A single ion-conducting nanocomposite of a substantially amorphous polyethylene ether and a negatively charged synthetic smectite clay useful as an electrolyte. Excess SiO.sub.2 improves conductivity and when combined with synthetic hectorite forms superior membranes for batteries. A method of making membranes is also disclosed.
CONTRACTUAL ORIGIN OF THE INVENTION
 The United States Government has rights in this invention pursuant to Contract No. W-31-109-ENG-38 between the U.S. Department of Energy (DOE) and The University of Chicago representing Argonne National Laboratory.