【作者】 张强；

【导师】 杨飘萍；

【作者基本信息】 哈尔滨工程大学 ， 化学工程与技术， 2016， 硕士

【摘要】 为了避免能源枯竭,进一步发展清洁能源,新型的能源转换和存储系统吸引了广泛的研究。超级电容器,又称作电化学电容器,由于其高能量密度、快速的充放电过程、高电容量、成本低廉以及循环寿命长等优异的性能,在电动车、电子设备以及其他电力供应设备等领域得到了广泛的关注。在通信技术、国防安全、航天航空以及民生交通等领域,具有巨大的发展潜力和应用前景。在电容器组分中,电极材料对电容器的性能起着决定性的作用。常用的电极材料包括碳材料、金属氧化物和导电聚合物等。其中碳材料及其复合材料作为超级电容器电极材料得到了广泛的研究与关注。但是,合成方法简单、电容性能优异且成本低廉的碳基材料还需要进一步的探索和发掘。论文中设计合成了具有特殊结构的介孔碳材料以及石墨烯基复合材料,并通过各种表征测试手段研究其电化学性能。具体研究如下:本文首先以纤维状介孔二氧化硅球为硬模板,酚醛树脂前驱体为碳源,通过硬模板法合成了形貌均一的纤维状中空介孔碳球（FHMCSs）。所合成的特殊形貌介孔碳材料具有较高的比表面积(1121 m² g^-1)和较大的孔体积(1.3cm³g^-1)。这种高的表面积-孔体积比,使得FHMCSs在作为超级电容器电极材料时具有更高的比电容和优异的倍率性能。电化学测试表明,FHMCSs电极材料在电流密度为1Ag^-1时,具有高达359.2Fg^-1的比电容。在循环5000次后,依然有92%的保持率,显示了优异的循环稳定性。FHMCSs特有的纤维壳体和中空介孔结构,在电化学反应过程中有利于离子和电子的传输,从而产生了优良的电化学性能。因此,纤维状中空介孔碳球材料在超级电容器和其他能量存储领域具有巨大应用潜力。通过溶剂热法,在石墨烯中复合钴纳米粒子,成功合成Co/rGO复合物。这是第一次由步骤简单、操作简便的溶剂热方法来合成Co/rGO复合物。通过界面作用,Co纳米颗粒原位还原在石墨烯片层上,形成复合物。复合物的微观结构和成分组成由XRD、拉曼光谱、XPS、SEM、TEM以及BET等方法来进行系统的表征分析。通过电化学测试分析,Co/rGO复合物作为超级电容器电极材料表现出优越的电化学性能。在电流密度为1.0 A g^-1时,2 M的KOH电解液中,比电容高达321.7 Fg^-1,显示了优异的倍率性能。在电流密度2.0 A g^-1下循环2000圈之后,复合物的比容量仍具有90%的保持率。Co/rGO复合物独特的三维网络结构以及石墨烯与钴纳米粒子的协同作用,使得复合物表现出优异的电化学性能。因此Co/rGO复合物在超级电容器领域展现出良好的应用前景。更多还原

【Abstract】 In order to avoid the energy depletion, considerable research efforts have been focused on alternative energy conversion and storage systems with high efficiency, low cost and environmental benignity. Supercapacitors （SCs）,also known as electrochemical capacitors（ECs）,have received a considerable amount of attention due to their attractive merits,such as higher power density,faster charge/discharge process,and longer cycle life,which can be applied in the field of electric vehicles, electronic devices, and other power supply facilities. It can be widely used in areas of mobile communication, transportation, aerospace and defense science and technology. Among all the components of capacitor, electrode material plays a decisive role in the electrochemical performance of supercapacitors. The electrode materials usually contain carbon materials, metal oxides and conducting polymers. The carbon materials and their composite materials as supercapacitors electrode material has been widely research and attention. However, carbon-based materials with simple synthesis method, excellent capacitance performance and low cost need further exploration. Herein, we have designed and prepared mesoporous carbon materials and graphene-based composites and analyzed their electrochemical properties. The main contents are summarized as follows:Uniform fibrous-structured hollow mesoporous carbon spheres （FHMCSs） have been synthesized by a simple template method using fibrous-structured mesoporous silica microspheres and resol precursor as silica template and carbon sources, respectively. It is found that FHMCSs have an ultra high specific surface area of 1121 m² g^-1 and large pore volume of 1.3 cm³ g^-1. The high surface-to-volume ratio is a favorable factor to obtain high specific capacitance and excellent rate performance. As expected, when used as supercapacitor electrodes,the FHMCSs exhibit high specific capacitance of 359.2 F g^-1 at current density of 1 A g^-1 and excellent cycle stability （92% retention after 5000 cycles）. The reason for this superior performance may be that the FHMCSs with interesting fibrous-structure is beneficial to the mass transfer during the electrochemical process, suggesting a potential application in supercapacitors and other energy storage fields.A series of cobalt nanoparticles/reduced graphene oxide （Co/RGO） composites have been successfully synthesized via an in situ crystal growth method under solvothermal conditions for the first time. The synthesized composites are comprised of Co particles that are uniformly anchored onto the surface of graphene sheets by in situ reducing. Powder X-ray diffraction（XRD）, Raman spectroscopy, Scanning electron microscopy （SEM）,Transmission electron microscopy （TEM）, X-ray photoelectron spectra （XPS）, and Brunauer-Emmett-Teller （BET）analysis are performed for systematically characterizing the microstructure and composition of the as-prepared Co/RGO composites. Interestingly, the as-prepared composites show superior electrochemical performance. As a result, Co/RGO composite exhibits a high specific capacitance of 321.7 F g^-1 at 1 A g^-1 in 2 M KOH aqueous solution as well as good rate capability. Meanwhile, the capacitance retention keeps about 90% of the initial value after 2000 cycles at a current density of 2 A g^-1. The excellent electrochemical performances are due to the 3D graphene conductive network and the synergetic effect of RGO and Co particles,suggesting that Co/RGO composite possesses a great potential application in supercapacitors.更多还原