance of the electrolyte and the interface impedance with the electrode. At the same time, the introduction of nano-SiO2 played a reinforcing role, giving the electrolyte both good flexibility and compressive strength (bending strength ≥15 MPa, compressive strength ≥30 MPa), effectively inhibiting lithium dendrite growth.

[0050] (4) The method of the present invention uses drying, ball milling, tableting and low temperature annealing as basic processes. It does not require complex equipment and harsh conditions. The process is short, energy consumption is low, batch stability is good, and it is suitable for large-scale industrial production. Attached Figure Description

[0051] The accompanying drawings are provided in this specification to more clearly explain the technical solutions of the present invention; however, the art is not limited thereto.

[0052] Figure 1 A flowchart illustrating the preparation process of a sulfide-halide composite solid electrolyte according to the present invention is shown.

[0053] Figure 2A scanning electron microscope (SEM) image of the sulfide-halide composite solid electrolyte prepared in Example 1 is shown. Detailed Implementation

[0054] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It will be understood that other embodiments may be implemented without departing from the scope or spirit of the invention. Therefore, the following detailed description is non-limiting.

[0055] Unless otherwise specified, all figures used in this specification to represent characteristic dimensions, quantities, and physical properties should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters listed in the foregoing specification are approximations, and those skilled in the art can appropriately modify these approximations to obtain the desired properties using the teachings disclosed herein.

[0056] As mentioned above, existing solid-state electrolytes suffer from the following problems: single sulfide electrolytes exhibit poor air stability, narrow electrochemical windows, and poor compatibility with electrode interfaces; single halide electrolytes suffer from low ionic conductivity and high mechanical brittleness. The synergistic effect of traditional sulfide-halide composite electrolytes is difficult to achieve, and interphase interface reactions are prone to occur, leading to high interfacial impedance and poor long-term stability. Furthermore, existing composite electrolyte preparation processes are complex and energy-intensive, failing to simultaneously meet the comprehensive requirements of solid-state batteries for high ionic conductivity, wide electrochemical windows, good air stability, interfacial compatibility, and mechanical properties. This invention aims to solve one or more of the above-mentioned technical problems.

[0057] According to one aspect of the present invention, a method for preparing a sulfide-halide composite solid electrolyte is provided. Figure 1 A flowchart illustrating the preparation process of a sulfide-halide composite solid electrolyte according to the present invention is shown, specifically including the following steps:

[0058] (1) The sulfide electrolyte, halide electrolyte, dopant and interface modifier are mixed and ball-milled under inert gas protection to obtain composite electrolyte powder;

[0059] (2) The composite electrolyte powder is pressed into tablets under inert gas protection to obtain composite solid electrolyte sheets;

[0060] (3) The composite solid electrolyte sheet is annealed under inert gas protection to obtain sulfide-halide composite solid electrolyte.

[0061] Specifically, the preparation method of the sulfide-halide composite solid electrolyte provided by this invention uses sulfide electrolyte and halide electrolyte as core substrates. Through the lattice regulation effect of dopants and the interface optimization effect of interface modifiers, the synergistic improvement of various properties of the composite electrolyte is achieved. Furthermore, the entire preparation process is simple, low-energy, and easily scalable, solving the technical problems of poor component synergy, frequent interfacial reactions, and complex preparation processes in existing composite electrolyte systems. The following provides a detailed description of the selection of raw materials, the proportion range, and each process step of this preparation method.

[0062] I. Raw material selection and proportioning for preparation method

[0063] In the preparation method of this invention, sulfide electrolytes provide a basis for high ionic conductivity, halide electrolytes broaden the electrochemical stability window and improve air stability, dopants achieve lattice defect modulation to enhance ion migration efficiency, and interface modifiers optimize the compatibility between the phase interface and the electrode interface. Synergistic performance effects are achieved by controlling the types and proportions of each raw material.

[0064] (a) Sulfide electrolytes

[0065] The sulfide electrolyte selected in this invention is one or more of Li6PS5Cl, Li6PS5Br, and Li6PS5I. These sulfide electrolytes are lithium superionic conductors, possessing intrinsically high lithium-ion transference numbers and room-temperature ionic conductivity. Their crystal structures contain numerous lithium-ion transport channels, making them the core substrate for achieving high conductivity in composite electrolytes. Among them, Li6PS5Cl and Li6PS5Br exhibit superior overall performance, with both showing better ionic conductivity and chemical stability than Li6PS5I. Therefore, in a preferred embodiment of this invention, the sulfide electrolyte is a mixture of Li6PS5Cl and Li6PS5Br in a weight ratio of 3:1 to 2:1. Within this ratio range, the high ionic conductivity of Li6PS5Cl and the good interfacial compatibility of Li6PS5Br complement each other, thereby simultaneously improving both electrical and interfacial properties.

[0066] Based on the total weight of the composite electrolyte powder (100%), the proportion of sulfide electrolyte is 40-80% by weight, preferably 55-70% by weight. When the proportion of sulfide electrolyte is less than 40% by weight, the composite electrolyte cannot obtain sufficient lithium-ion transport channels, and the room temperature ionic conductivity will drop significantly, making it difficult to meet the requirements of high-rate batteries. When the proportion of sulfide electrolyte is greater than 80% by weight, the proportion of halide electrolyte is excessively compressed, failing to effectively broaden the electrochemical stability window. Furthermore, the air stability of the composite electrolyte will revert to the level of a single sulfide electrolyte, making it prone to reacting with water vapor and oxygen in the air, while its mechanical brittleness will also increase significantly.

[0067] (ii) Halogenated electrolytes

[0068] The halide electrolyte used in this invention is a mixture of Li₂ZrCl₆ and Li₃InCl₆, rather than a single halide electrolyte. This is because Li₂ZrCl₆ alone has poor mechanical properties and high intrinsic brittleness, while Li₃InCl₆ alone has low ionic conductivity. The combination of the two allows for complementary performance. Li₂ZrCl₆ has the advantage of a wide electrochemical stability window, making it suitable for high-voltage cathode materials, while Li₃InCl₆ has good compatibility with lithium metal anodes and mechanical flexibility. The composite halide phase formed by the two retains the characteristics of a wide electrochemical window while improving mechanical properties and interfacial compatibility.

[0069] In a preferred embodiment of the present invention, the halide electrolyte is a mixture of Li₂ZrCl₆ and Li₃InCl₆ in a weight ratio of 6:1 to 4:1. At this ratio, Li₂ZrCl₆ is the main phase, ensuring a wide electrochemical window for the composite electrolyte, while Li₃InCl₆ is the secondary phase, playing a role in interface modification and mechanical property enhancement.

[0070] Based on the total weight of the composite electrolyte powder (100%), the halide electrolyte accounts for 15-50% by weight, preferably 25-40% by weight. When the halide electrolyte accounts for less than 15% by weight, its advantages of a wide electrochemical window and air stability cannot be fully realized, the electrochemical window of the composite electrolyte remains relatively narrow, and the humidity stability retention rate decreases significantly. When the halide electrolyte accounts for more than 50% by weight, it will squeeze out the proportion of sulfide electrolyte, resulting in a significant decrease in the ionic conductivity of the composite electrolyte.

[0071] (III) Dopant

[0072] The dopants selected in this invention are one or more of MgBr2, Ga2S3, Al2O3, Y2S3, CaCl2, InCl3, and SiS2. These dopants are all ionic dopants, with cation radii similar to those of lithium ions or metal cations in the sulfide / halide lattice. Lattice doping can introduce appropriate lattice defects, increasing lithium ion transport sites while suppressing phase reactions between sulfides and halides, thus improving the structural stability of the composite electrolyte. Among these, MgBr2 and Ga2S3 show the best doping effects, with Mg... 2+ Li can replace the sulfide lattice + Introducing cation vacancies, Ga 3+ Can replace P 5+To achieve lattice charge compensation, the synergistic doping of MgBr2 and Ga2S3 significantly improves lithium-ion migration efficiency. Therefore, in a preferred embodiment of the present invention, the dopant is a mixture of MgBr2 and Ga2S3 in a weight ratio of 3:1 to 1:1. Within this ratio range, the introduction of cation vacancies in MgBr2 and the charge compensation in Ga2S3 work synergistically to effectively improve ionic conductivity.

[0073] Based on the total weight of the composite electrolyte powder (100%), the dopant content is 0.5-8% by weight, preferably 2-4% by weight. The amount of dopant added is controlled by micro-scale. When the amount added is less than 0.5% by weight, sufficient lattice defects cannot be introduced, resulting in little improvement in ionic conductivity and inability to effectively suppress phase reactions. When the amount added is greater than 8% by weight, excessive dopant becomes impurity sites for lithium-ion transport, blocking lithium-ion transport channels and causing a decrease in ionic conductivity. At the same time, excessive doping will destroy the lattice structure of sulfides and halides, reducing the mechanical strength and structural stability of the composite electrolyte.

[0074] (iv) Interface modifiers

[0075] The interface modifier selected in this invention is SiO2 modified with a silane coupling agent. Unmodified SiO2 has poor interfacial compatibility with sulfide and halide electrolytes, easily generating interfacial voids. Modification with a silane coupling agent introduces organic functional groups onto the SiO2 surface. One end binds to the hydroxyl groups on the SiO2 surface, while the other end forms chemical bonds with the functional groups of the sulfide and halide electrolytes, thereby achieving tight interfacial bonding and reducing interfacial impedance. Simultaneously, SiO2, being nano-sized inorganic particles, can act as a reinforcing agent, improving the mechanical properties of the composite electrolyte. In a preferred embodiment of this invention, the interface modifier is SiO2 modified with γ-aminopropyltriethoxysilane. γ-aminopropyltriethoxysilane has both amino and ethoxy functional groups. The ethoxy group can undergo hydrolysis and condensation reactions with the hydroxyl groups on the SiO2 surface, and the amino group can react with the sulfur groups in the sulfide electrolyte. 2- Cl in halide electrolytes - It forms coordination bonds, resulting in better interfacial bonding than other silane coupling agents. Preferably, the degree of modification of γ-aminopropyltriethoxysilane is 5-30% by weight. Within this modification range, the density of organic functional groups on the SiO2 surface is moderate, which can ensure good interfacial compatibility without blocking lithium-ion transport channels due to excessive organic functional groups.

[0076] Meanwhile, the average particle size of the interface modifier is preferably in the range of 20-100 nm. This particle size is at the nanoscale and can be uniformly dispersed in the matrix of the composite electrolyte, playing a role in uniform interface modification and mechanical reinforcement.

[0077] Based on the total weight of the composite electrolyte powder (100%), the proportion of the interface modifier is 0.1-5% by weight, preferably 1-2% by weight. When the proportion of the interface modifier is less than 0.1% by weight, sufficient modification of the sulfide-halide phase interface and subsequent electrode interface cannot be achieved, and the interface impedance remains high. When the proportion is greater than 5% by weight, excess SiO2 will become an insulating phase, reducing the ionic conductivity of the composite electrolyte and increasing its brittleness.

[0078] (v) Optional antioxidants

[0079] In a preferred embodiment of the present invention, an antioxidant is optionally added, selected from one or more of di-tert-butyl-p-cresol, butylated hydroxyanisole, and sodium sulfite. This type of antioxidant, under inert gas protection, further inhibits the oxidation of the sulfide electrolyte by trace amounts of oxygen during the preparation process, avoiding the generation of byproducts such as Li₂S and SO₂, and ensuring the structural purity and performance stability of the composite electrolyte. The antioxidant accounts for 0.01-0.1% of the total weight of the composite electrolyte powder (100%).

[0080] (vi) Inert gases

[0081] All process steps of this invention are performed under inert gas protection. Argon or nitrogen is selected as the inert gas. The flow rate of the inert gas is in the range of 8-25 mL / min. Argon provides better protection than nitrogen and is a more preferred inert gas.

[0082] II. Process steps of the preparation method

[0083] The preparation method of the present invention uses drying, ball milling, tableting and annealing as basic steps, and the entire process does not require complex equipment, has low energy consumption, is easy to scale up, and is suitable for industrial mass production.

[0084] (I) Raw material drying pretreatment

[0085] In a preferred embodiment of the present invention, the sulfide electrolyte, halide electrolyte, dopant, and interface modifier are dried before the ball milling step.

[0086] Specifically, the sulfide electrolyte, halide electrolyte, and dopant are vacuum dried at 80-120°C for 8-12 hours; the interface modifier is vacuum dried at 60-80°C for 4-6 hours. After drying, all raw materials are cooled to room temperature and quickly transferred back to an inert gas glove box to prevent re-absorption of moisture.

[0087] (ii) Single electrolyte ball milling

[0088] In a preferred embodiment of the present invention, after drying, the dried sulfide electrolyte and the dried halide electrolyte are ball-milled separately under inert gas protection; that is, the single electrolyte is ball-milled first, followed by mixed ball milling. The purpose of this step is to refine the sulfide electrolyte and halide electrolyte to nanoscale particle size, increasing their specific surface area. This allows for more uniform mixing during subsequent mixed ball milling, preventing phase separation. Simultaneously, the nanoscale particle size increases the sulfide-halide phase contact area, enhancing synergistic performance.

[0089] For ball milling of sulfide electrolytes, the ball-to-material ratio is 10:1-20:1, the rotation speed is 200-400 r / min, and the milling time is 2-4 hours.

[0090] For ball milling of halide electrolytes, the ball-to-material ratio is 8:1-15:1, the rotation speed is 150-300 r / min, and the milling time is 1-3 hours.

[0091] The preferred grinding balls used in the ball milling process are zirconia grinding balls, and the particle size of the grinding balls can be selected according to the actual ball milling requirements, preferably 5-10 mm zirconia grinding balls.

[0092] (III) Mixed ball milling

[0093] Mixing and ball milling is one of the important steps in the preparation method of this invention. The ball-milled sulfide electrolyte powder, halide electrolyte powder, and dried dopant and interface modifier (preferably with added antioxidant) are mixed and ball-milled under inert gas protection to obtain composite electrolyte powder. The purpose of this step is to achieve uniform mixing of the raw materials at the molecular level. Simultaneously, the mechanical force of ball milling allows the dopant to be uniformly incorporated into the crystal lattice of the sulfide and halide, and the interface modifier to be uniformly adsorbed on the surface of each phase, thus achieving simultaneous lattice regulation and interface modification.

[0094] According to the present invention, the ball-to-material ratio of the mixed ball mill is 12:1-25:1, the rotation speed is 250-450 r / min, and the ball milling time is 4-8 hours. Within this range of process parameters, uniform dispersion of each raw material can be achieved, and the lattice doping and interface modification effects are optimal, forming a uniform sulfide-halide composite phase.

[0095] After the mixing and ball milling is completed, the resulting composite electrolyte powder is a nano-sized uniform powder with a uniform particle size distribution and no obvious agglomeration, providing a good raw material basis for subsequent tableting.

[0096] (iv) Tableting

[0097] The tableting process is the process of forming a dense composite solid electrolyte sheet from composite electrolyte powder. This involves pressing the composite electrolyte powder under an inert gas atmosphere to obtain the composite solid electrolyte sheet.

[0098] In this invention, the tableting pressure is 50-150 MPa, and the holding time is 5-15 minutes. Under this pressure and holding time, the composite electrolyte powder can be pressed into a sheet with a density higher than 90%. Preferably, the mold used for tableting is preheated at 80-100°C. Preheating the mold reduces the friction between the composite electrolyte powder and the mold, ensuring uniform pressure transmission, improving the density and surface smoothness of the sheet, and preventing the powder from clumping due to low temperature during tableting. Preferably, the thickness of the composite solid electrolyte sheet obtained after tableting is 0.1-1 mm.

[0099] The mold used in the tableting process is a stainless steel mold. The size of the mold can be selected according to actual needs, preferably a round mold with a diameter of 10-25 mm.

[0100] (v) Annealing treatment

[0101] Annealing is another important step in the preparation method of this invention. The composite solid electrolyte sheet is annealed under an inert gas atmosphere to obtain the final sulfide-halide composite solid electrolyte. The purpose of this step is to eliminate internal stress generated during the compression molding process, improve the crystallinity and structural stability of the composite electrolyte, promote the fusion between sulfides and halides, further reduce interfacial impedance, and improve lithium-ion transport efficiency.

[0102] The present invention specifies that the annealing temperature is 150-300℃ and the time is 2-6 hours.

[0103] Annealing can optionally employ programmed heating and cooling, with a heating rate of 5-10℃ / min and a cooling rate of 3-5℃ / min. Slow heating and cooling prevent cracking of the sheet due to sudden temperature changes, ensuring the integrity of the composite electrolyte sheet. After annealing, the composite solid electrolyte sheet is cooled to room temperature in the furnace to obtain the final sulfide-halide composite solid electrolyte.

[0104] III. Sulfide-halide composite solid electrolyte

[0105] According to another aspect of the present invention, a sulfide-halide composite solid electrolyte is provided, which is prepared by any of the above-described preparation methods.

[0106] The composite solid electrolyte of this invention has a room temperature ionic conductivity of 5-15 mS·cm. -1This value is higher than the ionic conductivity of existing single halide electrolytes and traditional sulfide-halide composite electrolytes, and is close to or even exceeds the ionic conductivity of liquid electrolytes, which can fully meet the lithium-ion transport requirements of high-rate solid-state batteries.

[0107] Furthermore, the electrochemical window of the composite solid electrolyte of the present invention is 0-5.0V (vs. Li / Li). + This wide electrochemical stability window is superior to that of single sulfide electrolytes (typically around 0-3.5V), and it is compatible with current mainstream high-voltage cathode materials (such as NCM811, NCA, etc., with operating voltages of 3.0-4.8V). At the same time, it has good compatibility with lithium metal anodes and will not undergo reduction reactions on the surface of lithium metal anodes, thus avoiding the formation of a high-resistivity solid electrolyte interphase (SEI) film.

[0108] Furthermore, the air stability of the composite solid electrolyte of this invention is significantly improved. After exposure to an environment with a humidity of 5-10% for 72 hours, the ionic conductivity retention rate is greater than or equal to 81%. The improved air stability is due to the good moisture resistance of the halide electrolyte and the modification of the composite electrolyte surface by the interface modifier, which forms a dense protective layer that effectively isolates water vapor and oxygen in the air, preventing the hydrolysis and oxidation of the sulfide electrolyte.

[0109] The composite solid-state electrolyte of this invention possesses excellent mechanical properties, with a flexural strength greater than or equal to 15 MPa and a compressive strength greater than or equal to 30 MPa. These superior mechanical properties ensure that the composite electrolyte is not easily broken during the assembly and use of solid-state batteries. Simultaneously, it effectively inhibits the growth of lithium dendrites in the lithium metal anode, preventing lithium dendrites from penetrating the electrolyte and causing short circuits, thus improving the safety and cycle life of solid-state batteries. The improved mechanical properties are attributed to the reinforcing effect of the nano-scale SiO2 interface modifier and the structural synergy of the sulfide and halide composite phases, giving the composite electrolyte both flexibility and compressive strength.

[0110] IV. Solid-state batteries

[0111] According to another aspect of the present invention, a solid-state battery is provided, comprising a positive electrode, a negative electrode, a solid electrolyte layer, and a casing, wherein the solid electrolyte layer is the aforementioned sulfide-halide composite solid electrolyte, the positive electrode and the negative electrode are respectively located on opposite sides of the solid electrolyte layer, and the casing is used to encapsulate the positive electrode, the negative electrode, and the solid electrolyte layer. This solid-state battery possesses advantages such as high energy density, high rate performance, long cycle life, and high safety, solving the safety hazards of traditional liquid lithium-ion batteries and the performance shortcomings of existing solid-state batteries. It can be widely used in new energy vehicles, energy storage systems, consumer electronics, and other fields.

[0112] Specifically, the solid-state battery of the present invention has a stacked structure, in which a positive electrode, a solid electrolyte layer, and a negative electrode are stacked sequentially to form a cell. The cell is encapsulated by a casing, which can be an aluminum-plastic film casing or a metal casing, depending on the battery's application scenario. The solid electrolyte layer is the aforementioned sulfide-halide composite solid electrolyte sheet, which can be adjusted according to the battery's energy density requirements. The positive and negative electrodes are tightly bonded to the solid electrolyte layer through hot or cold pressing to ensure good interfacial contact and reduce interfacial resistance.

[0113] The positive electrode comprises a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder. The preferred weight ratio of each component is as follows: based on 100% of the weight of the positive electrode, the positive electrode active material accounts for 80-95% by weight, the positive electrode conductive agent accounts for 3-10% by weight, and the positive electrode binder accounts for 2-10% by weight.

[0114] The positive electrode active material is preferably a high-voltage positive electrode material, selected from LiCoO2 and LiNi. x Co y Mn 1-x-y O2, LiNi x Co y Al 1-x-y A mixture of one or more of O2, LiMn2O4, and LiFePO4, wherein x = 0.6-0.9 and y = 0.05-0.2. This type of high-voltage cathode material has a high operating voltage and large specific capacity, which is compatible with the wide electrochemical stability window of the composite electrolyte of this invention. The cathode conductive agent is preferably selected from one or more of superconducting carbon black, acetylene black, Ketjen black, graphene, and carbon nanotubes. This type of conductive agent has high electronic conductivity and can form a continuous electron transport network in the cathode, thereby improving the rate performance of the cathode. The cathode binder is preferably selected from one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyimide, and sodium carboxymethyl cellulose.

[0115] The positive electrode is prepared by a conventional coating method, which involves dispersing the positive electrode active material, positive electrode conductive agent and positive electrode binder in a solvent to form a positive electrode slurry. The positive electrode slurry is then coated onto a current collector (such as aluminum foil), and after drying and rolling, a positive electrode sheet is obtained.

[0116] The negative electrode comprises a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder. The preferred weight ratio of each component is as follows: based on 100% of the weight of the negative electrode, the negative electrode active material accounts for 85-98% by weight, the negative electrode conductive agent accounts for 1-8% by weight, and the negative electrode binder accounts for 1-7% by weight.

[0117] The negative electrode active material is preferably selected from one or more of lithium metal foil, lithium alloy, graphite, hard carbon, soft carbon and silicon-based materials, wherein lithium metal foil is the preferred negative electrode active material.

[0118] The negative electrode conductive agent is the same type as the positive electrode conductive agent, selected from one or more of superconducting carbon black, acetylene black, Ketjen black, graphene, and carbon nanotubes, and can be selected according to the actual needs of the negative electrode.

[0119] The negative electrode binder is preferably selected from one or more of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose and styrene-butadiene rubber. This type of binder has good adhesion to the negative electrode active material and has no side reaction with the composite electrolyte. Among them, the composite binder of styrene-butadiene rubber and sodium carboxymethyl cellulose has good compatibility with negative electrode active materials with large volume expansion, such as silicon-based negative electrodes, and can alleviate their volume expansion.

[0120] The preparation method of the negative electrode is selected according to the type of negative electrode active material. If it is lithium metal foil, it can be used directly as the negative electrode sheet; if it is graphite, silicon-based material, etc., the same coating method as the positive electrode can be used to coat it on the copper foil current collector, and then the negative electrode sheet is obtained after drying and rolling.

[0121] The solid-state battery of this invention can be manufactured into various forms such as pouch battery, cylindrical battery, and square battery according to actual application needs, and can be widely used in new energy vehicles, energy storage power stations, smartphones, laptops, drones and other fields, with broad market application prospects.

[0122] In summary, the preparation method of the sulfide-halide composite solid electrolyte of the present invention is simple, low-energy, and easy to scale up. By limiting the selection and ratio of raw materials and optimizing the process parameters, the prepared composite solid electrolyte achieves a synergistic improvement in high room temperature ionic conductivity, wide electrochemical stability window, good air stability, excellent mechanical properties, and interfacial compatibility.

[0123] The present invention will now be described in more detail with reference to embodiments. It should be noted that these descriptions and embodiments are intended to facilitate understanding of the present invention and are not intended to limit the invention.

[0124] Example

[0125] In this invention, unless otherwise specified, all reagents used are commercially available products and are used directly without further purification. Furthermore, "%" refers to "weight %" and "parts" refers to "parts by weight".

[0126] Table 1 below lists specific information about the raw materials used in the embodiments and comparative examples of the present invention.

[0127] Table 2 below lists specific information about the experimental equipment used in the embodiments and comparative examples of the present invention.

[0128] Performance testing methods

[0129] (a) Room temperature ionic conductivity

[0130] The room temperature ionic conductivity of solid electrolyte samples prepared in the following examples and comparative examples was tested according to the methods described below.

[0131] Specifically, referring to the national standard GB / T 39864-2021 "Test Method for Ionic Conductivity of Solid Electrolytes", the AC impedance spectroscopy method was used for testing. The specific steps are as follows: The solid electrolyte tablet was cut into circular pieces with a diameter of 14 mm. Surface residual impurities were removed in an argon glove box, and the film thickness (L) was accurately measured to 0.1 μm. Then, the sample was clamped between two polished stainless steel blocking electrodes to create a symmetrical battery with a stainless steel blocking electrode (SS) / solid electrolyte / stainless steel blocking electrode (SS) structure. Subsequently, using an electrochemical workstation, the test temperature was set to 25℃ (room temperature), the frequency range to 1Hz-1MHz, and the AC signal amplitude to 10mV. The temperature was kept constant during the test. Then, the Nyquist impedance spectrum was obtained, and the bulk resistance (R) corresponding to the intersection of the high-frequency region and the real axis was read. The ionic conductivity (σ) was calculated using the formula σ = L / (R×A), where A is the effective contact area of ​​the electrode. Each group of samples was tested in parallel three times, and the average value was taken as the final result (unit: mS·cm). -1 ).

[0132] (II) Electrochemical stability window

[0133] Electrochemical stability window tests were performed on solid electrolyte samples prepared in the following examples and comparative examples according to the methods described below.

[0134] Specifically, referring to the relevant electrochemical performance testing specifications in the national standard GB / T 39864-2021 "Test Method for Ionic Conductivity of Solid Electrolytes", the linear sweep voltammetry (LSV) method was adopted. The specific steps are as follows: the solid electrolyte tablet was cut into 14 mm diameter discs, surface impurities were removed in an argon glove box, and the thickness was accurately measured. Lithium metal foil was used as the counter electrode and reference electrode (Li / Li + Stainless steel was used as the working electrode, and an SS / solid electrolyte / Li symmetric cell was assembled. Then, the electrochemical workstation was started, the test temperature was set to 25℃, and the scan range was 0-6V (vs. Li / Li). + The scan rate was 1 mV / s. A linear scan was initiated under argon protection, and the current-voltage (IV) curve was recorded to observe current abrupt changes. When the current density reached 10 μA / cm², the scan was completed. 2The voltage value corresponding to the time is the upper limit of the electrochemical stability window (unit: V). The test results are expressed as 0 to the corresponding upper limit voltage. The average value is taken from 3 parallel tests.

[0135] (III) Humidity stability retention rate

[0136] The humidity stability retention rate of solid electrolyte samples prepared in the following examples and comparative examples was tested according to the methods described below.

[0137] Specifically, the solid electrolyte tablets prepared in the examples and comparative examples were pressed into discs with a diameter of 14 mm and a thickness of approximately 0.8 mm. These discs were then stored for 24 hours in an argon glove box at 25°C and a humidity of ≤1% RH to eliminate the influence of historical adsorption. Immediately after removal, the initial room temperature ionic conductivity σ0 was measured using the AC impedance method specified in the national standard GB / T 39864-2021 "Test Method for Ionic Conductivity of Solid Electrolytes". The samples were then placed in a programmable temperature and humidity chamber, with the temperature set at 25±1°C and the relative humidity at 8±2% RH (simulating a typical drying room environment), and continuously exposed for 72 hours. Temperature and humidity fluctuations within the chamber were recorded every 24 hours during this process, ensuring that the humidity was controlled within the range of 5-10% RH. After exposure, the samples were transferred to an argon glove box, and surface cleaning was completed within 30 minutes. The room temperature ionic conductivity σ0 was then immediately remeasured. t .

[0138] Calculate the humidity stability retention rate using the following formula: Retention rate (%) = (σ t / σ0)×100%

[0139] Each group of samples was tested in parallel three times, and the average value was taken as the final result. A retention rate of ≥80% was considered to meet the basic stability requirements, and a retention rate of ≥85% was considered to have excellent humidity stability.

[0140] (iv) Mechanical properties (flexural strength, compressive strength)

[0141] Bending strength was tested according to the national standard GB / T 6569-2006 "Test Method for Bending Strength of Fine Ceramics", using the three-point bending method. The specific steps were as follows: The composite electrolyte powder prepared by the mixed ball milling process in the following examples or comparative examples was pressed into tablets and processed into standard specimens of 2mm × 4mm × 36mm. The specimens were placed in an argon glove box at 25℃ and humidity ≤1% RH for 24 hours. The electronic universal testing machine was zeroed, the span was set to 30mm, and the loading rate to 1mm / min. The specimens were then placed on the support platform of the testing machine, and a load was applied until the specimens fractured. The maximum load at fracture was recorded. The bending strength was then calculated, with 5 parallel specimens tested in each group and the average value taken. The unit is MPa.

[0142] In addition, the compressive strength was tested according to the national standard GB / T 8489-2006 "Test Method for Compressive Strength of Ceramic Materials". The specific steps were as follows: The composite electrolyte powder prepared by the mixed ball milling process in the following examples or comparative examples was pressed into discs with a diameter of 10 mm and a thickness of 5 mm. The discs were then placed in an argon glove box at 25°C and humidity ≤1% RH for 24 hours. The electronic universal testing machine was set to a loading rate of 1 mm / min. Subsequently, the discs were placed between the upper and lower pressure plates of the testing machine, ensuring uniform load application. The equipment was started to apply the load until the disc broke, and the maximum compressive load at breakage was recorded. The compressive strength was then calculated, with 5 parallel discs tested in each group and the average value taken, in MPa.

[0143] Example 1 (E1)

[0144] The specific preparation steps of Example 1 are as follows:

[0145] (1) Raw material drying pretreatment:

[0146] According to the proportions shown in Table 3 below, in an argon glove box, take the following: sulfide electrolyte Li6PS5Cl (40 wt%), a mixture of halide electrolytes Li2ZrCl6 and Li3InCl6 (50 wt%, weight ratio 1:1), dopant Al2O3 (8 wt%), and interface modifier silane-modified silica 1 (γ-aminopropyltriethoxysilane-modified SiO2) (2 wt%). Place the sulfide electrolyte, the halide electrolyte, and the dopant in a vacuum drying oven and dry under vacuum at 120°C for 8 hours. Furthermore, dry the interface modifier under vacuum at 60°C for 6 hours. After drying, cool to room temperature and transfer back to the glove box.

[0147] (2) Ball milling of sulfide electrolytes and sulfide electrolytes:

[0148] The dried sulfide electrolyte Li6PS5Cl was mixed with zirconia grinding balls at a ball-to-material ratio of 10:1 and ball-milled at 200 r / min for 4 hours under argon protection to obtain sulfide electrolyte powder with a particle size of approximately 200 nm. Furthermore, the dried halide electrolyte mixture Li2ZrCl6 / Li3InCl6 was mixed with zirconia grinding balls at a ball-to-material ratio of 8:1 and ball-milled at 150 r / min for 3 hours under argon protection to obtain halide electrolyte powder with a particle size of approximately 200 nm.

[0149] (3) Mixed ball milling:

[0150] The ball-milled sulfide electrolyte powder and halide electrolyte powder were mixed with the dried dopant Al2O3 and the interface modifier silane-modified silica 1. Zirconia grinding balls (ball-to-material ratio 12:1) were added, and the mixture was ball-milled at 250 r / min for 8 hours under argon protection (flow rate 8 mL / min) to obtain composite electrolyte powder.

[0151] (4) Tableting:

[0152] The composite electrolyte powder was loaded into a mold with a diameter of 25 mm (the mold was preheated to 80°C), and pressed into a sheet under argon protection at a pressure of 50 MPa for 15 minutes to obtain a composite solid electrolyte sheet with a thickness of 1 mm.

[0153] (5) Annealing treatment:

[0154] The electrolyte sheet was transferred to a tube furnace and annealed at 150°C for 6 hours under argon protection (flow rate 8 mL / min). It was then cooled to room temperature in the furnace to obtain sulfide-halide composite solid electrolyte sheet 1.

[0155] Test results show that the sulfide-halide composite solid electrolyte sheet 1 prepared in Example 1 has a room temperature ionic conductivity of 5.2 mS·cm. -1 The electrochemical stability window is 0-4.5 V (vs. Li / Li). + It exhibits a humidity stability retention rate of 81.2%, a flexural strength of 15.3 MPa, and a compressive strength of 30.5 MPa.

[0156] Figure 2 A scanning electron microscope (SEM) image of the sulfide-halide composite solid electrolyte sheet 1 prepared in Example 1 is shown. Figure 2 It is evident that the obtained electrolyte has a dense internal structure, with sulfide and halide phases evenly distributed and no obvious interfacial voids or phase separation, indicating that the interface modifier effectively improves the compatibility between components.

[0157] Examples 2-12 (E2-E12) and Comparative Examples 1-5 (CE1-CE5)

[0158] Examples 2-12 (E2-E12) and Comparative Examples 1-5 (CE1-CE5) were prepared in a manner similar to that of Example 1 to prepare sulfide-halide composite solid electrolyte sheets 2-12 and 1-5, respectively, except that the component types and ratios were changed as shown in Table 3 below.

[0159] The performance testing methods described above were used to test the room temperature ionic conductivity, electrochemical stability window, humidity stability retention, flexural strength, and compressive strength of the sulfide-halide composite solid electrolyte sheet 2-12 and the comparative sulfide-halide composite solid electrolyte sheets 1-5, and the results are shown in Table 4 below. Furthermore, the scanning electron microscope (SEM) images of the sulfide-halide composite solid electrolyte sheet 2-12 prepared in Examples 2-12 show a structure similar to that of the sulfide-halide composite solid electrolyte sheet prepared in Example 1.

[0160] As can be seen from the performance test results in Table 4 above, the sulfide-halide composite solid electrolytes prepared in Examples 1-12 of this invention exhibit significantly better performance than Comparative Examples 1-5. Specifically, the room temperature ionic conductivity of the samples in Examples 1-12 is ≥ 5.0 mS·cm. -1 The optimal embodiment 12 even reaches 14.5 mS·cm -1 The highest conductivity of the samples in Comparative Examples 1-5 was only 4.5 mS·cm. -1 And most of them are below 4.0 mS·cm -1 This highlights the role of the composite system of the present invention in enhancing ion conduction performance.

[0161] Regarding the electrochemical window, the samples in Examples 1-12 all achieved a window of 0-4.4 V or higher, with Examples 10-12 achieving a wide window of 0-5.0 V, suitable for high-voltage cathode materials. In contrast, the electrochemical windows of Comparative Examples 1-5 were narrower than 0-4.2 V, failing to meet the requirements of high-voltage batteries. Regarding humidity stability, the humidity stability retention rates of Examples 1-12 were all ≥ 80.8%, with Examples 10-12 even exceeding 92%. Comparative Examples 1-5, however, were all below 76%, with some even below 70%, demonstrating that the component formulation of this invention significantly improves the air stability of the electrolyte.

[0162] In terms of mechanical properties, the bending strength of Examples 1-12 is ≥ 15.1 MPa and the compressive strength is ≥ 30.2 MPa, which meets the mechanical requirements for solid-state battery assembly and use. However, Comparative Examples 1-5 have lower mechanical strength due to missing component ratios or types, with bending strength below 14 MPa and compressive strength below 29 MPa.

[0163] The comparison shows that the comparative examples cannot achieve synergistic performance due to problems such as a single halide electrolyte, lack of interface modifier, and sulfide / halide ratio exceeding the scope of the present invention. However, the present invention, by limiting the compound type of sulfide and halide, controlling the distribution ratio of each group, and combining the synergistic effect of dopants and interface modifiers, has successfully achieved a comprehensive improvement in ionic conductivity, electrochemical window, air stability, and mechanical properties. Among them, the performance of Examples 10-12, which adopt the preferred ratio, reaches the optimal level.

[0164] Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from the spirit and scope of this disclosure. Therefore, if such modifications and variations fall within the scope of this invention, this disclosure is also intended to include such modifications and variations.

Claims

1. A method for preparing a sulfide-halide composite solid electrolyte, characterized in that, Includes the following steps: (1) The sulfide electrolyte, halide electrolyte, dopant and interface modifier are mixed and ball-milled under inert gas protection to obtain composite electrolyte powder; (2) The composite electrolyte powder is pressed into a sheet under inert gas protection to obtain a composite solid electrolyte sheet; (3) The composite solid electrolyte sheet is annealed under inert gas protection to obtain a sulfide-halide composite solid electrolyte, wherein: The sulfide electrolyte is one or more of Li6PS5Cl, Li6PS5Br and Li6PS5I; The halide electrolyte is a mixture of Li2ZrCl6 and Li3InCl6; The dopant is selected from one or more of MgBr2, Ga2S3, Al2O3, Y2S3, CaCl2, InCl3 and SiS2; The interface modifier is silane coupling agent modified SiO2, and Based on the total weight of the composite electrolyte powder as 100%, the sulfide electrolyte accounts for 40-80% by weight, the halide electrolyte accounts for 15-50% by weight, the dopant accounts for 0.5-8% by weight, and the interface modifier accounts for 0.1-5% by weight.

2. The method for preparing the sulfide-halide composite solid electrolyte according to claim 1, characterized in that, The sulfide electrolyte is a mixture of Li6PS5Cl and Li6PS5Br in a weight ratio of 3:1 to 2:

1.

3. The method for preparing the sulfide-halide composite solid electrolyte according to claim 1, characterized in that, The halide electrolyte is a mixture of Li2ZrCl6 and Li3InCl6 in a weight ratio of 6:1 to 4:

1.

4. The method for preparing the sulfide-halide composite solid electrolyte according to claim 1, characterized in that, The dopant is a mixture of MgBr2 and Ga2S3 in a weight ratio of 3:1 to 1:

1.

5. The method for preparing the sulfide-halide composite solid electrolyte according to claim 1, characterized in that, The interface modifier is γ-aminopropyltriethoxysilane-modified SiO2; and / or The average particle size of the interface modifier is in the range of 20-100 nm.

6. The method for preparing the sulfide-halide composite solid electrolyte according to claim 1, characterized in that, The preparation method further includes a drying process for the sulfide electrolyte, the halide electrolyte, the dopant and the interface modifier before step (1).

7. The method for preparing the sulfide-halide composite solid electrolyte according to claim 6, characterized in that, The preparation method further includes the step of ball milling the dried sulfide electrolyte and the dried halide electrolyte under inert gas protection.

8. The method for preparing the sulfide-halide composite solid electrolyte according to claim 1, characterized in that, In step (3), the annealing treatment is performed at a temperature of 150-300℃ for 2-6 hours.

9. A sulfide-halide composite solid electrolyte, characterized in that, The sulfide-halide composite solid electrolyte is prepared by the method according to any one of claims 1-8.

10. A solid-state battery, comprising a positive electrode, a negative electrode, a solid electrolyte layer, and a casing, characterized in that, The solid electrolyte layer is a sulfide-halide composite solid electrolyte according to claim 9, the positive electrode and the negative electrode are respectively located on both sides of the solid electrolyte layer, and the outer shell is used to encapsulate the positive electrode, the negative electrode and the solid electrolyte layer.

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