高比容量石墨烯/过渡金属氢氧化物复合超级电容器电极材料研究

It is very important to investigate the energy-stored materials in developing and utilizing the clean resourses in China. In particular, this investigation is required in national wide to develop the dynamic electric sources for application in hybrid electric vehicles and railway transportation. Aim at raising the energy density for supercapacitor, this investigation employs both plasma enhanced chemical vapor deposition and electrochemical deposition to prepare graphene/transition metal hydroxide hybrid materal as an electrode for supercapacitor, via effectively ajusting the morphology and structure, as well as the hybridization of graphene and transition metal hydroxide. The effects of the morphology, structure, hybridization of graphene and transition metal hydroxide on the specific capacitance are explored. Also, the role of graphene and transition metal hydroxide in the electrode, the interaction between graphene and transition metal hydroxide, as well as the mechanism of redox for transition metal hydroxide, are revealed. Based on first-principles calculation, the reason why different transition metals play different roles in the electrochemical function as electrodes is explained. Furthermore, the experimental parameters are optimized to realize the maxmum synergetic function of both graphene with an electrical double layer capacitor and transition metal hydroxide with a Faradic capacitor. Finally, the supercapacitor of graphene/transition metal hydroxide hybrid material with a high energy density, high power density, and high cyclic numbers is realized. This investigation may lay a foundation for the application of the supercapacitor in which graphene/transition metal hydroxide is employed as electrode in automobiles and railway transportation.

储能材料研究对于我国清洁能源的开发与利用- - 特别是解决混合电动汽车和轨道交通动力电源等国家重大需求至关重要。本项目以提高超级电容器的储存能量密度为目标，采用等离子体增强化学气相沉积和电化学沉积技术，通过石墨烯、过渡金属氢氧化物形貌、结构的有效调控和复合，制备出石墨烯/过渡金属氢氧化物复合超级电容器电极材料；探索石墨烯、过渡金属氢氧化物形貌、结构、复合等对比容量的影响规律，揭示石墨烯、过渡金属氢氧化物在复合电极材料中所起作用、两者之间复合作用机制及各种过渡金属氢氧化物氧化还原反应本质；利用第一原理计算弄清不同过渡金属所引起的电化学性能差异的原因；优化实验参数实现石墨烯双电层电容与过渡金属氢氧化物法拉弟赝电容的电化学协同功能最大化；最终获得高比容量的石墨烯/过渡金属氢氧化物复合超级电容器。本研究将为高功率密度、高能量密度的石墨烯/过渡金属氢氧化物复合超极电容器电极材料制备奠定科学基础。

利用水解方法得到均匀混合的双层氢氧化钴纳米笼和石墨烯复合电极材料,获得高比电容、高倍率特性、高循环稳定性的复合电极，系统地研究了不同集流体与氢氧化钴电活性物质的相互作用从而提出了面向高性能过渡金属氢氧化物超级电容器集流体的选用准则，利用同步辐射原位X射线精细结构谱、先进电子显微分析和理论计算，精确地解析局域结构原子尺度的动态演变，发现氢氧化钴薄膜电极的高性能源于充放电两相的结构相似性和模拟电池中离子嵌入/脱出的储能机制。以金属氢氧化物为原料在碳纤维纸上制备了高取向的金属有机框架材料，具有高比电容、高功率和高能量密度。以此为基础研发了适用于氢氧化钴的零下三十摄氏度仍可正常工作的低温电解液，拓宽了其实际应用范围。