Layered vanadium oxides with proton and zinc ion insertion for zinc ion batteries

Rechargeable zinc ion battery is considered as a very promising energy storage system due to its high safety, low cost, and environmentally friendliness. Vanadium oxides with high capacity, good rate performance, and excellent cycle life are important cathode materials for zinc ion batteries. Herein, V₁₀O₂₄.12H₂O(VOH) with large interlayer spacing and high valence state is prepared by a facile hydrothermal method and used as the cathode material in zinc ion battery. The Zn/VOH battery delivers a capacity of 327 mAh g⁻¹ at 0.1 A g⁻¹, and exhibit excellent cycling performance with high retention capacity (115 mAh g⁻¹) after 3000 cycles at 1 A g⁻¹. Zinc ion and proton insertion mechanism is proposed by exploring the evolutions of the phase and morphology. Zinc ion and proton insertion mechanism is verified by different zinc salt electrolytes. The reaction kinetics tests of Zn/VOH (galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS)) indicate that the zinc ion insertion process has fast reaction kinetics and the proton insertion process slows down the reaction kinetics. The research of Zn/VOH system expand the cathode material of zinc ion battery and enrich the comprehension of zinc ion battery reaction mechanism.