Study on Supercapacity properties of manganese dioxide active material by the Cation Concentration Change on the Electrode Surface

摘要

A four-electrode system was developed to measure in-situ the cation concentration change on the supercapacitor electrode surface for the first time during the charge/discharge process. While the MnO_2 electrode was used in a supercapacitor in K_2SO_4 solution, the potassium ion concentration on the electrode surface was reversible change during the charging/discharging process, decreasing with the reduction process and increasing with the oxidation process. It is clearly clarified that the charge storage mechanism of mapganese dioxide, as a supercapacitor active material, involves a fast redox reaction through reversible insertion/desertion of potassium ion and variation of manganese valance.