High-Power Solid State Batteries with Silica-Gel Solid Nanocomposite Electrolytes Using FSI-Based Ionic Liquids

摘要

All-solid-state batteries are considered as one of the most promising power sources for electrical vehicles (EVs). To meet the demand of EVs, the development of a solid-state Li battery with high-capacity and high-power is required. The nanocomposite electrolyte composed of an ionic liquid, Li-salt and porous-inorganic material can be an option for the solid electrolyte material. We have demonstrated a high-rate performance in solid-state lithium batteries using a silica-gel solid nanocomposite electrolytes (nano-SCE) containing FSI-based ionic liquid. The nano-SCE made with EMI-FSI and Li-FSI confined in the mesoporous silica matrix exhibits an ionic conductivity of 6.2 mS/cm at room temperature. The capacity of the Li-LiFePO4 (LFP) cell using EMI-FSI based nano-SCE reached to 150 mAh/g at 0.1 C, which is higher than that of the other reported batteries composed of ionic liquids, Li-salts and porous-SiO2. The C-rate performance was comparable to that of cells with conventional LiPF6 electrolyte solution. Our results show that impregnation of liquid precursor is an efficient approach to make a good contact between electrode and electrolyte interface in the solid composite electrode as the reaction kinetics at the interface of the active mass and nano-SCE was sufficiently fast. This is a strong advantage compared to the other types of solid electrolytes.