In Situ Formation of Stable Interfacial Coating for High Performance Lithium Metal Anodes

Uncontrollable growth of Li dendrites is a big problem for Li metal batteries. In this work, we described a new universal strategy of in situ formation of interfacial coating with methyl viologen to achieve stable cycling of lithium metal anode. After treating the lithium metal layer with 0.5 wt % methyl viologen in the ether electrolyte, a highly uniform, stable, and ionically conductive interfacial coating can be formed on the surface because of the electrochemical reduction. The coating layer can generate better control of the lithium ion flow and suppress the lithium dendrite growth and therefore form a uniform and stable solid electrolyte interphase. Using this approach, a lifetime of 300 cycles with Columbic efficiency of 99.1% and 400 cycles with Columbic efficiency of 98.2% at a current density of 1 mA cm –2 in ether-based electrolyte can be obtained. This lifetime is more than three times higher than the control ether electrolyte. In addition, this approach can enhance the performances of lithium metal anode in carbonate-based electrolyte. Compared with the previous approaches, our new strategy has many advantages such as low cost, easy manipulation, and compatibility with current lithium ion batteries.