Facile preparation of high-performance MnO2/KB air cathode for Zn-air batteries

MnO2 has been demonstrated to be an effective catalyst for Zn-air batteries, but suffers from cripplingly low cell performance due to its limited electrical conductivity. In this work, we report a facile process for preparing the MnO2/C air cathode by directly anchoring the MnO2 onto Ketjen Black (KB) via an in-situ redox reaction. It is demonstrated that a Zn-air battery installed with the proposed MnO2/KB air cathode outperforms that installed with a commercial Pt/C cathode. Specifically, the MnO2/KB cathode presents a more positive ORR onset potential and a larger current density compared with that of the Pt/C cathode. Under ambient air, the prepared MnO2/KB air cathode allows the battery to reach a peak power density of 133.17 mW cm(-2) when operated at a current density of 188.51 mA cm(-2), which is among the highest values in the literature. More impressively, the battery installed with the proposed cathode can be operated at a high current density of up to 100 mA cm(-2) with a voltage discharge plateau larger than 1.0V. These results indicate that the MnO2/KB electrode offers a promising option for both alkaline fuel cells and metal-air batteries. (C) 2016 Elsevier Ltd. All rights reserved.