Electrodeposition of Nanoscale Manganese Oxide for Electrochemical Energy Storage Devices
In this work, nickel foam is coated with high surface area manganese oxide through a simple anodic electrodeposition procedure. Nickel foam is an excellent substrate for many energy storage devices because in addition to nickel’s good conductivity, the porosity of the foam increases surface area and also facilitates fluid flow through the substrate. The latter is important for applications where manganese oxide is being used as a catalyst.
The electrolyte used for deposition of manganese oxide contains manganese acetate, ammonium acetate and dimethyl sulfoxide. By varying deposition and post deposition annealing conditions, different microstructures are obtained. The microstructure, crystallography and chemical state of the manganese oxide deposits are characterized through scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). XPS analysis has been used to determine that manganese oxide is in the form of MnO2. Preliminary XRD and TEM results indicate that the deposits obtained in this work are nanocrystalline with grains less than 20 nm in size.
Electrochemical tests such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are used to determine performance (e.g., capacitance and cyclability) and to optimize the morphology and structure of the manganese oxide deposits. Preliminary CV measurements suggest that the manganese oxide deposits on nickel foam exhibit good areal and specific capacitance.