Morphologically controllable Li plating with stable electrochemistry realized in a newly developed DOL-DMM electrolyte system on Au-modified Cu current collector

Lithium (Li) ion batteries with Li-metal anode have shown some severe restrictions including low coulombic efficiency, dendritic growth behavior, and safety issues. The minimization of side reactions between Li and electrolyte and the fabrication of electrochemically plated Li with compact and flat microstructures have been effectively used for Li metal batteries with better performances. We proposed that an electrolyte system with lower binding energy for Li+ desolvation and a depositing surface with better affinity for Li might be beneficial to microscale homogeneous Li deposition. Fortunately, micro-spheric rather than dendritic Li was successfully deposited on gold (Au) element modified copper (Cu) foil in a newly developed 1,3-dioxolane/dimethoxymethane (DOL-DMM) electrolyte system under optimum conditions: The deposition of micro-spheric Li on Au-modified Cu current collector was performed in 1 M LiTFSI in DOL-DMM (v/v = 1: 1) with 0.1 M LiNO3 as additive. The Li|Cu half-cell also demonstrated good rate performance and long cycling stability with a coulombic efficiency of 98.4% in DOL-DMM electrolyte, which was much higher than those obtained in conventional carbonate electrolyte (83.3%) or in DOL-1,2-dimethoxyethane (DOL-DME) electrolyte (88.2%), respectively. The facile fabrication of micro-spheric Li on Au-modified Cu foil in DOL-DMM provides a new strategy for constructing safe and high-energy Li metal anodes, although it should be noted that the oxidation potential of this ether-based electrolyte needs to be further improved.