Electrochemically Induced Phase Transformation in Vanadium Oxide Boosts Zn-Ion Intercalation

Abstract

Vanadium oxides are excellent cathode materials with large storage capacities for aqueous zinc-ion batteries, but their further development has been hampered by their low electronic conductivity and slow Zn 2+ diffusion. Here, an electrochemically induced phase transformation strategy is proposed to mitigate and overcome these barriers. In situ X-ray diffraction analysis confirms the complete transformation of tunnel-like structural V 6 O 13 into layered V 5 O 12 • 6H 2 O during the initial electrochemical charging process. Theoretical calculations reveal that the phase transformation is crucial to reducing the Zn 2+ migration energy barrier and facilitating fast charge storage kinetics. The calculated band structures indicate that the bandgap of V 5 O 12 •6H 2 O (0.0006 eV) is lower than that of V 6 O 13 (0.5010 eV), which enhanced the excitation of charge carriers to the conduction band, favoring electron transfer in redox reactions. As a result, the transformed V 5 O 12 •6H 2 O delivers a high capacity of 609 mA h g −1 at 0.1 A g −1 , superior rate performance (300 mA h g −1 at 20 A g −1 ), fast-charging capability (<7 min charging for 465 mA h g −1 ), and excellent cycling stability with a reversible capacity of 346 mA h g −1 at 5 A g −1 after 5000 cycles.

Fabrication of a heterovalent dual-cation pre-embedded hydrated vanadium oxide cathode for high-performance zinc ion storage

“…Fortunately, after the initial cycle, the favorable structural reversibility of the KAlVOH cathode material after the charge/discharge processes was observed. Based on the ex situ XRD and XPS results, the overall Zn 2+ storage mechanism can be represented as follows ( x is the number of intercalated Zn 2+ ): 47,57–59…”

Confined Mn Ions Enhance Charge Transport for High-Performance Hydrated Vanadium Oxide Cathode

“…Aqueous rechargeable Zn-ion batteries (AZIBs) are promising candidates for large-scale energy storage owing to their cost-effectiveness, intrinsic safety, and environmental benefits. − However, the strong electrostatic interaction between Zn 2+ and host materials often leads to structural deterioration of the cathode material and sluggish electrochemical kinetics, thereby significantly limiting the electrochemical performance of AZIBs. − Therefore, developing advanced cathode materials that enable stable, rapid, and efficient Zn-ion insertion/extraction is a critical requirement for advancing aqueous zinc battery technologies.…”