Simultaneous Analysis of Thin-Film MnO2 Deposits Using Cyclic Voltammetry (CV), Step Potential Electrochemical Spectroscopy (SPECS), Electrochemical Quartz Crystal Microbalance (EQCM) and Electrochemical Impedance Spectroscopy (EIS)

Wednesday, 4 October 2017: 11:00
Chesapeake 6 (Gaylord National Resort and Convention Center)
H. Cameron and S. W. Donne (University of Newcastle)
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 manganese dioxide deposits have been observed to exhibit excellent behaviour and have become a popular research material for electrochemical capacitors and batteries.

In this project a method was developed in which the mass change for a thin film of manganese dioxide during electrochemical experiments could be observed. Manganese dioxide was electrodeposited onto a platinum EQCM electrode allowing for the mass change throughout the deposition process to be recorded providing a better understanding of the electrodeposition mechanism. Once the manganese dioxide was prepared 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 25 mV/s sweep in 0.5 M K2SO4 from 0-0.8V vs SCE for 250 cycles. By doing this the capacitive performance of the material was determined, and 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 charge. 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 combination of techniques 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.