Reconstructing the phase of vanadium oxides enables redox-catalysis manipulated reversible sulfur conversion for stable Zn–S batteries

The naturally sluggish redox kinetics and limited utilization associated with the sulfur conversion in Zn/S electrochemistry hinder its real application. Herein, we report an <i>in situ</i> phase reconstruction strategy that activates the catalytic activity of vanadium oxides for invoking redox-catalysis to manipulate reversible sulfur conversion. It was identified that the V₂O₃@C/S precursor derived from metal organic frameworks could be transformed into V₂O_5-<i>m</i> ·<i>n</i>H₂O@C/S by a facile electrochemical induction process. Vanadium oxides can realize a faster zinc ion storage process than sulfur components during the discharging process, thereby the pre-zincified Zn _<i>x</i> V₂O₅·<i>n</i>H₂O behaves as a redox medium to catalyze the sulfur reduction <i>via</i> a spontaneous reaction (Zn _<i>x</i>+1V₂O₅ + S = Zn _<i>x</i> V₂O₅ + ZnS, △<i>G</i> = -6.4 kJ mol^-1). For the reverse battery recharging, the electrodeposited ZnS around the active sites can be easily activated and the facile Zn²⁺ transport between Zn _<i>x</i> V₂O₅·<i>n</i>H₂O and ZnS enables the reversible conversion of ZnS back to S (Zn _<i>x</i> V₂O₅ + ZnS = Zn _<i>x</i>+1V₂O₅ + S, Δ<i>G</i> = -7.02 kJ mol^-1). Accordingly, the composite cathode delivers a high capacity of 1630.7 mA h g^-1 and maintains stable capacity retention after 150 cycles at 4 A g^-1. The proposed redox catalytic effect sheds light on the tunable Zn-S chemistry.