Anion deficiency motivated Na2V6O16 nanobelts for superior sustainable zinc ion storage

Abstract

Owing to the merits of high cost-effectiveness and satisfying eco-efficiency, rechargeable zinc ion batteries (ZIBs) are feasible electrical energy storage systems for improving grid reliability. However, viable cathode materials usually suffer from sluggish kinetics and limited stability. Herein, this article reports a facile recrystallization/reduction strategy to make anion-deficient Na₂V₆O₁₆ nanobelt (denoted as ANVO), in which the coexistence of nanostructure and oxygen vacancy facilitates Zn²⁺ reaction kinetics for a superior high specific capacity of 458 mA h g⁻¹ at 500 mA g⁻¹. DFT calculation demonstrates that the oxygen vacancy can strengthen V–O bonds and narrow the band gap to improve the electrical conductivity. The in-depth analysis of the storage mechanism is also revealed by in situ XRD. The ultra-thin Na₂V₆O₁₆ nanobelts (∼10 nm thickness) harvest prominent long-term reliability and gain favorable zinc storage ability even at a large current density of 10 000 mA g⁻¹ after 5000 cycles, suggesting its great potential for ZIBs. This work not only provides fresh insight into the design of deficiency-modified sodium vanadate cathodes but also broadens the scope for understanding its electrochemical properties and energy-storage mechanism in rechargeable zinc-ion batteries.