Preparation of coal pitch/polyacrylonitrile based activated carbon fiber film and investigation on its electrochemical performance

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.