【作者】 王冠；

【导师】 李宝华；

【作者基本信息】 清华大学 ， 材料科学与工程， 2011， 硕士

【摘要】 超级电容器具有容量大、功率密度高、寿命长、工作温限宽、电化学性能等特点，是一种高效、实用的能量储存装置。电极材料的性能决定了超级电容器的电化学性能。活性炭材料价格低廉、制备简单、电化学稳定性高，是最早应用于超级电容器的电极材料，一直以来是人们的研究重点之一。二氧化锰是一种新型高比容量电极材料，可应用于非对称电容器正极材料。导电添加剂是辅助电极材料发挥作用的关键因素。常用的导电添加剂有乙炔黑、炭纳米纤维等。目前，一种新型二维炭材料纳米石墨片因其具有良好的导电性得到了人们的关注。本论文采用石油焦为原料，利用NaOH化学活化法制备活性炭材料，并且组装成扣式电容器。对电容器进行恒电流充放电、循环伏安曲线以及交流阻抗等测试，分析其结果并对电容器的电化学性能进行了研究，考察了碱炭比对活性炭结构及其电容特性的影响。实验结果表明，碱炭比为2.5:1时，活性炭比表面积为929m²/g，在1M ET4NBF₄/PC电解液中比电容可达119F/g；碱炭比为3:1时，活性炭电极功率特性改善，大电流放电比容量衰减率降低。以膨胀石墨为原料，利用超声法制备纳米石墨片，用于超级电容器导电添加剂。按照不同的比例添加乙炔黑、纳米石墨片、炭纳米纤维制作活性炭电极。通过SEM和电化学测试手段对电极的微观形貌和电化学性能进行了研究。结果表明，二维纳米石墨片和乙炔黑同时加入，形成点面结合的接触方式，改善了电极物质间的导电性，提高了活性炭电极的比容量。以二氧化锰和活性炭为电极材料设计并组装了非对称超级电容器。解决了部分工艺问题，并对电容器器件性能进行测试。电容器比容量与设计理论容量一致。更多还原

【Abstract】 Electrochemical capacitor is an efficient energy storage device with theadvantages of high specific capacitance, long cycling life, wider worktemperatures and free service. The performance of super capacitors dependson the electrode materials. Activated carbon was the earliest material used insupercapacitors because of its characteristics of low cost, easy to prepare andelectrochemical stabilities. Manganese dioxide is a new material with highspecific capacitance for the positive electrode of asymmetric capacitor.Conductive additives such as acetylene black and carbon nanofibres can alsoaffect the performance of supercapacitors’ electrode. Graphite nanoplateletshave been paid much attention recently due to excellent electrical conductiveproperties and unique two dimensional nanostructure.In this paper, the low cost carbon electrode was prepared by NaOHchemical activation of petroleum coke for the first time, and then assembledto button capacitors. The effect of the weight ratio of NaOH/coke on thestructure and capacitance performance of the electrode materials forsupercapacitors was investigated by constant current discharge, cyclicvoltammetry and electrochemical impedance spectroscopy measurement. Thepetroleum coke based activated carbon prepared under2.5:1weight ratio ofNaOH/coke had specific surface areas over929m²/g and specific capacitanceabout119F/g in1M ET4NBF₄/PC electrolyte. The power stabilities ofpetroleum coke based activated carbon were also improved when the ratio was3:1.Graphite nanoplatelets were prepared from expanded graphite worm viaultrasonic treatment which was used as conductive additives later. Threecarbon materials with different dimensions were selected as conductiveadditives to apply for the electrodes of supercapacitors. The electrodes wereinvestigated by SEM and various electrochemical tests. The composite electrode with both acetylene black and graphite nanoplatelets showedexcellent discharge properties at different current densities. The“plane-to-point” conducting mode was the key factor for the high propertiesof supercapacitor.Designed and assembled the asymmetric capacitors with manganesedioxide electrode and activated carbon electrode. Certain problems in theproduct processes of the asymmetric capacitors were solved. And thecapacitance performance of asymmetric capacitors was in accordance withdesigned capacitance.更多还原