Reduced Energy Barrier for Li+ Transport Across Grain Boundaries with Amorphous Domains in LLZO Thin Films
Yanlin Zhu, Shuai Wu, Yilan Pan, Xiaokun Zhang, Zongkai Yan, Yong Xiang
Abstract
Abstract The high-resistive grain boundaries are the bottleneck for Li + transport in Li 7 La 3 Zr 2 O 12 (LLZO) solid electrolytes. Herein, high-conductive LLZO thin films with cubic phase and amorphous domains between crystalline grains are prepared, via annealing the repetitive LLZO/Li 2 CO 3 /Ga 2 O 3 multi-nanolayers at 600 °C for 2 h. The amorphous domains may provide additional vacant sites for Li + , and thus relax the accumulation of Li + at grain boundaries. The significantly improved ionic conductivity across grain boundaries demonstrates that the high energy barrier for Li + migration caused by space charge layer is effectively reduced. Benefiting from the Li + transport paths with low energy barriers, the presented LLZO thin film exhibits a cutting-edge value of ionic conductivity as high as 6.36 × 10 −4 S/cm, which is promising for applications in thin film lithium batteries.