Uncovering the Electrochemical‐Thermal Coupling Behavior of Li Plating at Elevated Temperatures

ABSTRACT The occurrence of unexpected Li plating and dendrite growth on graphite anodes poses significant challenges to the practical application of lithium‐ion batteries. While existing studies have highlighted the superiority of elevated temperatures in alleviating Li plating and Li dendrite growth. We enable a comprehensive electrochemical‐thermal investigation of the Li plating mechanism at an elevated temperature of 60°C, induced by slight over‐lithiation on Li|graphite coin cells. By combining voltage evolution with in‐situ heat generation, we identify a distinctive exothermic peak corresponding to the Li plating plateau. Intriguingly, we discover a characteristic exothermic peak during the relaxation stage, attributed to the simultaneous occurrence of Li stripping and re‐intercalation, which is beyond our regular cognition and serves as a novel indicator of Li plating. The heat contributions analysis further indicates the weakened Li intercalation heat generation once Li plating occurs. Finally, from the post‐mortem characterizations, the surface morphologies, chemical composition, and Li content quantification of the lithiated graphite without Li plating and at different Li plating cycles are obtained to reveal the Li nucleation‐growth mechanism. The results demonstrate that a total of 0.540 mg metallic Li is plated on a coin cell over the whole cycle. This work provides a new insight into the electrochemical‐thermal coupling mechanism of Li plating at elevated temperature.