In situ atomic-scale engineering of the chemistry and structure of the grain boundaries region of Li3xLa2/3-xTiO3

Severe deviation in structure and chemistry at grain boundaries has been regarded as the source of the poor conductivity of Li3xLa2/3-xTiO3. In this work, we report an in situ grain boundary engineering method to address this bottleneck. A lithium-rich electrolyte, Li3OCl, was introduced into Li3xLa2/3-xTiO3 to replenish lithium at the grain boundaries. Both the Li-gain on the boundary and generation of a Li-rich grain-engineered layer contributed to an optimized grain boundary conductivity of 1.52 x 10(-4) (S/cm) and a depressed activation energy of 0.32 eV for grain boundary. Full batteries were further employed to demonstrate the enhancement in conductivity. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.