Organic molecular intercalation regulated hydrated vanadate cathodes with improved electrochemical properties and fast kinetics for aqueous zinc-ion batteries

Abstract

Due to the large hydrated zinc ion radius resulting from the stable solvation structure with six water molecules in electrolyte, the interlayer spacing of most vanadium-based materials fails to meet the requirements for efficient insertion and extraction of Zn2+. Therefore, it is crucial to optimize and reconstruct the VO layer structure in order to achieve rapid and stable zinc storage. In this paper, composites of phenylalanine methyl ester (PM) inserted hydrated V2O5 (PMVO) are prepared using a one-step hydrothermal method. With the increase of PM insertion, the electrochemical properties initially exhibit enhancement followed by subsequent decline. Notably, PMVO-1.6 presents exceptional electrochemical performance, including a high capacity of 464 mAh g−1 at 0.1 A g−1, excellent rate capability with 220 mAh g−1 at 7 A g−1, and superior cycling stability with 97.5 % capacity retention after 1000 cycles at 4 A g−1. The incorporation of PM not only serves as stable structural pillars, but also reduces the solubilization of vanadium, facilitates the diffusion kinetics of hydrated zinc ions, and enhances the surface pseudo-capacitance effect.