Method of producing lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-2018316040-A1
Application number	US-201815962562-A
Country	US
Kind code	A1
Filing date	Apr 25, 2018
Priority date	May 1, 2017
Publication date	Nov 1, 2018
Grant date	—

Abstract

A method of producing a lithium ion secondary battery includes preparing a case in which an electrode group including at least a positive electrode and a negative electrode is accommodated; impregnating a first electrolyte solution into the electrode group, lowering a potential of the negative electrode to a first potential, injecting FEC into a case, and lowering a potential of the negative electrode to a second potential. The negative electrode contains at least graphite and silicon oxide. The first electrolyte solution does not contain FEC. An additive has a reductive decomposition potential of 0.5 V (vs. Li+/Li) or more and 1.5 V (vs. Li+/Li) or less. The first potential is higher than 0.2 V (vs. Li+/Li) and is equal to or lower than the reductive decomposition potential. The second potential is 0.2 V (vs. Li+/Li) or less.

First claim

What is claimed is:

1 . A method of producing a lithium ion secondary battery comprising:
preparing a case in which an electrode group including at least a positive electrode and a negative electrode is accommodated; injecting a first electrolyte solution containing an additive into the case so that the first electrolyte solution is impregnated into the electrode group; charging the electrode group into which the first electrolyte solution is impregnated so that a potential of the negative electrode is lowered to a first potential; preparing a second electrolyte solution containing fluoroethylene carbonate in the case by injecting fluoroethylene carbonate into the case after the potential of the negative electrode is lowered to the first potential; and charging the electrode group after the second electrolyte solution is prepared so that the potential of the negative electrode is lowered to a second potential, wherein the negative electrode contains at least graphite and silicon oxide, the first electrolyte solution does not contain fluoroethylene carbonate, the additive has a reductive decomposition potential of 0.5 V (vs. Li + /Li) or more and 1.5 V (vs. Li + /Li) or less, the first potential is higher than 0.2 V (vs. Li + /Li) and is equal to or lower than the reductive decomposition potential of the additive, and the second potential is 0.2 V (vs. Li + /Li) or less.

2 . The method according to claim 1 , wherein the additive is at least one selected from the group consisting of vinylene carbonate, propane sultone and ethylene sulfite.

3 . The method according to claim 1 , wherein the first potential is 0.5 V (vs. Li + /Li) or more.

4 . The method according to claim 1 , wherein the fluoroethylene carbonate has a proportion of 1 mass % or more and 7 mass % or less with respect to the second electrolyte solution.

5 . The method according to claim 1 , wherein the silicon oxide has a proportion of 3 mass % or more and 7 mass % or less with respect to a total amount of the graphite and the silicon oxide.

Assignees

• Toyota Motor Co Ltd

Inventors

• Iguchi Hiroki
• Fujita Hideaki
• Sano Hideki
• Inoue Kaoru

Classifications

• H01M10/049

  Processes for forming or storing electrodes in the battery container · CPC title

• H01M10/045 Primary

  Cells or batteries with folded plate-like electrodes · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H02J7/007

  Electricity · mapped topic

• H01M4/0447 Primary

  of complete cells or cells stacks · CPC title