Highly Durable Na₂V₆O₁₆·1.63H₂O Nanowire Cathode for Aqueous Zinc-Ion Battery

Abstract

Rechargeable aqueous zinc-ion batteries are highly desirable for grid-scale applications due to their low cost and high safety; however, the poor cycling stability hinders their widespread application. Herein, a highly durable zinc-ion battery system with a Na₂V₆O₁₆·1.63H₂O nanowire cathode and an aqueous Zn(CF₃SO₃)₂ electrolyte has been developed. The Na₂V₆O₁₆·1.63H₂O nanowires deliver a high specific capacity of 352 mAh g^-1 at 50 mA g^-1 and exhibit a capacity retention of 90% over 6000 cycles at 5000 mA g^-1, which represents the best cycling performance compared with all previous reports. In contrast, the NaV₃O₈ nanowires maintain only 17% of the initial capacity after 4000 cycles at 5000 mA g^-1. A single-nanowire-based zinc-ion battery is assembled, which reveals the intrinsic Zn²⁺ storage mechanism at nanoscale. The remarkable electrochemical performance especially the long-term cycling stability makes Na₂V₆O₁₆·1.63H₂O a promising cathode for a low-cost and safe aqueous zinc-ion battery.