A High-Efficiency Mo 2 C Electrocatalyst Promoting the Polysulfide Redox Kinetics for Na-S Batteries.

Room-temperature sodium-sulfur (RT Na-S) batteries, as promising next-generation energy storage candidates, are drawing more and more attention due to the high energy density and abundant elements reserved in the earth. However, the native downsides of RT Na-S batteries (i.e., enormous volume changes, the polysulfide shuttle, and the insulation and low reactivity of S) impede their further application. To conquer these challenges, hierarchical porous hollow carbon polyhedrons embedded with uniform Mo 2 C nanoparticles are designed deliberately as the host for S. The micro- and mesoporous hollow carbon indeed dramatically enhances the reactivity of the S cathodes and accommodates the volume changes. Meanwhile, the highly conductive dispersed Mo 2 C has a strong chemical adsorption to polysulfides and catalyzes the transformation of polysulfides, which can effectively inhibit the dissolution of polysulfides and accelerate the reaction kinetics. Thus, the as-prepared S cathode can display a high reversible capacity (1098 mAh g -1 at 0.2 A g -1 after 120 cycles) and superior rate performance (483 mAh g -1 at 10.0 A g -1 ). This work provides a new method to boost the performance of RT Na-S batteries.