煤沥青/聚丙烯腈基活性碳纤维无纺布的制备及电化学性能
Preparation of coal pitch/polyacrylonitrile based activated carbon fiber film and investigation on its electrochemical performance
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摘要: 煤沥青碳含量高、缩合芳环含量高、杂质含量低,是制备碳材料的优质碳源。以煤沥青为碳源,聚丙烯腈高分子聚合物为骨架,采用静电纺丝法制备煤沥青/聚丙烯腈基活性碳纤维无纺布,是实现煤沥青高值化和清洁化利用的重要途经之一。以等体积丙酮/二硫化碳混合溶剂萃取煤沥青,获得精制煤沥青萃取物,继而与聚丙烯腈混合制备纺丝溶液,在静电纺丝设备上制备前驱体纤维无纺布。前驱体纤维无纺布经预氧化、炭化和活化处理制备煤沥青/聚丙烯腈基活性碳纤维无纺布。采用高分辨率扫描电子显微镜(SEM)表征了不同质量比的前驱体纤维无纺布、碳纤维无纺布的形貌。前驱体纤维无纺布由连续的长丝所构成,呈现出网状结构,表面平滑,说明煤沥青萃取物和聚丙烯腈表现出良好的融合性和可纺性。采用BET测试分析了不同质量比的活性碳纤维无纺布的比表面积和孔分布特征,其中AC-E65表现出最大的孔容量和比表面积(2 541.8 m2/g)。通过循环伏安测试、恒电流充放电测试和电化学阻抗谱测试研究了煤沥青/聚丙烯腈基活性碳纤维无纺布的电化学性能。煤沥青/聚丙烯腈基活性碳纤维无纺布的双电层电容特性明显,倍率性能和可逆性能优异,循环性能良好,尤其是煤沥青萃取物质量比为70%时,煤沥青/聚丙烯腈基活性碳纤维无纺布表现出优良的电化学性能:电流密度为1 A/g时,比电容可达到186.3 F/g,循环充放电2 000次比电容保留率为95.2%。因此,以聚丙烯腈为纤维骨架,煤沥青为填充基质,结合静电纺丝法能有效实现煤沥青/聚丙烯腈复合碳纤维无纺布的制备,并表现出良好的电化学性能。Abstract: Coal pitch is a high-quality carbon resource for the preparation of carbon materials due to its high carbon content, high condensation aromatic ring content, and low impurity content. It is an effective and important approach to achieve the high value and clean utilization of coal pitch by preparing coal pitch/polyacrylonitrile based activated carbon fiber film using electrospinning method, and coal pitch as carbon source and polyacrylonitrile polymer as skeleton. The coal pitch extract was extracted from coal pitch with isometric acetone/carbon disulfide mixture, and then mixed with polyacrylonitrile to prepare the spinning solution. The precursor fiber film was prepared by electrospinning. Coal pitch/polyacrylonitrile based activated carbon fiber film was prepared by pre-oxidation, carbonization, and activation. The morphology of precursor fiber film and carbon fiber film with different mass ratios were characterized by high resolution scanning electron microscopy(SEM). The precursor fiber film shows continuous fibers, clear network structure and smooth surface, indicating that the coal pitch extract and polyacrylonitrile presents good blending character and spinnability. The specific surface area and pore distribution characteristics of activated carbon fiber film with different mass ratios were analyzed by BET test. The AC-E65 shows the largest pore capacity and specific surface area(2 541.8 m2/g). The electrochemical properties of coal pitch/polyacrylonitrile based activated carbon fiber film were analyzed by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. Coal pitch/polyacrylonitrile based activated carbon fiber film has obvious double layer capacitance characteristics, excellent rate and reversible performance, and good cycling performance. Especially when the mass ratio of coal pitch extract is 70%,the coal pitch/polyacrylonitrile based activated carbon fiber film shows an excellent electrochemical performance. When the current density is 1 A/g, the specific capacitance reaches to 186.3 F/g, and the specific capacitance retention rate is 95.2% for 2 000 cycles. Therefore, the coal pitch/polyacrylonitrile composite carbon fiber film was prepared with good electrochemical performance by electrostatic spinning, using polyacrylonitrile as fiber skeleton and coal pitch extract as filled matter.