# US 2025/0167291 A1 · Composite solid electrolyte for lithium secondary battery and method for preparing same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0167291 A1 - Document ID: US20250167291A1 - Status: Published application - Kind: A1 - Application number: 18/835,004 - Filed: 2023-05-31 - Published: 2025-05-22 - Earliest claimed: 2022-05-31 - Assignees: LG Energy Solution, Ltd. - Applicants: LG Energy Solution, Ltd. - Inventors: Sunghyun NAM; Hyeaeun HAN; Jung Pil LEE; Dong Kyu KIM - Web page: https://patentgrep.com/patent/US20250167291A1 ## CPC - H01M 10/056: characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes - H01M 10/052: Li-accumulators - H01M 10/0565: Polymeric materials, e.g. gel-type or solid-type - H01M 2300/0077: based on zirconium oxide - H01M 2300/0082: Organic polymers - H01M 2300/0088: Composites - Y02E 60/10: Energy storage using batteries - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract The present disclosure relates to a composite solid electrolyte for a lithium secondary battery and a preparation method thereof. ## Claims ### Claim 1 A method for preparing a composite solid electrolyte for a lithium secondary battery, comprising the steps of: (S1) preparing a first composite by forming a hydrogel of a first polymer from a solution including the first polymer having a cross-linkable functional group in its (side chain) and a ceramic compound; (S2) preparing a ceramic ion conductor by sintering the first composite; and (S3) preparing a second composite by immersing the ceramic ion conductor in a solution including a second polymer and a lithium salt and drying it. ### Claim 2 (depends on 1) The method for preparing the composite solid electrolyte for the lithium secondary battery according to claim 1, wherein the hydrogel of the first polymer comprises a cross-linked structure between the first polymer and the ceramic compound. ### Claim 3 (depends on 2) The method for preparing the composite solid electrolyte for the lithium secondary battery according to claim 2, wherein the cross-linked structure comprises: (a) a cross-linkage between cross-linkable functional groups, and (b) a cross-linkage between the cross-linkable functional group and the ceramic compound. ### Claim 4 (depends on 3) The method for preparing the composite solid electrolyte for the lithium secondary battery according to claim 3, wherein the cross-linkage (a) between cross-linkable functional groups comprises a hydrogen bond, and the cross-linkage (b) between the cross-linkable functional group and the ceramic compound comprises a linkage by Lewis acid-base interaction. ### Claim 5 (depends on 2) The method for preparing the composite solid electrolyte for the lithium secondary battery according to claim 2, wherein the cross-linked structure is formed by freezing and thawing the solution including the first polymer and the ceramic compound. ### Claim 6 (depends on 2) The method for preparing the composite solid electrolyte for the lithium secondary battery according to claim 2, wherein the cross-linked structure is formed by adding a chemical cross-linker to the solution including the first polymer and the ceramic compound. ### Claim 7 (depends on 5) The method for preparing the composite solid electrolyte for the lithium secondary battery according to claim 5, wherein the freezing is performed at −30° C. to −10° C. ### Claim 8 (depends on 5) The method for preparing the composite solid electrolyte for the lithium secondary battery according to claim 5, wherein the thawing is performed at 15° C. to 35° C. ### Claim 9 (depends on 1) The method for preparing the composite solid electrolyte for the lithium secondary battery according to claim 1, wherein the cross-linkable functional group comprises at least one selected from the group consisting of a hydroxyl group, a carboxyl group, and an amide group. ### Claim 10 (depends on 1) The method for preparing the composite solid electrolyte for the lithium secondary battery according to claim 1, wherein the first polymer having the cross-linkable functional group comprises at least one selected from the group consisting of polyvinyl alcohol (PVA), gelatin, methylcellulose, agar, dextran, poly(vinyl pyrrolidone), poly(acryl amide), starch-carboxymethyl cellulose, hyaluronic acid-methylcellulose, chitosan, poly(N-isopropylacrylamide), and amino-terminated polyethylene glycol (amino-terminated PEG). ### Claim 11 A composite solid electrolyte for a lithium secondary battery, comprising a ceramic ion conductor including a ceramic compound; a second polymer; and a lithium salt. ### Claim 12 (depends on 11) The composite solid electrolyte for a lithium secondary battery according to claim 11, wherein the ceramic compound comprises at least one selected from the group consisting of lithium-lanthanum-zirconium oxide based compound (LLZO), lithium-silicon-titanium phosphate based compound (LSTP), lithium-lanthanum-titanium oxide based compound (LLTO), lithium-aluminum-titanium phosphate based compound (LATP), lithium-aluminum-germanium phosphate based compound (LAGP) and lithium-lanthanum-zirconium-titanium oxide based (LLZTO) compounds. ### Claim 13 (depends on 11) The composite solid electrolyte for a lithium secondary battery according to claim 11, wherein the second polymer comprises at least one selected from the group consisting of polyvinyl alcohol (PVA), polyethylene oxide (PEO), polyacrylate, poly(methyl methacrylate) (PMMA), PSTFSI, polyurethane, nylon, poly(dimethylsiloxane), gelatin, methylcellulose, agar, dextran, poly(vinyl pyrrolidone), poly(acryl amide), poly(acrylic acid), starch-carboxymethyl cellulose, hyaluronic acid-methylcellulose, chitosan, poly(N-isopropylacrylamide) and amino-terminated polyethylene glycol (amino-terminated PEG). ### Claim 14 (depends on 11) The composite solid electrolyte for a lithium secondary battery according to claim 11, wherein the lithium salt comprises at least one selected from the group consisting of (CF3SO2)2NLi (Lithium bis(trifluoromethanesulphonyl)imide, LiTFSI), (FSO2)2NLi (Lithium bis(fluorosulfonyl)imide, LiFSI), LiNO3, LiOH, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB10Cl10, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, LiSCN and LiC(CF3SO2)3. ### Claim 15 (depends on 11) The composite solid electrolyte for a lithium secondary battery according to claim 11, wherein a molar ratio of lithium ([Li]) in the lithium salt to a molar concentration ([G]) of the second polymer is 0.1 to 0.5. ### Claim 16 (depends on 11) The composite solid electrolyte for a lithium secondary battery according to claim 11, wherein the composite solid electrolyte is in a form of a free-standing film. ### Claim 17 (depends on 11) The composite solid electrolyte for a lithium secondary battery according to claim 11, wherein an ionic conductivity of the composite solid electrolyte is 1.0×10−5 S/cm or more. ### Claim 18 (depends on 11) An all-solid-state battery, comprising the composite solid electrolyte for a lithium secondary battery of claim 11.