Simultaneous Analysis of Thin-Film Manganese Dioxide Deposits Using Eqcm, Cyclic Voltammetry, Step Potential Electrochemical Spectroscopy and Electrochemical Impedance Spectroscopy

As a population the reliance on portable electronics and rapid development in electric vehicles in order to combat global warming has caused researchers to search for materials that exhibit excellent energy storage properties. Thin film MnO2 deposits have been observed to exhibit these properties and has become a popular research material for capacitors and batteries. In this project a method was developed in which the mass change for a thin film of MnO2 during electrochemical experiments could be observed. It was conducted by depositing MnO2 onto a platinum quartz crystal, by doing this it allowed for the mass change throughout the deposition process to be recorded providing a better understanding of the deposition mechanism. Once the MnO2 was deposited the EQCM was used as a working electrode throughout further electrochemical testing which included cyclic voltammetry (CV), step potential electrochemical spectroscopy (SPECS), and electrochemical impedance spectroscopy (EIS) while recording the mass change throughout each test. Cyclic voltammetry was conducted with a 25mV sweep from 0 - 0.8V for 250 cycles. By doing this the capacitive performance of the material was determined, however, by recording the mass change throughout the experiment it was possible to determine if there were faradaic, non-faradaic process occurring on the surface of the electrode affecting the charge storage mechanism and to observe sample stability throughout cycling. SPECS and EIS immediately followed the cycling which allowed for the observation of the maximum charge storage capability of the material and the mechanism in which the material stores energy. The impedance data allows for the analysis of the charge transfer mechanism and the various interfacial resistance and capacitance at the electrode-electrolyte interface. This technique has allowed for significantly greater understanding of the processes that the electrode materials are undergoing throughout the experiments and can be used as a powerful tool in various aspects of electrochemical analysis. Figure 1