A functionalized polymer electrolyte membrane, and a method of preparing and using the same

Abstract

The application relates to a functionalized polymer electrolyte film and a preparation method and application thereof, relates to the field of electrochemistry, and forms a single-ion conductor polymer electrolyte layer on the surface of a gel polymer electrolyte film to effectively improve the ion conductivity of the polymer electrolyte, improve the transport behavior of anions and cations at the electrode / electrolyte interface, and meet the application requirements of solid-state batteries. The functionalized polymer electrolyte film comprises a gelable polymer electrolyte base film and a solution dispersion layer containing single-ion conductor polymer lithium salt monomers which is formed on one side or both sides of the surface of the gelable polymer electrolyte base film.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and in particular to a functionalized polymer electrolyte membrane, its preparation method, and its application. Background Technology

[0002] Lithium-ion rechargeable batteries have the advantages of high energy density, high specific power, good cycle performance, no memory effect, and no pollution. However, safety issues such as leakage and combustion caused by low flash point and liquid electrolyte have cast a shadow on their large-scale application.

[0003] The ultimate solution is to develop solid-state batteries that use solid electrolytes as the ion transport medium. Compared to inorganic solid electrolytes, polymer solid electrolytes have better interfacial compatibility and machinability, and are highly compatible with current commercial lithium-ion battery production technologies.

[0004] However, on the one hand, the ionic conductivity of general pure solid polymer electrolytes is relatively low, which makes it difficult to meet the requirements of applications; on the other hand, polymer electrolytes are often prepared by combining polymer matrix with lithium salt. The cations in lithium salt, namely lithium ions and anions, will migrate in the electrolyte. However, for lithium batteries, only lithium ions actually participate in the electrochemical energy conversion process. The migration of anions often accumulates on the electrode surface, forming a space charge layer, causing battery polarization and deteriorating the performance of solid-state batteries. Summary of the Invention

[0005] The purpose of this invention is to provide a functionalized polymer electrolyte membrane, its preparation method, and its application. By forming a single-ion conductor polymer electrolyte layer on the surface of the gel polymer electrolyte membrane, the ionic conductivity of the polymer electrolyte is effectively improved, and the transport behavior of anions and cations at the electrode / electrolyte interface is improved, thereby meeting the application requirements of solid-state batteries.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A functionalized polymer electrolyte membrane includes: a gellizable polymer electrolyte base membrane, and a solution dispersion layer containing a single-ion conductor polymer lithium salt monomer formed on one or both sides of the gellizable polymer electrolyte base membrane.

[0008] The gellizable polymer electrolyte base membrane includes a blend / copolymer system of any one or more polymers selected from vinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, polymethyl acrylate, and polyethylene oxide.

[0009] Specifically, in the solution dispersion layer containing the single-ion conductor polymer lithium salt monomer, the solvent is a solvent capable of dissolving the single-ion conductor polymer monomer, including: water, ethanol or acetone.

[0010] The single-ion conductor polymer lithium salt monomer includes any one or more of lithium acrylate, lithium vinyl sulfonate, lithium [(trifluoromethyl)(vinyl)]sulfonylimide, lithium vinyl borate, lithium allyl sulfonate, and 2-acrylamido-2-methylpropanesulfonic acid.

[0011] Furthermore, the mass fraction of the solution in the solution dispersion layer containing the single-ion conductor polymer lithium salt monomer is between 0.1% and 100%.

[0012] Furthermore, the thickness of the solution dispersion layer containing the single-ion conductor polymer lithium salt monomer is 50 nm-5 μm.

[0013] A method for preparing a functionalized polymer electrolyte membrane as described in any of the above claims involves dispersing a solution containing a single-ion conductor polymer lithium salt monomer on one or both sides of a pre-prepared gelable polymer electrolyte base membrane, and fixing it onto the surface of the polymer base membrane by co-irradiation grafting, thereby developing a polymer electrolyte material with a surface modified by a single-ion conductor.

[0014] In practical applications, the irradiation source for the co-irradiation grafting includes any one of the following: X-rays, gamma rays, beta rays, short-wave ultraviolet rays, and high-energy electron beams.

[0015] An application of a functionalized polymer electrolyte membrane as described in any of the preceding claims, wherein the functionalized polymer electrolyte membrane serves as a chemical power source electrolyte material for a lithium-ion secondary battery.

[0016] In practical applications, the lithium-ion secondary battery includes: a positive electrode material and a negative electrode material, and the functionalized polymer electrolyte membrane material located between the positive electrode material and the negative electrode material.

[0017] Compared with existing technologies, the functionalized polymer electrolyte membrane, its preparation method, and its application described in this invention have the following advantages:

[0018] The present invention provides a functionalized polymer electrolyte membrane, its preparation method and application. By forming a single-ion conductor polymer electrolyte layer on the surface of the gel polymer electrolyte membrane, the ionic conductivity of the polymer electrolyte is effectively improved, and the transport behavior of anions and cations at the electrode / electrolyte interface is improved, thereby meeting the application requirements of solid-state batteries. Detailed Implementation

[0019] For ease of understanding, the following provides a detailed description of a functionalized polymer electrolyte membrane, its preparation method, and its application, based on embodiments of the present invention. Example 1

[0020] A 30 μm thick vinylidene fluoride-hexafluoropropylene copolymer film prepared by casting was used. A 50% (w / w) aqueous solution of lithium vinyl sulfonate was dispersed on its surface. Due to the superhydrophobic properties of vinylidene fluoride-hexafluoropropylene, the dispersion did not enter the interior of the vinylidene fluoride-hexafluoropropylene copolymer film. The film was then placed in a 60Co γ-ray field for irradiation at a dose of 15 kGy. After irradiation, a polymer electrolyte with a surface modified by a single-ion conductor was obtained. Example 2

[0021] A 50 μm thick polyvinylidene fluoride (PVDF) polymer membrane with a microporous structure, prepared by phase inversion, was used. A 90% (w / w) aqueous solution of lithium allyl sulfonate was dispersed on its surface. Due to the superhydrophobic properties of PVDF, the dispersion did not penetrate into the interior of the PVDF polymer membrane. The membrane was then irradiated with a high-energy electron beam at a dose of 10 kGy. After irradiation, another 90% (w / w) aqueous solution of lithium allyl sulfonate was dispersed on the other side of the polymer membrane, and the membrane was irradiated with a high-energy electron beam at a dose of 10 kGy. This yielded a polymer electrolyte modified with a single-ion conductor on both sides. Example 3

[0022] A polyacrylonitrile film with a thickness of 10 μm prepared by casting was used. A layer of lithium [(trifluoromethyl)(vinyl)]sulfonylimide monomer was dispersed on its surface. The film was then placed in a 60Co γ-ray field for irradiation at a dose of 15 kGy. After irradiation, a polymer electrolyte with a surface modified by a single-ion conductor was obtained. Example 4

[0023] The polymer membrane obtained in Example 1 was immersed in a commercial electrolyte of 1 mol / L EC:DMC (volume ratio 1:1) for 1 hour to obtain a gel polymer electrolyte. Example 5

[0024] The polymer membrane obtained in Example 2 was immersed in a commercial electrolyte of 1 mol / L EC:DMC (volume ratio 1:1) for 1 hour to obtain a gel polymer electrolyte. Example 6

[0025] The polymer membrane obtained in Example 3 was immersed in a commercial electrolyte of 1 mol / L EC:DMC (volume ratio 1:1) for 1 hour to obtain a gel polymer electrolyte.

[0026] Comparative Example 1:

[0027] A vinylidene fluoride-hexafluoropropylene copolymer film with a thickness of 30 μm was prepared by casting.

[0028] Comparative Example 2:

[0029] A 50 μm thick polyvinylidene fluoride polymer membrane with a microporous structure was prepared by phase inversion method.

[0030] Comparative Example 3:

[0031] The polymer membrane obtained in Comparative Example 1 was immersed in a commercial electrolyte of 1 mol / L EC:DMC (volume ratio 1:1) for 1 hour to obtain a gel polymer electrolyte.

[0032] Comparative Example 4:

[0033] The polymer membrane obtained in Comparative Example 2 was immersed in a commercial electrolyte of 1 mol / L EC:DMC (volume ratio 1:1) for 1 hour to obtain a gel polymer electrolyte.

[0034] Table 1: Comparison of ionic conductivity and lithium-ion transference number of the gel polymer electrolytes in Examples 4-6 and Comparative Examples 3-4

[0035] electrolytes Example 4 Example 5 Example 6 Comparative Example 3 Comparative Example 4 Ionic conductivity mS / cm 1.4 3.2 2.5 1.3 2.8 Li ion transference number 0.64 0.58 0.88 0.32 0.22 Example 7

[0036] A battery comprising a positive electrode material and a negative electrode material, wherein a gel polymer electrolyte prepared in Example 4 is disposed between the positive electrode material and the negative electrode material. Example 8

[0037] A battery comprising a positive electrode material and a negative electrode material, wherein a gel polymer electrolyte prepared in Example 5 is disposed between the positive electrode material and the negative electrode material. Example 9

[0038] A battery comprising a positive electrode material and a negative electrode material, wherein a gel polymer electrolyte prepared in Example 6 is disposed between the positive electrode material and the negative electrode material.

[0039] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A functionalized polymer electrolyte membrane, characterized by, include: A gellable polymer electrolyte base film, the gellable polymer electrolyte base film comprising: vinylidene fluoride, vinylidene fluoride A blend / copolymer system of one or more polymers of hexafluoropropylene copolymer, polyacrylonitrile, polymethyl acrylate, polyethylene oxide; And a solution dispersion layer containing a single-ion conductor polymer lithium salt monomer is formed on one or both sides of the gellifiable polymer electrolyte base film; wherein, in the solution dispersion layer containing the single-ion conductor polymer lithium salt monomer, the solvent is based on a solvent capable of dissolving the single-ion conductor polymer monomer, including: water, ethanol, or acetone; the single-ion conductor polymer lithium salt monomer includes: lithium acrylate, lithium vinyl sulfonate, lithium [(trifluoromethyl)(vinyl)]sulfonylimide, lithium vinyl borate, lithium allyl sulfonate, 2 Acrylamide 2 One or more of methylpropanesulfonic acid.

2. The functionalized polymer electrolyte membrane according to claim 1, characterized in that, The mass fraction of the solution in the solution dispersion layer containing the single-ion conductor polymer lithium salt monomer is 0.1 100%.

3. The functionalized polymer electrolyte membrane according to claim 2, characterized in that, The thickness of the solution dispersion layer containing the single-ion conductor polymer lithium salt monomer is 50 nm 5 μm.

4. A device as described in claim 1 above. The method for preparing the functionalized polymer electrolyte membrane as described in any one of the 3 method is characterized in that, By dispersing a solution containing a single-ion conductor polymer lithium salt monomer on one or both sides of a pre-prepared gelable polymer electrolyte base membrane, and fixing it onto the surface of the polymer base membrane by co-irradiation grafting, a polymer electrolyte material with a surface modified by a single-ion conductor can be developed.

5. The method for preparing a functionalized polymer electrolyte membrane according to claim 4, characterized in that, The irradiation source for the co-irradiation grafting includes: X Rays, gamma rays Any one of the following: X-rays, beta rays, shortwave ultraviolet rays, or high-energy electron beams.

6. A device as described in claim 1 above. The application of the functionalized polymer electrolyte membrane described in any one of 3 is characterized in that, The functionalized polymer electrolyte membrane serves as the chemical power source electrolyte material for lithium-ion secondary batteries.

7. The application of the functionalized polymer electrolyte membrane according to claim 6, characterized in that, The lithium-ion secondary battery includes: a positive electrode material and a negative electrode material, and a functionalized polymer electrolyte membrane material located between the positive electrode material and the negative electrode material.