A multifunctional siloxane additive enabling fast charging of high-areal-loading Si-C||Ni-rich full batteries

The combination of Ni-rich cathodes and silicon-graphite (Si C) anodes offers high energy density and fast-charging potential for electric vehicle (EVs), yet their practical performance is limited by sluggish interfacial ion transport and unstable interphases in conventional carbonate electrolytes. Herein, we develop a novel multifunctional siloxane additive, dimethoxymethylvinylsilane (DOMS), and elucidate its mechanism in enabling fast charging. DOMS promotes Li + desolvation by weakening solvents-Li + coordination, while scavenging HF via the cleavage of Si O and Si C bonds. Importantly, the selective decomposition of DOMS induces the in-situ formation of robust inorganic interfacial phases enriched in Si O and Si F species on both electrode surface, which facilitate Li + transport and suppress interfacial side reactions. Meanwhile, the accompanying organic components composed of polyethylene (PE) and poly(methyldifluorosilylethylene) (PMDFSE) effectively buffer electrode volume effect during cycling. Collectively, these synergistic effects yield a chemically robust and kinetically favorable interface, enabling exceptional fast-charging performance. At an areal-loading of 17.53 mg cm −2 , Si-C||LiNi 0.9 Co 0.05 Mn 0.05 O 2 coin cells deliver 71% capacity retention after 300 cycles at a high current density of 499.6 mA g −1 , whereas pouch cells reach 85.58% after 400 cycles at 200 mA g-1. This work establishes a mechanism-driven siloxane additive strategy for fast-charging, high-energy-density lithium-ion batteries.