Electrochemical Performance Of The Electrode Materials Of Transition Metal(Mn,Co,Cu) Oxides Grown On Nickel Foam Obtained Via Hydrothermal Method

Electrochemical capacitors (ECs), a new promising energy accumulator, have attracted people's enormous attention because of the advantages of their long cycle life, rapid charge-discharge, high power densities and green environment protection to some other batteries. As known, active materials in electrodes of ECs have great effects on electrochemical performance and capacity of ECs. Up to now, all of the ECs' electrode materials could be arranged in three classes as follows: carbon materials, metal materials and conducting ploymers. This thesis was focused on the synthesis of the Mn-Co-O and CuxO/Cu(1<x<2) composites via hydrothermal synthesis method and the electrochemical performance of the Mn-Co-O(Mn0.63Co2.37O4) ,Cu4O/Cu (1<x<2)and CuO as ECs' electrode materials, in which the CuO was obtained by the calcination to the CuxO/Cu(l<x<2) composite. The crystal and morphology were characterized by SEM,TEM,XRD,XPS and EDS, and the electrochemical performances were studied by cyclic voltammetry (CV),electrochemical impedance spectrum (EIS), and galvanostatic charge/discharge test.In this thesis, the Mn-Co-O (Mn0.63Co2.37O4) material was synthesized through hydrothermal synthesis method with different initiate atomic ratio of Mn/Co from 10:10 to 10:0. Experimental evidence suggestes the Mn-Co-O (Mn0.63Co2.37O4)material with one-dimensional nanostructure obtained when the initiate atomic ratio of Mn/Co was 10:10 showes good electrochemical performance. The composite electrode shows initial specific capacitance of 580 F/g when the current density was 2.38 A/g, and stable 611 F/g after charge-discharge for 10 times. The capacitance loss is less than 2% after 500 charge-discharge cycles. The results indicate the good electrochemical performance and the excellent stability of the Mn-Co-O(Mn0.63Co2.37O4) material.In this thesis, the CuxO/Cu(1<x<2) composite was prepared via hydrothermal synthesis method with different reaction time from 8 h to 17 h. Experimental evidence demonstrate the CuxO/Cu(1<x<2) composite with cubic structure obtained when the reaction time was 14 h shows satisfactory electrochemical performance. The composite electrode shows a specific capacitance of 610 F/g when the current density was 2.5 A/g, and the capacitance decreased to 520 F/g because of the dissolution of the composite material from the electrode.At last,the CuO material was obtained by the calcination to the CuxO/Cu(1<x<2)composite at different temperatures(200?, 300? and 400?). It was found that the pure CuO was gained when the calcination temperature was 200? and 300?.At the same time,the former sample shows a better electrochemical performance. The specific capacitance was 213 F/g when the current density was 2.13 A/g, and the capacitance decreased to 186 F/g also because of the dissolution of the composite material from the electrode.