Single Additive with Dual Functional-Ions for Stabilizing Lithium Anodes.

The dendritic lithium formation and sustained lithium consumption caused by the uncontrollable side reactions between lithium and electrolytes seriously restrict the applications of lithium anodes in high-energy density batteries, especially in carbonate electrolytes. Ameliorating the surface status of lithium anodes is critical for modulating lithium deposition behavior and improving the cycling stability of lithium metal batteries. Herein, magnesium chloride salt is first reported as a carbonate electrolyte additive for lithium surface modification by in situ reaction. It is proved that both Cl- and Mg2+ play important roles in building a stable electrode/electrolyte interface with a fast Li+ diffusion property. The coexistence of inorganic LiCl and metallic Mg species in the interface can effectively decrease the surface side reactions, lower interphase resistance, promote Li ions diffusion, and result in uniform lithium deposition. The electrochemical tests show that the reversible utilization rate of lithium for Li/Cu asymmetrical cells increases by 10% and the polarization of Li/Li symmetrical cells is reduced noteworthily with such an additive. Furthermore, a significant improved cycling performance of Li/Li4T5O12 full cells is also achieved.