石墨烯改性椰壳活性炭复合材料的制备及其电化学性能研究

以椰壳为原料,水蒸气活化法制备了椰壳活性炭(AC),并以乙醇和水作为溶剂,采用水热法将AC与石墨烯(GR)按质量比90∶0、90∶5、90∶54、90∶90和54∶90复合,将制得的复合材料(GAC1~GAC5)作为电极应用于超级电容器。通过氮气吸脱附、X射线衍射(XRD)、扫描电镜(SEM)方法表征了活性炭的孔结构和表面形貌;采用循环伏安(CV)、恒电流充放电(GCD)方法分析比较不同复合比例下超级电容器电极材料的性能。实验结果表明:在炭化温度800℃,活化温度900℃及活化时间1.5 h的条件下制备的椰壳活性炭比表面积为2482 m^2/g,其孔径主要分布在2~4 nm,孔容可达1.33 cm^3/g,在6 mol/L KOH电解液中比电容为85 F/g,石墨烯改性的复合材料GAC-5作为电极材料具有优异的电化学性能,在电流密度1 A/g时比电容可达186 F/g。

Preparation of Graphene Modified Coconut Shell Activated Carbon Composite and Its Electrochemical Performance

Steam activated carbon(AC)was prepared by using coconut shell as raw material,followed by using hydrothermal method and ethanol and water as solvent to prepare capacitance super-capacitor(GAC1-GAC5)with the mass ratios of AC and graphene(GR)90∶0,90∶5,90∶54,90∶90 and 54∶90.By nitrogen adsorption-desorption,XRD and SEM methods,the pore structure and surface morphology of activated carbon were characterized.Comparison of different composite capacitance ratio super-capacitor electrode material was analyzed by cyclic voltammetry(CV),galvanostatic charge-discharge(GCD)method.The experimental results showed that the specific surface area of coconut shell activated carbon was 2482 m^2/g,and its pore diameter was mainly distributed at 2-4 nm,with the pore volume as 1.33 cm^3/g,specific capacitance was 85 F/g in 6 mol/L KOH electrolyte.Under the conditions of carbonization temperature of 800℃,activation temperature of 900℃ and activation time of 1.5 h,the addition of the graphite improved the composite material capacitance up to 186 F/g.