CONTROL OF STRUCTURE AND FUNCTIONAL PROPERTIES OF GA:M5+-CODOPED LITHIUM LANTHANUM ZIRCONATE (LI7LA3ZR2O12) (M=Ta, Nb) SOLID ELECTROLYTES BY AN OPTIMIZED PROCESSING PROFILE

Abstract

GARNET-TYPE LITHIUM FAST-ION CONDUCTOR LI7LA3ZR2O12 (LLZ) IS A PROMISING CANDIDATE TO FACILITATE THE DESIGN OF HIGH ENERGY BATTERIES DUE TO ITS STABILITY IN CONTACT WITH LITHIUM AND CATHODE MATERIALS AND HIGH LI+-ION YET NEGLIGIBLE ELECTRONIC CONDUCTIVITY. HERE, THE SYNTHESIS OF LLZ WITH PENTAVALENT (TA,NB), TRIVALENT (AL,GA), OR HEXAVALENT (TE) DOPANTS WAS SYSTEMATICALLY INVESTIGATED USING CONVENTIONAL SOLID-STATE REACTIONS OR LOW-TEMPERATURE SOL-GEL PROCESSES. EFFECTS OF DOPANTS ON STABILISATION OF THE FAST-ION CONDUCTING CUBIC PHASE, STRUCTURAL DETAILS, LI+-ION ORDERING AND CONDUCTIVITY AND THEIR CORRELATION WERE STUDIED SYSTEMATICALLY BY X-RAY OR NEUTRON DIFFRACTION, IMPEDANCE SPECTROSCOPY AND MOLECULAR DYNAMICS SIMULATIONS. FORMATION AND DECOMPOSITION MECHANISMS AND THE INFLUENCE OF CO2 THEREON WERE STUDIED. THE INCORPORATION OF GA2O3 AS A SINTERING AGENT RESULTED IN GA:TA5+/NB5+-CODOPED LLZ WITH ~10% INCREASED DENSITY AND HENCE AN ENHANCED LI+ ION CONDUCTIVITY. ITS APPLICATION AS