Low-Viscosity gamma-Butyrolactone-Based Concentrated Electrolyte Solutions for LiNi0.5Mn1.5O4 Positive Electrodes in Lithium-Ion Batteries

摘要

Highly concentrated electrolyte solution with a low viscosity and high stability against oxidation was obtained by using a single solvent system of LiBF4/gamma-butyrolactone (GBL). Although up to 4.65 molkg(-1) LiBF4 could be dissolved in GBL at room temperature, 3.87 molkg(-1) LiBF4/GBL was a reasonable compromise to attain a low viscosity (52.1 mPas) and a low GBL/Li molar ratio (3.00). Sodium carboxymethylcellulose and poly (acrylic acid) were used as binders for the spinel LiNi0.5Mn1.5O4 positive electrode and the graphite negative electrode, respectively, to suppress the swelling of conventional poly(vinylidene fluoride)-based binder. The charge and discharge performances of the LiNi0.5Mn1.5O4 positive electrode and the graphite negative electrode were improved by using 3.87 molkg(-1) LiBF4/GBL, as compared with concentrated propylene carbonate-based electrolyte solution.