A hydrophobic sulfide electrolyte film, and a preparation method and application thereof

Abstract

The application belongs to the technical field of all-solid-state lithium batteries, and provides a hydrophobic sulfide electrolyte film and a preparation method and application thereof. The method comprises the following steps: mixing polyvinylidene fluoride-hexafluoropropylene, a lithium salt and a solvent to react under a protective atmosphere to obtain a lithium salt polymer binder; mixing the sulfide electrolyte, the lithium salt polymer binder and the solvent, and sequentially coating and heat treating to obtain a sulfide electrolyte film under a protective atmosphere; mixing 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, tetraethyl silicate, germanium aluminum lithium phosphate, water, ethanol and ammonia water to react to obtain hydrophobic particles; and spraying a petroleum ether solution of the hydrophobic particles on the surface of the sulfide electrolyte film to obtain the hydrophobic sulfide electrolyte film. The hydrophobic sulfide electrolyte film prepared by the application has excellent ion conductivity, mechanical properties, air stability and hydrophobicity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of all-solid-state lithium batteries, in particular to a hydrophobic sulfide electrolyte film and a preparation method and application thereof. BACKGROUND

[0002] All-solid-state batteries have been recognized as the next generation of energy storage technology with high energy density and high safety. Among various solid electrolytes, sulfide electrolytes have attracted much attention due to their high ionic conductivity and good mechanical properties. However, sulfide powders have poor elasticity and weak inter-particle bonding, making them difficult to handle completely. It is usually necessary to form a relatively thick sulfide electrolyte layer by cold pressing sulfide powders to ensure that it is not easily broken due to brittleness. However, this approach reduces the volume and weight proportion of active materials in the battery, resulting in a significant decrease in the actual energy density of the battery, which is not conducive to the commercialization of solid-state batteries. Therefore, designing and preparing a sulfide electrolyte film with ultra-thin thickness and high ionic conductivity is crucial for realizing high-energy-density all-solid-state batteries.

[0003] On the other hand, in addition to the thickness of the electrolyte, the instability of sulfides to air is also a key factor limiting their use. Most sulfides are inherently unstable and easily react with H2O and O2 in the air to generate toxic H2S gas, and the reaction process can cause complete destruction of the structure of the sulfide electrolyte and rapid decrease in ionic conductivity. To this end, researchers have proposed methods such as oxygen substitution and soft acid substitution to improve the air stability of the electrolyte. However, these doping methods can only improve the air stability of the sulfide electrolyte, allowing it to be used in relatively dry (<10% relative humidity) environments, and there is still a certain gap in its use under humid conditions. Therefore, how to provide a simple method that can greatly improve the air stability of the sulfide electrolyte under humid conditions and thus reduce the transportation and storage costs of the sulfide electrolyte is also a difficult problem to be solved in the field. SUMMARY

[0004] The present application aims to overcome the problems in the prior art and provide a hydrophobic sulfide electrolyte film and a preparation method and application thereof.

[0005] To achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] The present application provides a preparation method of a hydrophobic sulfide electrolyte film, comprising the following steps:

[0007] (1) mixing polyvinylidene fluoride-hexafluoropropylene, a lithium salt and a solvent under a protective atmosphere to react, to obtain a lithium salt polymer binder;

[0008] (2) mixing sulfide electrolyte, lithium salt polymer binder and solvent under protective atmosphere, coating and heat treating in sequence to obtain sulfide electrolyte film;

[0009] (3) mixing 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, tetraethyl silicate, germanium aluminum lithium phosphate, water, ethanol and ammonia water to react to obtain hydrophobic particles;

[0010] (4) spraying petroleum ether solution of the hydrophobic particles on the surface of the sulfide electrolyte film to obtain the hydrophobic sulfide electrolyte film.

[0011] As preferred, the lithium salt in step (1) is one or several of lithium bis(trifluoromethylsulfonyl)imide, lithium bisfluorosulfonylimide, lithium trifluoromethylsulfonate and lithium perchlorate;

[0012] The solvent is acetonitrile and / or tetrahydrofuran;

[0013] The mass ratio of the polyvinylidene fluoride-hexafluoropropylene, lithium salt and solvent is 1:1-1.5:4-6.

[0014] As preferred, the temperature of the reaction in step (1) is 75-85℃ and the time is 2.5-3.5h.

[0015] As preferred, the sulfide electrolyte in step (2) is one or several of Li7P3S 11 , Li6PS5Cl, Li6PS5Br, Li6PS5I, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 and Li 10 GeP2S 12 .

[0016] The solvent is acetonitrile and / or tetrahydrofuran;

[0017] The mass-volume ratio of the sulfide electrolyte, lithium salt polymer binder and solvent is 80-97.5g:2.5-20g:15-25mL.

[0018] As preferred, the temperature of the heat treatment in step (2) is 80-100℃ and the time is 10-14h.

[0019] As preferred, the mass ratio of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, tetraethyl silicate, germanium aluminum lithium phosphate, water, ethanol and ammonia water in step (3) is 12-24:19-38:7-14:50-100:50-100:9-18;

[0020] The mass fraction of the ammonia water is 5.5-6.5%.

[0021] Preferably, the reaction in step (3) is carried out at a temperature of 20-40℃ for 18-30 hours.

[0022] Preferably, the mass-volume ratio of the hydrophobic particles to petroleum ether in the petroleum ether solution of the hydrophobic particles in step (4) is 0.05-0.15g:3-7mL;

[0023] The volume ratio of the petroleum ether solution of the hydrophobic particles to the surface area of the sulfide electrolyte thin film is 8-12mL:8-12cm 2 .

[0024] The application further provides the hydrophobic sulfide electrolyte thin film prepared by the preparation method.

[0025] The application further provides the application of the hydrophobic sulfide electrolyte thin film in solid-state batteries.

[0026] The application has the following advantages:

[0027] The application provides a preparation method of a hydrophobic sulfide electrolyte film, comprising the following steps: mixing polyvinylidene fluoride-hexafluoropropylene, a lithium salt and a solvent to react under a protective atmosphere to obtain a lithium salt polymer binder; mixing the sulfide electrolyte, the lithium salt polymer binder and a solvent, sequentially coating and heat treating to obtain a sulfide electrolyte film under the protective atmosphere; mixing 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, tetraethyl silicate, germanium aluminum lithium phosphate, water, ethanol and ammonia water to react to obtain hydrophobic particles; and spraying a petroleum ether solution of the hydrophobic particles on the surface of the sulfide electrolyte film to obtain the hydrophobic sulfide electrolyte film. The lithium salt polymer binder is mixed with the sulfide electrolyte to obtain a novel sulfide solid electrolyte film by a simple slurry coating method, and the process is simple and easy to scale up; compared with a conventional ion insulating binder, the lithium salt polymer binder has excellent conductivity and can promote ion transmission in the composite electrolyte. In addition, the lithium salt polymer binder is uniformly distributed in the electrode in the form of a film, rather than gathered together in a block, and this structure is beneficial to enhancing the mechanical properties of the electrolyte film. The application also prepares ion-conducting hydrophobic particles, and the hydrophobic particles are covered on the electrolyte film by a spraying method, so that the electrolyte can be stored and used under various extreme conditions. The sulfide electrolyte, as an oxide electrolyte particle, has an ion transmission function and can ensure that the hydrophobic coating has little effect on the ion conductivity of the composite electrolyte. 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane and tetraethyl silicate can form fluorinated organopolysiloxane under the catalysis of ammonia water, have low surface energy and can provide strong hydrophobic properties for the coating. The hydrophobic sulfide electrolyte film prepared by the application does not need to be stored in a glove box completely isolated from water and oxygen, greatly reducing the use and transportation cost, and has strong practicability.

[0028] In conclusion, the hydrophobic sulfide electrolyte film prepared by the application has excellent ion conductivity, mechanical properties, air stability and hydrophobic properties. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Figure 1 is a low-magnification cross-sectional SEM image of the sulfide electrolyte film a in Example 1;

[0030] Figure 2 Figure 2 is a high-magnification cross-sectional SEM image of the sulfide electrolyte film a in Example 1;

[0031] Figure 3 Figure 3 is a contact angle diagram of the hydrophobic sulfide electrolyte film in Example 1;

[0032] Figure 4The graph shows the relationship between the H2S generation rate and time after contact with water vapor in Example 1 for the sulfide electrolyte film a and the hydrophobic sulfide electrolyte film (Exposure time in air(s) — air exposure time(s), H2S generation rate(ppm·s)). -1 H2S gas generation rate (ppm·s) -1 ));

[0033] Figure 5 This is a graph showing the first charge-discharge curves of all-solid-state batteries 1 and 2 in Example 1 at a current density of 0.1C. (Specific Capacity (mAh·g)) -1 ) — Specific capacity (mAh·g) -1 Voltage (V) — Voltage (V)

[0034] Figure 6 This is a graph showing the first charge-discharge curves of all-solid-state batteries 1 and 2 in Example 1 after being exposed to humid air for 24 hours at a current density of 0.1C. (Specific Capacity (mAh·g)) -1 ) — Specific capacity (mAh·g) -1 Voltage (V) — Voltage (V)). Detailed Implementation

[0035] This invention provides a method for preparing a hydrophobic sulfide electrolyte film, comprising the following steps:

[0036] (1) Under a protective atmosphere, polyvinylidene fluoride-hexafluoropropylene, lithium salt and solvent are mixed and reacted to obtain lithium salt polymer binder;

[0037] (2) Under a protective atmosphere, the sulfide electrolyte, lithium salt polymer binder and solvent are mixed and coated and heat-treated in sequence to obtain a sulfide electrolyte film.

[0038] (3) 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, tetraethyl silicate, lithium aluminum germanium phosphate, water, ethanol and ammonia were mixed and reacted to obtain hydrophobic particles;

[0039] (4) The hydrophobic particles are sprayed onto the surface of the sulfide electrolyte film to obtain the hydrophobic sulfide electrolyte film.

[0040] In this invention, the protective atmosphere in step (1) is preferably argon, nitrogen or helium.

[0041] In the present application, the lithium salt in step (1) is preferably one or more of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium bisfluorosulfonylimide (LiFSI), lithium trifluoromethylsulfonate (LiCF3SO3) and lithium perchlorate (LiClO4).

[0042] In the present application, the solvent in step (1) is preferably acetonitrile and / or tetrahydrofuran.

[0043] In the present application, the mass ratio of polyvinylidene fluoride-hexafluoropropylene, lithium salt and solvent in step (1) is preferably 1:1-1.5:4-6, further preferably 1:1.1-1.4:4.5-5.5, and more preferably 1:1.2-1.3:5-5.2.

[0044] In the present application, the stirring speed of the reaction in step (1) is preferably 300-550 r / min, further preferably 400-500 r / min, and more preferably 450-455 r / min; the temperature is preferably 75-85℃, further preferably 77-83℃, and more preferably 80-81℃; and the time is preferably 2.5-3.5 h, further preferably 2.7-3.3 h, and more preferably 3-3.1 h.

[0045] In the present application, the protective atmosphere in step (2) is preferably argon, nitrogen or helium.

[0046] In the present application, the sulfide electrolyte in step (2) is preferably one or more of Li7P3S 11 , Li6PS5Cl, Li6PS5Br, Li6PS5I, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 and Li 10 GeP2S 12 ; the sulfide electrolyte can be obtained by purchase or prepared according to conventional preparation methods.

[0047] In the present application, the solvent in step (2) is preferably acetonitrile and / or tetrahydrofuran.

[0048] In the present application, the mass-volume ratio of the sulfide electrolyte, lithium salt polymer binder and solvent in step (2) is preferably 80-97.5 g:2.5-20 g:15-25 mL, further preferably 85-95 g:5-15 g:17-23 mL, and more preferably 88-90 g:8-10 g:20-21 mL.

[0049] In the present application, the mixing in step (2) is preferably vibration ball milling.

[0050] In the present application, the material of the coated plate in step (2) is preferably polytetrafluoroethylene, and the thickness of the coating is preferably 350-450 μm, further preferably 370-430 μm, and more preferably 395-400 μm.

[0051] In the present application, the vacuum degree of the heat treatment (heat treatment also means drying) in step (2) is preferably -0.01 to -0.12 MPa, further preferably -0.04 to -0.11 MPa, and more preferably -0.05 to -0.1 MPa; the temperature is preferably 80-100°C, further preferably 85-95°C, and more preferably 90-93°C; and the time is preferably 10-14 h, further preferably 11-13 h, and more preferably 11.5-12 h.

[0052] In the present application, the mass ratio of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, tetraethyl silicate, germanium aluminum lithium phosphate, water, ethanol and ammonia in step (3) is preferably 12-24: 19-38: 7-14: 50-100: 50-100: 9-18, further preferably 14-22: 25-32: 9-12: 60-90: 60-90: 12-16, and more preferably 18-20: 28-30: 10-11: 70-80: 70-80: 13-15.

[0053] In the present application, the ammonia in step (3) functions to catalyze the reaction; and the mass fraction of the ammonia is preferably 5.5-6.5%, further preferably 5.7-6.3%, and more preferably 5.9-6.0%.

[0054] In the present application, the temperature of the reaction in step (3) is preferably 20-40°C, further preferably 23-35°C, and more preferably 25-30°C; and the time is preferably 18-30 h, further preferably 20-29 h, and more preferably 24-28 h.

[0055] In the present application, the mass-volume ratio of the hydrophobic particles to petroleum ether in the petroleum ether solution of the hydrophobic particles in step (4) is preferably 0.05-0.15 g: 3-7 mL, further preferably 0.08-0.12 g: 4-6 mL, and more preferably 0.1-0.11 g: 5-5.5 mL.

[0056] In the present application, the ratio of the volume of the petroleum ether solution of the hydrophobic particles to the surface area of the sulfide electrolyte thin film in step (4) is preferably 8-12 mL: 8-12 cm 2 , further preferably 9-11 mL: 9-11 cm 2 , and more preferably 10-10.5 mL: 10-10.5 cm 2 .

[0057] In the present application, the spraying in step (4) is preferably performed using a spray pen, and the petroleum ether solution of the hydrophobic particles is sprayed to cover the surface of the sulfide electrolyte film.

[0058] The present application also provides the hydrophobic sulfide electrolyte film obtained by the preparation method.

[0059] The present application also provides the use of the hydrophobic sulfide electrolyte film in a solid-state battery.

[0060] The technical solutions provided by the present application will be described in detail below in conjunction with the examples, but they should not be understood as limiting the scope of protection of the present application.

[0061] Example 1

[0062] Under an argon atmosphere, 0.3 g of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), 0.33 g of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), and 1.5 g of acetonitrile were mixed and reacted at a rotation speed of 450 r / min and a temperature of 80℃ for 3 h to obtain a lithium salt polymer binder;

[0063] Under an argon atmosphere, 95 g of a sulfide electrolyte (Li7P3S 11 ), 5 g of the lithium salt polymer binder, and 20 mL of acetonitrile were subjected to vibration ball milling mixing, and then the mixed slurry was coated (the coated plate material was polytetrafluoroethylene, and the coating thickness was 400 μm), and then heat-treated at a vacuum degree of -0.1 MPa and a temperature of 90℃ for 12 h to obtain a sulfide electrolyte film a;

[0064] 1.2 g of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, 1.9 g of tetraethyl orthosilicate, 0.7 g of lithium aluminum germanium phosphate, 5 g of water, 5 g of ethanol, and 0.9 g of 6% ammonia water were mixed and reacted at a temperature of 30℃ for 24 h to obtain hydrophobic particles;

[0065] 0.1 g of the hydrophobic particles and 5 mL of petroleum ether were mixed to obtain a petroleum ether solution of the hydrophobic particles, and the petroleum ether solution of the hydrophobic particles was sprayed onto the surface of the sulfide electrolyte film using a spray pen (the ratio of the volume of the petroleum ether solution of the hydrophobic particles to the surface area of the sulfide electrolyte film was 10 mL: 10 cm 2 ), to obtain a hydrophobic sulfide electrolyte film.

[0066] The sulfide electrolyte film a obtained by heat treatment in the present example was subjected to cross-section scanning electron microscope (SEM) testing, and a low-magnification cross-section SEM image of the sulfide electrolyte film a in Example 1 was obtained, as shown in Figure 1As shown; a high-magnification cross-sectional SEM image of the sulfide electrolyte film a in Example 1, as shown. Figure 2 As shown; from Figure 1 As can be seen, the sulfide electrolyte film a exhibits a thickness of approximately 60 μm, with no obvious pores or cracks; Figure 2 As can be seen, the particles are tightly packed together and bonded together by the polymer electrolyte on the surface to form a dense film. It is noteworthy that the polymer is uniformly distributed in the electrode as a thin film rather than aggregated into lumps; this structure is beneficial for enhancing the mechanical properties of the electrolyte membrane.

[0067] A comparative example was set up, keeping other conditions unchanged in Example 1, and the mass of LiTFSI in the lithium salt polymer binder was replaced from 0.33g to 0.12g and 0g respectively, to obtain sulfide electrolyte film b and sulfide electrolyte film c.

[0068] The ionic conductivity of sulfide electrolyte films a, b, and c was tested using AC impedance spectroscopy at room temperature and at 40, 50, 60, 70, and 80 °C. The activation energies of different electrolytes were calculated, and the performance comparison results of different sulfide electrolyte films were obtained, as shown in Table 1.

[0069] Table 1. Performance comparison results of different sulfide electrolyte films

[0070]

[0071] As can be seen from Table 1, increasing the lithium salt concentration in the polymer binder is beneficial to improving the ionic conductivity of the sulfide electrolyte film and reducing the activation energy.

[0072] The contact angle of the hydrophobic sulfide electrolyte film prepared in this embodiment was tested, and a schematic diagram of the contact angle of the hydrophobic sulfide electrolyte film in Example 1 was obtained, as shown below. Figure 3 As shown. From Figure 3 As can be seen, the static contact angle of the hydrophobic sulfide electrolyte film is 150.1°, which proves that the film has good hydrophobic properties.

[0073] The rates of H2S gas generation from the sulfide electrolyte film a and the hydrophobic sulfide electrolyte film prepared in this embodiment were tested after contact with water vapor. The relationship between the H2S gas generation rate and time after contact with water vapor was obtained in Example 1, as shown in the graph. Figure 4 As shown. From Figure 4 As can be seen from the data, compared to sulfide electrolyte film a, the hydrophobic sulfide electrolyte film did not decompose after contact with water vapor, exhibiting good water vapor stability.

[0074] The sulfide electrolyte film a and the hydrophobic sulfide electrolyte film prepared in this example were respectively cut into small discs with a diameter of 10 mm as electrolytes of solid-state batteries, and lithium foil and indium foil were pressed under a pressure of 300 MPa for 10 min to obtain lithium-indium alloy anodes. The positive electrode material was not particularly limited, and commercially available LiCoO2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2 and Li3InCl6 were used as positive electrode materials; and they were assembled into full solid-state batteries, which were marked as full solid-state battery 1 (electrolyte was the sulfide electrolyte film a) and full solid-state battery 2 (electrolyte was the hydrophobic sulfide electrolyte film).

[0075] The full solid-state battery 1 and the full solid-state battery 2 were subjected to constant current charge-discharge tests using a Wuhan Blue Electric Battery Test System LAND CT-2001A, and the first cycle charge-discharge curve graphs of the full solid-state battery 1 and the full solid-state battery 2 in Example 1 under a current density of 0.1 C were obtained, as shown in Figure 5 The first cycle charge-discharge curve graphs of the full solid-state battery 1 and the full solid-state battery 2 in Example 1 after being exposed to humid air for 24 h under a current density of 0.1 C were obtained, as shown in Figure 6 It can be seen from Figure 5 that the first cycle discharge capacity and coulombic efficiency of the full solid-state battery 1 were 162.2 mAh·g -1 and 86.7%, respectively, while the first cycle discharge capacity and coulombic efficiency of the full solid-state battery 2 were reduced to 157.1 mAh·g -1 and 86.6%, respectively, which can be attributed to the slight decrease in the conductivity of the hydrophobic coated electrolyte. It can be seen from Figure 6 that the capacity of the full solid-state battery 1 almost completely disappeared, which was due to the reaction of the sulfide electrolyte with H2O in the air, resulting in complete destruction of the electrolyte structure and rapid decrease in ionic conductivity, while the performance of the full solid-state battery 2 almost did not change, which proved the excellent air stability of the hydrophobic coated electrolyte.

[0076] Example 2

[0077] Under an argon atmosphere, 0.3 g of polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), 0.36 g of lithium bisfluorosulfonylimide (LiFSI) and 1.65 g of tetrahydrofuran were mixed and reacted at a rotation speed of 455 r / min and a temperature of 85°C for 2.5 h to obtain a lithium salt polymer binder;

[0078] The 90 g sulfide electrolyte (Li6PS5Cl), 10 g lithium salt polymer binder and 21 mL tetrahydrofuran were mixed by vibration ball milling under an argon atmosphere, and then the mixed slurry was coated (the coated plate material was polytetrafluoroethylene, and the coated thickness was 395 μm), and then a sulfide electrolyte film was obtained by heat treatment under the conditions of a vacuum degree of -0.05 MPa and a temperature of 100 ℃ for 10 h;

[0079] The 1.8 g 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, 2.8 g tetraethyl silicate, 1.0 g lithium aluminum germanium phosphate, 7 g water, 7 g ethanol and 1.3 g ammonia water with a mass fraction of 6.3% were mixed and reacted under the conditions of a temperature of 25 ℃ for 28 h to obtain hydrophobic particles;

[0080] The 0.12 g hydrophobic particles and 5.5 mL petroleum ether were mixed to obtain a petroleum ether solution of the hydrophobic particles, and the petroleum ether solution of the hydrophobic particles was sprayed on the surface of the sulfide electrolyte film (the ratio of the volume of the petroleum ether solution of the hydrophobic particles to the surface area of the sulfide electrolyte film was 9 mL: 10 cm 2 ), to obtain a hydrophobic sulfide electrolyte film.

[0081] The same test method as in Example 1 was used, and the room temperature ionic conductivity of the sulfide electrolyte film in this example was 1.11 mS / cm, and the activation energy was 0.235 eV; the static contact angle of the hydrophobic sulfide electrolyte film in this example was 150°, and the hydrophobic performance was good; the first cycle discharge capacity and coulombic efficiency of the full solid-state battery assembled from the hydrophobic sulfide electrolyte film prepared in this example were 156.9 mAh·g -1 and 86.53% under a current density of 0.1 C, and after exposure to humid air for 24 h, the first cycle discharge capacity and coulombic efficiency were 156.5 mAh·g -1 and 86.5%, and the first cycle discharge capacity and coulombic efficiency changed little.

[0082] Example 3

[0083] The 0.3 g polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), 0.39 g lithium trifluoromethylsulfonate (LiCF3SO3) and 1.8 g acetonitrile were mixed under the conditions of a rotation speed of 500 r / min and a temperature of 75 ℃ for 3.5 h to obtain a lithium salt polymer binder;

[0084] The 85 g sulfide electrolyte (Li6PS5I), 15 g lithium salt polymer binder and 17 mL acetonitrile were mixed by vibration ball milling under an argon atmosphere, and then the mixed slurry was coated (the coated plate material was polytetrafluoroethylene, and the coated thickness was 370 μm), and then was heat-treated under the conditions of a vacuum degree of -0.11 MPa and a temperature of 80 ℃ for 14 h to obtain a sulfide electrolyte film;

[0085] The 2.0 g 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, 3.0 g tetraethyl silicate, 1.1 g lithium aluminum germanium phosphate, 8 g water, 8 g ethanol and 1.5 g ammonia water with a mass fraction of 5.7% were mixed and reacted at a temperature of 35 ℃ for 20 h to obtain hydrophobic particles;

[0086] The 0.05 g hydrophobic particles and 4 mL petroleum ether were mixed to obtain a petroleum ether solution of the hydrophobic particles, and the petroleum ether solution of the hydrophobic particles was sprayed on the surface of the sulfide electrolyte film (the ratio of the volume of the petroleum ether solution of the hydrophobic particles to the surface area of the sulfide electrolyte film was 10.5 mL: 10 cm 2 ), to obtain a hydrophobic sulfide electrolyte film.

[0087] The same test method as in Example 1 was used, and the room temperature ionic conductivity of the sulfide electrolyte film in this example was 1.14 mS / cm, and the activation energy was 0.23 eV; the static contact angle of the hydrophobic sulfide electrolyte film in this example was 150.3°, and the hydrophobic performance was good; the full solid-state battery assembled from the hydrophobic sulfide electrolyte film prepared in this example had a first cycle discharge capacity and coulombic efficiency of 157.5 mAh·g -1 and 86.65% at a current density of 0.1 C, and after being exposed to humid air for 24 h and then tested, the first cycle discharge capacity and coulombic efficiency were 157.2 mAh·g -1 and 86.61%, and the first cycle discharge capacity and coulombic efficiency had little change.

[0088] From the above examples, the lithium salt polymer binder is mixed with the sulfide electrolyte, and a new type of sulfide solid electrolyte film is prepared by a simple slurry coating method, which is simple in process and easy to scale up production; compared with the conventional ion insulating binder, the lithium salt polymer binder in the application has excellent electrical conductivity, which can promote ion transmission in the composite electrolyte. In addition, the lithium salt polymer binder is uniformly distributed in the electrode in the form of a thin film, rather than gathered together in a block, which structure is conducive to enhancing the mechanical properties of the electrolyte film. The application also prepares an ion-conducting hydrophobic particle, and covers the hydrophobic particle on the electrolyte film by a spraying method, so that the electrolyte can be stored and used under various extreme conditions. Among them, the sulfide electrolyte as an oxide electrolyte particle has the function of ion transmission, which can ensure that the hydrophobic coating will not have a great influence on the ionic conductivity of the composite electrolyte. 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane and tetraethyl silicate can form fluorinated organopolysiloxane under the catalysis of ammonia, which has low surface energy and can provide strong hydrophobic properties for the coating. The hydrophobic sulfide electrolyte film prepared by the application does not need to be stored in a glove box completely isolated from water and oxygen, which greatly reduces the use and transportation cost, and has strong practicability.

[0089] In summary, the hydrophobic sulfide electrolyte film prepared by the application has excellent ionic conductivity, mechanical properties, air stability and hydrophobic properties.

[0090] The above only describes the preferred embodiments of the application, and it should be noted that for those skilled in the art, without departing from the principles of the application, several improvements and refinements can be made, which should also be considered as the protection scope of the application.

Claims

1. A method for producing a thin film of a hydrophobic sulfide electrolyte, characterized by, The preparation method comprises the following steps: (1) mixing polyvinylidene fluoride-hexafluoropropylene, lithium salt and solvent to react under a protective atmosphere to obtain a lithium salt polymer binder; (2) mixing a sulfide electrolyte, the lithium salt polymer binder and solvent, coating and heat treating in sequence under a protective atmosphere to obtain a sulfide electrolyte film; (3) mixing 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, tetraethyl silicate, germanium aluminum lithium phosphate, water, ethanol and ammonia water to react to obtain hydrophobic particles; the mass ratio of the 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, tetraethyl silicate, germanium aluminum lithium phosphate, water, ethanol and ammonia water is 12-24:19-38:7-14:50-100:50-100:9-18; the mass fraction of the ammonia water is 5.5-6.5%; the reaction temperature in step (3) is 20-40℃, and the reaction time is 18-30h; (4) spraying a petroleum ether solution of hydrophobic particles on the surface of the sulfide electrolyte thin film to obtain the hydrophobic sulfide electrolyte thin film; the mass-volume ratio of the hydrophobic particles to the petroleum ether in the petroleum ether solution of hydrophobic particles is 0.05-0.15 g:3-7 mL; the ratio of the volume of the petroleum ether solution of hydrophobic particles to the surface area of the sulfide electrolyte thin film is 8-12 mL:8-12 cm 2 .

2. The production method according to claim 1, wherein The lithium salt in step (1) is one or more of lithium bis(trifluoromethyl imide), lithium bisfluorosulfonylimide, lithium trifluoromethyl sulfonate and lithium perchlorate; The solvent is acetonitrile and / or tetrahydrofuran; The mass ratio of the polyvinylidene fluoride-hexafluoropropylene, lithium salt and solvent is 1:1-1.5:4-6.

3. The production method according to claim 1 or 2, characterized by, The reaction temperature in step (1) is 75-85℃, and the reaction time is 2.5-3.5h.

4. The production method according to claim 3, wherein The sulfide electrolyte of step (2) is one or several of Li7P3S 11 , Li6PS5Cl, Li6PS5Br, Li6PS5I, Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 and Li 10 GeP2S 12 ​ The solvent is acetonitrile and / or tetrahydrofuran; The mass volume ratio of the sulfide electrolyte, lithium salt polymer binder and solvent is 80-97.5g:2.5-20g:15-25mL.

5. The production method according to claim 4, wherein The heat treatment temperature in step (2) is 80-100℃, and the heat treatment time is 10-14h.

6. The hydrophobic sulfide electrolyte film obtained by the preparation method in any one of claims 1-5.

7. The application of the hydrophobic sulfide electrolyte film in claim 6 in a solid-state battery.

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