Of Mno <sub>, Preparation And Properties Of 2 </ Sub>-based Supercapacitor Electrode Materials,

In this dissertation, Amorphous hydrous MnO₂ were successfully synthesized by chemical co-precipitation reaction between KMnO₄ and Mn(Ac)₂·4H₂O and it's physical properties and electrochemical properties were investigated.The experiment results showed that the optimal pH value was 1.0,the optimal reaction time was 6 hours,the optimal drying temperature was 100℃ and the drying time was 6 hours. Moreover, the crystal structure of the synthesized sample is mainly α -MnO₂ · nH₂O by XRD. SEM result showed that the shape is amorphous spherical material.Electrochemical properties of the resultant were investigated by testing the charge/discharge curves and cyclic voltammetrys of a three electrode system in different electrolyte, in which working electrode was made by the product. We founded that the manganese dioxide electrode has a good electrochemical capacitor performance and high reversibility in the neutral electrolyte. Cyclic voltammetrys showed the electrode has the best capacitor performance in 0.5mol/L Na₂SO₄ solution and -0.2⁰.9V(vs.SCE) potential range and the specific capacitance contains to 160F/g. By 5mA/cm² constant current charge/discharge in 0.5mol/L Na₂SO₄, MnO₂ electrode can provide a discharge specific capacitance of 180.2F/g, charge/discharge efficiency of 95.3%,which is the highest of all the other neutral electrolytes.MnO₂/activated carbon composite electrode materials were also prepared by chemical co-precipitation method. The results show that MnO₂/activated carbon composite electrode materials have better electrochemical kinetic reversibility and ideal capacitor performance than those of α -MnO₂ · nH₂O of activated carbon electrode by CV, alternating current impedance and constant current charge/discharge tests. The specific capacitance of composite electrodes keep constant with increase of active material.The basic capacitance expression of pseudocapacitors is deduced. Based on planar model and porous model, the impedance andcapacitance equations of supercapacitors are obtained.In this dissertation, our creative and innovational research in chemical co-precipitation reaction, neutral electrolyte, MnCVactivated carbon composite electrode materials and so on gives some significative results, we hope that will give some elicitation for the further investigation of supercapacitors, although there are still something needed given more research, such as composite electrode of MnO2N new current collector > new electrolyte.