Chemomechanically Tuned Li–In/Sn Intermetallic Anodes for Sulfide SSBs: Composition–Transport Coupling and Pressure-Stabilized Interfaces

Intermetallic Li–In and Li–Sn anodes with high lithium content are engineered to sustain intimate, crack-resistant contact with Li6PS5Cl under optimized stack pressure, en- abling dendrite-free cycling at 1 mA cm−2 over thousand-hour timescales. The paper links composition-dependent lithium mi- gration barriers to measured overpotentials through combined atomistic modeling and electrochemical testing, revealing how phase selection (e.g., Li13In3, Li17Sn4) governs transport and interfacial kinetics. Controlled synthesis and fabrication routes yield robust chemomechanical coupling at the alloy–sulfide inter- face, suppressing interfacial degradation pathways that typically initiate filament growth. These materials-centric insights provide a design map connecting alloy stoichiometry, interphase stability, and processing pressure to durable solid-state battery operation, emphasizing scalable materials processing and interface engineer- ing over cell-level optimization.