Altered S–S Coulomb Interactions in Polysulfides Associated with VS2/S Nanocomposite Electrodes for Na–S Batteries.

Despite the abundant reserves and high theoretical capacity of Na–S batteries, it is still limited by the sluggish reaction kinetics of polysulfides during ultrafast charging and discharging to provide stable and high sodium-ion storage performance. Herein, a catalytic strategy is proposed to change the direction of the Coulomb interaction of S–S bonds to achieve high rate reaction kinetics in polysulfides. In this strategy, a Na_xVS₂ structure is constructed in VS₂/S nanocomposite electrodes to support S for superior performance (784 mA h/g at 0.1 A/g and 512 mA h/g at 10 A/g) during sodium storage process. The electrode can still exhibit stable cycling performance at a very high current density (5000 cycles at 20 A/g). The Na-inserted VS₂ (Na_xVS₂) changes the charge distribution of S in polysulfide molecules, altering the Coulomb interaction between S atoms in polysulfide to form repulsion-induced breaking of S–S bond. This altering effect on the atomic Coulomb interaction is essential to promoting the conversion reaction of polysulfides. The above strategy of changing the Coulomb interaction between S atoms not only provides a reference for the design of nanostructures for electrochemical processes with multistep reactions but also inspires angles and ideas for realizing high-performance Na–S batteries. [ABSTRACT FROM AUTHOR]