分级多孔纳米炭纤维的结构及电容性能

以酚醛树脂为碳源、PVP为纺丝助剂、纳米MgO颗粒为模板剂,通过静电纺丝法制得酚醛树脂基纳米炭纤维,经过炭化、KOH活化、酸洗后得到分级多孔纳米炭纤维,利用SEM、XRD、XPS、拉曼光谱仪及氮气吸脱附实验,对所制多孔纳米炭纤维的结构和形貌进行表征,并将其作为模拟电容器的电极,利用循环伏安、恒电流充放电及交流阻抗方法测试了材料的电化学性能。结果表明,KOH活化引入了数量可观的微孔,所得纳米炭纤维表现出明显的"微孔-中孔-大孔"分级孔分布的特点,其比表面积达到1058.4m~2/g,总孔容为1.64cm~3/g。电化学测试结果表明,所制分级多孔纳米炭纤维在6mol/L KOH电解液中显示出优异的电容性能,在0.2A/g的电流密度下,其放电比容量达到198F/g,在20A/g电流密度下,电容保持率达到65%。

Structure and capacitive properties of hierarchical porous carbon nanofibers

With phenolic resin as carbon source, PVP as spinning agent and nano-MgO particles as template, the phenolic resin-based carbon nanofiber was prepared by electrospinning. Followed by carbonization, KOH activation and acid pickling processes, the carbon nanofiber with hierarchical porous structure was obtained. By means of SEM, XRD, XPS, Raman spectroscopy and N₂ adsorption-desorption tests, the morphology and structure of the porous carbon nanofibers were characteriezed. Moreover, the cyclic voltammetry, galvanostatic charge-discharge and alternating current impedance methods were adopted to investigate the electrochemical properties of the as-prepared materials used as the simulated capacitor electrodes. The results show that the carbon nanofiber with KOH activation has a larger number of micropores, and exhibits a well-devoloped hierarchical porous structure including micropores, mesopores and macropores with a specific surface area of 1058.4 m²/g and a total pore volume of 1.64 cm³/g. In addition, the results of electrochemical tests indicate that the obtained hierarchical porous carbon nanofiber exhibits a remarkable capacitance perfomance in 6 mol/L KOH electrolyte, its discharge specific capacity reaches 198 F/g at a current density of 0.2 A/g and the capacitance retention rate reaches 65% at a current density of 20 A/g.