Solid-state electrolyte material, solid-state electrolyte membrane, preparation method of solid-state electrolyte membrane and solid-state battery

Abstract

The invention discloses a solid electrolyte material, a solid electrolyte membrane and a preparation method thereof, and a solid-state battery, belongs to the technical field of solid-state electrolyte, and solves the problems that the existing solid-state electrolyte is unstable in air and is easy to lose efficacy. The solid electrolyte material comprises sulfide solid electrolyte particles and a coating layer arranged on the surfaces of the sulfide solid electrolyte particles, the coverage rate of the coating layer on the surface of the solid electrolyte particle is more than 99%; the coating layer is an ionic liquid. According to the invention, the air isolation capability is greatly improved, the stability of the sulfide solid electrolyte material in the air is improved, the sulfide solid electrolyte material can be maintained for several days under a certain humidity condition, and the limitation that the existing sulfide solid electrolyte transportation and subsequent industrial application process can only be carried out under an anhydrous condition is overcome.

Description

Technical Field

[0001] The present application relates to the field of solid electrolyte technology, and in particular to a solid electrolyte material, a solid electrolyte membrane and a preparation method thereof, and a solid-state battery. Background Art

[0002] As a chemical energy storage device, lithium-ion batteries offer advantages such as high energy density, long cycle life, and low cost, and have been widely used in a wide range of applications, including electric vehicles, grid energy storage, and portable devices. However, in new energy vehicles and large-scale grid energy storage, lithium batteries face more stringent safety and energy density requirements. All-solid-state batteries, with their high energy density, high safety factor, fast charging rate, and long cycle life, are considered the "next-generation power battery" that will drive the advancement and application of new energy technologies, as they are expected to overcome the limitations of liquid batteries.

[0003] As an important component of solid-state batteries, sulfide solid electrolytes in electrolyte materials exhibit ionic conductivity comparable to that of liquid electrolytes compared to oxide- or polymer-based solid electrolytes, and they also have excellent processing performance, which is of great significance for improving the energy density and cycle life of solid-state batteries. However, sulfide electrolytes face the challenge of poor air stability. Contact with H2O in the air will produce highly toxic H2S gas, leading to structural damage and a significant decrease in ionic conductivity. In addition, the extremely sensitive nature of sulfide electrolytes to moisture increases the cost of material processing technology and atmosphere control, posing a huge challenge to large-scale production.

[0004] To achieve industrial application of sulfide electrolytes, it is necessary to overcome the processing challenges in normal humidity environments. Existing technologies isolate the sulfide solid electrolyte from the air by coating it with an isolation layer. However, this method results in uneven distribution of the isolation material, resulting in poor protection of the sulfide solid electrolyte layer in air, and the ionic conductivity will still rapidly decrease to failure. Summary of the Invention

[0005] One of the purposes of this application is to provide a solid electrolyte material to solve the problem in the prior art that solid electrolytes are unstable and prone to failure in the air; the second purpose is to provide a method for preparing a solid electrolyte material; the third purpose is to provide a solid electrolyte membrane; the fourth purpose is to provide a method for preparing a solid electrolyte membrane; and the fifth purpose is to provide a solid-state battery.

[0006] In order to achieve the above objectives, the technical solutions adopted in this application are as follows:

[0007] In a first aspect, the present application provides a solid electrolyte material, comprising sulfide solid electrolyte particles and a coating layer disposed on the surface of the sulfide solid electrolyte particles;

[0008] The coverage rate of the coating layer on the surface of the solid electrolyte particles is greater than 99%;

[0009] The coating layer is an ionic liquid.

[0010] In one possible embodiment, the particle size D50 of the sulfide solid electrolyte particles is 1 to 20 μm;

[0011] In a possible implementation manner, the coating layer has a thickness of 5 to 10 nm.

[0012] In one possible embodiment, the sulfide electrolyte particles include Li6PS5Cl, Li6PS5Br, Li6PS5I, Li 3.25 Ge 0.25 P 0.75 One or more of S4;

[0013] In a possible embodiment, the ionic liquid includes at least one of 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-octyl-1-methylpyrrolidine bis(fluorosulfonyl)imide salt, and 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide salt.

[0014] In a second aspect, the present application provides a method for preparing a solid electrolyte material, comprising the following steps:

[0015] Step 1: preparing sulfide solid electrolyte particles by blade grinding or spray drying;

[0016] Step 2: Depositing ionic liquid on the surface of the sulfide solid electrolyte particles by low-temperature plasma-assisted vapor deposition or gradient pressure vapor deposition to obtain a solid electrolyte material.

[0017] In one possible embodiment, the blade grinding method includes: grinding the sulfide solid electrolyte at a speed of 8000 to 10000 rpm for 3 to 5 seconds, and then grinding at a speed of 18000 to 20000 rpm for 8 to 10 seconds in a protective atmosphere;

[0018] In one possible embodiment, the protective atmosphere includes argon and / or nitrogen;

[0019] In one possible embodiment, the spray drying method includes: mixing the sulfide solid electrolyte with a solvent to prepare a slurry, and simultaneously atomizing and drying the slurry through multiple nozzles;

[0020] In one possible embodiment, the concentration of the sulfide solid electrolyte in the slurry is 20-40 wt %;

[0021] In a possible embodiment, the number of nozzles is 2 to 20;

[0022] In one possible embodiment, the pressure of each nozzle is 0.2-0.5 MPa;

[0023] In one possible embodiment, the flow rate of the slurry in each nozzle is 300-400 mL / min;

[0024] In one possible embodiment, the drying is carried out in a high-temperature drying tower with an inlet temperature of 150-250°C and an outlet temperature of 80-120°C;

[0025] In one possible embodiment, the solvent includes one or more of acetonitrile, toluene, and xylene.

[0026] In one possible embodiment, the low-temperature plasma-assisted vapor deposition method includes: placing the sulfide solid electrolyte particles in a deposition chamber, and introducing an ionic liquid and a carrier gas into the deposition chamber at 50 to 80° C.;

[0027] In one possible embodiment, the low-temperature plasma-assisted vapor deposition method uses a mixture of argon and hydrogen as a carrier gas;

[0028] In one possible embodiment, the volume ratio of argon to hydrogen is (7-9):(1-3);

[0029] In one possible embodiment, the ionic liquid flow rate is 2 to 4 mL / min, and the carrier gas flow rate is 30 to 40 sccm;

[0030] In one possible implementation, the gradient pressure vapor deposition method includes:

[0031] S1, placing the sulfide solid electrolyte particles in a deposition chamber, -3 Pa vacuum treatment for 10 to 20 seconds;

[0032] S2, in (1~5)*10 -1 Pa, introducing ionic liquid and carrier gas into the deposition chamber, with an ionic liquid flow rate of 3-5 mL / min and a carrier gas flow rate of 20-30 sccm;

[0033] S3, raising the pressure of the deposition chamber to 10 5 Pa, maintain pressure for 1 to 2 minutes.

[0034] In one possible embodiment, the gradient pressure vapor deposition method uses a mixture of argon and hydrogen as a carrier gas; the volume ratio of the argon to hydrogen is (7-9): (1-3);

[0035] In a third aspect, the present application provides a method for preparing a solid electrolyte membrane, comprising mixing the solid electrolyte material or the solid electrolyte material prepared according to the preparation method with a binder, and then hot pressing the mixture to prepare a solid electrolyte membrane;

[0036] In one possible implementation, the mass ratio of the solid electrolyte material to the binder is (90-99):(1-10).

[0037] In one possible embodiment, the binder is a polymer binder;

[0038] In one possible embodiment, the polymer binder is selected from one or more of polyvinylidene fluoride, nitrile rubber, and styrene-ethylene-butylene-styrene block copolymer;

[0039] In a possible embodiment, the temperature of the hot pressing molding is 80-120° C. and the pressure is 10-50 MPa.

[0040] In a fourth aspect, the present application provides a solid electrolyte membrane produced using the preparation method.

[0041] In a fifth aspect, the present application provides a solid-state battery comprising the solid-state electrolyte membrane.

[0042] Beneficial effects of this application:

[0043] The solid electrolyte material of the present application includes sulfide solid electrolyte particles and a coating layer arranged on the surface of the sulfide solid electrolyte particles; the coverage rate of the coating layer on the surface of the solid electrolyte particles is above 99%; and the coating layer is an ionic liquid.

[0044] The surface of the sulfide solid electrolyte particles of the present application is coated with an ionic liquid that does not react with air, and the coverage rate is above 99%, that is, the coating formed on the surface of the sulfide solid electrolyte particles is more uniform. The ability to isolate air is greatly improved, and the stability of the sulfide solid electrolyte material in the air is improved. The sulfide solid electrolyte material can be maintained for several days under certain humidity conditions, overcoming the limitation that the existing sulfide solid electrolyte transportation and subsequent industrial application processes can only be carried out under anhydrous conditions. In addition, the present application sets a coating layer on the surface of each sulfide solid electrolyte particle, and then makes a solid electrolyte layer. Even if the coating layer on the surface of a sulfide solid electrolyte particle is damaged, it will not cause the entire solid electrolyte layer to fail. Ionic liquids have high ionic conductivity. While improving the air stability of the sulfide solid electrolyte, the present application can also maintain the high ionic conductivity of the solid electrolyte material. DETAILED DESCRIPTION

[0045] The following will describe the embodiments of the present application with reference to preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be understood that the preferred embodiments are only for the purpose of illustrating the present application and are not intended to limit the scope of protection of the present application.

[0046] In a first aspect, the present application provides a solid electrolyte material, comprising sulfide solid electrolyte particles and a coating layer disposed on the surface of the solid electrolyte particles;

[0047] The coverage rate of the coating layer on the surface of the sulfide solid electrolyte particles is greater than 99%;

[0048] The coating layer is an ionic liquid.

[0049] The surface of the sulfide solid electrolyte particles of the present application is coated with an ionic liquid that does not react with air, and the coverage rate is above 99%, that is, the coating formed on the surface of the sulfide solid electrolyte particles is more uniform. The ability to isolate air is greatly improved, and the stability of the sulfide solid electrolyte material in the air is improved. The sulfide solid electrolyte material can be maintained for several days under certain humidity conditions, overcoming the limitation that the existing sulfide solid electrolyte transportation and subsequent industrial application processes can only be carried out under anhydrous conditions. In addition, the present application sets a coating layer on the surface of each sulfide solid electrolyte particle, and then makes a solid electrolyte layer. Even if the coating layer on the surface of a sulfide solid electrolyte particle is damaged, it will not cause the entire solid electrolyte layer to fail. Ionic liquids have high ionic conductivity. While improving the air stability of the sulfide solid electrolyte, the present application can also maintain the high ionic conductivity of the solid electrolyte material.

[0050] The ionic liquid of the present application is a hydrophobic ionic liquid.

[0051] In one possible embodiment, the sulfide solid electrolyte particles have a particle size D50 of 1 to 20 μm. Particles of 1 to 20 μm provide a larger inter-particle contact area in the electrode or electrolyte layer, facilitating lithium ion transport within the particle network. For example, D50 can be any value among 1 μm, 10 μm, 15 μm, and 20 μm, or any value between any two values.

[0052] In one possible embodiment, the coating layer has a thickness of 5 to 10 nm. A coating layer with a thickness of 5 to 10 nm strikes an optimal balance between effectively avoiding physical / electrical side reactions and minimizing the impact on lithium ion transport, which is key to improving the cycle life of solid-state batteries. Exemplarily, the coating layer thickness can be any value among 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, or any value between any two points.

[0053] In one possible embodiment, the sulfide electrolyte particles include Li6PS5Cl, Li6PS5Br, Li6PS5I, Li 3.25 Ge 0.25 P 0.75 One or more of S4;

[0054] In a possible embodiment, the ionic liquid includes at least one of 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-octyl-1-methylpyrrolidine bis(fluorosulfonyl)imide salt, and 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide salt.

[0055] The ionic liquid of the present invention having bistrifluoromethanesulfonyl imide (TFSI-) or bisfluorosulfonyl imide (FSI-) anions has high ionic conductivity. Both TFSI- and FSI- are large-volume, weakly coordinated anions that promote the migration of Li+ and improve ionic conductivity. Secondly, both have interfacial stability and decompose on the electrode surface to form a fluorine-containing interface layer (such as LiF) to inhibit the side reaction between the sulfide electrolyte and the electrode. In addition, the sulfonyl groups and fluorine atoms of TFSI- and FSI- give the ionic liquid of the present application high oxidative stability, so that the solid electrolyte membrane prepared in the present application can match the high-voltage positive electrode.

[0056] In a second aspect, the present application provides a method for preparing a solid electrolyte material, comprising the following steps:

[0057] Step 1: preparing sulfide solid electrolyte particles by blade grinding or spray drying;

[0058] Step 2: Depositing ionic liquid on the surface of the sulfide solid electrolyte particles by low-temperature plasma-assisted vapor deposition or gradient pressure vapor deposition to obtain a solid electrolyte material.

[0059] In one possible embodiment, the blade grinding method includes: first grinding the sulfide solid electrolyte at a speed of 8000-10000 rpm for 3-5 seconds, and then grinding at a speed of 18000-20000 rpm for 8-10 seconds in a protective atmosphere. Grinding at a speed of 8000-10000 rpm for 3-5 seconds can quickly reduce the agglomeration of the solid electrolyte, improve the uniformity of the material particle size and the density between the grains. For example, the speed can be 8000 rpm, 9000 rpm or 10000 rpm for 3 seconds, 4 seconds or 5 seconds. Then grind at a speed of 18000-20000 rpm for 8-10 seconds to activate the surface of the electrolyte particles. Compared with traditional repeated grinding or ball milling for 1-2 hours, blade high-speed grinding avoids lattice distortion or amorphization caused by long-term grinding. At the same time, rapid mixing suppresses local heat accumulation and reduces the risk of side reactions. In addition, after the surface of the sulfide solid electrolyte particles is activated, the ionic liquid is more easily uniformly deposited, thereby improving the coverage of the coating layer.

[0060] In one possible embodiment, the protective atmosphere includes argon and / or nitrogen;

[0061] In one possible embodiment, the spray drying method includes: mixing the sulfide solid electrolyte with a solvent to prepare a slurry, and simultaneously atomizing and drying the slurry through a nozzle;

[0062] In one possible embodiment, the concentration of the sulfide solid electrolyte in the slurry is 20-40wt%; a slurry concentration of 20-40wt% ensures uniform dispersion of the sulfide solid electrolyte while avoiding poor fluidity (such as nozzle clogging) caused by high concentration or excessive energy consumption of solvent evaporation caused by low concentration. A moderate concentration is more likely to form a uniform pore structure when the solvent evaporates rapidly. Exemplarily, the slurry concentration can be any value among 20wt%, 25wt%, 30wt%, 35wt%, 40wt% or any value between any two points.

[0063] In a possible embodiment, 2 to 20 nozzles are provided; providing multiple nozzles and increasing the number of nozzles can increase the amount of solid electrolyte processed per unit time, thereby improving the preparation efficiency.

[0064] In one possible embodiment, the pressure of each nozzle is 0.2 to 0.5 MPa; illustratively, the pressure of each nozzle can be any value among 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, or any value between any two points. The pressure range of 0.2 to 0.5 MPa can achieve a particle size of 1 to 20 μm, meeting the diverse requirements of solid-state batteries for electrolyte particle size. The shear force generated by high-pressure atomization causes the surface tension of the droplets to dominate the formation, forming uniform and highly spherical particles. However, the traditional manual grinding method easily leads to uneven particle size of the sulfide solid electrolyte particles, thereby affecting the coating effect.

[0065] In one possible embodiment, the slurry flow rate in each nozzle is 300-400 mL / min. Increasing the spray flow rate can increase the amount of solid electrolyte processed per unit time, thereby improving preparation efficiency. For example, the flow rate can be 300 mL / min, 350 mL / min, or 400 mL / min.

[0066] Optionally, the drying is carried out in a high-temperature drying tower with an inlet temperature of 150-250°C and an outlet temperature of 80-120°C. The high-temperature inlet (150-250°C) allows the solvent to evaporate rapidly, forming uniform pores as the solvent evaporates; the outlet temperature (80-120°C) prevents the particles from sintering due to excessive heat, retaining the porous structure. Compared with existing vacuum low-temperature drying (e.g., <80°C) that takes several hours and has high solvent residues, the present invention achieves rapid drying in seconds through a gradient temperature while avoiding thermal degradation of the material.

[0067] The multi-nozzle spray drying method of the present application can produce spherical porous particles.

[0068] In one possible embodiment, the solvent includes one or more of acetonitrile, toluene, and xylene.

[0069] In one possible implementation,

[0070] The low-temperature plasma-assisted vapor deposition method involves placing the sulfide solid electrolyte particles in a deposition chamber and introducing an ionic liquid and a carrier gas at 50-80°C. The temperature used in this application is significantly lower than the 300°C or higher used in conventional vapor deposition, which prevents decomposition of the ionic liquid, further improves its uniformity, and enhances the air stability of the sulfide solid electrolyte material. Exemplary temperatures include 50°C, 60°C, 70°C, or 80°C.

[0071] In one possible embodiment, the low-temperature plasma-assisted vapor deposition method uses a mixture of argon and hydrogen as a carrier gas; hydrogen reduction can remove impurities on the surface of the sulfide solid electrolyte particles, and argon, as an inert gas, can activate the ionic liquid, thereby enhancing the adsorption capacity of the ionic liquid on the surface of the sulfide solid electrolyte particles, forming a nano-scale ultra-thin coating with a coverage rate of more than 99%, and retaining the electrochemical activity of the ionic liquid, thereby constructing an efficient ion transport channel, improving the overall ionic conductivity of the solid electrolyte material, alleviating concentration polarization during the charge and discharge process, and improving the capacity retention rate at high current density.

[0072] In a possible embodiment, the volume ratio of argon to hydrogen is (7-9):(1-3), and illustratively, it can be 9:1;

[0073] In a possible embodiment, in the low-temperature plasma-assisted vapor deposition method, the ionic liquid flow rate is 2 to 4 mL / min, and the mixed gas flow rate is 30 to 40 sccm;

[0074] In a possible embodiment, in the low-temperature plasma-assisted vapor deposition method, the deposition time of introducing the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and the carrier gas is 10 to 20 minutes.

[0075] In one possible implementation, the gradient pressure vapor deposition method includes:

[0076] S1, placing the sulfide solid electrolyte particles in a deposition chamber, -3 Pa vacuum treatment for 10 to 20 seconds;

[0077] S2, in (1~5)*10 -1 Pa, introducing ionic liquid and carrier gas into the deposition chamber for 2 to 3 minutes, with an ionic liquid flow rate of 3 to 5 mL / min and a carrier gas flow rate of 20 to 30 sccm;

[0078] S3, raising the pressure of the deposition chamber to 10 5 Pa, maintain pressure for 1 to 2 minutes.

[0079] The gradient pressure vapor deposition method of the present application first uses high vacuum to remove impurities on the surface of the sulfide solid electrolyte particles; then, ionic liquid and carrier gas are introduced under low pressure, and low pressure promotes the diffusion of the ionic liquid; the pressure of the deposition chamber is then raised to normal pressure, inducing the ionic liquid to self-assemble on the surface of the sulfide solid electrolyte particles to form an ordered layer of 5-10nm (i.e., a continuous, non-porous, and uniformly thick coating of ionic liquid), thereby achieving a uniform coating from the surface to the interior of the particles, reducing stress concentration, and improving the efficiency of interfacial ion transmission. Ionic liquid and carrier gas are continuously incorporated into S3, and the flow rate is the same as that of S2.

[0080] Low-temperature plasma-assisted vapor deposition or gradient pressure vapor deposition can form a defect-free, continuous nanoscale ionic liquid coating on complex surfaces (such as porous sulfide electrolytes). At the same time, the ionic liquid can be tightly bonded to the surface of the sulfide solid electrolyte through chemical bonds / van der Waals forces, reducing the interfacial contact impedance.

[0081] In a third aspect, the present application provides a method for preparing a solid electrolyte membrane, wherein the solid electrolyte material is mixed with a binder and then hot-pressed to form a solid electrolyte membrane;

[0082] In one possible embodiment, the mass ratio of the solid electrolyte material to the binder is (90-99):(1-10). Exemplary ratios may be 95:5, 96:4, 97:3, 98:2, or 99:1. Excessive binder may hinder ion transport, significantly reducing overall ionic conductivity. Furthermore, excessive binder may make the electrolyte too flexible, leading to structural damage due to volume changes during battery cycling, potentially causing a short circuit.

[0083] In one possible embodiment, the binder is a polymer binder;

[0084] Optionally, the polymer binder is selected from one or more of polyvinylidene fluoride, nitrile rubber, and styrene-ethylene-butylene-styrene block copolymer.

[0085] In a fourth aspect, the present application provides a solid electrolyte membrane produced using the above-mentioned preparation method.

[0086] In a fifth aspect, the present application provides a solid-state battery comprising the solid-state electrolyte membrane.

[0087] The present invention is further described in detail below with reference to specific examples, but the embodiments of the present invention are not limited thereto.

[0088] Example 1

[0089] This embodiment provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0090] (1) Li6PS5Cl sulfide solid electrolyte powder was placed in an argon atmosphere and placed in a blade-type high-speed grinder. It was first ground at 8000 rpm for 5 seconds and then at 20000 rpm for 10 seconds to obtain sulfide solid electrolyte particles with a particle size of 10 μm.

[0091] (2) Depositing a coating layer on the surface of the sulfide solid electrolyte particles by a low-temperature plasma-assisted vapor deposition process: The sulfide solid electrolyte particles prepared in (1) are placed in a deposition chamber, and the ionic liquid 1-hexyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt and a carrier gas are introduced into the deposition chamber at 60°C. The flow rate of the ionic liquid is 3 mL / min, and the carrier gas is an argon / hydrogen mixture (volume ratio 9:1). The flow rate of the mixed gas is 35 sccm. The deposition time is 10 min, and a coating layer with a thickness of 8 nm is formed on the surface of the sulfide solid electrolyte particles, and the coverage rate is 99.9%.

[0092] (3) The product of step (2) was mixed with polyvinylidene fluoride (Klamar reagent, FR904) at a mass ratio of 98:2, and hot-pressed at 80° C. and 20 MPa.

[0093] Example 2

[0094] This embodiment provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0095] (1) Li6PS5Cl sulfide solid electrolyte powder was placed in an argon atmosphere and placed in a blade-type high-speed grinder. It was first ground at 8000 rpm for 5 seconds and then at 20000 rpm for 10 seconds to obtain sulfide solid electrolyte particles with a particle size of 10 μm.

[0096] (2) Depositing a coating layer on the surface of the sulfide solid electrolyte particles by a gradient pressure vapor deposition process: placing the sulfide solid electrolyte particles in a deposition chamber, first using 10 -3 Pa high vacuum treatment of sulfide solid electrolyte particles for 20s; then switch to 10 -1 Pa, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and carrier gas were introduced at flow rates of 4 mL / min and 25 sccm, respectively. After 3 minutes, the pressure of the deposition chamber was increased to 10 5 Pa, deposited for 2 min, self-assembled into a coating layer with a thickness of 10 nm, and the ionic liquid coverage was 99.5%;

[0097] (3) The product of step (2) was mixed with polyvinylidene fluoride in a mass ratio of 98:2, and hot-pressed at 80° C. and 20 MPa.

[0098] Example 3

[0099] This embodiment provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0100] (1) Li6PS5Br sulfide electrolyte powder was placed in an argon atmosphere and placed in a blade-type high-speed grinder. It was first ground at 9000 rpm for 4 seconds and then at 18000 rpm for 9 seconds to obtain sulfide solid electrolyte particles with a particle size of 20 μm.

[0101] (2) Depositing a coating layer on the surface of the sulfide solid electrolyte particles by a low-temperature plasma-assisted vapor deposition process: The sulfide solid electrolyte particles prepared in (1) are placed in a deposition chamber, and the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and a carrier gas are introduced into the deposition chamber at 60°C. The flow rate of the ionic liquid is 3 mL / min, and the carrier gas is an argon / hydrogen mixture (volume ratio 9:1). The flow rate of the mixed gas is 35 sccm. A coating layer with a thickness of 8 nm is formed on the surface of the sulfide solid electrolyte particles, and the coverage rate is 99.2%.

[0102] (3) The product of step (2) was mixed with polyvinylidene fluoride in a mass ratio of 98:2, and hot-pressed at 80° C. and 20 MPa.

[0103] Example 4

[0104] This embodiment provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0105] (1) Li6PS5Br sulfide electrolyte powder was placed in an argon atmosphere and placed in a blade-type high-speed grinder. It was first ground at 9500 rpm for 5 seconds and then at 19000 rpm for 10 seconds to obtain sulfide solid electrolyte particles with a particle size of 15 μm.

[0106] (2) Depositing a coating layer on the surface of the sulfide solid electrolyte particles by a gradient pressure vapor deposition process: placing the sulfide solid electrolyte particles in a deposition chamber, first using 10 -3 The sulfide solid electrolyte particles were treated at a high vacuum of 10-1 Pa for 20 seconds. The pressure was then switched to 10-1 Pa, and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and carrier gas were introduced at flow rates of 4 mL / min and 25 sccm, respectively, for 3 minutes. The pressure in the deposition chamber was then raised to 10 Pa, and deposition was carried out for 2 minutes, resulting in self-assembly of a coating layer with a thickness of 10 nm. The ionic liquid coverage was 99.1%.

[0107] (3) The product of step (2) was mixed with polyvinylidene fluoride in a mass ratio of 98:2, and hot-pressed at 80° C. and 20 MPa.

[0108] Example 5

[0109] This embodiment provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0110] (1) Li6PS5Cl sulfide solid electrolyte powder was placed in an argon atmosphere, and the sulfide solid electrolyte was mixed with acetonitrile to form a 20 wt% slurry. The slurry was then atomized into micron-sized particles through 20 identical nozzles at 0.5 MPa at a high flow rate of 300 mL / min. The solvent was then rapidly evaporated in a high-temperature drying tower with an inlet temperature of 200°C and an outlet temperature of 100°C to obtain micron-sized uniform (particle size of approximately 18 μm) spherical porous particles.

[0111] (2) depositing a coating layer on the surface of the sulfide solid electrolyte particles by a low-temperature plasma-assisted vapor deposition process: placing the sulfide solid electrolyte particles prepared in (1) in a deposition chamber, introducing ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and a carrier gas into the deposition chamber at 60°C, wherein the flow rate of the ionic liquid is 3 mL / min, the carrier gas is an argon / hydrogen mixture (volume ratio 9:1), and the flow rate of the mixture is 35 sccm, and a coating layer with a thickness of 8 nm is formed on the surface of the sulfide solid electrolyte particles, and the coverage rate is 99.2%;

[0112] (3) The product of step (2) was mixed with polyvinylidene fluoride in a mass ratio of 98:2, and hot-pressed at 80° C. and 20 MPa.

[0113] Example 6

[0114] This embodiment provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0115] (1) Li6PS5Br sulfide solid electrolyte powder was placed in an argon atmosphere, and the sulfide electrolyte was mixed with acetonitrile to form a 30 wt% slurry. The slurry was then atomized into micron-sized particles through 20 identical nozzles at 0.4 MPa at a high flow rate of 300 mL / min. The solvent was then rapidly evaporated in a high-temperature drying tower with an inlet temperature of 150°C and an outlet temperature of 80°C, efficiently producing micron-sized uniform (particle size of approximately 20 μm) spherical porous particles.

[0116] (2) Depositing a coating layer on the surface of the sulfide solid electrolyte particles by a gradient pressure vapor deposition process: placing the sulfide solid electrolyte particles in a deposition chamber, first using 10 -3The sulfide solid electrolyte particles were treated at a high vacuum of 10-1 Pa for 20 seconds. The pressure was then switched to 10-1 Pa, and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and carrier gas were introduced at flow rates of 4 mL / min and 25 sccm, respectively, for 3 minutes. The pressure in the deposition chamber was then raised to 10 Pa, and deposition was carried out for 2 minutes, resulting in self-assembly of a coating layer with a thickness of 10 nm. The ionic liquid coverage was 99.3%.

[0117] (3) The product of step (2) was mixed with polyvinylidene fluoride in a mass ratio of 98:2, and hot-pressed at 80° C. and 20 MPa.

[0118] Comparative Example 1

[0119] This comparative example provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0120] (1) Li6PS5Cl sulfide solid electrolyte powder was placed in an argon atmosphere and placed in a blade-type high-speed grinder. It was first ground at 8000 rpm for 5 seconds and then at 20000 rpm for 10 seconds to obtain sulfide solid electrolyte particles with a particle size of 10 μm.

[0121] (2) The product of step (1) was mixed with polyvinylidene fluoride in a mass ratio of 98:2, and hot-pressed at 80° C. and 20 MPa.

[0122] Comparative Example 2

[0123] This comparative example provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0124] (1) Li6PS5Cl sulfide solid electrolyte powder was placed in an argon atmosphere and placed in a blade-type high-speed grinder. It was first ground at 8000 rpm for 5 seconds and then at 20000 rpm for 10 seconds to obtain sulfide solid electrolyte particles with a particle size of 10 μm.

[0125] Sulfide solid electrolyte particles and polyvinylidene fluoride were mixed in a mass ratio of 98:2 and hot-pressed in an argon atmosphere at 80°C and 20 MPa to produce solid electrolyte discs with a diameter of 10 mm and a thickness of 200 μm.

[0126] (2) Use a pipette to draw 50 μL of 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ionic liquid and drop it on the center of the solid electrolyte disc prepared in (1). Fix the solid electrolyte disc on a spin coater and spin coat it at a speed of 300 rpm for 30 seconds, and then continue to spin coat it at a speed of 1000 rpm for 30 seconds to obtain a solid electrolyte membrane with an ionic liquid coating thickness of about 3 μm.

[0127] Comparative Example 3

[0128] This comparative example provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0129] (1) Li6PS5Cl sulfide solid electrolyte powder was placed in an argon atmosphere and placed in a blade-type high-speed grinder. It was first ground at 8000 rpm for 5 seconds and then at 20000 rpm for 10 seconds to obtain sulfide solid electrolyte particles with a particle size of 10 μm.

[0130] (2) Depositing an oxide coating on the surface of the sulfide solid electrolyte particles by a low-temperature plasma-assisted vapor deposition process: Al2O3 was dispersed in a xylene solvent at a mass fraction of 1 wt%, and ultrasonicated for 30 min to obtain an Al2O3 dispersion; the sulfide solid electrolyte particles obtained in (1) were placed in a deposition chamber, and the Al2O3 dispersion and carrier gas were introduced into the deposition chamber at 60°C. The flow rate of the Al2O3 dispersion was 3 mL / min, and the carrier gas was an argon / hydrogen mixture (volume ratio 9:1). The flow rate of the mixture was 35 sccm, and an oxide coating with a thickness of 8 nm was formed on the surface of the sulfide solid electrolyte particles, and the coverage was 90%.

[0131] (3) The product of step (2) was mixed with polyvinylidene fluoride in a mass ratio of 98:2, and hot-pressed at 80° C. and 20 MPa.

[0132] Comparative Example 4

[0133] This comparative example provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0134] (1) Li6PS5Cl sulfide solid electrolyte powder was placed in a mortar under an argon atmosphere, a 20N pressure was applied in the vertical direction, and the powder was ground alternately clockwise and counterclockwise for 30 min to obtain sulfide solid electrolyte particles with a particle size of 30 μm.

[0135] (2) depositing a coating layer on the surface of the sulfide solid electrolyte particles by a low-temperature plasma-assisted vapor deposition process: placing the sulfide solid electrolyte particles prepared in (1) in a deposition chamber, introducing ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and a carrier gas into the deposition chamber at 60°C, wherein the flow rate of the ionic liquid is 3 mL / min, the carrier gas is an argon / hydrogen mixture (volume ratio 9:1), and the flow rate of the mixture is 35 sccm, and a coating layer with a thickness of 8 nm is formed on the surface of the sulfide solid electrolyte particles, and the coverage rate is 98.5%;

[0136] (3) The product of step (2) was mixed with polyvinylidene fluoride in a mass ratio of 98:2, and hot-pressed at 80° C. and 20 MPa.

[0137] Comparative Example 5

[0138] This embodiment provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0139] (1) Li6PS5Cl sulfide solid electrolyte powder was placed in an argon atmosphere and placed in a blade-type high-speed grinder. It was first ground at 8000 rpm for 5 seconds and then at 20000 rpm for 10 seconds to obtain sulfide solid electrolyte particles with a particle size of 10 μm.

[0140] (2) vapor deposition of ionic liquid onto the sulfide surface by conventional vapor deposition: ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was vaporized at 300°C and deposited for 1 h at a flow rate of 3 mL / min of ionic liquid and 50 sccm of argon gas to form a coating layer with a thickness of 200 nm and a coverage of 95%;

[0141] (3) The product of step (2) was mixed with polyvinylidene fluoride in a mass ratio of 98:2, and hot-pressed at 80° C. and 20 MPa.

[0142] Comparative Example 6

[0143] This embodiment provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0144] (1) Li6PS5Cl sulfide solid electrolyte powder was placed in an argon atmosphere and placed in a blade-type high-speed grinder. It was first ground at 8000 rpm for 5 seconds and then at 20000 rpm for 10 seconds to obtain sulfide solid electrolyte particles with a particle size of 10 μm.

[0145] (2) The ionic liquid was introduced into the sulfide surface by conventional solution impregnation method: the sulfide solid electrolyte particles were ultrasonically treated in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt at a mass ratio of 1:50 for 30 min to form a coating layer with a thickness of 3 μm and a coverage of 80%;

[0146] (3) The product of step (2) was mixed with polyvinylidene fluoride in a mass ratio of 98:2, and hot-pressed at 80° C. and 20 MPa.

[0147] Test method:

[0148] (1) The coverage of the coating layer on the surface of the sulfide solid electrolyte particles was measured by transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDS) surface scanning: the sulfide solid electrolyte particles containing the coating layer were dispersed in an inert solvent (such as anhydrous hexane), and after ultrasonication, a drop was added to the TEM grid. The particles were then transferred to the TEM using a glove box-electron microscope system to isolate the air. Atomic number contrast was used to distinguish the coating layer (bright) from the sulfide solid electrolyte matrix (dark), and the thickness and continuity of the coating layer were observed. The characteristic elements of the electrolyte and the characteristic elements of the coating layer were simultaneously scanned by EDS to generate an element distribution map. The coverage was obtained by calculating the area ratio of the particle surface covered by the element signal of the coating layer using image processing software.

[0149] (2) Particle size D50: The particle size of sulfide solid electrolyte particles was measured using a dry laser particle size analyzer using the laser diffraction method. The laser beam emitted by the illuminator was focused by a lens and irradiated onto the particles in the sample chamber. The beam was then scattered into multiple directions of light, which was collected and recorded by the lens and receiver. By analyzing the received light signal, the size, shape, and other information of the particles were calculated. In the glove box, 0.5 g of the sample to be tested was accurately weighed using an electronic balance. The sample to be tested was added to the sample inlet of the equipment. The dust collector was opened and the dust collector nozzle was connected to the dry powder test bench. The parameters of the particle size measurement and analysis system were set (optical mode: Mie; distribution type: volume distribution; refractive index upper limit: 10%; refractive index lower limit: 1%; shape coefficient: 1; sampling times: 27200; continuous times: 3; air pressure upper limit: 0.4 MPa; air pressure lower limit: 0.3 MPa). The particle size test was started by clicking the Start Test button. After the test, the volume distribution data of the sample particle size was obtained, D50 was recorded, and the test data was saved.

[0150] (3) Ionic conductivity: In a glove box, the solid electrolyte membranes prepared in each embodiment and comparative example were cut into discs with a diameter of 10 mm. The area of ​​the disc was S, and its thickness d was measured. One disc was placed between two steel sheets. After the connection between the electrochemical workstation circuit interface and the mold battery was completed, the electrochemical workstation was turned on, and the AC impedance test program was imported. The test parameters (frequency range: 10~10 6 Hz, bias: 20 mV), click the start test button to perform the electrochemical impedance spectroscopy test. After the test, the electrochemical impedance spectrum is obtained, the resistance value R is recorded, and the ionic conductivity σ value is calculated according to the formula (σ=d / (S×R)).

[0151] The test results are as follows:

[0152] Table 1 Ionic conductivity (mS / cm) after exposure to air for different days

[0153]

[0154]

[0155] As can be seen from Table 1, the ionic conductivity retention rate of the solid electrolyte membrane prepared in the embodiment of the present application after being exposed to air for 30 days is significantly improved, and the solid electrolyte membrane of the present application has good stability in air.

[0156] The above embodiments are only preferred embodiments for fully illustrating the present application, and the protection scope of the present application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art based on the present application are within the protection scope of the present application.

Claims

1. A solid electrolyte material, characterized in that It comprises sulfide solid electrolyte particles and a coating layer arranged on the surface of the sulfide solid electrolyte particles; The coverage rate of the coating layer on the surface of the solid electrolyte particles is greater than 99%; The coating layer is an ionic liquid.

2. The solid electrolyte material according to claim 1, characterized in that The particle size D50 of the sulfide solid electrolyte particles is 1 to 20 μm; and / or The coating layer has a thickness of 5 to 10 nm.

3. The solid electrolyte material according to claim 1, characterized in that The sulfide solid electrolyte particles include Li6PS5Cl, Li6PS5Br, Li6PS5I, Li 3.25 Ge 0.25 P 0.75 One or more of S4; and / or The ionic liquid includes at least one of 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-octyl-1-methylpyrrolidine bis(fluorosulfonyl)imide salt, and 1-butyl-3-methylimidazolium bis(fluorosulfonyl)imide salt.

4. A method for preparing the solid electrolyte material according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: preparing sulfide solid electrolyte particles by blade grinding or spray drying; Step 2: Depositing ionic liquid on the surface of the sulfide solid electrolyte particles by low-temperature plasma-assisted vapor deposition or gradient pressure vapor deposition to obtain a solid electrolyte material.

5. The method for preparing a solid electrolyte material according to claim 4, wherein: The blade grinding method comprises: first grinding the sulfide solid electrolyte at a rotation speed of 8000-10000 rpm for 3-5 seconds, and then grinding at a rotation speed of 18000-20000 rpm for 8-10 seconds in a protective atmosphere; Optionally, the protective atmosphere includes argon and / or nitrogen; The spray drying method comprises: mixing the sulfide solid electrolyte with a solvent to prepare a slurry, and simultaneously atomizing and drying the slurry through multiple nozzles; Optionally, the concentration of the sulfide solid electrolyte in the slurry is 20-40 wt %; Optionally, the number of the nozzles is 2 to 20; Optionally, the pressure of each nozzle is 0.2-0.5 MPa; Optionally, the flow rate of the slurry in each nozzle is 300-400 mL / min; Optionally, the drying is carried out in a high-temperature drying tower with an inlet temperature of 150-250°C and an outlet temperature of 80-120°C; Optionally, the solvent includes one or more of acetonitrile, toluene, and xylene.

6. The method for preparing a solid electrolyte material according to claim 4, wherein: The low-temperature plasma-assisted vapor deposition method comprises: placing the sulfide solid electrolyte particles in a deposition chamber, and introducing ionic liquid and carrier gas into the deposition chamber at 50-80° C.; Optionally, the low-temperature plasma-assisted vapor deposition method uses a mixture of argon and hydrogen as a carrier gas; Optionally, the volume ratio of argon to hydrogen is (7-9):(1-3); Optionally, the flow rate of the ionic liquid is 2 to 4 mL / min, and the flow rate of the carrier gas is 30 to 40 sccm; The gradient pressure vapor deposition method comprises: S1, placing the sulfide solid electrolyte particles in a deposition chamber, -3 Pa vacuum treatment for 10 to 20 seconds; S2, in (1~5)*10 -1 Pa, introducing ionic liquid and carrier gas into the deposition chamber, with an ionic liquid flow rate of 3-5 mL / min and a carrier gas flow rate of 20-30 sccm; S3, raising the pressure of the deposition chamber to 10 5 Pa, maintain pressure for 1 to 2 minutes.

7. A method for preparing a solid electrolyte membrane, characterized in that: The solid electrolyte material according to any one of claims 1 to 3 or the solid electrolyte material prepared by the preparation method according to any one of claims 4 to 6 is mixed with a binder and then hot-pressed to produce a solid electrolyte membrane.

8. The method for preparing a solid electrolyte membrane according to claim 7, wherein: At least one of the following conditions is met: (1) The mass ratio of the solid electrolyte material to the binder is (90-99):(1-10); (2) The binder is a polymer binder; Optionally, the polymer binder is selected from one or more of polyvinylidene fluoride, nitrile rubber, and styrene-ethylene-butylene-styrene block copolymer; (3) The temperature of the hot pressing molding is 80-120°C and the pressure is 10-50 MPa.

9. A solid electrolyte membrane, characterized in that The preparation method according to claim 7 or 8 is used.

10. A solid-state battery, characterized in that: Comprising the solid electrolyte membrane according to claim 9.

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