Double design of host and guest synergistically reinforces the Na-ion storage of sulfur cathodes.

Development of room-temperature sodium-sulfur batteries is significantly hampered by the shuttle effect of soluble intermediates and intrinsically sluggish conversion kinetics. In this work, a double design host and guest strategy ( i.e. , implantation of a polar V 2 O 3 adsorbent into a carbon substrate and selenium doping of a sulfur guest) is proposed to synergistically reinforce the electrochemical properties of sulfur electrodes in sodium ion storage. The V 2 O 3 adsorbent efficiently immobilizes sulfur species via strong polar-polar interactions, while the selenium dopant improves the electronic conductivity of sulfur cathodes and accelerates the redox conversion of sulfur cathodes. The synergistic effect between the V 2 O 3 adsorbent and selenium dopant is shown to inhibit the shuttle effect and improve the redox kinetics, thus realizing greatly enhanced Na-ion storage properties of sulfur cathodes. The as-designed sulfur cathode delivers a superior rate capability of 663 mA h g -1 at 2.0 A g -1 and demonstrates excellent cyclability of 405 mA h g -1 over 700 cycles at 1.0 A g -1 .