This paper reports on the cycling stability of Li plating/stripping on Li6.6La3Zr1.6Ta0.4O12 [LLZ(Ta0.4)] with high sintering density at 25, 60, and 100 °C. Plated/stripped Li thicknesses are sequentially increased to 200 nm, 1.0 μm, and 2.0 μm after every ten cycles. The overpotential gradually increases with cycling Li plating/stripping processes, and the cells eventually short-circuit at 25 and 60 °C. However, the cycling stability of Li plating/stripping significantly improves at 100 °C, and the short-circuiting is prevented perfectly. Moreover, the cycling stability of Li plating/stripping at 25 °C is dramatically improved by pre-cycling the cell at 100 °C. Only heating a cell with Li metal at 100 °C for the same duration does not improve the cycling stability of the cell. It is hence considered that forced migrations of Li atoms and ions across entire Li/LLZ(Ta0.4) interfaces at 100 °C change the properties of the interfacial regions even for the following plating/stripping cycles at 25 °C.