Preparation And Modification Of Carbon-based Supercapacitor Electrodes And Materials

Supercapacitors are widely used in household appliances,industrial facilities,military and other fields as a new type of energy storage device.Activated carbon is widely used as supercapacitor electrode material because of its wide source,low price,mature production and preparation technology.In this paper,in order to prepare excellent electrode materials and improve electrode performance,the effects of rapid cooling method on the specific surface area,pore size,surface functional groups and electrode properties of activated carbon under different process parameters were investigated by the orthogonal experiment.In addition,the preparation and characterization of phosphoric acid modified activated carbon electrode were studied.The structure and surface properties of activated carbon and activated carbon electrodes were characterized by scanning electron microscopy,low temperature nitrogen adsorption,Boehm titration,X-ray photoelectron spectroscopy and contact angle measurement.The electrochemical properties of activated carbon electrodes were investigated by cyclic voltammetry,galvanostatic charge-discharge method and electrochemical impedance spectroscopy.The results showed that in low activation temperature(500?),the rapid cooling method could improve the specific surface area and expand the aperture of activated carbons.Compared with the activated carbon obtained by slow cooling,the specific surface area of the activated carbon obtained by rapid cooling increased from 1081m~2/g to 1559 m~2/g,and the pore size increased from 2.64 nm to 3.05 nm,the specific capacitance reached 160 F/g and had good rate characteristics.Through phosphoric acid modification to the activated carbon electrode,the content of oxygen-containing functional groups on the modified activated carbon electrode surface raised nearly three times,resulting in a decrease of the surface contact angle from 130°to 90.5°,improving the wettability greatly.Meanwhile,the specific capacitance of the electrode increased by 35%,reaching 249 F/g.The capacitor retention rate reached 97%with great stability and reversibility after 10000charge/discharge at 4 A/g current density,showing excellent application prospects.