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 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 VO@C/S precursor derived from metal organic frameworks could be transformed into VO ·HO@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 VO·HO behaves as a redox medium to catalyze the sulfur reduction a spontaneous reaction (Zn VO + S = Zn VO + ZnS, △ = -6.4 kJ mol). For the reverse battery recharging, the electrodeposited ZnS around the active sites can be easily activated and the facile Zn transport between Zn VO·HO and ZnS enables the reversible conversion of ZnS back to S (Zn VO + ZnS = Zn VO + S, Δ = -7.02 kJ mol). Accordingly, the composite cathode delivers a high capacity of 1630.7 mA h g and maintains stable capacity retention after 150 cycles at 4 A g. The proposed redox catalytic effect sheds light on the tunable Zn-S chemistry.