Preset Lithium Source Electrolyte Boosts SiO Anode Performance for Lithium-Ion Batteries

SiO is a promising alternative to Si as the anode material for lithium-ion batteries, but it still suffers from a low initial coulomb efficiency, poor electrical conductivity, unstable cycling performance, etc. Various strategies have been attempted to solve these issues but were left unsolved. In this work, we propose a simple strategy that checks all of the right boxes by presetting a lithium source electrolyte (Li2CO3) into a SiO film using the magnetron sputtering method. The preset lithium source electrolyte provides both the lithium ions and the electrolyte required for the formation of a solid electrolyte interphase and thus significantly improves the initial coulomb efficiency. The lithium source electrolyte also acts as a medium to facilitate the growth of a solid electrolyte interphase inside this composite film in addition to its surfaces. The interior interphase provides an efficient and fast pathway for lithium-ion transmission during the lithiation process and thus improves the anode conductivity and the rate performance. The interior interphase also suppresses the brittle fracture by buffering the dramatic volume change during the lithiation/delithiation process and stabilizes the cycling performance substantially. In addition, this strategy is safe, green, and of low-cost, when compared to others, and provides a feasible way to commercialize the SiO anode for lithium-ion batteries.