Composite electrolyte membrane and preparation method and application thereof

Abstract

The application relates to a preparation method of a composite electrolyte membrane, and steps of the method comprise the following: S1, dissolving polyethylene terephthalate in a first organic solvent, and preparing a three-dimensional macroporous membrane through electrostatic spinning; after sequentially performing acid modification treatment and lithium ion exchange treatment on the three-dimensional macroporous membrane, a carrier is obtained; S2, dissolving a sulfide electrolyte, a binder and a dispersant in a second organic solvent to obtain a slurry; S3, scraping the slurry on the surface of the carrier, and performing first drying on the carrier coated with the slurry to obtain an intermediate electrolyte membrane; spraying the slurry on the surface of the intermediate electrolyte membrane again, and performing second drying on the intermediate electrolyte membrane coated with the slurry to obtain the composite electrolyte membrane. Through the acid modification treatment, the lithium ion exchange treatment and the scraping and then spraying, the preparation method improves the interaction force between the electrostatic spinning membrane and the sulfide electrolyte slurry, so that the compactness of the composite electrolyte membrane is improved.

Description

Technical Field

[0001] This invention relates to the field of all-solid-state battery technology, and in particular to a composite electrolyte membrane, its preparation method, and its application. Background Technology

[0002] With the increasing demand for longer driving ranges in electric vehicles, all-solid-state batteries have become a key research focus due to their advantages such as safety, higher energy density, fast charging, and convenient recycling. Solid-state electrolyte technology is the core of all-solid-state battery technology, and currently, the main types of all-solid-state electrolytes include oxides, polymers, sulfides, and halides. Solid-state electrolytes generally have lower conductivity than liquid electrolytes, but sulfide electrolytes can achieve conductivity as high as 10⁻⁶. -2 S / cm.

[0003] Currently, the film formation methods for solid electrolytes are mainly divided into dry and wet methods. Among them, the wet method mainly involves introducing binders and solvents into the electrolyte to form a slurry, and then coating the slurry onto the substrate by a doctor blade. However, the binders and solvents will significantly reduce the conductivity of the electrolyte, and the poor mechanical strength will prevent subsequent industrial processing.

[0004] Therefore, there is an urgent need for a composite electrolyte membrane, its preparation method, and its application. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a composite electrolyte membrane, its preparation method, and its applications.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of this invention is to provide a method for preparing a composite electrolyte membrane, comprising the steps of:

[0008] S1. Preparation of the carrier: Polyethylene terephthalate is dissolved in a first organic solvent and a three-dimensional macroporous membrane is prepared by electrospinning. The three-dimensional macroporous membrane is then subjected to acidification modification and lithium-ion exchange treatment in sequence to obtain the carrier.

[0009] S2. Preparation of slurry: Dissolve the sulfide electrolyte, binder and dispersant in a second organic solvent to obtain the slurry;

[0010] S3. Preparation of composite electrolyte membrane: The slurry is coated onto the surface of the carrier and the carrier coated with the slurry is first dried to obtain an intermediate electrolyte membrane; the slurry is then sprayed onto the surface of the intermediate electrolyte membrane and the intermediate electrolyte membrane coated with the slurry is second dried to obtain the composite electrolyte membrane.

[0011] Preferably, the first organic solvent includes N,N-dimethylformamide and acetone.

[0012] Furthermore, the volume ratio of N,N-dimethylformamide to acetone is 1:9 to 3:7.

[0013] Preferably, the thickness of the carrier is 10 μm to 20 μm.

[0014] Preferably, the acidification modification treatment includes: immersing the three-dimensional macroporous membrane in a dilute acid solution and performing acid treatment at 50℃~300℃ for 1h~12h; cleaning the acid-treated three-dimensional macroporous membrane and then immersing it in a dilute alkali solution for alkali treatment for 1h~12h; and then performing neutralization treatment and drying on the alkali-treated three-dimensional macroporous membrane to obtain the acid-modified three-dimensional macroporous membrane.

[0015] Furthermore, the acid treatment temperature is 25℃~100℃.

[0016] Preferably, the lithium-ion exchange treatment includes: immersing the acid-modified three-dimensional macroporous membrane in a solution containing lithium ions for lithium-ion exchange treatment for 1 to 12 hours, thereby obtaining the lithium-ion exchange treated three-dimensional macroporous membrane.

[0017] Preferably, the slurry comprises, by weight parts:

[0018]

[0019] Further, by weight, the slurry comprises:

[0020]

[0021] Preferably, the sulfide electrolyte comprises: Li₂S-P₂S₅, Li 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 10 SnP2S 12 At least one of Li6PS5Cl, Li6PS5I, or Li6PS5Br.

[0022] Preferably, the adhesive comprises at least one of styrene-butadiene-styrene block copolymer, nitrile rubber, styrene-butadiene rubber, or hydrogenated nitrile rubber.

[0023] Preferably, the dispersant comprises at least one of Croda dispersant or carboxymethyl cellulose (CMC).

[0024] Preferably, the second organic solvent includes at least one of toluene, anisole, or n-heptane.

[0025] Preferably, the solid content of the slurry is 30% to 70%.

[0026] Preferably, the coating thickness of the slurry on the surface of the carrier is 20 μm to 100 μm.

[0027] Preferably, the thickness of the slurry sprayed onto the surface of the intermediate electrolyte membrane is 20 μm to 100 μm.

[0028] Preferably, the first drying process includes: drying the carrier coated with the slurry at room temperature at a dew point of -50°C to -60°C for 1 hour to 12 hours, and then transferring it to a vacuum dryer at 50°C to 120°C for 2 hours to 12 hours.

[0029] Preferably, the second drying process includes: drying the intermediate electrolyte membrane coated with the slurry at room temperature at a dew point of -50°C to -60°C for 1 to 12 hours, and then transferring it to a vacuum dryer at 50°C to 120°C for 2 to 12 hours.

[0030] A second aspect of the present invention is to provide a composite electrolyte membrane prepared by the preparation method described above.

[0031] A third aspect of the present invention is to provide an all-solid-state battery, comprising: a composite electrolyte membrane as described above.

[0032] The present invention adopts the above technical solution and has the following technical effects compared with the prior art:

[0033] The preparation method of this invention uses an electrospun polyethylene terephthalate (PET) membrane as a carrier for the sulfide electrolyte slurry to improve the mechanical strength of the composite electrolyte membrane. Simultaneously, the structure of the electrospun membrane facilitates the penetration and encapsulation of the sulfide electrolyte slurry, thereby improving the conductivity of the composite electrolyte membrane. Furthermore, the preparation method of this invention enhances the interaction between the electrospun membrane and the sulfide electrolyte slurry through acid modification treatment, lithium-ion exchange treatment, and a combination of scraping and spraying, thereby improving the density of the composite electrolyte membrane. Attached Figure Description

[0034] Figure 1 This is a graph showing the results of the cyclic performance test in the test embodiment of the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0038] Example 1

[0039] This embodiment provides a composite electrolyte membrane and its preparation method. The preparation method includes the following steps:

[0040] S1. Preparation of the carrier:

[0041] S1-1. Polyethylene terephthalate (PET) is dissolved in a mixed organic solvent (N,N-dimethylformamide and acetone in a volume ratio of 3:7) and a three-dimensional macroporous membrane with a thickness of 15 μm is obtained by electrospinning.

[0042] S1-2. The three-dimensional macroporous membrane is subjected to acid modification treatment, including: immersing the three-dimensional macroporous membrane in a 0.3 mol / L hydrochloric acid solution and acid treating it at 30°C for 2 hours; washing the acid-treated three-dimensional macroporous membrane with deionized water and then immersing it in a 0.1 mol / L sodium hydroxide solution for alkali treatment for 1 hour; and then subjecting the alkali-treated three-dimensional macroporous membrane to hydrochloric acid neutralization treatment and drying it at 100°C to obtain the acid-modified three-dimensional macroporous membrane.

[0043] S1-3. The three-dimensional macroporous membrane after acidification and modification is subjected to lithium-ion exchange treatment, including: immersing the three-dimensional macroporous membrane after acidification and modification in a 1 mol / L LiTFSI solution for lithium-ion exchange treatment for 2 hours, and the resulting three-dimensional macroporous membrane after lithium-ion exchange treatment is the carrier.

[0044] S2. Preparation of slurry: Dissolve 1.96g of Li6PS5Cl, 0.04g of nitrile rubber (NBR) and 0.01g of Croda dispersant in 2g of toluene to obtain the slurry;

[0045] S3. Preparation of composite electrolyte membrane: The slurry is coated onto the surface of the carrier with a coating thickness of 50 μm. The carrier coated with the slurry is dried at room temperature at a dew point of -50° to -60° for 6 hours, and then transferred to vacuum drying at 80° for 12 hours to obtain an intermediate electrolyte membrane. After rolling the intermediate electrolyte membrane, the slurry is sprayed onto the surface of the intermediate electrolyte membrane with a spray thickness of 50 μm. The intermediate electrolyte membrane coated with the slurry is dried at room temperature at a dew point of -50° to -60° for 6 hours, and then transferred to vacuum drying at 80° for 12 hours to obtain the composite electrolyte membrane.

[0046] In a preferred embodiment, the three-dimensional macroporous membrane has an average pore size of 20 μm and a porosity of 35%.

[0047] In a preferred embodiment, the parameters of the rolling process include: a rolling pressure of 370 MPa.

[0048] Example 2

[0049] This embodiment provides a composite electrolyte membrane and its preparation method. The preparation method includes the following steps:

[0050] S1. Preparation of the carrier:

[0051] S1-1. Polyethylene terephthalate (PET) is dissolved in a mixed organic solvent (N,N-dimethylformamide and acetone in a volume ratio of 3:7) and a three-dimensional macroporous membrane with a thickness of 15 μm is obtained by electrospinning.

[0052] S1-2. The three-dimensional macroporous membrane is subjected to acid modification treatment, including: immersing the three-dimensional macroporous membrane in a 0.3 mol / L hydrochloric acid solution and acid treating it at 50°C for 2 hours; washing the acid-treated three-dimensional macroporous membrane with deionized water and then immersing it in a 0.1 mol / L sodium hydroxide solution for alkali treatment for 3 hours; and then subjecting the alkali-treated three-dimensional macroporous membrane to hydrochloric acid neutralization treatment and drying it at 80°C to obtain the acid-modified three-dimensional macroporous membrane.

[0053] S1-3. The three-dimensional macroporous membrane after acidification and modification is subjected to lithium-ion exchange treatment, including: immersing the three-dimensional macroporous membrane after acidification and modification in a 1 mol / L LiTFSI solution for lithium-ion exchange treatment for 2 hours, and the resulting three-dimensional macroporous membrane after lithium-ion exchange treatment is the carrier.

[0054] S2. Preparation of slurry: Dissolve 1.96g of Li6PS5Cl, 0.04g of nitrile rubber (NBR) and 0.01g of Croda dispersant in 2g of toluene to obtain the slurry;

[0055] S3. Preparation of composite electrolyte membrane: The slurry is coated onto the surface of the carrier with a coating thickness of 50 μm. The carrier coated with the slurry is dried at room temperature at a dew point of -50° to -60° for 6 hours, and then transferred to vacuum drying at 80° for 12 hours to obtain an intermediate electrolyte membrane. After rolling the intermediate electrolyte membrane, the slurry is sprayed onto the surface of the intermediate electrolyte membrane with a spray thickness of 20 μm. The intermediate electrolyte membrane coated with the slurry is dried at room temperature at a dew point of -50° to -60° for 6 hours, and then transferred to vacuum drying at 80° for 12 hours to obtain the composite electrolyte membrane.

[0056] In a preferred embodiment, the three-dimensional macroporous membrane has an average pore size of 30 μm and a porosity of 30%.

[0057] In a preferred embodiment, the parameters of the rolling process include: a rolling pressure of 300 MPa.

[0058] Example 3

[0059] This embodiment provides a composite electrolyte membrane and its preparation method. The preparation method includes the following steps:

[0060] S1. Preparation of the carrier:

[0061] S1-1. Polyethylene terephthalate (PET) is dissolved in a mixed organic solvent (N,N-dimethylformamide and acetone in a volume ratio of 3:7) and a three-dimensional macroporous membrane with a thickness of 15 μm is obtained by electrospinning.

[0062] S1-2. The three-dimensional macroporous membrane is subjected to acid modification treatment, including: immersing the three-dimensional macroporous membrane in a 0.3 mol / L hydrochloric acid solution and acid treating it at 70°C for 2 hours; washing the acid-treated three-dimensional macroporous membrane with deionized water and then immersing it in a 0.1 mol / L sodium hydroxide solution for alkali treatment for 3 hours; and then subjecting the alkali-treated three-dimensional macroporous membrane to hydrochloric acid neutralization treatment and drying it at 80°C to obtain the acid-modified three-dimensional macroporous membrane.

[0063] S1-3. The three-dimensional macroporous membrane after acidification and modification is subjected to lithium-ion exchange treatment, including: immersing the three-dimensional macroporous membrane after acidification and modification in a 1 mol / L LiTFSI solution for lithium-ion exchange treatment for 2 hours, and the resulting three-dimensional macroporous membrane after lithium-ion exchange treatment is the carrier.

[0064] S2. Preparation of slurry: Dissolve 1.96g of Li6PS5Cl, 0.04g of nitrile rubber (NBR) and 0.01g of Croda dispersant in 2g of toluene to obtain the slurry;

[0065] S3. Preparation of composite electrolyte membrane: The slurry is coated onto the surface of the carrier with a coating thickness of 50 μm. The carrier coated with the slurry is dried at room temperature at a dew point of -50° to -60° for 6 hours, and then transferred to vacuum drying at 80° for 12 hours to obtain an intermediate electrolyte membrane. After rolling the intermediate electrolyte membrane, the slurry is sprayed onto the surface of the intermediate electrolyte membrane with a coating thickness of 90 μm. The intermediate electrolyte membrane coated with the slurry is dried at room temperature at a dew point of -50° to -60° for 6 hours, and then transferred to vacuum drying at 80° for 12 hours to obtain the composite electrolyte membrane.

[0066] In a preferred embodiment, the three-dimensional macroporous membrane has an average pore size of 30 μm and a porosity of 34%.

[0067] In a preferred embodiment, the parameters of the rolling process include: a rolling pressure of 300 MPa.

[0068] Application Examples

[0069] This application example provides an all-solid-state battery and its preparation method. The preparation method includes the following steps:

[0070] After the composite electrolyte membrane described in Example 1 is subjected to isostatic pressing, it is assembled with NCM811 material (positive electrode) without lithium nickel oxide coating and Si (negative electrode) to form a pouch battery.

[0071] In this application embodiment, the isostatic pressure of the isostatic pressing treatment is 50 MPa-800 MPa.

[0072] In another preferred embodiment, the isostatic pressure of the isostatic pressing treatment is 100 MPa.

[0073] In another preferred embodiment, the isostatic pressure of the isostatic pressing treatment is 200 MPa.

[0074] In another preferred embodiment, the isostatic pressure of the isostatic pressing treatment is 300 MPa.

[0075] In another preferred embodiment, the isostatic pressure of the isostatic pressing treatment is 500 MPa.

[0076] In this application embodiment, the isostatic pressing time for the isostatic pressing treatment is 10s-10min.

[0077] In another preferred embodiment, the isostatic pressing time for the isostatic pressing treatment is 30 seconds.

[0078] In another preferred embodiment, the isostatic pressing time for the isostatic pressing treatment is 5 minutes.

[0079] In another preferred embodiment, the isostatic pressing time for the isostatic pressing treatment is 6 minutes.

[0080] In another preferred embodiment, the isostatic pressing time for the isostatic pressing treatment is 10 minutes.

[0081] Comparative Example

[0082] This comparative example provides another all-solid-state battery and its fabrication method, the fabrication method including the following steps:

[0083] S1. Preparation of the carrier:

[0084] S1-1. Polyethylene terephthalate (PET) is dissolved in a mixed organic solvent (N,N-dimethylformamide and acetone in a volume ratio of 3:7) and a three-dimensional macroporous membrane with a thickness of 15 μm is obtained by electrospinning.

[0085] S1-2. The three-dimensional macroporous membrane is subjected to acid modification treatment, including: immersing the three-dimensional macroporous membrane in a 0.3 mol / L hydrochloric acid solution and acid treating it at 50°C for 2 hours; washing the acid-treated three-dimensional macroporous membrane with deionized water and then immersing it in a 0.01 mol / L sodium hydroxide solution for alkali treatment for 5 hours; and then subjecting the alkali-treated three-dimensional macroporous membrane to hydrochloric acid neutralization treatment and drying it at 70°C to obtain the acid-modified three-dimensional macroporous membrane.

[0086] S1-3. The three-dimensional macroporous membrane after acidification and modification is subjected to lithium-ion exchange treatment, including: immersing the three-dimensional macroporous membrane after acidification and modification in a 1 mol / L LiTFSI solution for lithium-ion exchange treatment for 2 hours, and the resulting three-dimensional macroporous membrane after lithium-ion exchange treatment is the carrier.

[0087] S2. Preparation of slurry: Dissolve 1.96g of Li6PS5Cl, 0.04g of nitrile rubber (NBR) and 0.01g of Croda dispersant in 2g of toluene to obtain the slurry;

[0088] S3. Preparation of electrolyte membrane: The slurry is coated onto the surface of the carrier with a coating thickness of 50 μm. The carrier coated with the slurry is dried at room temperature at a dew point of -50° to -60° for 6 hours, and then transferred to vacuum drying at 80° for 12 hours to obtain the electrolyte membrane.

[0089] S4. After isostatic pressing, the electrolyte membrane is assembled with NCM811 material (positive electrode) without lithium nickel oxide coating and Si (negative electrode) to form a pouch battery.

[0090] In this comparative example, the parameters of electrospinning, the parameters of the three-dimensional macroporous membrane, the parameters of rolling, and the parameters of isostatic pressing are the same as those in Example 1 or the application example.

[0091] Detection Examples

[0092] Cycle performance tests were performed on the all-solid-state battery as described in the application examples and the all-solid-state battery as described in the comparative examples. The results are shown in Table 1 and... Figure 1 As shown:

[0093] Table 1. Electrochemical performance characterization of application examples and comparative examples.

[0094]

[0095] The all-solid-state battery, including the composite electrolyte membrane described in Example 1, has a high initial efficiency, good rate performance, no degradation after 100 cycles, and no short circuit was found during the cycling process.

[0096] Mechanical performance and density tests were performed on the all-solid-state batteries described in the application examples and the all-solid-state batteries described in the comparative examples. The results are shown in Table 2.

[0097] Table 2. Porosity and Mechanical Strength Characterization of Application Examples and Comparative Examples

[0098] Porosity / % Mechanical strength / MPa Application Examples 25 25 Comparative Example 34 20

[0099] The all-solid-state battery, including the composite electrolyte membrane described in Example 1, exhibits significantly improved mechanical strength and good density.

[0100] In summary, the preparation method of this invention uses an electrospun polyethylene terephthalate (PET) membrane as a carrier for the sulfide electrolyte slurry to improve the mechanical strength of the composite electrolyte membrane. Simultaneously, the structure of the electrospun membrane facilitates the penetration and encapsulation of the sulfide electrolyte slurry, thereby improving the conductivity of the composite electrolyte membrane. Furthermore, the preparation method of this invention enhances the interaction between the electrospun membrane and the sulfide electrolyte slurry through acid modification treatment, lithium-ion exchange treatment, and a combination of scraping and spraying, thereby improving the density of the composite electrolyte membrane.

[0101] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a composite electrolyte membrane, characterized in that the steps include... include: S1. Preparation of the carrier: Polyethylene terephthalate is dissolved in a first organic solvent and a three-dimensional macroporous membrane is prepared by electrospinning. The three-dimensional macroporous membrane is then subjected to acidification modification and lithium-ion exchange treatment in sequence to obtain the carrier. S2. Preparation of slurry: Dissolve the sulfide electrolyte, binder and dispersant in a second organic solvent to obtain the slurry; S3. Preparation of composite electrolyte membrane: The slurry is coated onto the surface of the carrier and the carrier coated with the slurry is first dried to obtain an intermediate electrolyte membrane; the slurry is then sprayed onto the surface of the intermediate electrolyte membrane and the intermediate electrolyte membrane coated with the slurry is second dried to obtain the composite electrolyte membrane. The acidification modification process includes: immersing the three-dimensional macroporous membrane in a dilute acid solution and treating it at 50°C to 300°C for 1 to 12 hours; cleaning the acid-treated three-dimensional macroporous membrane and then immersing it in a dilute alkali solution for alkali treatment for 1 to 12 hours; and then neutralizing and drying the alkali-treated three-dimensional macroporous membrane to obtain the acid-modified three-dimensional macroporous membrane.

2. The preparation method according to claim 1, characterized in that, The first organic solvent includes N,N-dimethylformamide and acetone; wherein the volume ratio of N,N-dimethylformamide to acetone is 1:9 to 3:

7.

3. The preparation method according to claim 1, characterized in that, The thickness of the carrier is 10μm~20μm.

4. The preparation method according to claim 1, characterized in that, The lithium-ion exchange process includes: The acid-modified three-dimensional macroporous membrane is immersed in a solution containing lithium ions for lithium ion exchange treatment for 1 to 12 hours to obtain the lithium ion exchange-treated three-dimensional macroporous membrane.

5. The preparation method according to claim 1, characterized in that, The slurry comprises, by weight parts: Sulfide electrolytes: 23-67.5 parts; 2-5 parts adhesive; Dispersant 0.5~2 parts; 30-70 parts of the second organic solvent; The sulfide electrolyte includes: Li₂S-P₂S₅, Li 10 GeP2S 12 Li9. 54 Si1. 74 P1. 44 S 11 .7Cl0.3、Li 10 SnP2S 12 The adhesive comprises at least one of Li6PS5Cl, Li6PS5I, or Li6PS5Br; the binder comprises at least one of styrene-butadiene-styrene block copolymer, nitrile rubber, styrene-butadiene rubber, or hydrogenated nitrile rubber; the dispersant comprises carboxymethyl cellulose; the second organic solvent comprises at least one of toluene, anisole, or n-heptane. The solid content of the slurry is 30% to 70%.

6. The preparation method according to claim 1, characterized in that, The thickness of the slurry coated on the surface of the carrier by scraping is 20μm to 100μm; the thickness of the slurry coated on the surface of the intermediate electrolyte membrane by spraying is 20μm to 100μm.

7. The preparation method according to claim 1, characterized in that, The first drying process includes: drying the carrier coated with the slurry at room temperature (dew point -50°C to -60°C) for 1 to 12 hours, and then transferring it to vacuum drying at 50°C to 120°C for 2 to 12 hours; the second drying process includes: drying the intermediate electrolyte membrane coated with the slurry at room temperature (dew point -50°C to -60°C) for 1 to 12 hours, and then transferring it to vacuum drying at 50°C to 120°C for 2 to 12 hours.

8. A composite electrolyte membrane, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

9. An all-solid-state battery, characterized in that, include: The composite electrolyte membrane as described in claim 8.

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