In situ reductive construction of a silicon-based polymer/indium alloy hybrid layer for stable lithium metal anodes in sulfide solid-state batteries

Abstract

All-solid-state lithium-metal batteries that use sulfide electrolytes deliver high energy and improved safety, yet their practical use is impeded by poor chemical matching and mechanical failure at the sulfide/Li interface. Herein, on the lithium surface, we directly grow a thin indium-polysiloxane hybrid layer that contains in-situ-generated inorganic nanodomains (LiF, In/LiIn, LiSi_xO_y) formed by the co-reduction of In³⁺ salts and polysiloxane’s fluorine/silicon-containing moieties (PFSIn-Li). Disclosed by a series of physicochemical and electrochemical characterizations, this hybrid layer, synthesized by a single-step solution-cast coating, is chemically inert to Li_5.5PS_4.5Cl_1.5 (LPSC) and mechanically robust against dendrite penetration, which simultaneously halts parasitic reactions, blocks dendrite growth and preserves intimate interfacial contact and rapid Li-ion transport during repeated plating/stripping. Resultantly, symmetric cells using PFSIn-Li sustain an ultrahigh critical current density of 3.5 mA cm⁻², while PFSIn-Li∣LPSC∣LiNi_0.7Co_0.1Mn_0.2O₂ full cells provide 129.8 mA h g⁻¹ at the initial cycle under 0.5 C and retain 82.3% of this capacity after 300 cycles, more than double the retention of bare-Li cells (43.0%). This scalable, low-cost polysiloxane-In³⁺ chemistry furnishes a durable sulfide/lithium interface for next-generation, long-life, high-energy all-solid-state batteries.