Paper Title
Synthesis And Characterization Of -Mno2/Carbon Black Air Cathodes For Zinc-Air Batteries

Abstract
In spite of the worse electric conductivity, manganese dioxide possesses the excellent catalytic ability for the oxygen reduction reaction (ORR). To improve the electric conductivity, manganese dioxide in the  phase (denoted as -MnO2) anchored onto carbon black powders (XC-72) has been synthesized by a reflux method. Although the specific surface area and electric conductivity of the XC-72/-MnO2 composites are generally enhanced by increasing the XC-72 content, a too high XC-72 content induces phase transformation from -MnO2 to MnOOH which shows a worse ORR catalytic activity than -MnO2. The air cathodes have been optimized toward the highest ORR catalytic ability at the XC-72/-MnO2 mass ratio equal to 1 determined by the thermogravity analysis. A Zn-air battery consisting of the best air cathode shows excellent quasi-steady-state full-cell discharge voltages (1.353 and 1.178 V at 2 and 20 mA cm2, respectively) and high discharge peak power density (67.51 mW cm2). The power density is equal to 47.22 mW cm2 and the specific capacity is more than 750 mAh g1 (Zn) when this cell is operated at 1 V by using this optimized cathode under the air atmosphere.