An Additive-Assisted Hydrolysis-Blocking Route Enables Thermally Stable Interfacial Chemistry of Silicon-Based Anode Materials in a Rechargeable Lithium Battery

Abstract

Silicon-based anodes are promising for building the next-generation high-energy lithium-ion batteries (LIBs). Currently, the safe use of Si-anode-based LIBs has been hindered by unstable electrolyte chemistry at a high temperature. The thermal decomposition of lithium hexafluorophosphate (LiPF₆) and hydrolysis of the decomposition products can generate corrosive species (e.g., HF and PO_xF_y) and exacerbate the surface parasitic reaction of Si, accelerating materials aging and posing challenges to stable Li storage. Here it is shown that the introduction of a functional electrolyte additive, 1,3-Divinyl-1,3-diphenyl-1,3-dimethyldisiloxane (DK244) effectively mitigates the issue. As a Lewis base, DK244 interacted with the Lewis acid PF₅ from the thermal decomposition of LiPF₆, so it helped to suppress the generation of the corrosive species and improve the high-temperature anode stability against electrolyte. The aging mechanisms of deeply lithiated SiO_x/C (x ≈ 1) anodes during calendar storage at 60 °C are studied by using multiscale materials and electrochemical characterizations. The results revealed that DK244 assisted in mitigating the hydrolysis of the electrolyte while maintaining the chemically stable and mechanically robust of solid electrolyte interface so that it contributed to stable Li⁺ transport after high-temperature storage. The findings provide critical insights into optimizing the anode-electrolyte interface for high-energy and high-temperature-durable LIBs.