A sulfide-based composite solid electrolyte membrane, and a preparation method and application thereof

Abstract

The application provides a preparation method of a sulfide-based composite solid electrolyte film, comprising the following steps: adding 65-95 parts of a sulfide electrolyte, 1-10 parts of a lithium salt, 3-20 parts of a liquid polyether, 0.5-5 parts of a liquid organic modifier and 0.5-5 parts of a flame retardant into a high-speed blender according to mass fractions, and mixing by high-speed stirring, wherein one of the liquid polyether and the liquid organic modifier contains an amino group, and the other contains an epoxy group; rolling the mixed sample to obtain a thin film sample with a thickness of 20-50 microns; and placing the thin film sample in a vacuum oven for heat treatment to obtain the sulfide-based composite solid electrolyte film. The application also provides a sulfide-based composite solid electrolyte film and application thereof. The sulfide-based composite solid electrolyte film prepared by the preparation method has good film forming performance, and the film thickness can reach 20-50 microns.

Description

Technical Field

[0001] This application belongs to the field of solid electrolyte technology, specifically relating to a sulfide-based composite solid electrolyte membrane, its preparation method, and its application. Background Technology

[0002] Solid-state lithium batteries use solid electrolytes instead of liquid electrolytes. Compared to traditional liquid lithium batteries, they can be paired with high-energy-density materials to achieve higher energy density, effectively addressing the application pain points of liquid lithium batteries. As the core component of solid-state batteries, solid electrolytes should possess properties such as high room-temperature ionic conductivity, the thinnest possible thickness, light weight, and good mechanical strength. Among them, sulfide electrolytes have high conductivity, comparable to liquid electrolytes, and show great development potential. However, sulfides have poor stability, and currently, most sulfide electrolytes are produced by direct hot-pressing of dry powder films, making it difficult to achieve a thickness below 50μm.

[0003] Therefore, it is necessary to provide a sulfide-based composite solid electrolyte membrane, its preparation method, and its application to solve the problems mentioned in the background art. Summary of the Invention

[0004] This application provides a sulfide-based composite solid electrolyte membrane, its preparation method, and its application. It utilizes the reaction of amino and epoxy groups in a liquid organic modifier / liquid polyether system to form a well-stable two-phase structure. The connection between the organic polymer and inorganic particles can increase the air stability of the sulfide electrolyte. Furthermore, the organic polymer has good lithium-ion dissolving ability and flexibility, which makes the electrolyte membrane have good film-forming properties, and the film thickness can be 20-50 μm.

[0005] To solve the above-mentioned technical problems, the technical solution of this application is as follows:

[0006] A method for preparing a sulfide-based composite solid electrolyte membrane includes the following steps:

[0007] S1: According to the mass fractions, add 65-95 parts of sulfide electrolyte, 1-10 parts of lithium salt, 3-20 parts of liquid polyether, 0.5-5 parts of liquid organic modifier and 0.5-5 parts of flame retardant into a high-speed mixer and mix at high speed. The liquid polyether and the liquid organic modifier contain an amino group and an epoxy group, respectively.

[0008] S2: The sample mixed in step S1 is rolled to obtain a thin film sample with a thickness of 20-50μm;

[0009] S3: The thin film sample obtained in step S2 is placed in a vacuum oven and heat-treated to obtain a sulfide-based composite solid electrolyte membrane.

[0010] Preferably, the liquid organic modifier is selected from aminopropyltrimethoxysilane or aminopropyltriethoxysilane; the liquid polyether is polyethylene glycol diglycidyl ether.

[0011] Preferably, the liquid organic modifier is 3-glycidyl etheroxypropyltrimethoxysilane; the liquid polyether is an amino-terminated polyether with a relative molecular mass of 230-4000, and its structural formula is shown below:

[0012] Preferably, the flame retardant is selected from one of toluene diphenyl phosphate, tri(xyl) phosphate, and tricresyl phosphate.

[0013] Preferably, the sulfide electrolyte is selected from Li7P3S. 11 Li3PS4, Li2P5, Li 10 GeP2S 12 One or more of Li6PS5Cl.

[0014] Preferably, the lithium salt is any one or a combination of two of lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, and lithium bis(trifluoromethanesulfonyl)imide.

[0015] Preferably, the stirring time in step S1 is 1-24 hours and the temperature is 60-80℃.

[0016] Preferably, in step S3, the heat treatment temperature is 60-80℃ and the treatment time is 24h.

[0017] This application also provides a sulfide-based composite solid electrolyte membrane, which is prepared by the above-described preparation method, and the thickness of the sulfide-based composite solid electrolyte membrane is 20-50 μm.

[0018] This application also provides an application of a sulfide-based composite solid electrolyte membrane, which is used in a solid-state secondary lithium-ion battery.

[0019] The beneficial effects of this application are as follows:

[0020] (1) The amino and epoxy groups in the liquid organic modifier / liquid polyether system react to form a good and stable two-phase structure. The reaction process does not require solvents and is green and environmentally friendly. In the preparation process, the surface of the sulfide electrolyte is coated and modified by the liquid modifier, and then reacted with the liquid polyether to construct a polymer electrolyte network on the surface of the sulfide electrolyte, which can increase the compatibility of the two-phase interface. The polymer electrolyte network has good lithium-ion dissolution ability. After bonding with the sulfide electrolyte, it can form a continuous lithium-ion conductive channel and increase the conductivity of the electrolyte film.

[0021] (2) After the polymer electrolyte network is connected to the sulfide electrolyte, it can play an insulating role and increase the air stability of the sulfide electrolyte.

[0022] (3) The polymer electrolyte network has good flexibility, which makes its film-forming performance good and makes it easier to achieve thickness control and continuous production;

[0023] (4) The addition of ester flame retardants can not only increase the bonding performance of organic polymers and inorganic sulfide electrolytes, but also improve the flame retardant performance of the electrolyte membrane and enhance the safety of use. Detailed Implementation

[0024] The technical solutions of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0025] This application provides a method for preparing a sulfide-based composite solid electrolyte membrane, comprising the following steps:

[0026] S1: According to the mass fractions, add 65-95 parts of sulfide electrolyte, 1-10 parts of lithium salt, 0.5-5 parts of flame retardant, 3-20 parts of liquid polyether and 0.5-5 parts of liquid organic modifier into a high-speed mixer and mix at high speed. The liquid polyether and the liquid organic modifier contain an amino group and an epoxy group, respectively.

[0027] The sulfide electrolyte is selected from Li7P3S. 11 Li3PS4, Li2P5, Li 10 GeP2S 12 One or more of Li6PS5Cl; the lithium salt is any one or a combination of two of lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, and lithium bis(trifluoromethanesulfonyl)imide; the flame retardant is selected from one of toluene diphenyl phosphate, tri(xyl) phosphate, and tricresyl phosphate.

[0028] In one embodiment of this application, the liquid organic modifier is selected from aminopropyltrimethoxysilane or aminopropyltriethoxysilane; the liquid polyether is polyethylene glycol diglycidyl ether. The aminopropyltrimethoxysilane or aminopropyltriethoxysilane provides the amino groups required for the reaction, and the polyethylene glycol diglycidyl ether provides the epoxy groups required for the reaction.

[0029] In another embodiment of this application, the liquid organic modifier is 3-glycidyl etheroxypropyltrimethoxysilane; the liquid polyether is an amino-terminated polyether, wherein the 3-glycidyl etheroxypropyltrimethoxysilane provides the epoxy groups required for the reaction, and the amino-terminated polyether provides the amino groups required for the reaction. The relative molecular mass of the amino-terminated polyether is 230-4000, and its structural formula is shown below:

[0030]

[0031] In the liquid organic modifier / liquid polyether system, amino and epoxy groups react to form a well-structured and stable two-phase structure. The reaction process is solvent-free and environmentally friendly. During preparation, the surface of the sulfide electrolyte is coated and modified using a liquid modifier, and then reacted with liquid polyether to construct a polymer electrolyte network on the surface of the sulfide electrolyte, which can increase the compatibility of the two-phase interface. The polymer electrolyte network has good lithium-ion dissolving ability. After bonding with the sulfide electrolyte, it can form a continuous lithium-ion conductive channel, increasing the conductivity of the electrolyte film. After the polymer electrolyte network is connected to the sulfide electrolyte, it can also act as an insulator, increasing the air stability of the sulfide electrolyte.

[0032] The flame retardant is also encapsulated within the organic polymer and uniformly distributed within it, which can increase the flame retardant properties of the electrolyte membrane. Furthermore, the flame retardant is selected as an ester, which can also increase the adhesion between the sulfide electrolyte and the organic phase, further enhancing the flexibility of the electrolyte membrane and contributing to the reduction of membrane thickness.

[0033] In step S1, the stirring time is 1-24 hours and the temperature is 60-80℃, so that the added materials are fully mixed and reacted.

[0034] S2: The sample mixed in step S1 is rolled to obtain a thin film sample with a thickness of 20-50 μm.

[0035] Polymer electrolyte networks have good flexibility, which makes them have good film-forming properties, and it is easy to achieve thickness control and continuous production. The film thickness can be 20-50μm.

[0036] S3: The thin film sample obtained in step S2 is placed in a vacuum oven and heat-treated to obtain a sulfide-based composite solid electrolyte membrane.

[0037] Preferably, in step S3, the heat treatment temperature is 60-80℃ and the treatment time is 24h.

[0038] The preparation method provided in this application adopts a one-pot method, in which all materials are added into a high-speed mixer at once before the reaction. The operation is quick and convenient, and it is suitable for industrial mass production.

[0039] This application also provides a sulfide-based composite solid electrolyte membrane, which is prepared by the above-described preparation method, and the thickness of the sulfide-based composite solid electrolyte membrane is 20-50 μm.

[0040] This application also provides an application of a sulfide-based composite solid electrolyte membrane, which is used in a solid-state secondary lithium-ion battery.

[0041] Example 1

[0042] This embodiment provides a method for preparing a sulfide-based composite solid electrolyte membrane, comprising the following steps:

[0043] (1) According to the mass fractions, 75 parts of Li3PS4 powder, 20 parts of polyethylene glycol diglycidyl ether, 2 parts of aminopropyltriethoxysilane, 3 parts of lithium bis(trifluoromethanesulfonyl)imide, and 0.5 parts of toluene diphenyl phosphate were added into a high-speed mixer and stirred at 50 rpm for 12 hours at a temperature of 80°C.

[0044] (2) The sample after mixing in step (1) is rolled into a film by a roller press;

[0045] (3) The thin film sample prepared in step (2) was placed in a vacuum oven and heat-treated at a temperature of 60°C for 24 hours to obtain sample 1.

[0046] Example 2

[0047] (1) According to the mass fraction, 75 parts of Li6PS5Cl powder, 15 parts of polyethylene glycol diglycidyl ether, 5 parts of aminopropyltriethoxysilane, 5 parts of lithium perchlorate, and 3 parts of tri(xylene) phosphate were added to a high-speed mixer and stirred at 50 rpm for 24 hours at a temperature of 60℃.

[0048] (2) The sample after mixing in step (1) is rolled into a film by a roller press.

[0049] (3) The thin film sample prepared in step (2) was placed in a vacuum oven and heat-treated at a temperature of 60°C for 24 hours to obtain sample 2.

[0050] Example 3

[0051] (1)Li7P3S 11 80 parts of powder, 15 parts of polyethylene glycol diglycidyl ether, 1 part of aminopropyltriethoxysilane, 4 parts of lithium bis(trifluoromethanesulfonyl)imide, and 5 parts of tricresyl phosphate were added to a high-speed mixer and stirred at 50 rpm for 10 hours at 70°C.

[0052] (2) The sample after mixing in step (1) is rolled into a film by a roller press.

[0053] (3) The thin film sample prepared in step (2) was placed in a vacuum oven and heat-treated at a temperature of 60°C for 24 hours to obtain sample 3.

[0054] Example 4

[0055] (1)Li 10 GeP2S 12 70 parts of powder, 20 parts of polyetheramine, 2 parts of 3-glycidyl etheroxypropyltrimethoxysilane, 5 parts of lithium bis(trifluoromethanesulfonyl)imide, and 3 parts of tricresyl phosphate were added to a high-speed mixer and stirred at 100 rpm for 12 hours at 80°C.

[0056] (2) The sample after mixing in step (1) is rolled into a film by a roller press.

[0057] (3) The thin film sample prepared in step (2) was placed in a vacuum oven and heat-treated at a temperature of 60°C for 24 hours to obtain sample 4.

[0058] Example 5

[0059] (1)Li7P3S 11 75 parts of powder, 15 parts of polyetheramine, 2 parts of 3-glycidyl etheroxypropyltrimethoxysilane, 5 parts of lithium bis(trifluoromethanesulfonyl)imide, and 3 parts of diphenyl toluene phosphate were added to a high-speed mixer and stirred at 50 rpm for 24 hours at 80°C.

[0060] (2) The sample after mixing in step (1) is rolled into a film by a roller press.

[0061] (3) The thin film sample prepared in step (2) was placed in a vacuum oven and heat-treated at a temperature of 60°C for 24 hours to obtain sample 5.

[0062] Comparative Example 1

[0063] (1) According to the mass fraction, 75 parts of Li3PS4 powder, 20 parts of polyethylene glycol diglycidyl ether, and 3 parts of lithium bis(trifluoromethanesulfonyl)imide were added to a high-speed mixer and stirred at 50 rpm for 12 hours at 80°C.

[0064] (2) The sample mixed in step (1) is rolled into a film by a roller press.

[0065] (3) The thin film sample prepared in step (2) was placed in a vacuum oven and heat-treated at a temperature of 60°C for 24 hours to obtain sample 6.

[0066] Comparative Example 2

[0067] (1) According to the mass fraction, 75 parts of Li6PS5Cl powder, 15 parts of polyethylene glycol diglycidyl ether, and 5 parts of lithium perchlorate were added to a high-speed mixer and stirred at 50 rpm for 24 hours at a temperature of 60℃.

[0068] (2) The sample after mixing in step (1) is rolled into a film by a roller press;

[0069] (3) The thin film sample prepared in step (2) was placed in a vacuum oven and heat-treated at a temperature of 60°C for 24 hours to obtain sample 7.

[0070] Comparative Example 3

[0071] (1) According to the mass fraction, Li7P3S 11 80 parts of powder, 15 parts of polyethylene glycol diglycidyl ether, and 4 parts of lithium bis(trifluoromethanesulfonyl)imide were added to a high-speed mixer and stirred at 50 rpm for 10 hours at a temperature of 70°C.

[0072] (2) The sample after mixing in step (1) is rolled into a film by a roller press.

[0073] (3) The thin film sample prepared in step (2) was placed in a vacuum oven and heat-treated at a temperature of 60°C for 24 hours to obtain sample 8.

[0074] Samples 1-6 were tested, and their ionic conductivity, electrochemical stability, film thickness, and flame retardant properties were measured. The test results are shown in Table 1.

[0075] Table 1

[0076]

[0077]

[0078] Comparing samples 1-5 with samples 6-8, it can be seen that the ionic conductivity of samples 1-5 is significantly higher than that of samples 6-8. This is because liquid organic modifiers are added to samples 1-5, which act as a bridge in the system and can enhance the compatibility between the sulfide electrolyte and the organic phase. Furthermore, samples 1-5 also maintain good electrochemical stability and flame retardancy, and the film thickness can be below 50 μm.

[0079] The embodiments of this application have been described above, but this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for preparing a sulfide-based composite solid electrolyte membrane, characterized in that, Includes the following steps: S1: According to the mass percentages, add 65-95 parts of sulfide electrolyte, 1-10 parts of lithium salt, 3-20 parts of liquid polyether, 0.5-5 parts of liquid organic modifier, and 0.5-5 parts of flame retardant to a mixer and mix. The liquid polyether and the liquid organic modifier shall each contain an amino group and an epoxy group, respectively. The selection of the liquid polyether and the liquid organic modifier shall satisfy one of the following conditions: (1) The liquid organic modifier is selected from one of aminopropyltrimethoxysilane or aminopropyltriethoxysilane; the liquid polyether is polyethylene glycol diglycidol; (2) The liquid organic modifier is 3-glycidyl etheroxypropyltrimethoxysilane; the liquid polyether is an amino-terminated polyether with a relative molecular mass of 230-4000, and its structural formula is shown below: ； S2: The sample mixed in step S1 is rolled to obtain a thin film sample with a thickness of 20-50μm; S3: The thin film sample obtained in step S2 is placed in a vacuum oven and heat-treated to obtain a sulfide-based composite solid electrolyte membrane. The stirring time in step S1 is 1-24 hours, the temperature is 60-80℃, and the stirring speed is 50 rpm or 100 rpm. In step S3, the heat treatment temperature is 60-80℃ and the treatment time is 24h.

2. The method for preparing a sulfide-based composite solid electrolyte membrane according to claim 1, characterized in that, The flame retardant is selected from one of toluene diphenyl phosphate, tri(xyl) phosphate, and tricresyl phosphate.

3. The method for preparing a sulfide-based composite solid electrolyte membrane according to claim 1, characterized in that, The sulfide electrolyte is selected from Li7P3S. 11 Li3PS4, Li2P5, Li 10 GeP2S 12 One or more of Li6PS5Cl.

4. The method for preparing a sulfide-based composite solid electrolyte membrane according to claim 1, characterized in that, The lithium salt is any one or a combination of two of lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, and lithium bis(trifluoromethanesulfonyl)imide.

5. A sulfide-based composite solid electrolyte membrane, characterized in that, The sulfide-based composite solid electrolyte membrane is prepared by any one of the preparation methods described in claims 1-4, and the thickness of the membrane is 20-50 μm.

6. The sulfide-based composite solid electrolyte membrane according to claim 5, characterized in that, The sulfide-based composite solid electrolyte membrane is used in solid-state secondary lithium-ion batteries.

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