Characterization of Manganese Oxide Bi-Functional Catalyst for Study of Cathode-Electrode Materials in Zinc-Air Batteries

Zinc-air batteries are metal-air batteries that utilize zinc and a bi-functional oxygen catalyst to catalyze oxygen-reduction and oxygen-evolution reactions.  Zinc-air batteries are a suitable replacement to lithium-ion batteries as they have shown significantly higher energy densities in addition to being made from cheaper, more abundant materials.  The performance of zinc-air batteries has been shown to be affected by the type of catalyst, loading of catalysts, types of binders used, the weight percentage of those binders, and hydroxide concentrations within the cell.  A common issue in zinc-air batteries is the passivation of the zinc electrode.  A symmetric air electrode cell removes this issue and allows us to study cathode-electrode materials without interference of the zinc-electrode.  In this configuration, both the cathode and the anode are identical.  MnO_x catalysts were synthesized and characterized with x-ray diffraction (XRD), scanning electron microscopy (SEM), and rotating disc electrode voltammetry (RDE).  An experiment was run where MnO_x mixed with a polytetrafluoroethylene (PTFE) binder was spray painted onto gas diffusion layers and placed in a symmetric-fuel cell.  The symmetric cell was characterized with polarization curves and cycling.  Different MnO_x loadings, PTFE weight percentages, and hydroxide concentrations were tested using this method.