Temperature Effects on Li Nucleation at Cu/LiPON Interfaces

This study reports the effect of temperature on Li nucleation at the Cu/LiPON interface. Galvanostatic Li plating is performed on LiPON glass electrolytes at different temperatures ranging from 25 to 100 °C. At any temperature, the negative voltage peak appears, indicating Li nucleation, immediately after starting Li plating. The nucleation overpotential and nucleation number density decrease with increasing temperature. This is because the diffusivity of Li adatoms/ions along the Cu/LiPON interface increases with temperature, resulting in an increase in the amount of Li atoms incorporated into a single Li nucleus. The critical nucleation area also extends with increasing temperature. It is found that the activation energy for the interfacial diffusion of Li adatoms/ions along the Cu/LiPON interface is 51 kJ mol^-1 (0.53 eV), which is close to the activation energy for Li⁺ conduction in LiPON.