Amorphization of halide solid electrolytes for lithium super-ionic conductivity

Abstract

All-solid-state Li batteries (ASSLBs) have drawn attention as strong contenders for future energy storage owing to their extreme safety. When paired with uncoated 4 V-class layered positive materials, halide solid-state electrolytes (SSEs) exhibit excellent stability and compatibility, strong Li⁺ conductivity, and softness, making them highly potential SSE materials. Despite its cost-effective precursors, Li₂ZrCl₆ is plagued by its inherently poor ionic conductivity. Herein, we report a non-crystalline halide SSE, Li_2.2ZrCl_5.8S_0.2, which possesses a superior Li⁺ conductivity (0.86 mS cm⁻¹) and can be applied in high-performance ASSLBs. By integrating the Li_2.2ZrCl_5.8S_0.2 SSE with a LiIn negative material and an uncoated LiCoO₂ positive material, we acquire ordinary-temperature ASSLBs exhibiting excellent cycle-life (93.4% capacity retention under 1C for 100 cycles) and high-rate capacity (exceeding 80 mA h g⁻¹ at 2C). The work proposes a non-crystalline strategy to improve Li⁺ conductivity in Li₂ZrCl₆-family SSEs for ASSLSBs.