Faradaic and non-faradaic contributions to the power and energy characteristics of electrolytic manganese dioxide for electrochemical capacitors

Step potential electrochemical spectroscopy (SPECS) has been applied to a range of different electrolytic manganese dioxide (EMD) samples to examine the changes in the charge storage mechanism as a function of the scan rate. The SPECS method allowed the charge storage contributions due to double layer and pseudo-capacitance to be decoupled. The charge storage mechanism has been shown to transition from predominantly pseudo-capacitive behavior to predominantly double layer behavior as the scan rate is increased. The relative contributions from each of these processes to the overall specific energy and power of each EMD samples has been analyzed and related to the properties of each material.