Aluminium pre-intercalated orthorhombic V2O5 as high-performance cathode material for aqueous zinc-ion batteries

Highlights: • Al ions are successfully intercalated into the interstitial sites of orthorhombic V₂O₅. • The pre-intercalation of Al³⁺ improves the Zn²⁺ diffusion coefficient of the Al_0.2V₂O₅ electrodes. • The formation of "dead Zn²⁺" is effectively prevented by the pre-intercalation of Al³⁺. • The Al_0.2V₂O₅ sample shows a high capacity, impressive rate capability and excellent cycling stability. Rechargeable aqueous zinc-ion batteries (AZIBs) are emerging as promising candidates for large-scale energy storage systems because of their low cost and high safety. However, the slow migration rate and strong electrostatic repulsion of divalent Zn²⁺ put forward many requirements for the properties of cathode materials. Herein, we present an aluminium pre-intercalated orthorhombic V₂O₅ (Al_0.2V₂O₅) as a new cathode material for AZIBs. The analyses of GITT, ex-situ XRD, TEM and XPS indicate that the Al_0.2V₂O₅ electrode possesses a higher Zn²⁺ diffusion coefficient than V₂O₅. And, the pre-intercalated Al³⁺ can stabilize the crystal structure and prevent Zn²⁺ from being trapped in the lattice. Because of the above advantages, Al_0.2V₂O₅ shows much-enhanced electrochemical performance including a high capacity of 448.4 mA h g⁻¹ at 0.1 A g⁻¹, excellent rate capability of 143.9 mA h g⁻¹ at 10 A g⁻¹ and impressive long-term cycling stability with a capacity retention of 61.4% after 5000 cycles at 5 A g⁻¹. Furthermore, the Al_0.2V₂O₅/Zn battery can provide a high energy density of 327.1 W h kg⁻¹ at 0.1 A g⁻¹ and a high power density of 5491.8 W kg⁻¹ at 10 A g⁻¹, which shows great potential in the applications of large-scale energy storage.