고용량 활성탄소 제조와 전기이중층 커패시터의 전기화학적 특성

Abstract

Apparently non-porous activated carbon with a specific surface area less than 100 m²/g(BET) prepared from calcined carbon of petroleum coke is studied as the polarized electrode for an electric double layer capacitor (EDLC). The non-porous carbon makes negligibly small electric double layer when it is dipped into an electrolyte solution in the beginning. During the initial charging process, however, "solvent co-intercalation of ions" builds double layers in the positive and the negative electrodes, and during the discharging process, the excess ions go out. while the opposite ions come in, to maintain the double layers electrically neutral. This experimentals with a brief historic outline of the developments in graphite intercalation compounds(GICs) and their predominant application in the field of electrochemical energy system. The structural outline of ideal GICs and real irreversible transformations during intercalation/de-intercalation cycles is considered in detail. After that, the electrodes behave like conventional activated porous carbon electrodes with an extra high dense capacitance. The observed phenomenon is discussed from the viewpoints of the inter-layer distance in graphite-like structure of graphizable carbon, the amount of NaClO₃(sodium chlorate) of oxidizing agent of the process formation GICs, the molecular volume of solvent for electrolyte, the residual functional groups such as active oxidized hydrogen observed by FT-IR or elemental analysis(EA), and of the elimination method for the residual active oxidized hydrogen by heat treatment in vaccum furnance, as well as the preparation method for source carbon. And pore distribution were compared after composite GICs and charging/discharge process by nitrogen gas adsorption. At result from that experimental, we conclusion mechanism of conformation electric double layer(EDL) is d002 distance of graphitizable carbon is few far than nature graphite. and oxidizer formed oxide functional group between graphene layer with bring about falling crystallity. high capacitance activated carbon with oxidizing method has higher specific capacitance about 2times for F/ml than EDLC fabricated porous activated carbon.