Abstract: Natural mineral montmorillonite was found to be a new kind of fast ionic conductor. Using impedance measurement the conductjvities of Li and Na-montmorillonite with water content of 15% at 25℃ were determined as 1.04×10^-3 and 2.76×10^-3S·cm^-1, activation energy 0.13eV and 0.11eV respectively. By DC polarization technique the electronic conductivity of Li-montmorillonite was measured to be 4×10^-10s·cm^-1. The ionic conductivities of Li and Na-montmorillonite vary with water content and were 6×10^-3 and 8×10^-3s·cm^-1 respectively at 25℃ with 20% water content.

Key words: Solid electrolyte, Superionic conductor, Montmorillonite