Reconstructing the phase of vanadium oxides enables redox-catalysis manipulated reversible sulfur conversion for...

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 in situ 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- ·nH₂O@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 V₂O₅·nH₂O behaves as a redox medium to catalyze the sulfur reduction via a spontaneous reaction (Zn V₂O₅ + S = Zn V₂O₅ + ZnS, △G = -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 V₂O₅·nH₂O and ZnS enables the reversible conversion of ZnS back to S (Zn V₂O₅ + ZnS = Zn V₂O₅ + S, ΔG = -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.