Hybrid ternary co-intercalation in the interlayer of a vanadium oxide cathode enables high-capacity and stable zinc ion batteries†

Abstract

Aqueous rechargeable zinc ion batteries (ARZIBs) are highly suitable for grid-scale energy storage because of their high safety, low cost, and environmental friendliness. However, developing high-capacity and stable cathode materials for their wide applications is still a significant challenge. Herein, Na_x(NH₄)_2−xV₁₀O₂₅·8H₂O (NNVO), a novel hybrid ternary co-intercalation vanadium oxide cathode, has been prepared by a facile sequential hydrothermal method. The interlayer space of NNVO can be expanded by H₂O, NH₄⁺, and Na⁺ embedding, promoting a collaborative increase in Zn²⁺ storage active sites, lattice structure stability, and Zn²⁺ migration ability. Hence, NNVO displays a near-theoretical capacity of 481.2 mA h g⁻¹ at 0.1 A g⁻¹ and it can still be maintained at about 50% (239.5 mA h g⁻¹) when the current density is increased by 50 times. Meanwhile, NNVO displays a meagre attenuation rate of 0.02% per cycle during 500 cycles at 0.2 A g⁻¹, indicating high low-current cycle stability. Meanwhile, the assembled pouch battery exhibits a long cycle life of 2000 times and excellent capacity retention of 95% at 2.0 A g⁻¹, displaying valuable practical potential. This work highlights a promising NNVO cathode for high-capacity and highly stable ARZIBs, and provides a serviceable co-intercalation strategy and method to improve capacity and stability for interlayer-adjustable cathode materials.