S/MWCNt/LLZO composite electrode with e−/S/Li+ conductive network for all-solid -state Lithium–Sulfur batteries

Traditional liquid lithium-sulfur batteries have two key problems: poor safety and shuttle effect . These two challenges can be overcome by using solid-state electrolytes. But poor ionic and electronic conductivity due to solid/solid contact between the electrode and the electrolyte for all-solid-state lithium-sulfur batteries (ASSLSBs). Here, we have synthesized Li 6.4 Ga 0.2 La 3 Zr 2 O 12 (LLZO) conductive ceramics with high ionic conductivity . LLZO is used as the lithium-ion conductor and multi-walled carbon nanotubes (MWCNt) are used as the electronic conductor to form S/MWCNt/LLZO by the thermal diffusion method, resulting in an e − /S/Li + conductive network. The prepared S/MWCNt/LLZO composite material, composite solid electrolyte, and lithium metal are assembled into ASSLSBs. After 50 cycles, the high capacity of 825 ​mAh·g −1 is maintained with 72.62% capacity retention at 0.2C and 45 ​°C. The higher capacity indicates the success of forming a conductive network that can improve the electrochemical performance of ASSLSBs. At 0.2C, the capacity of the S/MWCNt/LLZO composite cathode remains at 873 ​mAh·g −1 after 60 cycles when the operating temperature is increased to 60 ​°C, indicating good cycle performance.