Water-Scavenging Suspended Mediator in Electrolytes for Silicon-Based Lithium-Ion Batteries with High-Nickel Cathode

Trace amounts of H₂O are inevitably introduced during lithium battery manufacturing processes, which induces the hydrolysis of LiPF₆, leading to HF formation, which triggers a cascade of deleterious reactions that degrade the solid electrolyte interphase (SEI) and corrode electrode materials. In this work, a water-scavenging electrolyte was constructed by employing a boroxine-linked covalent organic framework (COF) as the suspended phase. The ring-opening reaction of the boroxine ring units in COFs can effectively capture H₂O, thereby suppressing the hydrolysis of PF₆^- and mitigating electrode corrosion caused by HF. Consequently, a Li-metal battery with a high-nickel cathode retained 73% of its initial capacity after 500 cycles at 1 C, and a silicon-based lithium-ion battery with a high-nickel cathode sustained stable cycling over 500 cycles at a high rate of 10 C. This suspension strategy, leveraging a boroxine-linked COF with dual H₂O-scavenging capability, offers a scalable and versatile platform for electrolyte engineering toward practical next-generation lithium batteries.