【作者】 杜嬛；

【导师】 王成扬；

【作者基本信息】 天津大学 ， 化学工艺， 2009， 博士

【摘要】 超级电容器是一种介于传统电容器和电池之间的新型储能器件,它具有比传统电容器更高的比能量,比电池更高的比功率。电极材料是决定超级电容器性能的关键因素,因此相关的研究工作一直是该领域的研究热点。本论文系统地研究了植物基多孔活性炭的制备、表面改性及其作为炭基双电层电容器电极材料的电化学性能。首次研究了用微波法自制的纳米氧化铁与植物基活性炭组成的非对称超级电容器的电化学性能。综合运用扫描电镜(SEM)、X射线衍射(XRD)、低温氮气吸附、傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)等技术手段对活性炭材料和纳米氧化铁颗粒的结构及表面性质进行分析表征,通过恒流充放电、循环伏安、交流阻抗等方法研究了活性炭材料和氧化铁材料的电化学性能。探讨了电极材料的结构及表面性质对其电化学性能的影响。主要研究结果如下:首次以苎麻纤维为原料,采用ZnCl2一步活化法在短时间、低温条件下制备出具有高比表面积、高收率的微孔型活性炭纤维材料。系统考察了ZnCl2/原料纤维浸渍比、活化温度和活化时间对苎麻基活性炭纤维结构、表面性质及电容性能的影响。在最优工艺条件下制备的苎麻基活性炭纤维具有超过1600 m2/g的比表面积,孔径集中分布在0.5~2 nm,其在30wt.% KOH水溶液中具有高达253 F/g的放电比电容、良好的功率性能和循环性能。以椰壳、杏壳基活性炭为原料,采用浓硝酸对活性炭进行表面氧化改性。研究表明氧化处理后活性炭的比表面积和孔容虽有减小,但炭表面的含氧官能团数量大幅增加,其中羟基的增幅最明显。由羟基产生的赝电容对活性炭材料比容量的提高贡献最大;同时表面含氧官能团的增多对活性炭材料的大电流密度放电性能也有较大改善。首次采用以微波法制备的氧化铁纳米颗粒为正极材料,椰壳基活性炭为负极材料,组装成非对称电容器,并深入研究了其电化学行为。研究表明,与椰壳基活性炭电容器相比,氧化铁/活性炭非对称电容器具有较高的工作电压,可达1.2 V;能量密度可达9.25 Wh/kg,提高了53.4%。循环寿命测试结果表明非对称电容器具有稳定的充放电性能。更多还原

【Abstract】 Supercapacitor is a new device for electric energy storage. It has not only much more energy than conventional capacitors, but also much higher power density than batteries. Electrode material is one of the most important components of supercapacitor. It is a key factor influencing the performance of supercapacitor. The research and development of electrode materials have been the focus in the recent years.In this dissertation, the preparation, modification and electrochemical performance of plant-based porous activated carbon (AC) were studied in detail. In addition, Fe3O4 nano-particles, prepared by microwave method, were used as the electrode material of hybrid supercapacitor together with AC for the first time. The electrochemical properties of the hybrid capacitor were studied. The properties of ACs and Fe3O4 nano-particles were investigated by modern instruments, such as SEM, XRD, N2 adsorption, FTIR, XPS and so on. The performance of the resultant electrode materials and testing supercapacitors were tested by electrochemical measurements through constant current charge-discharge, cyclic voltammogram, impedance spectrum etc. The relationship between the structure and surface properties of electrode materials and its electrochemical performance was studied. In this paper, main works were done as following:Microporous activated carbon fibers (ACFs) with high surface area and high yield were successfully prepared by chemical using ramee as raw materials and ZnCl2 as activating agents. The activation was carried under low temperature and short activation time. The effects of activation parameters on the structure, surface and capacity properties of ACFs were systematically studied. The results showed that the ACF, which specific area is more than 1600 m2/g, pore size distributes in 0.5~2 nm and specific capacitance can reach to 253 F/g in 30wt.% KOH, can be produced under optimal condition. In addition, it also showed good power and cyclic properties.Apricot shell-based AC and coconut shell-based AC were modified by concentrated nitric acid. The results showed that after modification, the specific area and pore volume of ACs decreased while the content of oxygen functional groups, especially which of hydroxyl, increased obviously. The contribution of hydroxyl to the specific capacitance of AC is the most among all of functional groups. At the same time, the increase of functional group content is also benefit to the improvement of capacitance at high current density.Iron oxide nanoparticles, prepared by microwave method, was used as anode material of the hybrid supercapacitor for the first time, in which coconut shell-based activated carbon was used as cathode material. The electrochemical performances of the hybrid supercapacitor were studied. The results showed that the asymmetric capacitor has an operating voltage of 1.2 V and energy density up to 9.25 Wh/kg, 53.4% higher than the coconut shell-based activated carbon double-layer capacitor. At the same time, the asymmetric capacitor also showed stable cycle performance.更多还原