Harnessing reaction kinetics for wet chemical synthesis of Li-Si-Sb-S-I quinary Li-argyrodite solid electrolytes

초록

Sulfide-based Li-argyrodites are leading candidates for solid electrolytes (SEs) in solid-state Li-ion batteries (SSLBs); however, their practical use is limited by their poor air stability and energy-intensive synthesis. Herein, we present a rationally designed, low-energy, wet chemical route for the synthesis of a dual-cation-substituted argyrodite, Li6.5Si0.5Sb0.5S5I (LSSSI). Guided by thermodynamic modeling, the reaction pathway was carefully designed to overcome the kinetic barriers associated with incorporation of multiple elements. LSSSI was successfully synthesized at a reduced annealing temperature and (400 degrees C) and exhibited a high ionic conductivity of 3.86 mS cm-1. Notably, LSSSI showed significantly improved stability against moisture and lithium metal compared to conventional P-based argyrodites. When employed in SSLBs, LSSSI delivers excellent electrochemical performance, maintaining 97.7 % of its capacity even after atmospheric exposure. This study establishes a new framework for synthesis of scalable and air-stable high-performance SEs.

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