石墨烯基超级电容器：电极材料制备及储能机理研究

发布时间：2018-02-25 05:01

本文关键词： 超级电容器石墨烯宏观体孔结构表面化学二氧化锰　出处：《天津大学》2014年博士论文　论文类型：学位论文

【摘要】：超级电容器作为一种绿色储能器件，其性能主要依赖于电极材料。石墨烯作为sp2杂化碳质材料的基元单位，具有独特的二维结构和优异的物化特性，使得其在超级电容器领域具有巨大的应用潜力。尽管目前石墨烯的结构特征和物化性质可以得到有效调控，然而其作为超级电容器电极材料的实际比电容均与理论值存在一定差距，能量密度偏低。针对这些不足，本论文主要以石墨烯基碳质材料作为超级电容器电极材料，，探讨其电化学储能机理，可控构建结构独特的电极材料，使其性能得以优化，组装高性能超级电容器。在石墨烯基碳质电极材料储能机制方面：（1）论文以两种极限结构石墨烯基碳质材料作为模板电极材料，考察了它们在水系电解液中的电化学特性，提出表面化学是影响完全外表面无孔炭电化学性能的决定因素，孔结构决定了完全内表面微孔炭的电化学行为，孔结构和表面化学协同影响其电容特性。（2）全面考察了微观结构、比表面积和含氧官能团对层次孔石墨烯宏观体电化学性能的影响，通过提高电极材料表面含氧官能团的浓度，可增加电极材料的亲水特性，降低电解质离子的扩散阻力，提高电极材料的比电容和倍率性能。在超级电容器电极材料可控制备及应用方面：（1）以结构致密但孔隙发达的高密度多孔石墨烯宏观体直接作为超级电容器电极材料，其表现出超高体积比电容，并组装了高体积能量密度超级电容器。依据相同的脱水机制，以石墨烯宏观体作为支撑骨架，均匀负载金属氧化物纳米粒子，利用溶液浸渍法制备了超高密度的RuO2/石墨烯复合宏观体，二者的协同储能效应确保了该复合材料具有超高体积能量密度和功率密度。（2）以三维结构石墨烯水凝胶作为反应物和模板，在温和条件下，发展了新型反应性模板法，制备了三维多孔MnO2纳米材料，该材料表现出良好的电化学性能，其优异的倍率性能大大拓展了MnO2的应用范围。通过调整反应物的摩尔比，可以获得三维结构MnO2/石墨烯复合宏观体。
[Abstract]:As a kind of green energy storage device, the performance of supercapacitor mainly depends on the electrode material. As the unit of sp2 hybrid carbon material, graphene has unique two-dimensional structure and excellent physical and chemical properties. It has great potential for application in the field of supercapacitors, although the structure and physicochemical properties of graphene can be effectively regulated at present. However, the actual specific capacitance of the supercapacitor electrode material is far from the theoretical value and the energy density is low. In view of these shortcomings, the graphene based carbonaceous material is mainly used as the electrode material of the supercapacitor in this paper. The mechanism of electrochemical energy storage was discussed, and the electrode material with unique structure was constructed, which made the performance optimization and assembled high performance supercapacitor. In the aspect of energy storage mechanism of graphene based carbon electrode materials, two kinds of limit structure graphene based carbon materials were used as template electrode materials to investigate their electrochemical characteristics in aqueous electrolyte. It is suggested that surface chemistry is the decisive factor affecting the electrochemical performance of porous carbon on the complete outer surface. The pore structure determines the electrochemical behavior of the microporous carbon on the complete inner surface, and the pore structure and surface chemistry synergistically affect the capacitance characteristics of the carbon. The effect of specific surface area and oxygen-containing functional groups on the electrochemical properties of macroporous graphene macrobodies was investigated. By increasing the concentration of oxygen-containing functional groups on the surface of electrode materials, the hydrophilicity of electrode materials was increased and the diffusion resistance of electrolyte ions was reduced. The specific capacitance and rate performance of electrode materials are improved. In the field of controllable preparation and application of electrode materials for supercapacitors, the macroporous graphene with dense structure but well developed pores is directly used as electrode material for supercapacitor, which shows ultra-high volume specific capacitance. A high volume energy density supercapacitor was assembled. According to the same dehydration mechanism, the graphene macrostructure was used as the support skeleton, and the metal oxide nanoparticles were uniformly loaded. The ultrahigh density RuO2 / graphene composite macrostructure was prepared by solution impregnation method. The synergistic energy storage effect between the two materials ensures that the composite has ultra-high volume energy density and power density. The novel reactive template method has been developed under mild conditions using three-dimensional graphene hydrogels as reactants and templates. Three-dimensional porous MnO2 nanomaterials have been prepared. The materials exhibit good electrochemical properties, and their excellent rate performance greatly expands the scope of application of MnO2. By adjusting the molar ratio of reactants, Three dimensional structure MnO2 / graphene composite macrostructure can be obtained.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TQ127.11;TM53

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