A Superionic Conductor Lithium Argyrodite Sulfide of Li_7–<i>x</i>(GeSi)_{(1–<i>x</i>)/2}Sb_<i>x</i>S₅I toward All-Solid-State Lithium-Ion Batteries

Abstract

Li 6 PS 5 I 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 )/2 Sb x S 5 I, was developed through multi-cation substitution of Ge, Si, and Sb for P, increasing configurational entropy of the Li 6 PS 5 I. 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 Li 3 InCl 6 as the catholyte and interlayer, the LiNi 0.8 Co 0.1 Mn 0.1 O 2 @Li 3 InCl 6 |Li 3 InCl 6 |Li 20/3 (GeSiSb) 1/3 S 5 I|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.