Boosting Zn2+ and NH4+ Storage in Aqueous Media via In-Situ Electrochemical Induced VS2/VOx Heterostructures

Aqueous-ion batteries have received much attention owing to the merits of high safety, low cost, and environmental friendliness. Among potential cathode candidates, transition metal sulfides drew little attention since they suffer from low capacity, low working potential, and fast capacity fading. Here, advantage is taken of the chemical instability of VS2 in aqueous electrolyte to in situ fabricate a heterostructural VS2/VOx material. Benefiting from the internal electric field at heterointerfaces, high conductivity of vanadium sulfide and high chemical stability of vanadium oxides, heterostructural VS2/VOx delivers an enhanced working potential by 0.25 V, superior rate capability with specific capacity of 156 mA h g(-1) at 10 A g(-1), and long-term stability over 3000 cycles as Zn2+ storage electrode. In addition, heterostructural VS2/VOx is employed as the cathode for aqueous NH4+ ion storage with high reversible capacity over 150 mA h g(-1) and long lifespan over 1000 cycles, surpassing the state-of-the-art materials. VS2/VOx is proved to demonstrate a (de)intercalation process for Zn2+ storage, while a conversion reaction accompanied by insertion is responsible for nonmetal NH4+. The strong insight obtained in this study sheds light on a new methodology of exploring the potential of transition metal sulfides-based cathode materials for aqueous ion batteries.

Automated summary

This study demonstrates the excellent electrochemical performance of heterostructural VS2/VOx material in aqueous ion batteries, including enhanced working potential, superior rate capability, and long-term stability.