炭化温度对酚醛树脂基活性炭孔结构及电化学性能的影响研究

以酚醛树脂为炭前驱体,KOH作活化剂,通过调节炭化温度在相同活化条件下制备了具有不同孔隙结构的活性炭材料.N_2吸附测试表明随着炭化温度降低,活性炭材料比表面积先增大后减小,孔容则不断增大.其中,550℃炭化样品与KOH反应活性最佳,可制得比表面积为2983m~2/g,总孔容为1.58cm~3/g,中孔孔容达到0.59cm~3/g的活性炭材料.采用直流充放电法、交流阻抗法和循环伏安法测定以上述多孔炭为电极材料的双电层电容器的电化学性能,结果表明,PF550活性炭材料电容性能最佳,在有机电解液中100mA/g充放电时,比电容达到160F/g,电流密度增大50倍容量保持率达到82%,显示出良好的功率特性;活性炭材料中存在一定比例的中孔不仅可以改善电极材料的功率特性,而且可以提高微孔的利用率.

Study of carbonization temperature on pore structure and electrochemical properties of phenolic resin-based activated carbon

Activated carbon with distinct pore structure used for electric double layer capacitor ( EDLC) was prepared with resol phenolic resin as raw material and KOH as activator by chemical activation.The specific surface area and pore structure of activated carbon were characterized by nitrogen adsorption isotherm at 77K.The pore volume and mesoporosity of activated carbons increased with decrease of carbonization temperature,while the BET surface area increased firstly and decreased afterwards.The electrochemical behaviors were characterized by means of galvanostatic charging/discharging,cycle voltammetry and impedance spectroscopy.The correlation between electrochemical properties and pore structure was investigated.The results show that PF550 exhibited excellent specific dc capacitance over 160F/g at 100mA/g and the capacitance maintenance achieve 82% at 5000mA/g in organic electrolyte.The high current charge/discharge performance was improved by a reasonable mesoporosity and somewhat wide pore size distribution.