Nanometer Manganese Dioxide Preparation And Applied Research

The precursor of nanostrucured MnO2 was prepared by the method of precipitation. The nanostrucured MnO2 was obtained after the methods of Supercritical Fluid Drying (SCFD) and calcinations. The SCFD method was used, it effectively solved the problem that the particle size was largely affected by the temperature of the drying procedure. Thermogravimeteric and differential thermal analyse,X-ray diffraction, scanning electron microscophy, laser diffraction particle size analyzer were used to characterize the product.Results showed that the optimal reaction temperature was 20 C,the concentration of MnCl2 was 0.1mol-L-1,the pH value was 8.3,the optimal reaction time was 2 hours, the temperature of SCFD was 263 C,the pressure of SCFD was 6.6MPa and optimal calcining temperature was 240 C. Moreover, the crystal structure of the synthesized samples were mainly Y -MnO2 and the average particle size was 60nm. Finally,its electrochemical behaviour .were investigated by constant current diacharge,cyclic voltammerty etc.and compared with that of common particle size sample d (electrolytic manganese dioxide).It was found that the discharge capacity of the synthesized nanostrucured MnO2 was lower than that of sample d,but its electrochemical activity was greatly increased after acid treatment.The results showed the discharge capacity of sample after acid treatment improved 24% at the first discharge step; the favorable performance was more remarkable under the condition of heavy load discharge,its discharge capacity improved 33%(-0.4V) and 110%(-0.9V). Insertion and deinsertion for protons and electrons into nanostrucured MnO2 were easier than electrolytic MnO2. Nanostrucured MnO2 after acid treatment was better than electrolytic MnO2 as the anode material of the Mercury-free alkaline manganese battery.