Preparation Of Transition Metal Molybdates Based On Metal-organic Compound Precursors And Their Application In Supercapacitors

Energy storage is one of the major challenges in the 21st century and supercapacitors have emerged as an important device in the exploring new energy storage solutions.S upercapacitors have the characteristics such as high power density,fast charge and discharge and long cycle life,which make them a promising energy storage device.Electrode material is the most critical part in determining the performance of supercapacitors,which can affect the specific capacitance,and thus the energy density and power density of supercapacitors.Among metal oxides,transition metal molybdates have many advantages,such as excellent electrochemical performance,low cost,environmental friendliness and abundant resources.However,it remains a great challenge to synthesize them by a simple,environmentally friendly and reliable method.In this thesis,we expect to prepare transition metal molybdates with good electrochemical performance via a simple solvothermal route.The main contents are as follows:(1)NiMoO₄ compound was successfully synthesized by simple solvothermal method and high temperature annealing,and the electrochemical performance of the synthesized NiMoO₄ was tested by constructing the electrodes for supercapacitors.A maximum specific capacity of 95 C g-1 was achieved at a current density of 0.5 A g-1.At a current density of 1 A g-1,the initial specific capacity of the electrode can still reach 83.15%after 3000 cycles of galvanostatic charge-discharge test.The electrodes were assembled into an asymmetric supercapacitor device,NiMoO₄//AC,and the maximum energy density and power density were 16.85 Wh kg-1 and 383.92 W kg-1,respectively.(2)CoMoO₄ compound was successfully prepared by simple solvothermal method and high temperature annealing,which was used as the electrode material of supercapacitor.At a current density of 0.5 A g-1,the maximum specific capacity is 71.7 C g-1.The asymmetric supercapacitor CoMoO₄//AC was assembled with CoMoO₄ electrode.The maximum energy density and power density of the device were 20.99 Wh kg-1 and 5715 W kg-1,respectively.(3)MnMoO₄ compound was also successfully fabricated by simple solvothermal method and high-temperature annealing,which could be effecrtively applied in the electrode of supercapacitors.The maximum specific capacity of it could reach 74.6 C g-1 at 0.5 A g-l.The asymmetric supercapacitor MnMoO₄//AC was further assembled with MnMoO₄ electrode.The maximum energy density and power density of the device were 21.43 Wh kg-1 and 7750 W kg-1,respectively.