Preparation And Electrochemical Properties Of Nano Electrode Materials For Supercapacitors

Supercapacitors are novel charge-storage devices of high power energy density, which exhibit excellent reversibility and a long cycle life. Based on the above, supercapacitors have attracted much attention throughout the world. The research on supercapacitors is mainly focused on the preparation of high capability electrode material and electrode. Selecting multi-wall carbon nanotubes and manganese oxide with low cost and greater environmental compatibility as electrode materials for supercapacitors, this paper has investigated the material preparation, craftwork optimization, electrode preparation and capacitive property by means of various electrochemical testing methods and material characterization instrument, the main results are as follows:1. For the first time, a novel Sunflower-like Manganese Oxide Three-Dimensional Nanostructures is synthesized and characterized.α-MnO2,γ-MnO2 andβ-MnO2 of different shapes are also synthesized by hydrothermal treatment. It indicates that shapes ofβ-MnO2 are mainly influenced by the reactant concentration. Using cyclic voltammogram and constant current charge/discharge methods, capacitive characteristics of three crystalline MnO2 (α,β,γ) and the effects of crystal shapes on capacitive characteristics ofβ-MnO2 are investigated. The results show that lamellar crystallineβ-MnO2 is obtained from 3% Mn(NO3)2 solution, which exhibits typical double-layer capacitive behavior and largest specific capacitance of 78.9F/g in 1mol/L Na2SO4 electrolyte at 20mA; howeverβ-MnO2 nanorods with high degree of crystallinity are got from 9% Mn(NO3)2 solution, which has the smallest specific capacitance of 36.8F/g.2. Amorphous MnO2 nano-articles are prepared from optimized liquid chemical reaction at normal temperature and pressure, which exhibits ideal capacitive characteristics in the wide range of -0.8-0.8V with small impedance of 7.5? at scan rate of 5mV/s. the capacitive property of nano sized MnO2 from liquid chemical, hydrothermal and solid-state reaction is studied, which is indicated that from liquid chemical reaction exhibits better capacitive property than the latter.3. The vacuum treatment has been used firstly for the preparation of MWCNTs/MnO2 composite electrode material for supercapacitors. The specific capacitance of the composite electrode as high as 516F/g is achieved in 1mol/L Na2SO4 electrolyte at 50mA, which is more higher than that of 135 F/g by unvacuum treatment. Moreover the as-prepared MWCNTs/MnO2 composite electrode still keeps excellent capacitive property after 100 cycles.