石墨烯复合物多孔纤维的结构设计及相关线状电容器件性能研究

Yarn supercapacitors represent a new type of capacitors possessing vast prospects in energy storage textiles. The balance between mechanical strength, electric conductivity and porosity via rational structural design of fiber is pivotal for improving the energy density of yarn supercapacitor. This proposal aims to wet-spin porous graphene-carbon nanotubes-N doped carbon quantum dots composite (G-CNTs-NCQDs) fibers from large sized graphene oxides, carbon nanotubes (CNTs) and N doped carbon quantum dots (NCQDs), further enhance the mechanical strength and electric conductivity by covalent connection between the components, so that maximize the capacitances and rate capabilities of fiber electrodes. Meanwhile, graphene-CNTs composite fiber is to be employed as matrix for deposition of pseudo-capacitive transition metal oxides to enhance the capacitance via coupled electric double layer-pseudocapacitive mechanism. Furthermore, asymmetric yarn supercapacitors are assembled using graphene-CNTs-metal oxides composite fibers as positive electrodes and G-CNTs-NCQDs fibers as negative electrodes, thus enhance the energy densities of the devices by widening of voltage window. Additionally, the microscopic mechanisms influencing the capacitive performances of graphene composite fibers are elucidated based on the analyses of structural and surface features, as well as the related interfacial resistances during energy storage process. This proposal would potentially offer essential experimental foundation for future applications of high-performance yarn and textile supercapacitors.

线状超级电容器是一类新型的电容器件，在储能纺织品领域极具发展前景。通过合理结构设计，平衡纤维力学强度、导电性和多孔度是提高线状电容器件能量密度的关键。本项目拟以大尺寸氧化石墨烯、碳纳米管（CNTs）和N掺杂碳量子点（NCQDs）为原料，湿法纺丝制备石墨烯-CNTs-NCQDs复合物多孔纤维，通过共价键连接提高纤维力学强度和导电性，优化纤维电极比容和倍率性能。同时以石墨烯-CNTs复合纤维为基体，在其表面沉积赝电容活性过渡金属氧化物，通过双电层-赝电容双重机理提高纤维比容。进而以石墨烯-CNTs-氧化物复合纤维为正极，石墨烯-CNTs-NCQDs复合纤维为负极组装非对称线状电容器件，通过拓宽电压窗口提高器件能量密度。分析石墨烯复合纤维电极的结构、表面特性及储能过程中的界面阻抗，揭示石墨烯复合纤维结构对其电容性能的影响机理，为高性能线状及织物电容器件的应用提供重要实验依据。

在项目支持下，我们采取不同碳化、活化方法，合成了一系列碳质材料及石墨烯复合物，通过提高比表面积、石墨化程度以及异质元素掺杂，优化电子离子迁移率及可接触表面积，通过双电层及赝电容双重机理提高电容性能。此外，采取不同策略，合成了一系列过渡金属化合物法拉第电极材料，通过调控双金属化合物组成、构建异质结及p-n结，提高材料法拉第活性；并通过构筑低维阵列、多级结构以及与石墨烯复合，优化电子离子扩散速率，研究电极材料组成、形貌、界面相互作用等物理化学特性与其储能性能之间的构效关系。进而结合碳质双电层电极和法拉第电极组装非对称电容器件，平衡两个电极电量并拓宽电压窗口，获得了均衡的能量、功率密度，良好循环性能和较慢自放电速率。考虑到电解质中氧化还原活性物质能充分参与电极表面法拉第反应，我们在碳质电容器件的电解质中引入氧化还原活性物质，通过活性电解质的充分、快速法拉第反应，以及电极与电解质的相互促进作用，大幅提高电极体系及电容器件输出性能。通过项目的开展，我们在各类超级电容器方面都进行了研究拓展，做出了系列研究工作，相关的后续研究正在持续进行当中。项目达到了预期的成果目标，为以后课题组在电容和储能领域的研究打下了坚实的基础。