Rechargeable zinc-ion batteries with aqueous electrolytes could be a safe, low-cost, and environmentally friendly alternative to other commercially available batteries. However, there is a lack of suitable cathode materials with high rate capabilities.

Shubin Yang, Beihang University, Beijing, China, and colleagues have found that vanadium dioxide nanofibers in the VO₂ (B) phase can intercalate Zn²⁺ ions with ultrafast kinetics and, thus, can act as the cathode material with a very high rate capability for zinc-ion batteries. The team synthesized VO₂ (B) nanofibers using a hydrothermal approach and used them in a zinc-ion battery with an aqueous Zn(CF₃SO₃)₂ electrolyte.

The vanadium dioxide phase used is composed of distorted VO₆ octahedra which form tunnel-like frameworks (pictured). These tunnels offer pathways for the fast transport of Zn²⁺ ions, with little structural change on Zn²⁺ intercalation. Thus, VO₂ (B) nanofibers exhibit a high reversible capacity of 357 mAh g⁻¹, a high rate capability of 171 mAh g−1 at 300 C, and high energy- and power densities for zinc-ion storage.

• Ultrafast Zn²⁺ Intercalation and Deintercalation in Vanadium Dioxide,
  Junwei Ding, Zhiguo Du, Linqing Gu, Bin Li, Lizhen Wang, Shiwen Wang, Yongji Gong, Shubin Yang,
  Adv. Mater. 2018.
  https://doi.org/10.1002/adma.201800762