In Situ Electrochemically Transforming VN/V2O3 Heterostructure to Highly Reversible V2NO for Excellent Zinc Ion Storage

Achieving aqueous zinc-ion batteries (AZIBs) with high capacity and long lifetime remains challenging because the intense charge repulsion of multivalent ions causes structural instability and sluggish kinetics. The electrochemical activity brought by in situ structure optimization has dramatically improved the electrochemical performance. Hereinto, the nanocomposites consisting of VN/V2O3 heterostructure composited with carbon (VN/V2O3@C) by a self-template strategy are synthesized. The VN/V2O3 heterostructure undergoes an in situ electrochemical activation phase transition to highly reversible V2NO after the first cycle. The interface of V2O3 and VN induces ion displacement polarization under the action of the applied electric field, making it easier for oxygen and nitrogen atoms to dope into the crystal structure of VN and V2O3, contributing to V2NO phase formation. Furthermore, theory calculations demonstrate that V2NO can provide favorable adsorption for reversible Zn2+ storage. The V2NO@C electrode thus delivers high reversible capacities of 490.2 mAh g(-1) after 310 cycles at 200 mA g(-1) and impressive long-cycle stability over 6000 cycles at 10 A g(-1). Herein, it sheds new light on the mechanism of in situ electrochemical phase transition from heterostructures into one phase, which is a great revolution in designing cathode materials for AZIBs.