Compatibility of LiCoPO₄ Cathode Material with Li_1.5Al_0.5Ge_1.5(PO₄)₃ Lithium-Ion-Conducting Solid Electrolyte

Abstract

: The stability of the LiCoPO₄ electrode material in contact with a NASICON-type lithium ion conducting solid electrolyte having the composition Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) and a wide range of electrochemical stability has been studied for the first time. We have found the optimal temperature at which there is no reaction between the starting components of the composites and they retain their chemical and thermal stability. Cosintering a mechanical mixture of synthesized single-phase LiCoPO₄ and LAGP powders with a submicron particle size at 750°C, we have obtained a stable LiCoPO₄/LAGP two-phase composite whose room-temperature electrical conductivity is three orders of magnitude higher than that of the lithium cobalt double phosphate. Composites based on LiCoPO₄ and the LAGP ionic conductor can be regarded as promising cathode materials for all-solid-state lithium ion batteries.