氧化石墨的合成工艺优化及电容特性

Research on synthesis technology optimization and capacitance performance of graphite oxide

采用改良的Hummers法,设计L9(34)正交实验研究了石墨来源、浓硫酸用量、合成温度及95℃控温时间对所合成氧化石墨(GO)特征峰强度的影响。用X射线衍射光谱法(XRD)、激光粒度分析仪及比表面和孔隙度分析仪,对GO晶体结构和粒径分布进行了分析;利用CV和线性极化曲线法研究了GO的电容特性。结果表明,石墨来源、浓硫酸用量和95℃控温时间影响最为显著。当石墨来源为鳞片石墨、浓硫酸用量为58 m L、合成温度为25℃和95℃控温时间为12 h的工艺参数,为最佳合成工艺条件。该工艺下所制备的GO试样层间距为0.73 nm,中值粒径D50为11.02μm,极化电阻仅为0.24Ω。在2 m V/s扫速下,其放电比电容达到234.1 F/g,即使扫速增加到50 m V/s,该电极仍然能放出高达121.5 F/g的比电容结构。

Graphite oxide （GO） was prepared using the modified Hummers approach, and the orthogonal test L9（34） was designed to study the impacts of graphite source, concentrated sulfuric acid amount, synthesis temperature and temperature control ing time at 95℃ on the characteristic peaks intensity of GO. The crystal structure and particle diameter distribution of samples were characterized by XRD, laser particle size analyzer, specific surface area and pore distribution analyzer. The capacitance characteristic of GO was studied by cyclic voltammetry and linear polarization curves. The results show graphite source, concentrated sulfuric acid amount and temperature control ing time at 95 ℃ make the most significant influence on the capacitance characteristic of GO. The optimum reaction conditions are as fol ows： the graphite source is flake graphite; the concentrated sulfuric acid amount is 58 mL; the synthesis temperature is 25℃;the temperature control ing time at 95℃is 12 h. The as-prepared GO powders have the layer distance of 0.73 nm;the mean median grain size 50 is 11.02μm;the polarization resistance is only 0.24Ω. The discharge specific capacitance is 234.1 F/g with the scan rate of 2 mV/s, and 121.5 F/g with the high scan rate of 50 mV/s.