Synergistic effect of ionic liquid and organo-functional silane on the preparation of silica based hybrid ionogels as solid-state electrolyte for Li-ion batteries

Abstract

Having excellent safety and potentially high energy density, solid-state electrolytes can be used in large-scale energy storage applications instead of flammable and volatile organic solvent-based electrolytes. Aerogels are notable candidates for solid-state electrolytes due to their low density, high porosity, high specific surface area, stable thermal behavior, and ultralow dielectric constant. In this work, Li-doped silica ionogels were synthesized by the two-step sol-gel method by using trifunctional organosilane Methyltrimethoxysilane (MTMS), as silica co-precursor along with conventional precursor TEOS. In addition, 1,3-Butylmethylimidazolium bis(trifluorosulfonyl)imide (BMIMTFSI) was selected as an ionic liquid to provide ion mobility throughout the solid skeleton. The synthesized hybrid ionogels were characterized by FTIR, SEM, BET, and TGA analyzes. It was observed that the specific surface areas of the obtained ionogels varied between 685 and 725 m2/g. To examine the effect of Li+ ion concentration on ion conductivity, electrolyte solutions have prepared in different concentrations (0.5 ~ 2 M). The Li+ ion conductivity of the ionogel prepared with 2 M of Li+ ion solution (M-IGE-2) was determined as 4.06 × 10−4 S/cm by Potentiostatic EIS measurement and it possessed 3.3V of electrochemical stability.