活性炭纤维在热处理过程中的结构变化及电化学性能

Structure Changes and Electrochemical Performance of Activated Carbon Fibers during Heat-Treatment

对黏胶基、沥青基和聚丙烯腈基活性炭纤维这3种典型的活性炭纤维进行不同温度的热处理,热处理温度范围700～2 800℃,通过氮气吸附法、X射线衍射、元素分析和电阻率测试等分析方法详细考察了温度对活性炭纤维的孔隙结构、微晶结构、元素组成和电导率的影响,并研究其在无机体系和有机体系下作为超级电容器电极材料时电化学性能的变化。研究结果表明:活性炭纤维在经过热处理后,比表面积随着热处理温度的升高先增大后减小,当温度高于1 200℃时,炭纤维层间距不断减小,微晶尺寸逐渐增大,石墨化度有所提高,电导率逐渐增大,电容性能在一定温度热处理后得到较大提升。

Supercapacitors have been widely studied and applied in hybrid vehicles,new energy generation,aerospace and other fields due to their high power density,high charge/discharge speed,long cycle life and environmental friendliness.Carbon materials have become popular in the field of supercapacitor electrode materials,because of their high conductivity,stable chemical properties and low cost.As a type of microporous carbon,activated carbon fiber (ACF) is a good supercapacitor electrode material because of its large specific surface area,high adsorption rate and concentrated pore size distribution.As most carbon materials,the porous structure and microstructure of ACF will change significantly after heat-treatment,which affects the performance of supercapacitor.At present,there are few studies on the changes of surface structure and properties of ACF during heat-treatment.In this work,three typical ACFs (cellulose,pitch and polyacrylonitrile-based ACFs were treated at different temperatures ranging from 700 ℃ to 2 800 ℃.The effects of temperature on porous structure,micro-structure,elemental composition and conductivity of ACFs were investigated by nitrogen adsorption,X-ray diffraction,elemental analysis and resistivity test.In the meantime,ACFs were used as supercapacitor electrode materials to study the electrochemical performance in inorganic and organic systems.It was shown that after heat-treatment,the BET specific surface area increased first and then decreased with the increase of heat-treatment temperature and the capacitance performance of ACFs showed variations in inorganic and organic systems.