A new reflowing strategy based on lithiophilic substrates towards smooth and stable lithium metal anodes

In this work, we propose a facile, efficient and novel reflowing strategy to smooth the surface and decrease the interfacial resistance of lithium metal pre-deposited on a lithiophilic substrate, leading to a stable lithium metal anode with high electrochemical performance. First, on the basis of lithiophilic modification of a Cu substrate with a Au sputtering layer, the Li metal nucleation overpotential on the substrate is decreased, thus favoring uniform Li nucleation and growth. Second, owing to morphology reshaping by the reflowing treatment, the surface of the lithium metal anode could be further smoothed, and the interfacial resistance could also be reduced due to the modified solid electrolyte interface (SEI) film after the reflowing treatment. Therefore, a novel reflowing-treated Li/Au/Cu (RF-Li/Au/Cu) anode exhibits excellent electrochemical performance. Through galvanostatic measurements, stable cycling of the symmetric cells with the RF-Li/Au/Cu electrode for more than 1600 h and nearly 900 h is achieved at 0.5 mA cm^-2 and 1 mA cm^-2 with a capacity of 1 mA h cm^-2, respectively. In addition, LiFePO₄ cells with the RF-Li/Au/Cu anode show better rate performance and longer cycling life compared with those with an untreated Li/Au/Cu anode. This work provides a new concept and facile approach for developing stable Li metal anodes with high electrochemical performance.