Reduced Energy Barrier for Li(+) Transport Across Grain Boundaries with Amorphous Domains in LLZO Thin Films

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.