Physicochemical Features of Fluorinated Ethyl Acetate-Based Highly Concentrated Electrolyte Solutions and Their Effects on Electrochemical Properties of LiNi<sub>0.8</sub>Co<sub>0.1</sub>Mn<sub>0.1</sub>O<sub>2</sub> Positive Electrodes
Takayuki Doi, Ryo Fujii, Yasuhito Aoki, Tsuyoshi Nagashima, Kyosuke Takehara, Minoru Inaba
Abstract
Fluorinated ethyl acetate with a low dielectric constant was used as a solvent to obtain highly concentrated electrolyte solutions. LiPF6 and LiBF4 were dissolved at various concentrations in fluorinated ethyl acetate, and the solution structures were studied by Raman and Fourier transform infrared spectroscopy. The nearly saturated electrolyte solutions showed unique physicochemical characteristics different from those of conventional carbonate ester-based solutions. The effects on the electrochemical properties of LiNi0.8Co0.1Mn0.1O2 (NCM811) positive electrodes were also investigated. The fluorinated ethyl acetate-based electrolyte solutions had an excellent feature of suppressing the polarization even at high concentrations of lithium salts and delivered superior charge/discharge properties.