柔性核鞘结构石墨烯复合纤维超级电容器直接纺丝制备、界间结构调控与性能研究

Fiber-shaped supercapacitors(SCs) are of significant importance in the emerging wearable technique. Compared with parallel and twisted fiber SCs, the coaxial ones have obvious advantages in the aspects of larger electrode area, higher structural stability and more flexibility. Graphene fiber is regarded as ideal material for the fabrication of fiber-shaped SCs, however, graphene only has electrical double-layer capacitance, pure graphene fiber is brittle, and the electrical conductivity of flexible graphene/polymer composite fibers is very poor, which all together hiders the wide use of graphene fiber in fiber-shaped SCs. Focusing on key problems mentioned above, we propose an approach based on the co-spinning of graphene oxide(GO)-MnO2(or Co2O3)-Vitamin C(VC) and sodium carboxymethyl cellulose(CMC)-H3PO4 dispersions, respectively, using a three-capillary spinneret for the direct fabrication of flexible core-sheath graphene composite fiber SCs, where metal oxide nanoparticles are used to improve the flexibility and capacity of the device, and VC is for the in situ selective reduction of GO into rGO. Both the spinning process and device properties will be deeply studied and optimized. Moreover, we will try to reveal the mechanism of the layer-layer assembly and the interface formation during the fabrication process, seeking for effective modulations and optimization of the microstructures and performance of the devices, and finally develop a novel approach for the one-step continuous fabrication of flexible fiber-shaped SCs towards future wearable technique.

纤维状超级电容器是可穿戴技术研究的热点。相对于平行和缠绕结构，同轴纤维状超级电容器在电极面积、结构稳定性等方面更具优势，但其目前亦存在能量密度低、无法实现直接高效构建等重大问题。石墨烯纤维是构建此类器件的理想材料，但其柔性差，且仅有双电层电容，虽与高分子复合能提升柔性，却对导电性影响很大，这极大限制了其在此领域的应用。为此，本项目提出核鞘结构石墨烯复合纤维超级电容器直接纺丝制备方法：采用3层同轴针头，以GO-MxOy-VC和CMC为纺丝液，VC为GO的选择性原位还原剂，研究超级电容器的直接构建技术。并拟通过MnO2、Co2O3纳米粒子对纤维增韧，提高器件纤维柔韧性与电容。开展电容器直接纺丝制备工艺与性能研究，突破GO原位精准还原、界面结构表征关键技术，揭示其间的层间组装行为与器件界面结构调控原理，力求实现器件结构与性能的有效调控，以期为高性能柔性纤维状超级电容器提供新的设计原理和加工方法。

纤维状超级电容器是可穿戴技术研究的热点。相对于平行和缠绕结构，同轴纤维状超级电容器在电极面积、结构稳定性等方面更具优势，但其目前亦存在能量密度低、无法实现直接高效构建等重大问题。石墨烯纤维是构建此类器件的理想材料，但其柔性差，且仅有双电层电容，虽与高分子复合能提升柔性，却对导电性影响很大，这极大限制了其在此领域的应用。为此，本项目提出了一种核鞘结构石墨烯复合纤维超级电容器直接纺丝制备方法：采用3层同轴针头，以GO-MnO2-VC和CMC-H3PO4/PVDF分别为内外电极和隔膜/电解质纺丝液，VC为GO的选择性原位还原剂，建立了一种同轴石墨烯纤维状超级电容器的直接纺丝打印技术。并通过器件层层组装行为及界面结构调控机理的研究，实现了同轴纤维器件结构与性能的有效调控。最后，所构筑的柔性同轴赝电容纤维状储能器件表现出优异的电容性能（410.7 mF cm-2）、循环稳定性及结构稳定性，为性能柔性纤维状超级电容器提供新的设计原理和加工方法。