高比表面、高密度石墨烯基材料的制备、形成机理及储能研究

Supercapacitor is highly promising for the application in the military and daily life due to its ultra-short charge/discharge time. However, the low energy density has largely restrained its practical use. Although it has been demonstrated that supercapacitor based on high specific surface area (SSA) could achieve high energy density when calculated by the weight of electrode materials, the low density of graphene-based materials still decrease the energy density based on the whole weight of the supercapacitor device. And few attentions have been drawn on the density of the electrode materials. Therefore, in this project, we plan to realize the synthesis of graphene-based materials with both high surface area and density. With hydrothermal process, carbon source with high density will be introduced to graphene oxide to form graphene based 3D network with high density, followed by by fully activation process to achieve graphene-based materials with both high SSA and density, which will be applied in high energy density supercapacitors. The mechanism of formation of graphene based 3D network with high density will be well studied, as also the relationship between the ratio of carbon sources and on the density of the products. Overall, through the project, new insight of controlled synthesis of graphene based materials with both high SSA and density can be brought, as well as the fundamental mechanism can be well studied, which can highly improve the development of high energy-density supercapacitor based on graphene materials.

储能器件超级电容器能量密度低一直限制其广泛应用。虽然高比表面积石墨烯材料的出现，使超级电容器基于材料质量计算的能量密度较高；但是石墨烯材料密度过低，最终仍导致器件整体能量密度低。目前的研究仍集中于提升石墨烯材料的比表面积，而对提升其密度关注很少。因此，本项目拟开展制备兼具高比表面积和高密度石墨烯基材料的研究。通过溶剂热处理实现氧化石墨烯与高密度碳源之间稳定复合，形成高密度石墨烯基三维交联网络；通过活化处理实现石墨烯基材料的高比表面和高密度，为高能量密度超级电容器提供关键材料；揭示石墨烯与高密度碳源在实现有效复合的要求及机理；找到产物密度和比表面积与复合碳源比例之间的变化规律，获得可控致密化高比表面积石墨烯基材料的方法。通过本项目的研究，必将强有力推动高能量密度超级电容器的研究和发展，为研究可控致密化高比表面积石墨烯基材料提供参考和理论依据。

储能器件如超级电容器、液基温差电池的能量密度较低一直是亟待解决的问题，其中电极材料比表面积较低和密度较低是最主要的原因。虽然高比表面积石墨烯基材料的出现，使储能器件基于材料质量计算的能量密度较高；但是石墨烯材料本身密度通常过低，最终仍导致器件整体能量密度低。目前的研究仍集中于提升石墨烯材料的比表面积，而对提升其密度关注很少。本项目在系列研究的基础上，成功制备获得了兼具高比表面积和高密度石墨烯基材料。我们通过溶剂热反应将酚醛树脂前体原位聚合在氧化石墨烯三维网络结构之中，并通过调节两者前体质量比，实现了高密度碳源酚醛树脂与石墨烯基三维交联结构的有效结合，获得了高密度石墨烯基三维交联网络，该比例下中间产物的比表面积为460平方米每克，其密度为0.55克每立方厘米；随后我们采用氢氧化钾处理高密度三维石墨烯交联材料，利用增加微孔的原理来进一步提升大幅增加其比表面积。我们所制备得到的石墨烯基材料的比表面积可高达2700平方米每克，并且其密度与商业活性炭的密度也比较接近。基于该石墨烯材料的超级电容器在有机溶剂中的能量密度可以达到90瓦时每千克，远高于基于商业活性炭的54瓦时每千克；而基于该材料的液基温差电池的输出功率可以达到12瓦每平方米，而基于传统碳电极材料的液基温差电池的输出功率仅2瓦每平方米。该项目研究结果将强有力推动高能量密度超级电容器和高功率液基温差电池的研究和发展，对将其应用到小型热丝点火装置和低温区温差自发电装置等国防和民用领域具有重要的推动作用。