Conductivity and capacitance studies of silica glass composites containing [BMIM]Br and LiCl

Abstract

Ionic liquid (IL) 1-butyl-3methylimidaolium bromide ([BMIM]Br) confined Li+ ion containing silica glass composites have been prepared by hydrolytic sol-gel process. The IL dispersed amorphous systems exhibit improved ionic conductivity. It has been revealed that presence of IL in a low concentration (upto 1 mol %) facilitates Li+ ion motion. Conductivity does not show any appreciable change with increasing IL content in the matrix, particularly when salt content is fixed. However, when the IL content is fixed in the matrix and salt content is gradually increased, the conductivity exhibits a monotonic rise. A maximum ionic conductivity of 4.7 × 10−7 Ω−1 cm−1 with 30 mol % LiCl and only 1 mol% IL has been observed at 523 K. Incorporation of heavy metal ions (Pb2+) in the system further enhances the conductivity marginally. Optimized compositons exhibit high capacitance values of 14.1 Fg−1 at room temperature when sandwiched between high surface area (260 m2 g−1) activated carbon electrodes. These samples exhibit good potential as solid electrolytes in solid state supercapacitor applicatons.