聚吡咯/取向碳纳米管构建柔性超级电容器的结构设计和性能研究

As an indispensable component of flexible electronics, flexible energy storage devices need to be developed in the first place. However, the lagged development of flexible energy storage devices becomes a bottleneck of the development of flexible electronics. Nowadays, supercapacitor is a ubiquitous and prevalent energy storage device. The big challenge of developing flexible supercapacitors lies in simultaneously realizing high flexibility and good electrochemical properties. The reason is it is difficult to make electrons and ions high-flux, fast and stably transport when the electrodes suffer a distortion or at a dynamic state. In our previous work, it has been demonstrated as an effective method of using conducting polymers as electrode materials and designing hybrid electrodes to obtain flexible supercapacitors with high performance. Moreover, carbon nanotubes can be made into macroscopic objects using aligned arrangement and controllable assembly. And the objects possess excellent mechanical and electrical properties, which may lead to high-performance hybrid electrodes. Herein, we apply aligned carbon nanotubes to construct a three-dimensional framework with a hierarchical pore structure using multi-level controllable assembly. The fast transportation of electrons and ions will be realized owing to excellent electrical properties of the framework. The stable transportation of electrons and ions will be realized due to excellent mechanical properties of the framework. The hierarchical pore structure facilitate a high loading of polypyrrole and consequent high-flux transportation of electrons and ions. At last, a supercapacitor with high flexibility and good electrochemical properties will be realized.

储能器件的柔性化是实现柔性电子的必要步骤，然而其进展缓慢成为制约柔性电子发展的一个主要瓶颈。超级电容器是现今主流的储能器件之一。目前发展柔性超级电容器的一个关键挑战在于无法同时实现良好的柔性和储能性能。其原因是在超级电容器电极内无法保证电子与离子的高通量、快速传输以及在曲面和动态下的稳定传输。在我们前期工作中，已经证明采用高比电容的导电高分子为电极材料以及设计杂化电极结构是一种有效的解决途径。并且碳纳米管通过取向排列和可控组装，能够实现碳纳米管的优异力学和电学性能从微观到宏观的有效传递，以此可以获得高性能杂化电极。本项目拟采用取向碳纳米管多层级组装形成具有多尺度多级孔结构的三维框架。利用框架优异的电学性能实现电子与离子的快速传输；利用框架优异的力学性能实现电子与离子的稳定传输；利用框架的结构特性获得聚吡咯的高负载从而实现电子与离子的高通量传输。最终实现兼具良好柔性和储能性能的超级电容器。

储能器件的柔性化是实现柔性电子的必要步骤，然而其进展缓慢成为制约柔性电子发展的一个主要瓶颈。超级电容器是现今主流的储能器件之一。目前发展柔性超级电容器的一个关键挑战在于无法同时实现良好的柔性和储能性能。其原因是在超级电容器电极内无法保证电子与离子的高通量、快速传输以及在曲面和动态下的稳定传输。本项目从组分和结构出发解决上述问题：采用具有优异力学和电学性能的碳纳米管以及具有良好电化学性能的聚吡咯为电极组分；并且设计有序织物结构为电极结构。具体地，首先采用浮动化学气相沉积方法制备碳纳米管纤维，然后经过加捻成纱线，接着经过编织获得碳纳米管有序织物，随后通过化学聚合方法把聚吡咯纳米颗粒负载到碳纳米管织物上形成聚吡咯/碳纳米管复合织物，并以此作为电极构建对称型超级电容器。主要研究纱线股数、加捻角度、织物结构、聚吡咯形貌等参数对织物的力学和电学性能以及超级电容器的电化学性能的影响规律。结果显示，碳纳米管织物具有高的抗拉强度、大的拉伸应变量和良好的导电性；并且由于碳纳米管织物具有碳纳米管之间的纳米级孔隙、碳纳米管纤维之间的微米级孔隙以及织物结构所拥有的毫米级孔径获得了聚吡咯的高负载量；最终电子能够在碳纳米管织物框架内进行快速传输，而离子能够在织物所形成的各级孔隙中快速移动，从而实现了兼具良好柔性和储能性能的超级电容器。该超级电容器能够承受数百上千次的弯折而不损坏，其活性材料的负载量超过10 mg/cm2，面积比电容大于2000 mF/cm2，预期在柔性电子设备特别是可穿戴电子设备具有广阔应用前景。