Effects Of Oxygen Functional Groups On The Electrochemical Performance Of Activated Carbon Electrode Material

Supercapacitor is a new energy storage device between the traditional capacitor and battery.The electrode materials are the key-factors to determine the electrochemical properties of supercapacitor. The surface functional groups of the electrode material plays a decisive role on its surface properties, and can have a significant impact on their electrochemical behaviors.In this paper, bulk oxygen- enriched carbon / metal oxide composites materials was prepared from the precursor,and as an electrode material electrical properties were also characterized both in inorganic electrolyte electrical system(3M KOH) and organic electrolyte system(1M Et4NBF4/PC) by electrochemical test system.The structural and surface chemical analysis investigated by N2 adsorption, XPS,FTIR and other technical. The influences of different kinds of oxygen-containing functional groups of the activated carbon electrode material on the electrochemical properties were also investigated.The results showed that the oxygen-containing functional groups in different electrolytes have a different effects.The different types of oxygen-containing functional groups on the electrochemical properties play different roles. The impact of oxygen-containing functional groups on the electrochemical properties of the electrode material from three aspects: the specific surface area and pore size distribution; generation of Pseudo capacitance and improvement of surface wettability.Inorganic electrolyte systems, the impact of oxygen-containing functional groups on specific capacitance can be 20%~40%. The hydroxyl and ether were found to improve the wettability of the surface of activated carbon, so that the specific surface area of activated carbon electrode material can be fully utilized; It was also proved that carbonyl and phenolic hydroxyl group can be converted mutually which lead the generation of Pseudo capacitance.Specific capacitance is reduced for that the hydrogen evolution reaction caused by carboxyl groups impedes surface charging process. In organic electrolyte, the impact of oxygen-containing functional groups on specific capacitance can be 17%~42%.The carboxyl groups reduce the leakage current and self-discharge in the organic electrolyte. The quinone and carbonyl were also found to play a positive role, while other oxygen-containing groups play a negative role. It also shows that the oxygen-containing functional groups has a strong complexing ability,It can be utilized so that carbon-based metal oxides composites material can be prepared by further carbonization.