2019 Fiscal Year Annual Research Report

Synthesis of Fire-Extinguishing High-Voltage Electrolytes for Safe Batteries

Research Project

Project/Area Number	18F18332
Research Institution	The University of Tokyo
Principal Investigator	山田淳夫東京大学, 大学院工学系研究科(工学部), 教授 (30359690)
Co-Investigator(Kenkyū-buntansha)	ZHENG QIFENG 東京大学, 工学(系)研究科(研究院), 外国人特別研究員
Project Period (FY)	2018-11-09 – 2021-03-31
Keywords	Lithium-ion battery / nonflammable electrolyte / high-voltage / SEI formation / cyclic phosphate
Outline of Annual Research Achievements	The lack of a suitable alternative solvent has hindered further exploration of new functional electrolytes. Herein we design and synthesize a fluorinated cyclic phosphate solvent, 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane 2-oxide (TFEP), for use in LIBs. An electrolyte formula composed of 0.95 M LiN(SO2F)2 in TFEP/2,2,2-trifluoroethyl methyl carbonate shows excellent non-flammability with zero self-extinguishing time and enables the highly stable operation of graphite anodes (ca. 0.1 V vs lithium) and high-voltage LiNi0.5Mn1.5O4 cathodes (ca. 4.7 V vs lithium), thereby outperforming the traditional electrolytes. This work opens new frontiers in electrolyte developments toward safe LIBs with higher energy densities, which was recently accepted for publication on Nature Energy.
Research Progress Status	翌年度、交付申請を辞退するため、記入しない。
Strategy for Future Research Activity	翌年度、交付申請を辞退するため、記入しない。