Engineering CoMoO4 in reduced graphene oxide as superior cathode hosts for advanced room-temperature sodium-sulfur batteries

Promising room-temperature sodium-sulfur (RT Na-S) battery systems rely on purposely designed high-performing and low-cost electrode materials. Nevertheless, there are the challenges of irreversible dissolution and slow redox kinetics of NaPSs in the complete discharge of sulfur capacity. Herein, engineered CoMoO4 in reduced graphene oxide (CoMoO4@rGO) is reported as a class of superior cathode hosts for RT Na-S batteries. The CoMoO4@rGO matrix is designed to facilitate the reversible sodiation and desodiation of sulfur, considering the strong chemisorption between sulfur (and short-chain sodium sulfides) and CoMoO4, which alleviates the shuttle effect of sodium sulfides and accelerates the electrochemical reaction rate at RT. The obtained S/CoMoO4@rGO cathode with ∼52% S loading exhibits a high capacity of 520.1 mA h g−1 after 100 cycles at 0.1 A g−1. Moreover, an enhanced long-term performance at high current densities (212.2 mA h g−1 at 4 A g−1 over 1000 cycles) with high Coulombic efficiency (∼100%) is also achieved. This work demonstrates a novel multifunctional additive for RT Na-S battery cathodes, which is expected to promote the long-waited development towards practical applications of RT Na-S batteries.