Impacts of Oxygen Vacancies on Zinc Ion Intercalation in VO₂

Abstract

The aqueous zinc ion battery has emerged as a promising alternative technology for large-scale energy storage due to its low cost, natural abundance, and high safety features. However, the sluggish kinetics stemming from the strong electrostatic interaction of divalent zinc ions in the host crystal structure is one of challenges for highly efficient energy storage. Oxygen vacancies (VO ••), in the present work, lead to a larger tunnel structure along the b axis, which improves the reactive kinetics and enhances Zn-ion storage capability in VO2 (B) cathode. DFT calculations further support that VO •• in VO2 (B) result in a narrower bandgap and lower Zn ion diffusion energy barrier compared to those of pristine VO2 (B). VO ••-rich VO2 (B) achieves a specific capacity of 375 mAh g–1 at a current density of 100 mA g–1 and long-term cyclic stability with retained specific capacity of 175 mAh g–1 at 5 A g–1 over 2000 cycles (85% capacity retention), higher than that of VO2 (B) nanobelts (280 mAh g–1 at 100 mA g–1 and 120 mAh g–1 at 5 A g–1, 65% capacity retention).

Defect Chemistry on Electrode Materials for Electrochemical Energy Storage and Conversion

“…The presence of oxygen vacancy led to a larger tunnel structure along the B‐axis, which is beneficial to improve the reaction kinetics and increase the zinc storage capacity of VO 2 cathode. As show in Figure 6 (A–B), the defective VO 2 cathode electrode showed a specific capacity of 375 mAh g −1 at the current density of 100 mA g −1 for aqueous zinc ion batteries, which had a higher storage capacity compared to the VO 2 cathode without oxygen vacancies [42] . Gu and co‐workers reported a synergistic engineering between carbon and oxygen defects for improving the rapid energy storage of Li‐ions.…”

“…B) Galvanostatic charge/discharge profiles for samples. Reproduced with permission [42] . Copyright 2020, American Chemical Society.…”

Interlayer Doping in Layered Vanadium Oxides for Low‐cost Energy Storage: Sodium‐ion Batteries and Aqueous Zinc‐ion Batteries

“…Generally, the interlayered metal cations pre‐intercalation is always accompanied by the co‐doping of water molecules especially in AZIBs. Similar to the pre‐intercalation of water molecules, the structural water here also acts as an electrostatic shield for Zn 2+ , broadens the diffusion tunnels, and alters the working potential, which can reduce electrostatic bond strength and enhance Zn 2+ intercalation kinetics [9,79,80] . As for the difference in electrochemical performance of ion and molecular pre‐intercalation layers, it is mainly determined by the diversity of intercalated metal ions.…”

“…On the other hand, the unique electronic characteristics endow them with considerable pseudocapacitance behaviour especially in aqueous systems (such as more than 400 mAh g −1 of V 6 O 13 in AZIBs) [7] . Furthermore, most vanadium‐based oxides, including the VO 2 , [8,9] V 2 O 5 , [10] V 3 O 7 , [11] MV 2 O 6 , [12] M 3 V 2 O 8 , [13] etc. with layered structure, could allow interlayered 2D diffusion owing to the open framework [14,15] .…”

2020 Roadmap on Zinc Metal Batteries

“…Li et al. designed oxygen vacancies‐rich VO 2 , which gains a specific capacity of 375 mAh g −1 at 100 mA g −1 and long‐term cyclic stability with 175 mAh g −1 at 5 A g −1 over 2000 cycles (85% capacity retention) [46] . Corresponding DFT calculations show that the cathode has narrower bandgap and lower Zn ion diffusion energy barrier.…”