Ultrastable and High-Performance Zn/VO₂ Battery Based on a Reversible Single-Phase Reaction

Abstract

The aqueous zinc ion batteries (ZIBs) composed of inexpensive zinc anode and nontoxic aqueous electrolyte are attractive candidates for large-scale energy storage applications. However, their development is limited by cathode materials, which often deliver inferior rate capability and restricted cycle life. Herein, the VO 2 nanorods show significant electrochemical performance when used as an intercalation cathode for aqueous ZIBs. Specifically, the VO 2 nanorods display high initial capacity of 325.6 mAh g −1 at 0.05 A g −1 , good rate capability, and excellent cycling stability of 5000 cycles at 3.0 A g −1 . Furthermore, the VO 2 unit cell expands in a, b, and c directions sequentially during the discharge process and contracts back reversibly during the charge process, and the zinc storage mechanism is revealed to be a highly reversible single-phase reaction by operando techniques and corresponding qualitative analyses. Our work not only opens a new door to the practical application of VO 2 in ZIB systems but also broadens the horizon in understanding the electrochemical behavior of rechargeable ZIBs.

Vanadium‐Based Nanomaterials: A Promising Family for Emerging Metal‐Ion Batteries

“…Recently, Ding et al reported a Zn/VO 2 aqueous battery and obtained a high reversible capacity of 357 mAh g −1 at 0.25 C and 171 mAh g −1 at 300 C. Based on the kinetics analyses and in situ XRD characterizations, it was demonstrated that VO 2 shows abundant tunnel transport pathways with slight structural change upon Zn 2+ intercalation, which triggers the intercalation pseudocapacitance behavior of VO 2 for Zn 2+ storage and thus results in the observed excellent rate capability. Soon after that, Chen et al also reported the superior cycling and rate performance of Zn/VO 2 batteries. Besides, the reversible single‐phase reaction with a more detailed lattice parameters variation during Zn 2+ insertion/extraction was revealed.…”

Recent Advances and Prospects of Cathode Materials for Rechargeable Aqueous Zinc‐Ion Batteries

“…The metastable VO 2 (B) stand out from various phases of vanadium dioxide (VO 2 ), owing to its distinct layered structure formed by edge‐sharing [VO 6 ] octahedra, which can support the de‐intercalation/intercalation of zinc ions guest ( Figure a). Monoclinic structure VO 2 (B) has been reported by several workers in the last two years . Wei et al used the VO 2 nanobelts as AZIBs cathode materials, which displayed a high capacity (274 mAh g −1 at 0.1 A g −1 ) , a specific energy density (271.8 Wh kg −1 ), and an outstanding cycling stability (79% capacity retention over 10 000 cycles at 10 A g −1 ) as shown in Figure b.…”

“…However, the reported works about vanadium oxides were just focused on the V 2 O 5 for AZIBs, which delivered limited cycle numbers and fleetly fading capacity. Until recent years, many kinds of vanadium oxides have been appropriated as prospective cathode materials for AZIBs …”

“…However, the specific zinc‐ion diffusion processes of the VO 2 (B)//Zn battery are still unclear. Recently, the highly reversible single‐phase reaction mechanism of VO 2 nanorods for AZIBs has been revealed by in situ monitoring and corresponding quantitative analysis . The lattice parameters ( a, b, c and cell volume) expand/shrink simultaneously, and feature three steps during discharge and charge processes (Figure c,d).…”

“…d) Most significant changes of lattice parameter ( a, b, c axis and cell volume) in each stage. c,d) Reproduced with permission . Copyright 2018, American Chemical Society.…”