葱叶一步法裂解制备多孔炭及其电容性能研究（英文）

Porous carbons produced by the pyrolysis of green onion leaves and their capacitive behavior

以葱叶为炭前驱体,在不添加任何活化剂的条件下,炭化活化同时进行,制备了孔径分布主要集中于0.6~1.2nm和3~5nm之间的葱基多孔炭材料,并对其电容性能进行研究。分别采用扫描电子显微镜(SEM)、场发射扫描电子显微镜(FE-SEM)、能量弥散X射线光谱(EDX)、火焰原子吸收光谱(FAAS)、X射线衍射(XRD)、热重分析(TGA)和氮气吸脱附曲线等方法表征了葱基炭的形貌、成分、比表面积及孔径分布等性能;通过循环伏安(CV)、交流阻抗(EIS)、恒流充放电(GCD)等电化学方法考察了材料的比电容和循环寿命等电化学性能。结果表明,葱叶中本身含有的微量矿物质如钙、钾等在其炭化的过程中同时起到了活化的作用。研究了不同温度下(600~800℃)制备的多孔炭的性能,发现800℃条件下制得的样品性能最佳,以微孔为主,介孔辅之,孔径为0.6~1.2 nm的微分孔隙体积达2.608 cm^(-3)/g/nm,3~5 nm的微分孔隙体积有0.144 cm^(-3)g/nm,BET比表面积为551.7 m^2/g,质量比电容为158.6 F/g,有效面积电容可高达28.8μF/cm^2。这表明孔径分布情况对多孔炭的电荷存储能力有很重要的影响,此法也为提高"有效面积电容"提供了思路。

Porous carbons were prepared by the simple carbonization of green onion leaves at temperatures from 600 to 800 ℃ and used as the electrode materials of supercapacitors.SEM,FESEM,EDX,AAS,XRD,TGA and nitrogen adsorption were used to characterize their morphology,pore structure and surface elemental composition.Cyclic voltammetry,electrochemical impedance spectroscopy and galvanostatic charge/discharge were carried out to evaluate their specific capacitance,resistance and cycling life.Results showed that the initial mineral elements present in the leaves such as calcium（Ca） and potassium（K） play an activating role during the carbonization.All samples have a bimodal pore distribution of micropores（mainly 0.6-1.2 nm） and mesopores（mainly 3-5 nm）.The carbon prepared at 800 ℃ had the highest surface area of 551.7 m^2/g,a specific capacitance of 158.6 F/g at 0.2 A/g and an effective areal capacitance of 28.8 μF/cm^2.The effective areal capacitance of the carbon prepared at 800 ℃ is higher than of most porous carbons reported in the literature,which is ascribed to its pore size distribution that favors ion access to its pores.