Construction Of Vanadium-based Compound Nanostructures And Study Of Their Zinc Storage Propertie

With the development of modern technology,large-scale energy storage is crucial to ensuring the reliability of smart grid systems and the integration of renewable intermittent energy sources（e.g.,solar and wind）.Lithium-ion batteries dominate the energy market due to their high energy density and cycle stability,but they still face problems such as low safety,high cost,environmental unfriendliness,and resource shortage.In contrast,aqueous zinc ion batteries have been favored by researchers for their promising applications in energy storage due to their abundant reserves on earth,low cost,and high safety.However,problems such as cathode dissolution,structural collapse,and slow kinetics have hindered their marketable applications.Based on these problems,we synthesized ammonium-intercalated carbon-coated vanadium oxide and oxynitride-rich vanadium cathode materials,and analyzed their zinc storage properties by various electrochemical performance tests and characterization methods.（1）Nanoflower-like vanadium oxide（NHVO/C）consisting of a large number of nanoribbons with uniform distribution was synthesized using a simple and rapid microwave hydrothermal method.It was demonstrated that the introduction of NH₄⁺ions enlarges the layer spacing with fast Zn ion diffusion kinetics and achieves rapid insertion and removal of Zn²⁺;proper high-temperature calcination not only increases the nitrogen content but also improves the stability.Secondly,the carbon coating on the surface of nanoribbons can significantly improve their electrical conductivity.The synthesized NHVO/C obtained up to 73.1%pseudocapacitance storage at a high scan rate of 1.0 mV s^-1,which in turn improved the electrochemical performance.The NHVO/C cathode has a high specific capacity of 458.6 mAh g^-1 at 0.1 Ag^-1 and long-term cycling stability with 90%capacity retention after 2800 cycles at a high current density of 10 Ag^-1.And the energy density of layered NHVO/C was as high as 238.4Wh kg^-1 at a power density of 10.0 k W kg^-1.In addition,the electrochemical reactions of the NHVO/C electrode were investigated by in situ XRD,ex situ Raman spectroscopy,XPS and SEM,revealing the reversible embedding/de-embedding process of Zn²⁺.（2）Oxygen-rich vanadium nitride material（O-VN）was obtained by microwave hydrothermal and high-temperature nitridation.After nitridation,the material changed into a mesh structure connected by irregular nanoparticles,the contact area between the electrode and electrolyte increased,the active sites involved in the reaction increased substantially,and the ion transport rate was enhanced.O-VN as the cathode,Zn foil as the anode,and 3 M Zn（CF₃SO₃）₂ as the electrolyte were assembled into a cell to test the electrochemical performance,and the O-VN//Zn battery obtained a pseudo-capacitance storage of up to 94.9%at a high scan rate of 1.0 mV s^-1 and a specific capacity of 701.2 mAh g^-1 at a current density of 0.1 Ag^-1 and 20.0 Ag^-1 current density with 100%capacity retention after 1000 cycles,demonstrating excellent zinc storage behavior.