Mechanochemically Prepared Li₂S–P₂S₅–LiBH₄ Solid Electrolytes with an Argyrodite Structure

摘要

Solid electrolytes with compositions of (100 – x )(0.75Li_(2)S·0.25P_(2)S_(5))·x LiBH_(4) (mol %, 0 ≤ x ≤ 100) were mechanochemically prepared from the 75Li_(2)S·25P_(2)S_(5) (mol %) glass and LiBH_(4) crystal. The samples with x ≥ 43 have crystalline phases and those with x ≤ 33 formed a glassy phase. The crystalline phase was identified as argyrodite Li_(6)PS_(5)(BH_(4)). The x = 50 sample formed a crystalline phase and demonstrated a high lithium-ion conductivity of 1.8 × 10~(–3) S cm~(–1) at 25 °C with an activation energy of 16 kJ·mol~(–1). The argyrodite-type crystal with a BH_(4)~(–) anion that occupies the halide site is a novel and promising solid electrolyte.