连续多孔石墨烯及其杂化纤维的可控制备与柔性器件设计

It remains a great challenge to assemble graphene into macroscopic continuous fibers and keep most of their properties comparable to those of single graphene sheets. In this project, the effects of the concentration of graphene oxide(GO), the morphology of inclusions and the pH value on the rheological and liquid-crystal-phase transition behaviors of GO suspension will be investigated systematically by polarized optical microscopy（POM）, small angle X-ray diffraction（XRD） and viscosity test. By investigation of the coagulant induced phase separation and the fiber formation mechanism, optimized processing conditions would be obtained to prepare GO bulk and hybrid fibers(GOF and GOHF). A further reduction and post treatment of those fibers will be carried on to obtain continuous graphene bulk and hybrid fibers (GF and GHF) with good conductivity and high porosity. The structure of graphene fibers will be characterized by SEM, XRD, FTIR, Raman and nitrogen adsorption test, while their properties investigated by mechanical, electrical and electrochemical tests, then the structure-property relationship will be elucidated. Finally, polymer gel electrolyte will be dip-coated onto graphene fibers(1D) or woven fabrics(2D), which will be assembled into flexible and wearable supercapacitors. Their capacitance parameters will be tested and cycle stability wll be evaluated. This project could extend the application potential of graphene materials, and help people understand the relationship among microscopic properties, processing and macroscopic performances of nanomaterials. The case of graphene fibers in this project would also serve as an good example for studying other 2-dimentional nanomaterials.

将石墨烯组装成宏观连续纤维并保持其优异特性是材料和纳米科学领域的挑战。本项目将以氧化石墨烯（GO）为石墨烯的前驱体，采用SAXRD、POM、流变仪等表征手段系统研究GO分散液浓度、杂化组份、pH值等因素对纺丝液晶转变和流变行为的影响，优化纺丝液配制方法；研究沉淀剂诱导的相分离行为，揭示纤维成型机理，优化纺丝工艺制备连续氧化石墨烯及其杂化纤维；进一步对它们进行还原和后处理获得连续多孔石墨烯及其杂化纤维（GF和GHF）。采用SEM、XRD、氮吸附和力学、电学和电化学测试等手段表征纤维的结构和性能，建立结构-性能对应关系。最后将GF、GHF及其织物与凝胶电解质进行封装，设计组装出纱线型和织物型柔性电容器，表征电容等基本参数并分析储能机制。本项目研究将获得新型特种功能纤维，拓宽石墨烯的应用维度，加深对纳米材料微观特性、加工行为和宏观性能之间关系的理解，同时对其他二维纳米材料的研究开发具有借鉴价值。

近年来，随着便携式、甚至可穿戴电子设备（如电子书、柔性显示器、柔性生物传感和可植入式多媒体设备）的快速发展，柔性、轻质、高机械强度和高效的储能设备吸引了越来越多研究者的关注。在众多的储能设备中，超级电容器因具有高的功率密度、长的循环寿命、快的充放电速率和安全的操作条件等优点，被认为是最有前景的储能设备。在日常生活中，纤维是一种最常见的柔性材料，具有质轻、可折叠弯曲及可编织等特点。如果能够把超级电容器制备成纤维状，就能够满足电子设备柔性和可穿戴的需求。石墨烯纤维是由石墨烯纳米片互相堆积、取向排列形成的一维材料，它继承了石墨烯的优异性能，如显著的机械和电学性能，因此石墨烯纤维非常有希望作为柔性超级电容器的电极材料。然而，基于纯石墨烯纤维的超级电容器能量密度仍然较低，限制了其实际应用。针对石墨烯纤维超级电容器能量密度低的问题，本项目采用湿法纺丝制备了多种杂化纤维，对其孔结构和比表面积进行调控，得到了多孔石墨烯杂化纤维。系统研究了其力学、电学和电化学性能，并探讨了其在柔性可穿戴超级电容器中的应用。