Preparation Of Nanocomposite Electrode Based On TiO₂ Nanotube Arrays And Its Capacitive Performance Research

Supercapacitors have the characteristics of high power density,high specific capacity,short charging and discharging time,good cycle stability and so on.It has great development potential in the national defense,manned spaceflight,information technology,instrument manufacturing and other industries.However,the low energy density is the main problem of supercapacitors.Electrode is one of the most important components of supercapacitors,which plays a decisive role in the storage performance.The main methods to improve the electrical properties of the electrode are the use of nano electrodes with large surface area and the synthesis of composite electrodes with different active materials.In this paper,we studied the growth conditions of TiO₂ nanotubes and explored the best experimental parameters for the deposition of NiO in nanotubes.Finally,the high performance composite electrode was prepared by enhancing the conductivity of Ti O₂ nanotubes,the characteristics of the double layer capacitance and adjusting the microstructure of nanomaterials.Firstly,the original TiO₂ nanotube electrode was fabricated by anodic oxidation technique.The morphology and crystal type of the original TiO₂ electrode were characterized,and the effect of the roughness of titanium surface and the amount of water in the solution on the growth of the tube arrays were also investigated.The reaction mechanism and the measurement results are explained reasonably by recording and analyzing the current-time curves during the reaction process.The electrochemical test results show that the original TiO₂ array electrode has the characteristics of double electric layer,but its electrical properties are poor,its areal capacitance is 0.6mF/cm2 at a current density of 0.08mA/cm2.Secondly,the nickel oxide was deposited into the tubular structure to make the NiO/TiO₂ composite materials by chemical bath and pulse deposition.The differences between the two methods were compared and analyzed,we can obtain the best morphology and performance of the nanocomposite electrode for the preparation of high performance electrode by optimizing the experimental parameters.Scanning electron microscopy was used to observe the microstructure of the composites.The data tested show that the NiO particles on the nanocomposite electrode prepared by the electrochemical deposition method at the pulse voltage of 200 mV were small and uniform,the performance of the nanocomposite electrode is the best and its average areal capacitance is 90 mF/cm2 at a current density of 0.5 mA/cm2.Finally,an electrochemical hydrogen doping method was used to improve the conductivity and capacitance characteristics of the original TiO₂ electrode in order to prepare the high performance TiO₂@NiO composite electrode material.The morphology of hydrogen doped electrode material?H-Ti O₂?has no big changes.The results show that the hydrogen doping method not only improves the conductivity of the original TiO₂ electrode,but also improves the electric double layer characteristics greatly.The H-TiO₂ electrode delivers an average areal capacitance of 71mF/cm2 at a current density of 0.5mA/cm2,¹00 times more than the pristine TiO₂ nanotube electrodes.The TiO₂@NiO composite electrode material was synthesized by depositing nickel oxide in the tubular structure of H-TiO₂ electrode material with the best experimental parameters.The new TiO₂@NiO electrode was observed and tested by SEM,XRD,EDS and electrochemical workstation.The results show that TiO₂@NiO nanostructure has obtained excellent electrical properties and exhibits a very high average specific capacitance of 285mF/cm2 at a current density of 10mA/cm2.