(A) study on the characterization of the conductive metal oxide nanofibers for electrochemical capacitor

Abstract

Electrochemical energy storage techniques have developed using nanotechnology have attracted much attention due to their high capacity, long term stability, and fast response time for application in portable power sources and hybrid electric vehicles (HEVs). The enhanced performance of nanostructured energy storage is mainly due to the mesoporous architectures, which lend higher surface area as well as shorter diffusion length of ions and electrons. In particular, electrochemical capacitors offer advantages in capability, utilizing a broad range of power vs. energy density. Accordingly, considerable efforts have been focused on the fabrication of nanostructured oxide materials to achieve improved capacitive performance. Among various metal oxides, hydrous ruthenium oxide, i.e. $RuO_2-\It{n}H_2O$, is an active material of interest to researchers due to its excellent proton transport characteristics. The remarkably high specific capacitance of hydrous $RuO_2$ is obtained by virtue of highly reversible redox transitions based on high proton conductivity. However, the high price of Ru, the problem of $RuO_2$ fabrication and low electron transport property of hydrous $RuO_2$ has proved a major drawback for the application of electrochemical capacitors. To overcome these barriers, researches for new materials with low price for electrochemical capacitor and for the suitable structure to achieve fast electron transport keeping the activity with the proton are going on enhanced. In spite of the high capacitance of hydrous $RuO_2$, the relatively low electron transport property of hydrous $RuO_2$ has proved a disadvantage for fast power capability of electrochemical capacitors. I introduce the structure combining conducting nanostructures and hydrous $RuO_2$ coating layers to improve the rate capability of electrochemical capacitors. It has the merits leading to good electron and proton conductivity simultaneously. In this sense, a highly conductive material architec...