Sn-doped thioantimonate superionic conductors with high air stability and enhanced Li-ion conduction for all-solid-state lithium batteries

Abstract

The sulfide-based solid electrolyte (SSE) has been considered as a strong candidate for potential uses in all-solid-state lithium batteries (ASSLBs). Nevertheless, most of the reported SSEs are plagued with their intrinsic air-sensitive behaviors and Li-incompatibility, which largely preclude scalable fabrication and widespread practical application. Herein, we report the Li_6+xSb_1−xSn_xS₅I (LSSSI-x) SSEs using nontoxic inexpensive Sn substitution to deal with these issues. The ionic conductivity of Li_6+xSb_1−xSn_xS₅I can achieve a maximum value of 3.49 × 10⁻⁴ S cm⁻¹ at room temperature when x = 0.4, which is over 40-fold that of the pristine Li₆SbS₅I. The Li symmetric cell with I-rich Li_6.4Sb_0.6Sn_0.4S₅I (LSSSI-0.4) electrolyte delivers a stable Li⁺ plating/stripping behavior over 450 h at a current density of 0.1 mA cm⁻². Benefiting from the decent Li-compatibility of LSSSI-0.4, the assembled ASSLB with LiNi_0.8Co_0.1Mn_0.1O₂-based composite cathode and Li-metal anode displays good cycling performance. The LSSSI-0.4 electrolyte also possesses excellent moisture stability. ASSLB using the dried LSSSI-0.4 electrolyte still exhibits a well-maintained initial discharge capacity of 184.0 mA h g⁻¹ at 0.1C and an impressive capacity retention rate of 70.6% after 600 cycles at 0.2C. This work offers a feasible option with superior integrated properties to push forward the advancement of high-performance ASSLBs.