Lithiophilic NiF2 coating inducing LiF-rich solid electrolyte interphase by a novel NF3 plasma treatment for highly stable Li metal anode

Abstract A three-dimensional lithiophilic skeleton is an effective strategy that is widely studied due to its large specific surface area and the lithiophilicity for suppressing the growth of dendrites on Li metal anodes. However, there are few studies on the lithiophilicity of the metal fluoride. In this study, we employ a novel NF3 plasma fluoridized strategy to fabricate a NiF2 coating on Ni foams for the first time. Due to the lithiophilic NiF2 layer, the Li+ flux tends to deposit preferentially on the sites of NiF2 and homogeneously distributes around the surface of the Ni foam, leading to a smooth and dense Li deposition. Moreover, the LiF-rich solid electrolyte interphase layer generated from the reaction between Li and NiF2 significantly improves the interfacial stability. The fluoridized Ni foam exhibits a highly stable cycling performance of over 2000 cycles at 2 mA cm−2 and over 1600 h at 1 mA cm−2. In addition, the fluoridized Ni foam@Li || LiFePO4 full cell delivers a capacity retention of 93% after 250 cycles at 1C. This work provides a safe and simple plasma strategy to construct a lithiophilic metal fluoride coating for strengthening the solid electrolyte interphase and suppressing the growth of Li dendrites.