超级电容器用新型微晶炭的结构及其电容性能

以热处理后的煤沥青焦为原料,采用KOH活化法制备了具有较小比表面积(＜200m~2/g)的系列微晶炭.采用N_2吸附、X射线衍射(XRD)和X射线光电子能谱(XPS)等手段表征了微晶炭的孔结构、微晶结构以及表面化学性质,研究了微晶炭作为超级电容器电极材料在1 mol/L的四乙基四氟化硼酸铵盐/碳酸丙烯酯电解液体系中的电容性能.结果表明:制得的微晶炭具有大量类石墨微晶和较高的石墨化度,d_(002)(晶面层间距)为0.356～0.666 nm,表面含碳量大于95%;活化6 h后,在4.0 V下微晶炭的质量比电容高达139 F/g.微晶炭的储电行为包括插层电容和双电层电容两部分,其中电活化所造成的插层电容是决定微晶炭最终比电容的主要因素,插层电容主要由电极材料的石墨化度决定.

Structures and Capacitance Characteristics of the Novel Crystallite Carbon for Supercapacitor

Crystallite carbons(CCs)with low BET specific surface area(＜200 m~2/g)have beenprepared by KOH activation from pre-heated coal pitch based cokes.The pore structure,crystallite structure and surface chemistry of CCs were investigated by N_2 adsorption,X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS),respectively.The capacitance performance of CCs as electrode materials for supercapacitors in 1 mol/L tetraethylammonium tetra-fluoroborate/propylene carbonate (Et_4 NBF_4/PC)electrolyte was evaluated.Results reveal that CCs have a large amount of graphite-like crystallites and high graphitization degree.The value of d_(002) is in the range of 0.356 to 0.666 nm and the surface carbon contents are above 95%.When activating time is 6 h,the obtained CCs shows maximum mass capacitance of 139 F/g charging at 4.0 V.The energy storage behaviors are mainly composed of intercalation capacitance and electrochemical double-layer capacitance.The intercalation capacitance initiated by"electrical activation"iS the main part of the whole capacitance and the value iS determined by graphitization degree of the electrode material.