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 Li6.4Ga0.2La3Zr2O12(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 degrees 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 degrees C, indicating good cycle performance.

Automated summary

By synthesizing highly ionic conductive LLZO ceramics and combining them with multi-walled carbon nanotubes to form a conductive network, the electrochemical performance of solid-state lithium-sulfur batteries has been successfully improved.