A Selective-Transport Elastomeric Coating Regulating Hierarchical Solid Electrolyte Interphase for Low-Temperature Lithium-Metal Batteries.

Abstract

Enhancing the low-temperature cycling performance of lithium metal batteries (LMBs) relies on the rational design of solid electrolyte interphases (SEIs). Conventional approaches typically involve tuning electrolyte compositions to indirectly generate SEIs dominated by organic or inorganic components. However, organic-rich SEI fails to inhibit the growth of Li dendrites, compromising sluggish Li⁺ kinetics, and inorganic-rich SEI suffers from mechanical brittleness at low temperatures, resulting in inadequate interfacial mechanical stability. Herein, we introduce a siloxane-based elastomeric coating on the Li anode surface by leveraging its intrinsic solvent phobicity to achieve selective ion conduction, facilitating the formation of a LiF-rich inner SEI, which synergizes with the elastomer to construct a double-layer organic-inorganic SEI. Theoretical calculations and experimental results demonstrate that such a double-layer SEI combines mechanical flexibility enabled by organic components with promoted Li⁺ transport imparted by inorganic components, synergistically improving the cycling stability of LMBs under low-temperature conditions. The target LMBs paired with industrial-standard NCM811 cathodes deliver 99% capacity retention over 300 cycles at -25°C. Unlike indirect electrolyte modification approaches, our method enables direct manipulation of SEI structures and is compatible with various electrolyte systems.