Anodic Oxidation Strategy toward Structure-Optimized V2O3 Cathode via Electrolyte Regulation for Zn-Ion Storage

Abstract

The lack of suitable cathodes is one of the key reasons that impede the development of aqueous zinc-ion batteries. Because of the inherently unsuitable structure and inferior physicochemical properties, the low-valent V 2 O 3 as Zn 2+ host could not be effectively discharged. Herein, we demonstrate that V 2 O 3 (theoretical capacity up to 715 mAh g –1 ) can be utilized as a high-performance cathode material by an in situ anodic oxidation strategy. Through simultaneously regulating the concentration of the electrolyte and the morphology of the V 2 O 3 sample, the ultraefficient anodic oxidation process of the V 2 O 3 cathode was achieved within the first charging, and the mechanism was also schematically investigated. As expected, the V 2 O 3 cathode with a hierarchical microcuboid structure achieved a nearly two-electron transfer process, enabling a high discharging capacity of 625 mAh g –1 at 0.1 A g –1 (corresponding to a high energy density of 406 Wh kg –1 ) and cycling stability (100% capacity retention after 10 000 cycles). This work not only sheds light on the phase transition process of low-valent V 2 O 3 but also exploits a method toward design of advanced cathode materials.