On the La_(2/3-x)Li_(3X)TiO_3/Al_2O_3 composite solid-electrolyte for Li-ion conduction

摘要

An effective ceramic processing route including tape casting and relatively low-temperature calcination has been adopted to fabricate La_(0.56)Li_(0.33)TiO_3 (LLTO)/A1_2O_3 composite electrolytes. Correlation among additional amount of A1_2O_3, microstructure and Li-ion conductivity of the composites is examined and evaluated. What is most interesting from X-ray diffraction and transmission electron microscopy is that LiAl_5O_8 phase is found to form in the LLTO/A1_2O_3 composites during calcination. The present study indicates that the presence of LiAl_5O_8 has a beneficial effect of increasing ionic conductivity and decreasing activation energy. It was observed that the LLTO/10 wt% A1_2O_3 composite electrolyte exhibits a higher conductivity at bulk (~6 times) and grain boundary (~3 times) compared to pure LLTO at room temperature. An Arrhenius temperature dependence of Li-ion motion in this composite electrolyte is obtained, displaying low activation energy of 0.17 and 0.37 eV for bulk and grain boundary conduction, respectively.