三维高密度石墨烯基复合材料的设计、可控合成与高比能量储能特性研究

In this project, we intend to prepare 3D porous graphene/carbon nanotube (CNT) composite with CNTs as spacer in-between porous graphene layers. Then nanoscale MnO2 or MoO3 will be grown on the surface of porous graphene/CNT composite to form ternary porous graphene/CNT/metal oxide composites with high packing density. This composite will take full advantage of the synergistic effect of the three components. Finally, we will fabricate asymmetric supercapacitors with both high gravimetric and volumetric performances, excellent cycling stability as well as superior rate capability by using porous graphene/CNT/MnO2 and porous graphene/CNT/MoO3 composites as the positive and negative electrodes, respectively. The mechanism and influencing factors of the formation of porous graphene and porous graphene/CNT composite will be investigated in detail. In addition, the effect of process parameters on the growth of metal oxides and their growth mechanism will be systematically studied to achieve the controllable synthesis of electrode materials with both high gravimetric and volumetric performances. The influence of microstructure of electrode materials on their electrochemical performances will be also revealed. We will discuss the diffusion and transport mechanism of electrolyte ions and electrons during the electrochemical energy-storage process and reveal the relationship between microstructure and property of electrode materials to provide scientific basis and technical guidance for optimizing the design and development of high-performance energy-storage materials. Finally, this project will facilitate the development of fabrication technology of asymmetric supercapacitors and promote the large-scale application of supercapacitors in new energy automotives and aerospace as well as other fields.

本项目拟以氧化石墨烯为前躯体把碳纳米管作为支撑剂引入到多孔石墨烯的片层中形成三维结构的多孔石墨烯/碳纳米管复合材料，并在其表面生长纳米级的氧化锰或氧化钼形成高密度的三维多孔石墨烯/碳纳米管/氧化物三元复合材料。最后分别以多孔石墨烯/碳纳米管/氧化锰为正极、多孔石墨烯/碳纳米管/氧化钼为负极组装成兼具高质量比容量、高体积比容量与良好循环稳定性和倍率性能的非对称超级电容器。探究多孔石墨烯的形成机制，阐明多孔石墨烯与碳纳米管复合的机理及影响因素，揭示高密度金属氧化物在多孔石墨烯/碳纳米管复合材料表面生长的机制及调变因素，实现兼具高体积与质量性能电极材料的可控制备。深入研究电化学储能过程中电解液离子、电子的扩散传输机制，阐明电极材料的构效关系，为主动优化设计和开发高性能储能材料提供科学依据和技术指导，建立非对称超级电容器的组装技术，推进超级电容器在新能源汽车、航空航天等领域的大规模应用。

超级电容器具有较高的功率密度，但是其能量密度远低于电池。多孔炭等电极材料的密度较低，导致超级电容器的体积性能较差，难以满足器件便携性、小型化的要求。本项目以氧化石墨烯为前躯体把碳纳米管作为支撑剂引入到多孔石墨烯的片层中形成三维结构的多孔石墨烯/碳纳米管复合材料，并在其表面生长氧化锰纳米粒子或氧化钼纳米带形成高密度的三维多孔石墨烯/碳纳米管/氧化物三元复合材料。最后分别以制备的多孔石墨烯/碳纳米管/氧化锰复合材料为正极、多孔石墨烯/碳纳米管/氧化钼纳米带复合材料为负极组装了兼具高质量能量密度、高质量功率密度、高体积性能与良好循环稳定性和倍率性能的非对称超级电容器。该非对称超级电容器显示出超高的质量与体积能量密度(150 Wh kg-1, 319 Wh L-1)和良好的循环稳定性(30000次循环后保持率为101%)。揭示了高密度金属氧化物在多孔石墨烯/碳纳米管复合材料表面生长的机制及调变因素，实现了兼具高体积与质量性能电极材料的可控制备。研究了电化学储能过程中电解液离子、电子的扩散传输机制，阐明了电极材料的构效关系，为主动优化设计和开发高性能储能材料提供了科学依据和技术指导。