Two species redox reaction in sulfur-incorporated magnesium vanadate composite as a cathode for aqueous zinc-ion batteries

Abstract

The vanadium (V)- based materials are treated as potential cathodes for aqueous zinc-ion batteries (ZIBs) owing to their excellent safety feature. Although the layer structure of the V-based cathodes is unstable, it results in drastic capacity decay. Sulfur incorporation of V-based materials is an effective strategy to protect the layer structure as well as boost the redox reaction. Herein, we designed a sulfur-incorporation of magnesium vanadate (MgV2O4) to form the magnesium vanadate and vanadium sulfide (V3S4) composite (i.e., MgV2O4@V3S4) using a microwave-assisted solvothermal method and utilized it as a cathode for aqueous ZIBs. For the comparison, using the same synthesis procedures, the MgV2O4@V2O3sample also prepared without any sulfur incorporation. The MgV2O4@V3S4cathode composite demonstrates excellent electrochemical performance due to the positive valence conversion of sulfur. Impressively, the MgV2O4@V3S4cathode composite obtains a high discharge capacity of 340 mA h g−1over 200 cycles at 500 mA g−1(capacity retention: 93.4 %). The Zn//MgV2O4@V3S4cell exhibits a very impressive energy density of 442 Wh kg−1 at 733 W kg−1, and 2690 W kg−1 at 132.6 Wh kg−1, revealing the good power features. Ex-situ XPS study reveals that the zinc-ion storage mechanism in MgV2O4@V3S4occurs through V4+/V5+and S2−/S4+redox reaction.

Publication Title

Journal of Power Sources

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