A significant enhancement of cycling stability at fast charging rate through incorporation of Li3N into LiF-based SEI in SiOx anode for Li-ion batteries

Abstract

SiOx has attracted significant attention as an advanced anode material for next-generation lithium-ion batteries for electric vehicles. However, low Li-ion conductivity, chemical instability, morphological inhomogeneity, and the subsequent uneven growth of solid electrolyte interphase (SEI) are still unresolved and hinder its practical application. The LiF-rich SEI obtained using a conventional electrolyte with vinyl carbonate (VC) additive generally exhibits enhanced mechanical rigidity and low ionic conductivity. Herein, we report the use of octadecylamine (ODA) as additional electrolyte additives to enhance the ionic conductivity and physicochemical stability of the SEI by incorporating Li3N into the LiF-based SEI of SiOx anode. The Li3N with high ionic conductivity obtained by addition of ODA provides excellent lithium storage stability and fast charge/discharge performance; the NCM-811||Ti-SiOx@C full cell with VC and ODA additives exhibits approximately 2 times increased capacity retention even after 1000 cycles at 5 C-rate compared to the conventional electrolyte with VC additive only (approximately 5 times compared to the electrolyte without an additive).