Free standing flexible graphene oxide plus alpha-MnO2 composite cathodes for Li-Air batteries

Abstract

The most important factor regarding to influence the electrochemical performance of lithium-air battery is to choose an effective catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this study, alpha-MnO2 (manganese oxide) nanowires were used as an active electrocatalyst synthesized by microwave hydrothermal method. Graphene oxide (GO) and alpha-MnO2 nanowires were combined to obtain free standing paper cathodes and alpha-MnO2+ GO free standing paper cathodes were produced with dispersing different amounts of alpha-MnO2 nanowires (10 wt.%, 30 wt.%, 50 wt.%, and 70 wt.%) by using vacuum filtration method. The morphologies and structures of cathodes are evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. The electrochemical tests were carried out at the voltage window between 1.0 and 4.5 V in ECC-Air test cell. alpha-MnO2+ GO composite paper containing 70wt.% alpha-MnO2 catalyst showed the highest specific discharge capacity value of 2900 mAh g(-1). Moreover, the experimental findings showed that dispersing of ce-MnO2 catalyst in GO structure results in remarkable improvement of the electrochemical performance of Li-air battery cathodes. (C) 2015 Elsevier B.V. All rights reserved.