In-situ cross-linking strategy for stabilizing the LEDC of the solid-electrolyte interphase in lithium-ion batteries

Lithium ion batteries (LIBs) are seriously plagued by the unstability of the lithium ethylene dicarbonate (LEDC), the primary organic reduced product of carbonate-based electrolytes, in solid electrolyte interface (SEI). Herein, we propose an in-situ cross-linking strategy driven by an electrolyte additive of SiCl₄ to address this challenge with Si as a representative anode platform for LIBs. The theoretical and experimental results jointly confirmed that during the lithiation process, the SiCl₄ additive can spontaneously react with LEDC by in-situ cross-linking to form a stable Si-linked LEDC organic species, which serves as a benign “plasticizer” in the SEI layer to improve its intrinsic flexibility, while the inorganic LiCl formed after the dehalogenation of SiCl₄ has an ultralow Li⁺ diffusion barrier (0.08 eV), which endows the SEI layer with faster ion transport capability. This work provides a new avenue and insight into the design of stable and robust electrode/electrolyte interface of LIBs.