Synthesis and structures of novel solid-state electrolytes

Abstract

Two classes of new materials possessing ion conductivity have been developed: a lithium ion conductor and a hydride ion conductor. Conventional perovskite and ordered rock-salt structures were adopted as frameworks for lithium migration, and electrochemically stable elements such as Al, Ga, Ta, and Sc were used in the materials to facilitate their use as low-potential negative electrodes. New compositions of (Li 0.25 Sr 0.625 V (Li,Sr)0.125 )(Ga 0.25 Ta 0.75 )O 3 , and Li 0.9 Sc 0.9 Zr 0.1 O 2 were found to be novel oxide-based lithium ion conductors. Oxyhydrides with K 2 NiF 4 -type structures were synthesized via a high-pressure synthesis method and their use in pure hydride ion conduction was demonstrated. The La 2-x-y Sr x+y LiH 1-x+y O 3-y oxyhydrides showed wide composition ranges of solid solution formation and the conductivity increased with anion vacancies or the introduction of interstitial hydride ions. The performance of an all-solid-state TiH 2/o -La 2 LiHO 3 (x = y = 0, o: orthorhombic)/Ti cell provided conclusive evidence of pure H - conduction.