Chemically Evolved Composite Lithium-Ion Conductors with Lithium Thiophosphates and Nickel Sulfides

The development and application of all-solid-state batteries with a fast lithium-ionic conductor are hampered by structural instability and rigid stoichiometry restrictions. Here, we present a family of lithium thiophosphate prototypes with a novel principle, controlling sulfur deficiencies with the addition of nickel sulfide-based additives, for fast lithium-ion conduction and distinct electrochemical stability under the extended material constituent. Well-controlled sulfur deficiency of the Li3PS4 framework accompanied by nickel sulfide additive offers the notable increase of lithium-ion conductivity (2 × 10–3 S cm–1 at 25 °C) and high electrochemical stability (up to 10 V vs Li/Li+) in a wide composition range. We further confirm the potential application of our fast composite lithium-ion conductor as an electrolyte for the all-solid-state battery with 117 mAh g–1 capacity delivery and stable cycle life.