Improving Rate Performance of MnO2 Positive Electrode for Fuel Cell/Battery Systems by Blending with Ni(OH)2

Abstract

To improve the discharge rate performance of the positive electrode of fuel cell/battery systems, we fabricated electrodes by blending manganese dioxide with small amounts (5 and 10 wt%) of nickel hydroxide. Electrochemical characterization techniques including galvanostatic and electrochemical impedance spectroscopy measurements determined the discharge rate performance and electrical and reaction resistance of the electrodes. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) measurements were used to observe the crystal structure and morphology of the electrode before and after the electrochemical tests. The experimental results indicate that the positive electrode containing nickel hydroxide had a better discharge rate performance than the pure manganese dioxide electrode. This was because of inhibition of δ-MnO2 formation during charge. XRD analysis confirmed that the formation of δ-MnO2, which is transformed into unreactive Mn3O4 after electrochemical discharging, was inhibited by the presence of nickel hydroxide.