Solid electrolyte thin film, method for manufacturing the same, and lithium-sulfur battery using the same

Abstract

This invention provides a solid electrolyte sheet, its preparation method, and a lithium-sulfur battery using the same. The solid electrolyte sheet of this invention is an oxide solid electrolyte with a controllable thickness range of 50~200μm. The lithium-sulfur battery of this invention contains a liquid polysulfide as the cathode active material. The liquid polysulfide has the general formula Li2Sx, where 4 ≤ x ≤ 8, and exhibits high cycle stability and polarization control capability.

Claims

1. A solid electrolyte sheet, characterized in that the solid electrolyte sheet is an oxide solid electrolyte, and has a controllable thickness range of 50~200μm, and the solid electrolyte sheet has an ionic conductivity of 5×10-4~1.5×10-3 S / cm at room temperature.

2. The solid electrolyte sheet as described in claim 1, wherein, The oxide solid electrolyte is selected from one or more of lithium lanthanum titanium oxide (LLTO), lithium titanium aluminum phosphate (LATP), lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium tantalum oxide (LLZTO), and lithium germanium aluminum phosphate (LAGP).

3. The solid electrolyte sheet as described in claim 1, wherein, The density of the solid electrolyte sheet is approximately 5 g / cm³.

4. A method for preparing a solid electrolyte sheet, characterized by comprising the following steps: (1) Slurry preparation step: 40-60% by weight of oxide solid electrolyte powder, 0-5% by weight of dispersant, 1-10% by weight of binder, 1-10% by weight of plasticizer and the remaining weight percentage of solvent are mixed according to the total weight of the slurry, and after two-stage ball milling, a slurry is obtained; (2) Scalpel forming step: The slurry obtained in step (1) is coated onto a substrate with a scalpel and dried to form a single-layer solid electrolyte green sheet; (3) Lamination step: One or more single-layer solid electrolyte green sheets obtained in step (2) are laminated and pressed according to the required thickness; (4) Degreasing step: The green sheet obtained in step (3) is subjected to low-temperature degreasing treatment to remove the organic components therein. The degreasing treatment temperature is 120-800℃ and the temperature is held for 0.5-10 hours; (5) Sintering step: The degreased product obtained in step (4) is subjected to high-temperature sintering treatment at a temperature of 800~1400℃ and held for 0.5~20 hours to obtain a solid electrolyte sheet, and the solid electrolyte sheet has an ionic conductivity of 5×10-4~1.5×10-3 S / cm at room temperature.

5. The method for preparing a solid electrolyte sheet as described in claim 4, wherein, The oxide solid electrolyte powder is selected from one or more of lithium lanthanum titanium oxide (LLTO), lithium titanium aluminum phosphate (LATP), lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium tantalum oxide (LLZTO), and lithium germanium aluminum phosphate (LAGP).

6. The method for preparing a solid electrolyte sheet as described in claim 4, wherein, The dispersant is one or more of triethanolamine (TEA), triton-x, herring oil, polyacrylic acid (PAA), polyethylene glycol (PEG), linseed oil, triglycerides, and polyoxyethylene alkylamine; the binder is one or more of polyvinyl butyral (PVB), polyvinylidene difluoride (PVDF), ethyl cellulose, polymethyl methacrylate (PMMA), polyethylene glycol, polyisobutylene, and polyvinyl alcohol (PVA); the plasticizer is one or more of polyethylene glycol (PEG), benzyl butyl phthalate (BBP), and dibutyl phthalate (Dibutyl phthalate). The solvent may be one or more of phthalate (DBP) and di-octyl phthalate (DOP); the solvent may be one or more of ethanol, isopropanol, water, acetone, toluene, butanol, and xylene.

7. The method for preparing a solid electrolyte sheet as described in claim 4, wherein, In step (3) above, the single-layer solid electrolyte embryo obtained in step (2) is stacked and pressurized by one to four layers. After step (4) and step (5) above, a solid electrolyte sheet with a thickness of 50 to 200 micrometers is obtained.

8. A lithium-sulfur battery, characterized in that it comprises: a solid electrolyte sheet as described in any one of claims 1 to 3 or a solid electrolyte sheet prepared by a method described in any one of claims 4 to 7; and a cathode containing a liquid polysulfide as an active material; wherein the liquid polysulfide has the general formula Li2Sx, wherein 4 ≤ x ≤ 8.

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