石墨烯/导电聚合物复合纤维组装体的可控制备及其电容性能研究

Graphene fiber supercapacitors are promising energy storage devices in wearable electronics. However, the chemically modified graphene suffers from aggregation and relatively low conductivity, thus the further improvement in volumetric specific capacitance and rate capability of graphene fiber electrode has been limited. This project has designed the co-assembly method of graphene oxide and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), constructing highly-conductive graphene/ PEDOT:PSS hydrogel fiber assemblies as porous substrate and controllably assembling highly electroactive conducting polymer (polyaniline or polypyrrole) via chemical or electrochemical polymerization. Finally, the ternary fiber of graphene/ PEDOT:PSS /conducting polymer has been prepared. The microstructural design of the ternary fiber composite can achieve an effective combination of high-conductivity, abundant ions transportation channels as well as highly-active capacitive sites in graphene composite fiber. Thus, flexible energy storage device with high-performance will be fabricated. This project will also investigate the microstructure-control method and co-assembly mechanism of graphene/ PEDOT:PSS hybrid hydrogel fiber. The relationship between the microstructure of hybrid fibers and their electrochemical performance will be studied and the synergistic effect between structural units will also be explored. This project will provide new strategy for the research of graphene fiber supercapacitor and promote the development of wearable electronics.

石墨烯纤维超级电容器是可穿戴电子学领域非常有潜力的能源存储器件。然而，化学修饰石墨烯的堆叠问题以及较低的导电性，限制了石墨烯纤维电极的体积比电容与倍率性能进一步提升。本项目设计了氧化石墨烯与PEDOT:PSS的共组装方法，以构建高导电的石墨烯/PEDOT:PSS凝胶纤维组装体，并以其为多孔载体，采用（电）化学聚合方法可控负载高电活性的导电聚合物（聚苯胺、聚吡咯），制备石墨烯/PEDOT:PSS/导电聚合物三元复合纤维。这种微纳结构的设计有望实现高导电性、充足的离子扩散通道与高活性位点在石墨烯复合纤维的有效结合，获得高性能的柔性储能器件。本项目还将探究石墨烯/PEDOT:PSS复合凝胶纤维的微结构调控方案与共组装机制，研究三元复合纤维的微结构与电容性能之间的构效关系，并揭示结构单元之间的协同作用机理。本项目的研究结果将为石墨烯纤维超级电容器的研究开拓新的思路，并将推动穿戴电子学的发展。

可穿戴电子学的快速发展推动着与之匹配的能源存储器件向小型化、柔性及高效方向发展。石墨烯基纤维超级电容器因其独特的优势受到了广泛关注；然而，化学修饰石墨烯片层易堆叠影响离子吸附和扩散，且较低的导电性限制电子在电极内部的转移，导致器件的体积比电容和倍率性能较差。针对上述问题，本项目从氧化石墨烯的化学结构和电子结构出发，以小片高氧化石墨烯和PEDOT:PSS为原料，采用低温水热组装和酸处理双重策略，构建了高导电、多孔的石墨烯/PEDOT:PSS复合纤维，探索了其微结构调控规律及二者的共组装机制。高度氧化的小尺寸氧化石墨烯前驱体能够赋予石墨烯纤维丰富的离子扩散通道和离子吸附界面以获得大量双电层电容；而丰富的含氧官能团能够贡献大量赝电容；经浓硫酸处理的PEDOT:PSS提高导电性之外还可防止石墨烯片层的堆积，同时提供部分电容。得益于各组分之间的协同效应及增强的电子/离子协同传输，该纤维状超级电容器表现出超高的体积/面积比电容和优异的倍率性能。在此基础上，我们以酸处理的PEDOT:PSS和石墨烯/PEDOT:PSS凝胶纤维为多孔导电载体，利用原位化学聚合方法可控生长高活性导电聚合物（聚苯胺/聚吡咯），获得了兼具高导电、丰富离子通道和高电容活性的新型复合纤维结构，所得到的器件展现了破纪录的体积比电容和倍率性能以及优异的循环稳定性。我们深入研究了复合纤维微结构和电化学性能之间的构效关系，揭示了组分间的协同作用机理，特别阐释了石墨烯在提高导电聚合物电极电化学稳定性所发挥的重要作用。该项目研究成果为高导电且具有发达离子扩散通道的石墨烯复合纤维的设计与制备提供科学依据和科学方法，对高性能的纤维超级电容器电极材料的开发具有重要理论意义和实际应用价值。