A cost-effective dual-anion electrolyte stabilizing silicon anodes via a conductive LiF–Li2O–LiCl-rich interphase

Abstract

Silicon (Si) anodes offer ultrahigh theoretical capacity (∼4200 mAh g⁻¹) for next-generation lithium-ion batteries but suffer from drastic volume expansion (>300%) and interfacial instability. Ether-based electrolytes form flexible solid electrolyte interphase (SEI) layers enriched with polyether-based compounds that accommodate Si expansion, but their intrinsic oxidative instability (<4.0 V vs. Li/Li⁺) fundamentally restricts compatibility with high-voltage cathodes. Here, a novel conventional-concentration dual-anion electrolyte strategy is designed to overcome these limitations synergistically. The introduced ClO₄⁻ anion eliminates aluminum corrosion at >4.0 V via in situ passivation while optimizing solvation structures to enhance the oxidation stability of ether solvents. Crucially, cooperative decomposition of FSI⁻/ClO₄⁻ generates a ternary SEI architecture comprising LiF for mechanical robustness and Li₂O/LiCl for high ionic conductivity. Coupling with polyether components with favorable flexibility, this multifunctional SEI enables superior cycling stabilities in both Li‖Si/C half cells and high voltage Si/C‖LiNi_0.8Co_0.1Mn_0.1O₂ batteries. This work establishes scalable dual-anion electrolyte engineering as a paradigm for commercializing high-energy-density Si anodes without compromising cost or voltage compatibility.