Coupling of S@aerogel and Si/SiO_<i>x</i> Nanospheres Electrodes with “Polysulfide” Salt‐Free Electrolytes in a Fluorine‐Free Lithium‐Ion Batteries

Li‐ion batteries play a pivotal role in powering electric vehicles and storing renewable energy. To enable their widespread adoption, it is imperative to explore new materials that reduce costs and enhance energy density. Sulfur and silicon exhibit promising characteristics as cathodes and anodes, respectively, and perform well in Li half‐cells. However, their effective coupling in Li‐ion configurations presents challenges. A major hurdle lies in identifying an electrolyte that ensures stable interphases and prolonged cycling while prioritizing safety and cost‐effectiveness. This study introduces a groundbreaking approach by customizing a “salt‐free” electrolyte solution compatible with both Li/sulfur and Li/silicon cells. The innovation involves dissolving lithium polysulfide in a diglyme solvent to facilitate Li‐ion transfer. This improves cell safety due to the low flammability of the solvent and the absence of fluorine, while also ensuring faster Li‐ion transport and prolonged stability of the solid electrolyte interphase. By integrating this tailored electrolyte with engineered electrodes, including a free‐standing reduced graphene oxide aerogel with ≈74% sulfur and high areal capacity Si/SiO x nanospheres, a unique “salt‐free” Li‐ion battery configuration is demonstrated. The findings present a promising avenue for developing cost‐effective, safe, high‐performance lithium‐ion batteries.