The Preperation And Research Of MnO₂ Cathode For Aqueous Rechargeable Batteries

With the progress of modern science and technology development, more and more equipment need to rely on the power operation in civil and industrial production. In order to meet the modern electronics industry demand for electrical energy storage devices, it is imperative to develop high capacity and long life battery. We got MnO2 nanomaterials by different synthetic methods. We carried out on the material structure and morphology characterization by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the electrochemical performance was measured by cyclic voltammetry (CV), impedance and constant current charge and discharge. The results are as follow:1> Different crystal structure MnO2 was synthesized by controlling the pH and reaction time. The electrochemical performance of MnO2 was tested by constant current charge-discharge and cyclic voltammograms. The a-MnO2, amorphous MnO2 and ε-MnO2 have the similar elecreochemical performance which was got from the structure and motphology analyze. With the Zn2+ embedded in and out of the MnO2, the structure of MnO2 was changed.2、The electrochemical performance of MnO2 was tested in the electrolytes of 1M Li2SO4,2M ZnSO4,1M Li2SO4+0.05M MnSO4 and 1M Li2SO4+2M ZnSO4+0.05M MnSO4. The rectangular cyclic voltammograms curve is the accurate capacitance characteristic which was got in 1M Li2SO4 electrolyte. Both of the cyclic voltammograms tested in 2M ZnSO4 and 1M Li2SO4+2M ZnSO4 got reduction and oxidation peaks. The data proved that the embedding and emerging of Zn2+ was two steps reaction. There was no attenuation in the electrolyte of 1M Li2SO4+2M ZnSO4+0.05M MnSO4. It was found that the Mn2+ can inhibit the change of the MnO2 and prevent structure collapse, which can promote the capacity of MnO2.3、The electrochemical performance of MnO2 was tested in the range of different potential in the electrolyte of 1M Li2SO4+2M ZnSO4+0.05M MnSO4. It was found that the reduction and oxidation peak could be found in the cyclic voltammograms curve only if in the appropriate potential range. The ions of the electrolyte can perform best electrochemical performance in the appropriate potential range.4、The MnO2 was made into electrode with acetylene black and carbon nanotubes respectively as conductive agent in a certain proportion. The two kinds of electrodes were tested. But the MnO2 with carbon nanotubes synthetized through stirring perform higher capacity. That is because the electrode can mix uniformity through stirring.