A Superionic Conductor Lithium Argyrodite Sulfide of Li7–x(GeSi)(1–x)/2SbxS5I toward All-Solid-State Lithium-Ion Batteries

Abstract

Li₆PS₅I based solid-state electrolytes (SSEs) show promising interface compatibility for all-solid-state batteries (ASSBs), but they still suffer from limited ionic conductivity. Herein, a superionic conductor lithium argyrodite sulfide, Li_7–x(GeSi)_(1–x)/2Sb_xS₅I, was developed through multi-cation substitution of Ge, Si, and Sb for P, increasing configurational entropy of the Li₆PS₅I. This approach enhanced Li⁺ content and anion site disorder, leading to a low activation energy of 0.17 eV for Li⁺ migration, and consequently a high cold-pressed ionic conductivity of 12.7 mS cm^–1, and a record value of 32.2 mS cm^–1 after hot-pressing. When incorporating Li₃InCl₆ as the catholyte and interlayer, the LiNi_0.8Co_0.1Mn_0.1O₂@Li₃InCl₆|Li₃InCl₆|Li_20/3(GeSiSb)_1/3S₅I|Li-In ASSBs exhibited a high capacity of 219 mAh g^–1 at 0.1 C, and a notable capacity of 135 mAh g^–1 with 84.4% retention at 1 C after 550 cycles. Our ASSBs demonstrated stable cycling across −20 to 60 °C and operated well at an ultrahigh cathode loading of 100 mg cm^–2. These findings advance sulfide SSEs for high-performance and wide-temperature ASSBs.