Enhanced Air Stability and High Li-Ion Conductivity of LiPNbSO Glass-Ceramic Electrolyte for All-Solid-State Lithium-Sulfur Batteries.

The development of novel sulfide solid-state electrolytes with high Li-ion conductivity, excellent air-stability, and a stable electrode-electrolyte interface is needed for the commercialization of all-solid-state cells. Currently, an ideal solid electrolyte, which can integrate the solid-state batteries, has not been developed. Herein, the Nb and O codoping strategy is excogitated to improve the chemical and electrochemical performance of sulfide electrolytes. The interactive effect of Nb and O in the novel LiPNbSO glass-ceramic electrolyte results in a superior Li conductivity of 2.82 mS cm and remarkable air-stability and electrochemical stability against the Li metal compared to the LiPS counterpart at 25 °C. Solid-state P MAS-NMR revealed that doping of LiNbO (0 ≤ ≤ 1) not only enhances the degree of crystallization but also produces POS units with bridging oxygen atoms in the LiPNbSO glass-ceramic electrolyte and hence boosts the conductive deportment of glass-ceramics. Impressively, the developed electrolyte exhibits a stable full voltage window of up to 5 V versus Li/Li. Furthermore, electrochemical impedance spectroscopy analysis shows that the interface resistance of the LiS/LiPNbSO/Li-In cell is lower than that of the cell with LiPS electrolyte. Besides, the battery of the LiPNbSO electrolyte delivers initial discharge capacities of 472.7 and 530.9 mAh g after 50 cycles with 98.88% capacity retention from the second cycle. The Coulombic efficiency of the cell remains at ∼100% after 50 cycles. Thus, the proposed codoped strategy produced a sulfide electrolyte, which addressed the challenging issues of chemical/electrochemical stabilities and showed promising industrial prospects for next-generation all-solid-state batteries.