石墨烯/短链聚苯胺三维结构调控与超电容性能优化

As a supercapacitor electrode, polyaniline exhibits advantages of high specific capacitance and high specific power. It suffers from low cycling stability. The results of the applicant’s pre-research on aniline tetramer/graphene oxide composites suggest that shot-chain polyaniline shows stronger electrochemical stability. Therefore, we attempt to design and fabricate the three-dimensional strutted graphene/short-chain polyaniline composites (3D-GP). By controlling the length of molecular chain and the structures of molecular aggregation, the stability of polyaniline molecular could be enhanced while the mechanical stability can be improved by coupling the short-chain polyaniline and three-dimensional strutted graphene. At the same time, highly conductive three-dimensional carbon frame will be developed to realize fast transport of electrons and ions as well as high electrochemical activity so as to achieve high cycling stability, high energy density and high power density of polyaniline electrode. The method for controlling the three-dimensional structures, molecular structures and interface structures of 3D-GP will be explored. Understanding on the relationship between the structures and capacitive behaviors of 3D-GP would be improved to reveal the mechanism of performance enhancement by controlling material structure. Our project can provide a new idea for enhancing the cycling stability of polyaniline and other conducting polymers. Furthermore, this work will explore theoretical and experimental fundament on fabricating high performance short-chain polyaniline based electrode materials, which is also important to its practical applications.

超级电容器用聚苯胺电极材料具有高比电容、高比功率等优点，但其循环稳定性差。申请人关于苯胺四聚体/氧化石墨烯的预研结果表明采用短链聚苯胺能增强电化学稳定性。据此，本项目拟开展三维框架支撑石墨烯/短链聚苯胺复合电极材料的设计和制备，通过调控聚苯胺链长与聚集态结构，进一步增强分子结构稳定性，并利用短链聚苯胺与石墨烯间的耦合作用，提高其机械稳定性；同时设计导电性良好的碳三维框架，提供电子和离子快速传输通道并提高其电化学活性，从而解决聚苯胺循环稳定性、功率密度和能量密度不易兼顾的问题。研究复合电极材料三维形态结构、分子结构及界面结构的调控方法；深入认识材料结构与超电容特性之间的关系，揭示结构调控对材料性能的促进机制。本项目不仅为增强聚苯胺及其他导电聚合物的电化学稳定性提供了一种思路，而且为通过结构调控获得综合性能优越的短链聚苯胺基复合电极材料奠定理论和实验基础，对其实用化有重要意义。

电极材料是决定超级电容器性能的关键因素，改善聚苯胺基电极材料结构稳定性对提升其电化学循环寿命，实现实用化具有重要意义。本项目从分子结构、材料复合以及电极层面结构几个方面协同调控，研究其对聚苯胺循环寿命的增强机理，同时研究了材料三维结构对其电化学性能的调控机制。首先通过简单的原位化学氧化法制备了分子链长度不同的四聚苯胺、八聚苯胺以及长链聚苯胺电极材料。研究了分子链长对电化学性能、材料结构以及电荷存储过程中对电极结构的影响机制。研究发现长链和较长链的聚苯胺分子之间相互作用较强，电极的电导率较好，表现出较高的比容量和倍率性能；而四聚苯胺则在循环稳定性方面有一定优势。其次，将分子结构调控、材料复合和自修复功能有机结合起来，协同调控聚苯胺基电极的结构稳定性和电化学循环寿命。基于四聚苯胺/氧化石墨烯的自修复功能器件展现了非常好的电化学循环寿命，经过9000次循环后，电容量仍能保持其初始值的97.5%，同时器件的比容量仍能达到140 F g-1以上。揭示了分子结构调控、材料复合和自修复功能对聚苯胺基电极稳定性的增强机制。再者，通过结构设计，构建了碳纤维支撑三维结构石墨烯/聚苯胺复合电极材料。这种三维一体化结构，有利于实现快速的电子传导和快速的离子扩散，同时能提高聚苯胺负载量，实现了998 F g-1的高比容量；而且组装了非对称超级电容器，获得了50 Wh kg-1的高比能量，并具有良好的倍率性能和循环稳定性。本项目为发展高性能的聚苯胺基超级电容器提供了理论和实验基础。