Unexpected Role of the Interlayer "Dead Zn2+" in Strengthening the Nanostructures of VS2 Cathodes for High‐Performance Aqueous Zn‐Ion Storage.

Layered VS2 holds great potential as a cathode material for aqueous Zn‐ion batteries owing to its large interlayer spacing, high electrical conductivity, and the rich redox chemistry of vanadium. Nevertheless, structural instability during charge/discharge severely hinders the further development of VS2 cathodes. Herein, distinctive hierarchitectures of 1T‐VS2 nanospheres assembled by nanosheets, which feature abundant active sites, superior electron/ion transport property, and robust structure, are developed. More intriguingly, Zn2+ "pillars" residing in VS2 interlayers, achieved by controlling the charge cut‐off voltage are first proven to reinforce the layered structure of VS2 upon repeated Zn2+ insertion/extraction, redefining the commonly perceived "dead Zn2+". Hence, exceptional rate performance (212.9 and 102.1 mA h g−1 at 0.1 and 5 A g−1, respectively) and ultralong cycling life (86.7% capacity retention over 2000 cycles at 2 A g−1) are obtained. The rapid and highly reversible Zn‐ion (de) intercalation behavior within the VS2 nanospheres is verified by first‐principles computations and multiple ex‐situ characterizations. Finally, the flexible quasi‐solid‐state rechargeable Zn battery employing the tailored VS2 cathode demonstrates great application prospects in wearable devices. This work provides new perspectives for prolonging the lifespan of layered Zn‐storage materials by simply modulating the charge/discharge processes. [ABSTRACT FROM AUTHOR]