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Separating the faradaic and non-faradaic contributions to the total capacitance for different manganese dioxide phases
journal contributionposted on 2015-01-01, 00:00 authored by Madeleine Dupont, S W Donne
Six different phases of manganese dioxide have been examined to determine the different contributions made by double layer capacitance and pseudo-capacitive redox reactions (or diffusion limited processes) to the total charge storage. These processes were separated using a novel combination of step potential electrochemical spectroscopy (SPECS), in which the electrode is charged and discharged in a series of small (±25 mV) potential steps, combined with modelling of the current response to determine the different charge storage processes occurring at the electrode. The manganese dioxide phases were all cycled in 0.5 M Na2SO4 between 0.0-0.8 V (vs SCE). The results indicate that the different properties of the samples, such as crystal structure, surface area and porosity affect the relative contributions from the each charge storage process.