Mechanothermal-milling-assisted removal of native passivation layer for refreshing lithium metal anodes

Securing the stable and reliable operation of high-energy lithium (Li) metal batteries (LMBs) is crucial for fundamental studies and practical applications. However, commercial Li metal anodes (LMAs) suffer from unreliable pre-passivation during vendor-specific manufacturing, which deteriorates their surface quality and compromises the reproducibility of novel post-treatments and new electrolytes. To avoid chemical and structural degradation originating from the initial LMA, this study presents a mechanothermal milling (MTM) method using heating blades to smoothly peel off the native passivation layer (NPL) on the LMA surface, thereby exposing near-fresh Li. Compared to as-received LMA, the LMA revitalized by the MTM process (MTM-Li) exhibited faster kinetics and less interfacial resistance, promoting spatially uniform, dendrite-less Li plating and pit-less Li stripping. The MTM-guided surface equalization of the LMA enables an accurate comparison of the electrolyte-derived SEI properties, which is essential for identifying an electrolyte that is genuinely compatible with freshly exposed Li. By combining it with highly stable electrolytes, MTM-Li can regulate the structural evolution of LMAs, effectively securing cycling stability for LMBs, even under stringent conditions.