石墨烯基高密度多孔碳材料构建及高体积能量密度储能研究

Low packing density, together with the resulted limited volumetric capacitance, is one of the major bottlenecks for novel nanocarbons to find their real applications in commercial electrochemical energy storage (EES) devices.The purpose of the proposed project is to develop a preparation strategy for a densely structured but highly porous carbon that is constructed by compactly interlinked graphene nanosheets and shows ultrahigh volumetric capacitance for electrochemical capacitors (ECs). This project focuses on following several aspects.1) The formation process of graphene oxide hydrogel is well understood through correlating the hydrogel structure and hydrothermal condition; 2) By realizing a control on how the water trapped in the hydrogel is removed, a very dense but porous infrastrcuture (high density porous graphene-based macroform, abbreviated as HPGM) is formed, where two characteristics of high contrast: rich porosity and high density are well balanced; 3) By optimazing the preparation parameters of the HPGM and hybrdization the HPGM with foreign components, a high performance electrode material holding high volumetric capacitance is obtained. 4) More promisingly, such a carbon is conductive and moldable, which allow such a carbon employed as an well-shaped electrode sheet directly for the assembly of a supercapacitor device free from any additives, which results in a device-level high energy density ECs. In general, this project is of great importance not only from the points of fundamental study but also in promoting nanomaterials into real applications electrochemcial energy storage.

碳纳米材料用于电化学储能系统的瓶颈之一是其密度低，导致其体积比容量有限，很难满足人们对器件的小型化、便携式的要求。本项目的研究目标是发展基于石墨烯的高密度多孔碳材料自组装制备方法，获得体积比容量性能优异的三维宏观体材料，进而构建高体积能量密度的储能器件。通过考察反应条件对组装过程的影响，揭示三维空间下石墨烯凝胶的形成机制；探讨石墨烯凝胶中结合水的脱除过程对片层织构的影响，实现石墨烯片层在三维空间的紧密搭接，平衡多孔性和高密度两大矛盾因素，获得致密多孔、高体积能量密度的三维宏观体材料；同时通过不同活性组分的复合，获得高体积能量密度的多孔复合材料；探索成型电极材料的制备，实现超级电容器的直接组装，从而将材料水平上优异的体积容量性能最大程度反映在器件上。本项目的实施不仅为新型电化学储能材料和器件的组装、构建提供新的思路，具有重要的理论研究价值，同时推动基于纳米材料的电化学储能器件的实用化进程。

随着碳纳米储能材料的迅速发展，其质量比容量不断提高，但通常其密度较低，导致体积比容量有限，难以满足人们对器件便携性和小型化的要求。本项目的研究目标是发展完善石墨烯基高密度多孔碳材料的制备方法，获得高体积比容量电极材料，进而构建高体积能量密度的储能器件。本项目发明了采用毛细蒸发技术致密化石墨烯网络，基于石墨烯结构单元实现了高密度多孔碳的制备；在此基础上，平衡孔隙和密度两个矛盾因素，获得了高体积容量的三维石墨烯宏观体材料；通过与高化学容量的非碳组分复合，并对复合材料电子和离子的传输机制进行了研究，为高体积容量的碳-非碳复合电极材料提供了构建方案；从材料、电极、器件三个方面提出了高体积能量密度储能器件的设计原则，实现了材料层面上的优异性能在器件水平上的发挥。本项目的实施不仅为实现材料和器件的致密储能提供了新的设计原则，具有重要的理论研究价值，同时推进了基于碳纳米材料新型电化学储能器件的实用化进程。