中低温活化条件下超级电容器用活性炭的制备与表征

Preparation and characterization of activated carbons for supercapacitor under moderate temperature activation condition

以印尼褐煤为原料,KOH为活化剂,在400～580℃的中低温活化条件下制备出超级电容器用煤基活性炭,采用低温N2吸附、X射线衍射(XRD)及扫描电子显微镜(SEM)对其孔结构、微晶结构以及表面形貌等进行表征,并评价了其用作超级电容器电极材料的电化学性能。结果表明:在KOH活化制备煤基活性炭的活化过程中,KOH与煤中C的反应始于400～460℃;随着活化温度的升高,活性炭的比表面积及总孔容增大,孔径分布变宽,中孔率提高。当活化温度达到580℃时,所制活性炭的比表面积高达1 598 m2/g,总孔容达0.828 cm3/g,中孔率达41.4%,该活性炭用作电极材料在3 mol/L KOH电解液中具有良好的充放电性能,在50 mA/g的低电流密度下比电容高达369 F/g,在2 500 mA/g的高电流密度下比电容仍保持305 F/g,其漏电流仅为0.02 mA,且具有良好的循环性能,经1 000次循环后,比电容保持率超过92%,是一种理想的超级电容器电极材料。

Activated carbons were prepared from Indonesia lignite under moderate temperature（400～580 ℃） activation condition with KOH as activation agent.The pore structure,crystallite structure and surface morphology of activated carbons were characterized by hypothermia nitrogen adsorption,X-ray diffraction（XRD）,scanning electron microscope（SEM）.The electrochemical characteristics of supercapacitor with activated carbons as electrodes were evaluated by galvanostatic charge-discharge and cyclic voltammetry.The results show that during the activation process of preparing coal-based activated carbons,the reaction between KOH and C begins from 400 ℃ to 460 ℃.With increasing of activation temperature,the specific surface area and total pore volume of activated carbons increase,the pore size distributions widens and the ratio of mesopore improves.The BET specific surface area,total pore volume and the ratio of mesopore of activated carbons（denoted as AC580） can reach 1 598 m2/g,0.828 cm3/g and 41.4% respectively when the activation temperature is 580 ℃.In 3 mol/L KOH electrolyte,the supercapacitor with AC580 as electrodes has excellent charge-discharge performance,exhibits a high specific capacitance of 369 F/g at a low current density of 50 mA/g and still remains 305 F/g even at a high current density of 2 500 mA/g,its leakage current is only 0.02 mA and has excellent cycling stability,the residual specific capacitance is beyond 92% after 1 000 cycles.The results have demonstrated that the activated carbons AC580 is a perfect electrode materials for supercapacitor.