V4C3 MXene-derived Zn0.99V5O12·nH2O nanoribbons as advanced cathodes for ultra-long life aqueous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (ZIBs) are of great interest due to their low cost, high safety, and eco-friendly nature. Vanadium oxide is a common cathode material for ZIBs owing to its high capacity. However, its unstable structure and slow ion diffusion kinetics result in poor rate capability and cycling reliability. In this study, three vanadium oxide materials (M_xV₅O₁₂, M = Zn²⁺, Co²⁺, and Ni²⁺) with a series of pre-inserted cations derived from V₄C₃ MXene are successfully produced by an easy one-step hydrothermal process. The pre-intercalated Zn²⁺ creates a larger interlayer spacing and promotes ion diffusion in the interlayer channels. Hence, Zn_0.99V₅O₁₂·nH₂O (ZnVO) nanoribbons with a width of about 100 nm and an interlayer spacing of 13.465 Å exhibit the best Zn²⁺ storage capacity, including a high reversible capacity (416 mA h g⁻¹) at 0.1 A g⁻¹, good rate capability (188 mA h g⁻¹) at 10 A g⁻¹, and a low decay ratio of 0.000687% per cycle at 5 A g⁻¹ over 15 000 cycles. Flexible packaging batteries also demonstrate a capacity maintenance rate of up to 96% at 1 A g⁻¹ over 350 cycles, showing practical application value. ZnVO offers excellent performance owing to its low charge transfer resistance (R_ct), high Zn²⁺ diffusion coefficient, high capacitive contribution, and excellent reversible phase transition.