Poly(ethyl α-cyanoacrylate)-Based Artificial Solid Electrolyte Interphase Layer for Enhanced Interface Stability of Li Metal Anodes

The inhomogeneous deposition/dissolution of Li metal and an unstable SEI layer are still tough issues for lithium metal batteries, causing severe safety problems and low Coulombic efficiency. In this paper, we design an artificial SEI layer based on in situ polymerization of ethyl α-cyanoacrylate precursor with LiNO3 additive. The CN– and NO3– groups can react with lithium metal during cycling to form a nitrogenous interface inorganic layer, facilitating ions conduction and blocking further undesirable interface reaction. The poly(ethyl α-cyanoacrylate) with excellent mechanical property presents as the dominate organic species in the artificial SEI layer to offer a uniform and firm protective outer layer. A lithium metal battery with this artificial SEI film exhibits a capacity retention of 93% even after 500 cycles at a rate of 2C. A smooth surface morphology of the lithium metal anode is obtained without any cracks and dendrites.