Vanadium pentoxide nanosheets as cathodes for aqueous zinc-ion batteries with high rate capability and long durability

Abstract

Aqueous zinc-ion batteries have been considered as a promising candidate for large-scale energy storage owing to their low-cost, safety and environment friendly. However, the development of high performance cathode materials using for zinc-ion de/intercalation is still a challenge. Herein, we prepared the V2O5·1.6H2O nanosheet with an ultrathin thickness of 2 nm and lateral size up to several micrometers by a simple hydrothermal method. The nanosheet configuration is an impressive microstructure to enhance the ion diffusion kinetics during the electrochemical reactions. As a proof of concept, we built a rechargeable aqueous Zn-V2O5 battery, assembling with the V2O5·1.6H2O nanosheet cathodes, Zn anode and 3 M Zn(CF3SO3)2 electrolyte. Owing to the high percentage of capacitive contribution (86.6% at 1 mV s−1) and rapid diffusion coefficient of Zn2+ in the V2O5·1.6H2O nanosheet cathodes, the aqueous Zn-V2O5 battery delivers a high reversible capacity (426 mAh g−1 at 0.1 A g−1), exceptional rate capability (251 mAh g−1 at 20 A g−1), long-term cycle performance (95% capacity after 5000 cycles at 10 A g−1) and excellent energy/power densities (151 Wh kg−1 energy density at a high power density of 11.9 kW kg−1). These merits make the aqueous Zn-V2O5 battery hold potential for grid storage applications.