基于水滑石包覆碳纳米管多尺度复合物构建燃料电池用高性能碱性阴离子交换膜

Anion exchange membrane fuel cells have received much attention due to their independence on expensive Pt-based electrocatalysts, which are necessary in traditional proton exchange membrane fuel cells. However, how to simultaneously increase the ionic conductivity and mechanical property of anion exchange membranes is the key factor for the high-performance application of fuel cells. In this project, to resolve this dilemma, a novel composite alkaline anion exchange membrane composed of quaternized poly(phenylene oxide) and Mg-Al layered double hydroxide, an excellent hydroxide ion conductor, coated carbon nanotube (LDH@CNTs) will be designed and prepared. First, LDH@CNTs intercalated with carbonate ion (CO32-) is prepared through an in-situ co-precipitation route. And subsequently, electrically isolated and hydroxide ion conductive LDH@CNTs intercalated with the organic anion (RN+(CH3)2CH2COO-) is fabricated using a facile anion exchange.method. Finally, the composite anion exchange membrane simultaneously possessing high ionic conductivity and mechanical strength is obtained after introduction of LDH@CNTs into quaternized poly(phenylene oxide) matrix. The coating layer of LDH@CNTs can effectively prohibit electron conduction among the nanotubes while be able to act as a new OH- conducting pathway for rapid OH- transport through the.composite membrane. Moreover, the organic anion interlayer can promote the dispersion and interfacial adhesion of LDH@CNTs in quaternized poly(phenylene oxide) matrix, and hereby obviously improve the mechanical strength. The effects of coating structure and thickness of LDH@CNTs, composition of membrane materials on the ionic conductivity and mechanical strength of the composite membrane will be investigated. This project will provide a new methodology of producing high-performance alkaline anion exchange membranes.

为克服传统酸性质子交换膜燃料电池对铂催化剂的依赖，可使用非铂催化剂的碱性阴离子交换膜燃料电池成为了研究新热点。如何同时提高阴离子交换膜的离子电导率和力学强度是电池高性能化的关键。本项目拟结合季铵化聚苯醚和离子导体-镁铝水滑石包覆碳纳米管(LDH@CNTs)寻求一条解决途径。首先利用原位共沉淀法制备碳酸根插层LDH@CNTs，再经离子交换得到有机离子插层LDH@CNTs，最后与季铵化聚苯醚复合得到离子电导率和力学性能兼优的阴离子交换膜。一方面，水滑石包覆既能屏蔽CNTs的电子传导，还能在膜中充当新的OH-传输位点，显著提高其离子电导率；另一方面，有机离子插层能促进CNTs在基体中的分散，增加两者的界面粘结，改善其力学性能。通过研究LDH@CNTs包覆结构和厚度、复合膜组成对阴离子交换膜性能的影响，揭示其离子电导率和力学性能调控规律，为高性能碱性阴离子交换膜材料提供新的研究思路和方法。

为克服传统质子交换膜燃料电池对贵金属催化剂的依赖，可使用非贵金属催化剂的碱性阴离子交换膜燃料电池（AEMFC）成为了研究新热点。作为AEMFC的核心部件之一，阴离子交换膜（AEM）起着传导氢氧根离子以及分隔燃料和氧化剂的双重作用，其性能的优劣直接影响燃料电池的工作性能。如何同时提高阴离子交换膜的离子电导率和力学强度是电池高性能化的关键。. 本项目主要围绕燃料电池用碱性阴离子交换膜面临的共性关键科学问题即离子电导率和机械性能之间存在此升彼降的博弈效应（trade-off效应），以离子传递过程强化和机械性能强化为研究目标，提出了基于二维层片状阴离子导体-水滑石为功能添加物的有机-无机复合阴离子交换膜。通过巧妙设计具有不同多级结构的水滑石复合物，以最大程度暴露水滑石的活性位点和离子传输特性，并深入研究了不同体系高效离子传导网络结构的构筑方法及其实现途径。取得了如下成果：（1）设计制备了基于水滑石包覆CNTs多尺度复合物的阴离子交换膜，研究了包覆结构、包覆的水滑石层片数与所得水滑石包覆无机物的性能之间的关系，为在阴离子交换膜内构筑连续、高效的离子传导通道探索了新方法；（2）设计制备了纳米花状结构的水滑石，充分发挥了水滑石作为优异氢氧根离子导体的功能，促进了无机材料在AEM中应用；（3）以纳米纤维素作为生物质模板，利用其本征矿化能力和空间限域效应构建多层次跨尺度、长程有序的多级结构水滑石复合物，促进膜内连续离子传输通道的搭建，从而显著提高膜的离子电导率；（4）通过内、外场作用结合，设计制备了基于磁场诱导Fe3O4@LDH的复合阴离子交换膜；（5）从构筑密集型离子通道出发，制备了双功能PVDF电纺纤维网络的复合阴离子交换膜，表面高浓度的阳离子基团在连续纳米纤维的辅助下可以形成快速离子传输通路，而无机物包覆的三维连续纤维网络，能起到无机物和纤维协同增强的效果。本项目的研究结果为制备高离子电导率、高化学与机械稳定性的碱性阴离子交换膜材料提供新的理论基础和科学依据。

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