Chemically assembling chromium vanadate into an urchin-like porous rich matrix with ultrathin nanosheets for rapid Zn²⁺ storage

Aqueous zinc ion battery (AZIB) is a promising battery system developed in recent years, which has the advantages of safety, environmental protection and low price. However, it is still a puzzle to develop and improve cathode materials with satisfactory performance. In this paper, the chromium vanadate (CrVO₃) electrode material was reported for the first time. The obtained CrVO₃ have mesoporous structure (the mesopore sizes: 2-50 nm), excellent conductivity, high surface area (129.3 m² g^-1) and uniform thickness of 2 nm, which provides a short path for rapid transfer of zinc ions, a large surface area for high pseudocapacitance, and sufficient voids to mitigate volume expansion. Given these structural advantages, the CrVO₃ cathode delivers high capacities of 188.8 and 112.8 mAh g^-1 at 0.5 and 4 A g^-1 and excellent long cycle stability, respectively. More importantly, the Zn//CrVO₃ battery provided an energy density of 231.9 Wh kg^-1 at a power density of 100.4 W kg^-1. Meanwhile, insight into the formation mechanism and Zn²⁺ storage mechanism by ex situ methods. The results show that the porous CrVO₃ is a promising cathode material for AZIBs, which provide a valuable idea for the design of porous vanadate with significantly enhanced performances in electrochemical energy storage.