Grain boundary stability and influence on ionic conductivity in a disordered perovskite - A first-principles investigation of lithium lanthanum titanate

The origin of ionic conductivity in bulk lithium lanthanum titanate, a promising solid electrolyte for Li-ion batteries, has long been under debate, with experiments showing lower conductivity than predictions. Using first-principles-based calculations, we find that experimentally observed type I boundaries are more stable compared with the type II grain boundaries, consistent with their observed relative abundance. Grain boundary stability appears to strongly anti-correlate with the field strength as well as the spatial extent of the space charge region. Ion migration is faster along type II grain boundaries than across, consistent with recent experiments of increased conductivity when type II densities were increased.

Duke Scholars

Author Miaofang Chi Thomas Lord Department of Mechanical Engineering and Materia ...