In-situ electrochemical conversion of vanadium dioxide for enhanced zinc-ion storage with large voltage range

Abstract VO2(B) is a promising cathode candidate for aqueous zinc ion batteries owing to its special tunnel lattice structure. However, the zinc storage mechanisms of VO2(B) are elusive over large voltage range, especially at the high potential. Via combined structure and composition characterizations such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy as well as electrochemical tests, it is demonstrated that VO2(B) goes through a conversion reaction when the potential approaching about 1.5 V during the first charging process. The obtained conversion product Zn3(OH)2V2O7·2H2O shows high zinc ion storage capacity of 330 mA h g−1 at 0.1 A g−1, fast zinc ion diffusion kinetics, and high rate performances (130 mA h g−1 at 10 A g−1). This work provides a novel strategy for the rational design of electrode materials with large voltage range, especially for aqueous multi-valence ion batteries.