MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027, PR China.
Nanoscale. 2015 Mar 7;7(9):4080-7. doi: 10.1039/c4nr07038k.
Supercapacitors with porous electrodes of graphene macroscopic assembly are supposed to have high energy storage capacity. However, a great number of "close pores" in porous graphene electrodes are invalid because electrolyte ions cannot infiltrate. A quick method to prepare porous graphene electrodes with reduced "close pores" is essential for higher energy storage. Here we propose a wet-spinning assembly approach based on the liquid crystal behavior of graphene oxide to continuously spin orientational graphene hydrogel films with "open pores", which are used directly as binder-free supercapacitor electrodes. The resulting supercapacitor electrodes show better electrochemical performance than those with disordered graphene sheets. Furthermore, three reduction methods including hydrothermal treatment, hydrazine and hydroiodic acid reduction are used to evaluate the specific capacitances of the graphene hydrogel film. Hydrazine-reduced graphene hydrogel film shows the highest capacitance of 203 F g(-1) at 1 A g(-1) and maintains 67.1% specific capacitance (140 F g(-1)) at 50 A g(-1). The combination of scalable wet-spinning technology and orientational structure makes graphene hydrogel films an ideal electrode material for supercapacitors.
具有石墨烯宏观组装多孔电极的超级电容器被认为具有高储能能力。然而，多孔石墨烯电极中的大量“封闭孔”是无效的，因为电解质离子无法渗透。因此，开发一种能够减少“封闭孔”的制备多孔石墨烯电极的快速方法对于更高的储能至关重要。在这里，我们提出了一种基于氧化石墨烯液晶行为的湿纺组装方法，可连续纺制具有“开式孔”的定向石墨烯水凝胶薄膜，可直接用作无粘合剂超级电容器电极。所得超级电容器电极表现出比具有无序石墨烯片更好的电化学性能。此外，使用三种还原方法，包括水热处理、水合肼和氢碘酸还原，评估了石墨烯水凝胶薄膜的比电容。水合肼还原的石墨烯水凝胶薄膜在 1 A g(-1) 时表现出 203 F g(-1) 的最高电容，并在 50 A g(-1) 时保持 67.1% 的比电容（140 F g(-1)）。可扩展的湿纺技术和定向结构的结合使石墨烯水凝胶薄膜成为超级电容器的理想电极材料。
