Rational design of F, N-rich artificial interphase via chemical prelithiation initiation strategy enabling high coulombic efficiency and stable micro-sized SiO anodes

Silicon monoxide (SiO) is regarded as a potential candidate for anode materials of lithium-ion batteries (LIBs). Unfortunately, the application of SiO is limited by poor initial Coulombic efficiency (ICE) and unsteady solid electrolyte interface (SEI), which induce low energy, short cycling life, and poor rate properties. To address these drawbacks of SiO, we achieve in-situ construction of robust and fast-ion conducting F, N-rich SEI layer on prelithiated micro-sized SiO (P-μSiO) via the simple and continuous treatment of μSiO in mild lithium 4, 4′-dimethylbiphenyl solution and nonflammable hexafluorocyclotriphosphazene solution. Chemical prelithiation eliminates irreversible capacity through pre-forming inactive lithium silicates. Meanwhile, the symbiotic F, N-rich SEI with good mechanical stability and fast Li+ permeability is conductive to relieve volume expansion of μSiO and boost the Li+ diffusion kinetics. Consequently, the P-μSiO realizes an impressive electrochemical performance with an elevated ICE of 99.57% and a capacity retention of 90.67% after 350 cycles. Additionally, the full cell with P-μSiO anode and commercial LiFePO4 cathode displays an ICE of 92.03% and a high reversible capacity of 144.97 mA h g−1. This work offers a general construction strategy of robust and ionically conductive SEI for advanced LIBs.