Synergistic interface stability and high room-temperature ionic conductivity for wide-temperature all-solid-state batteries based on Li6+xSixSb1−xS5I electrolytes

Solid-state lithium-ion batteries (LIBs) are increasingly recognized for their exceptional energy density and safety, yet their widespread adoption is challenged by persistent issues such as thermal and electrochemical instability, dendrite formation, and limited compatibility with high-voltage cathodes. Sulfide-based solid electrolytes (SEs), particularly iodide argyrodites, offer outstanding ionic conductivity and stability; however, practical application is constrained by the formation of space-charge layers, slow ion transport, and susceptibility to dendrite penetration. To address these challenges, we synthesize a novel Li 6.6 Si 0.6 Sb 0.4 S 5 I argyrodite electrolyte via ball milling and heat treatment, achieving a remarkable room-temperature ionic conductivity of 9.9 mS cm −1 . The electrolyte is integrated with a LiNbO 3 -coated LiNi 0.7 Co 0.1 Mn 0.2 O 2 cathode to form an all-solid-state battery, which demonstrates an initial discharge capacity of 174.8 mAh g −1 , retains 68.2% of its capacity after 300 cycles at 0.5C, and maintains stable cycling across a broad temperature range (−20 °C to 60 °C). Our study shows that tailored electrolyte composition and a composite cathode configuration significantly enhance cycling stability and improve interfacial protection. These findings highlight the potential of Si-doped antimony-type iodide argyrodites for next-generation high-performance all-solid-state batteries, offering durable operation under diverse thermal conditions.