Enabling Durable Quasi-Solid-State Li–S Batteries with an Organic Nitrate Additive for Anode Protection and Polysulfide Confinement

Poly(1,3-dioxolane) (PDOL)-based electrolytes are promising candidates for lithium-sulfur (Li-S) batteries due to their high ionic conductivity and low cost. However, their poor interfacial compatibility with lithium metal impedes the formation of a stable solid electrolyte interphase (SEI). This challenge is further exacerbated by the fact that conventional nitrate additives (e.g., LiNO₃) inhibit 1,3-dioxolane (DOL) polymerization. Herein, we propose isosorbide dinitrate (ISDN), a covalent organic nitrate, as a multifunctional additive that not only promotes DOL polymerization but also enables the formation of an inorganic-rich hybrid SEI (Li₃N and LiNxOy), as verified through X-ray photoelectron spectroscopy (XPS) analysis and theoretical calculations. The reinforced SEI enhances interfacial ion transport and mechanical robustness, thereby achieving uniform and dendrite-free lithium deposition. Density functional theory (DFT) calculations further reveal strong chemical interactions between ISDN and PDOL, which effectively enhance the adsorption of polysulfide onto PDOL to suppress the shuttle effect. Benefiting from these synergistic functions, Li|PDOL@ISDN|Li symmetric cells achieve stable cycling exceeding 1000 h without short-circuit failure. Quasi-solid-state Li-S batteries also demonstrate excellent cycling stability, with a capacity retention of 84.7% after 100 cycles at 0.2C. This work offers a promising strategy for designing high-performance solid-state Li-S batteries based on PDOL electrolytes.