Lithium Dendrite Suppression with Li3n-Rich Protection Layer Formation on 3d Anode Via Ultra-Low Temperature Nitriding

We demonstrate an effective strategy to prohibit lithium dendrite formation in lithium metal batteries (LMBs) by forming a Li3N-rich protection solid electrolyte interphase (SEI) layer on a three-dimensional (3D) austenitic stainless steel (SS) surface. The porous SS with 20% Cr is treated by ultra-low temperature ion-nitriding (250~350oC) for energy-saving, resulting in a lithiophilic nitride layer with a chromium nitride (CrN) phase on the surface, evidenced by the X-ray photoelectron spectroscopy (XPS) and further confirmed by Density functional theory (DFT) calculation. Upon cycling, it reacts with metallic Li to form a strong and highly ionic conductive Li3N protection layer, which functionally inhibit side reactions with electrolyte and facilitate the Li+ transport, consequently leading to a flat Li deposition. The 3D skeleton of SS reduces the areal current density and provides space to relieve volume expansion. The electrochemical results showed that the N-350-SS/Li (porous SS nitrided at 350℃ and composited with Li metal) in symmetrical cells exhibited extremely low voltage hysteresis of 14 mV and prolonged excellent cycling for over 2500 h at 1 mA cm−2. The half cells retained an excellent Coulombic efficiency (CE) of above 98%. It can be successfully applied in the real high-energy-density LMBs