Sulfide solid electrolyte thin film with high ionic conductive from slurry-casting strategy for all-solid-state lithium batteries

Sulfide solid-state electrolyte (SSE) in all-solid-state lithium batteries (ASSLBs) has attracted increasing attention due to its outstanding safety and high energy density. Nevertheless, the two main challenges of sulfide-based electrolyte are how to reduce the thickness of its film and improve its interfacial stability. In this work, Li₆PS₅Cl is used as a solid electrolyte, cellulose membrane as a self-limiting skeleton, heptane as a dispersant and SEBS as a binder, and a 90 μm ultrathin sulfide electrolyte film is prepared by using the free-standing slurry casting strategy. The ionic conductivity of sulfide SSE film is 1.09 × 10⁻³ S cm⁻¹ at room temperature. Furthermore, the ASSLBs with cathode (LiNbO₃@LiNi_0.6CO_0.2Mn_0.2O₂) and anode materials (lithium-indium alloy) are prepared. The discharge capacity of the button cells assemble with sulfide solid electrolyte film is 161.2 mAh/g after 150 cycles with a capacity retention of 87 % under 0.1 C at 25 °C. This study provides ultrahigh ionic conductivity sulfide-based electrolyte film design principle towards promising possible strategies for ASSLBs.