Preparation And Electrochemical Performance Of New Type Supercapacitor Electrode Materials

Electrochemical capacitors, also called supercapacitors, are considered as the potential energy storage devices due to their excellent reversibility, the high power density and the long cycle life, and thus they got extensive investigation in recent years. Electrode materials is the key point as they take a decisive effect on the performance of the supercapacitors. In recent years, people constantly explore ideal electrode materials for supercapacitors, and have obtained some good research results. In this thesis, NiCo2O4/C, NaCo2O4, Na0.71Co0.96O2were synthesized by chemical coprecipitation method and simple solid phase sintering method the simple solid phase method. The structure and the morphology of samples were characterized using the X-ray diffraction (XRD) and the scanning electron microscopy (SEM). The electrochemical performances of samples were investigated by galvanostatic charge/discharge and cyclic vohammetry testing. The research content and the main conclusion listed as below are:(1) NiCo2O4/C nano-particles was prepared by chemical coprecipitation method. The best synthetic material conditions were obtained through the comparison of physical and electrochemical properties electrode materials in different conditions. The specific discharge capacitance of NiCo2O4/C electrode was290.49F/g in the6mol/L KOH solution between0-0.9V at50mA/g current density. It possesses a favourable electrochemical reversibility and excellent super capacitor properties. In addition, it also showes an admirable cycle performance.(2) NaCo2O4nano-particles was prepared via solid phase sintering method with Co3O4and Na2CO3as raw material. The XRD diffraction patterns show the as-prepared NaCo2O4is the single-phase, belonging to P6322space group with hexagonal layer structure. The particle size of as-prepared material is between50-150nm and presents a spherical morphology. The specific discharge capacitance of NaCo2O4was337F/g in the6mol/L NaOH solution between0.15-0.65V at50mA/g current density. It possesses a favourable electrochemical reversibility and excellent super capacitor properties. In addition, it possesses an admirable cycle performance. Therefore NaCo2O4, originally as a thermoelectric material, can be working as a new type supercapacitor material.(3) Na0.71Co0.96O2particles within sub-micron scale was prepared by solid phase sintering method. The results of X-ray diffraction show the synthesized Nao.71Coo0.96O2belongs to hexagonal layer structure. The morphology of Na0.71Co0.96O2by scanning electron microscopy (SEM) was proved to be a spherical particles with a uniform size distribution. The electrochemical performances of Nao.71Co0.96O2possesses a specific discharge capacitance of270.5F/g in6mol/L NaOH solution. Moreover, this supercapacitor shows the very good stability and circulation performance.