# US 12,015,123 B2 · Lithium ion secondary battery > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,015,123 B2 - Document ID: US12015123B2 - Status: Granted - Kind: B2 - Application number: 17/968,121 - Filed: 2022-10-18 - Published: 2023-03-02 - Granted: 2024-06-18 - Earliest claimed: 2017-03-15 - Assignees: AESC Japan Ltd. - Applicants: AESC Japan Ltd. - Inventors: Satoru Hirakawa; Hideaki Sasaki - Web page: https://patentgrep.com/patent/US12015123B2 ## CPC - H01M 10/0567: characterised by the additives - H01M 4/505: of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy - H01M 4/525: of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy - H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries - H01M 10/0565: Polymeric materials, e.g. gel-type or solid-type - H01M 10/0568: characterised by the solutes - H01M 2004/028: {Positive electrodes} - H01M 2300/004: Three solvents - Y02E 60/10: Energy storage using batteries - Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product - 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 - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract Provided is a lithium ion secondary battery including a positive electrode which is capable of storing and releasing lithium, a negative electrode which is capable of storing and releasing lithium, and a nonaqueous electrolyte which contains lithium salts and cyclic disulfonic acid ester, in which as the nonaqueous electrolyte, a nonaqueous electrolyte containing a polymer is used, and as at least a part of the lithium salts, imide lithium salts are used. Here, the content of the cyclic sulfonic acid ester is preferably in a range of 2.0% to 5.0% by mass with respect to a total content of the nonaqueous electrolyte. Also, the proportion of the imide lithium salts is preferably in a range of 10 to 50 mol % with respect to a total amount of lithium salts in the nonaqueous electrolyte. ## Claims ### Claim 1 A method of making a lithium ion secondary battery, the method comprising: obtaining a positive electrode which is capable of storing and releasing lithium; obtaining a negative electrode which is capable of storing and releasing lithium; obtaining a nonaqueous electrolyte which contains lithium salts, cyclic disulfonic acid ester, and a crosslinked polymer that contains a crosslinked product of meth(acrylate)-based polymer having a cyclic ether structure as a crosslinkable group in a side chain, at least a part of the lithium salts are imide lithium salts, and the nonaqueous electrolyte is a liquid having a fluidity; combining the positive electrode, the negative electrode, and the nonaqueous electrolyte to obtain a lithium ion secondary battery which has not been subjected an initial charge and thus a solid electrolyte interphase (SEI) is not present on a surface of the negative electrode, and further comprising performing an initial charging of the lithium ion secondary battery, wherein the initial charging the cyclic disulfonic acid ester forms a coated solid electrolyte interphase (SEI) film on a surface of a negative electrode. ### Claim 2 (depends on 1) The method of claim 1, wherein the step of obtaining the nonaqueous electrolyte comprises: mixing a precursor of the crosslinked polymer with the lithium salts and the cyclic disulfonic acid ester; and allowing the precursor to react to obtain the crosslinked polymer. ### Claim 3 (depends on 2) The method of claim 2, wherein the step of allowing the precursor to react includes a crosslinking reaction. ### Claim 4 (depends on 2) The method of claim 2, wherein the precursor comprises one or more selected from the group consisting of ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, propylene di(meth)acrylate, dipropylene di(meth)acrylate, tripropylene di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and pentaerythritol tetra(meth)acrylate. ### Claim 5 (depends on 2) The method of claim 2, wherein the precursor comprises a bifunctional (meth)acrylate, a trifunctional (meth)acrylate, or a tetrafunctional (m eth)acrylate. ### Claim 6 (depends on 1) The method of claim 1, wherein the step of obtaining the nonaqueous electrolyte comprises: synthesizing the crosslinked polymer. ### Claim 7 (depends on 1) The method of claim 1, wherein the step of obtaining the nonaqueous electrolyte comprises: synthesizing the crosslinked polymer; and mixing the crosslinked polymer with the lithium salts and the cyclic disulfonic acid ester. ### Claim 8 (depends on 1) The method of claim 1, wherein a content of the cyclic disulfonic acid ester is in a range of 2.0% to 5.0% by mass with respect to a total content of the nonaqueous electrolyte. ### Claim 9 (depends on 1) The method of claim 1, wherein a proportion of the imide lithium salts is in a range of 10 to 50 mol % with respect to a total amount of lithium salts in the nonaqueous electrolyte. ### Claim 10 (depends on 1) The method of claim 1, wherein a content of the polymer in the nonaqueous electrolyte is in a range of 0.5% to 2.0% by mass with respect to the total content of the nonaqueous electrolyte. ### Claim 11 (depends on 1) The method of claim 1, wherein the positive electrode contains a lithium nickel composite oxide as a positive electrode active material. ### Claim 12 (depends on 1) The method of claim 1, wherein the lithium nickel composite oxide is a compound represented by LiaNixM1-xO2, wherein 0