A polymer electrolyte composition includes a hard polymer segment covalently bound to an ionically-conducting segment, and a salt that includes an element M selected from an alkali metal, an alkaline earth metal, zinc, and aluminum. The hard polymer segment has a glass transition temperature (T.sub.g) greater than or equal to 110.degree. C., or a melting temperature (T.sub.m) greater than 110.degree. C. The ionically-conducting segment has a molecular weight of 800 to 10,000 g/mol. The polymer electrolyte composition has an ionic conductivity for an M ion greater than or equal to 1.times.10.sup.-8 S/cm at 25.degree. C. Methods for the preparation of the polymer electrolyte composition are also provided, as are articles (e.g., electrochemical cells and energy storage devices) that contain the polymer electrolyte composition.
GOVERNMENT RIGHTS STATEMENT
 This invention was made with U.S. Government support under Grant Number DE-SC0001086 awarded by US Department of Energy. The United States Government has certain rights in the invention.