流动状态下聚苯胺纳米纤维的结构精细调控与储能增强机制

Although the application of polyaniline (PANI)–based electrode materials for supercapacitors has shown tremendous promise thus far, some lingering shortcomings prevent the realization of its optimal performance. These limitations include low energy storage density, poor capacitance retention at high charge/discharge rates and poor durability after long term cycling. The molecular and condensed structure of PANI directly affects its energy storage properties. However, the orientated growth and assembly always occurred in same reaction system, as a result, it is difficult to identify clearly the dynamic evolution of the aggregation structures and the synergistic effect of multiple weak interactions. This project is planning to develop a novel method for producing continuously PANI nanofibers by means of the combination of small micro–tube and thick tube. Firstly, the aligned feed of aniline oligomers will be prepared through rapid mixing polymerization in the constricted tube under flowing condition, then the products will be introduced into thick tube, and the growth and assembly of PANI will be tuned precisely through on–line adding of aniline monomers and oxidants and the introduce of non–colvant interactions between building blocks. It is expected that as–prepared PANI nanofibers can possess well dispersibility, high electrical conductivity, high orientation as well as narrow size distribution. The effects of preparation methods and assemble conditions on the structures, ion transport, charge transfer and decay mechanism will be investigated in detail for understanding the influence of micro/nanostructure, interfacial effect and size effect on the energy storage properties. Moreover, the universal relationship between structure and property will be set up based on the knowledge of orientated assembly and enhanced energy storage mechanism of PANI nanofibers. The results will not only enrich the research content of condensed state physics for conjugated polymers, but also bring new ideas for designing the high-efficient and durable electrode materials for supercapacitors.

聚苯胺作为高性能超级电容器电极材料还需克服其比电容较小、倍率特性偏低和循环稳定性较差等瓶颈问题，而其分子与聚集态结构直接影响着其储能特性。但目前聚苯胺的有序生长与组装过程发生在同一体系，难以厘清聚集态结构动态演变及多重弱相互作用协同效应的影响。本工作将发展出一种连续化制备聚苯胺纳米纤维的流动聚合方法，采用粗细管搭配方式，先通过快速混合、空间约束在细管中合成出高品质的纤维状苯胺齐聚物种子；再采用在线添加与非共价键作用精细调控来影响粗管中聚苯胺的生长组装，从而制备出高分散、高电导与高取向的聚苯胺纳米纤维。深入研究制备方法、组装条件对聚苯胺有序结构及其离子迁移、电荷传递和衰减机制的影响，阐明其尺寸效应、界面效应与协同效应对储能特性的影响；明确聚苯胺有序结构的组装机制与储能增强机理，并提炼出普适的构效关系。本研究将丰富共轭高分子本体凝聚态物理的研究内容，并为设计高效耐久的电极材料带来新思路。

在纳米尺度上实现聚苯胺高度有序组装，并能实现结构性能可控和规模化制备，明确其储能特性与纳米结构的依赖关系，是发展性能优异的聚苯胺电极材料及其实用化的关键。通过四年研究，课题组很好地完成了计划任务，取得了如下成果：（1）提出流动种子聚合制备聚苯胺纳米纤维的方法，采用粗细管搭配的流动装置，可对种子的形成（细管内）和纳米纤维的生长（粗管内）进行独立的调控，有利于揭示聚苯胺氧化聚合过程和其纳米结构与储能特性之间的内在联系；而流动空间约束与二次单体在线添加，保证了高品质聚苯胺纳米纤维的规模化绿色制备；（2）通过考察各类无机和有机组分的引入对聚苯胺纳米结构构筑过程的影响并对其进行分子角度的解析，实现了聚苯胺纳米纤维的在线表面修饰和与碳基材料的在线复合；较为深层次地理解聚苯胺纳米纤维制备过程中各种弱相互作用的影响，阐明聚苯胺纳米纤维储能性能的增强机制；（3）提出聚苯胺三维阵列结构的自支撑柔性电极材料的高效制备方法，研究不同尺度、高度有序聚苯胺材料的储能特性，特别是研发平面化全固态超级电容器的柔性电极材料；实现与具有高度稳定性的低维碳材料一体化在线复合，有效地克服了聚苯胺固有的倍率特性和循环稳定性不足等性能缺陷；（4）建立起组装体系中组分间相互作用、物性调控及功能传递的构效分析方法，明确聚苯胺的结构、形貌、维度、尺寸等诸多因素对其电荷传输与存储的影响，厘清高度有序纳米纤维的构筑过程和奇特物性的起因，并为聚苯胺电极材料的高效设计和规模化制备提供强有力的理论和技术指导，有望推进聚苯胺作为储能器件电极材料（特别是在可穿戴电子器件中）实用化进程；（5）目前已发表学术论文17篇，其中SCI收录期刊14篇；申请发明专利2项，其中1项已授权；参加国际学术研讨会4次，共提交会议论文6篇；其他主体工作将在近期发表。培养博士研究生7名（3人已毕业），硕士研究生5名（3人已毕业），其中3人获得国家奖学金。