High-Conductivity Argyrodite Li6PS5Cl Solid Electrolytes Prepared via Optimized Sintering Processes for All-Solid-State Lithium–Sulfur Batteries

Highly Li-ion conductive Li6PS5Cl solid-state electrolytes (SSEs) were prepared by solid-state sintering method. The influence of sintering temperature and duration on the phase, ionic conductivity, and activation energy of Li6PS5Cl was systematically investigated. The Li6PS5Cl electrolyte with a high ionic conductivity of 3.15 × 10–3 S cm–1 at room temperature (RT) was obtained by sintering at 550 °C for just 10 min, which was more efficient taking into account such a short preparation time in comparison with other reported methods to synthesize Li6PS5Cl SSEs. All-solid-state lithium sulfur batteries (ASSLSBs) based on the Li6PS5Cl SSE were assembled by using the nano-sulfur/multiwall carbon nanotube composite combined with Li6PS5Cl as the cathode and Li–In alloy as the anode. The cell delivered a high discharge capacity of 1850 mAh g–1 at RT for the first full cycle at 0.176 mA cm–2 (∼0.1C). The discharge capacity was 1393 mAh g–1 after 50 cycles. In addition, the Coulombic efficiency remained nearly 100% during galvanostatic cycling. The experimental data showed that Li6PS5Cl was a good candidate for the SSE used in ASSLSBs.