多级孔结构纤维复合膜微结构调控与质子传递过程强化

The development of highly conductivie proton conductor and the corresponding materials is urgently required for fuel cell technology at present. For obtaining novel structure and highly conductive proton exchange membrane (PEM) and deeply exploring the proton transfer mechanisms, hierarchical porous fiber composite membranes (HPFCMs) will be developed, which could achieve intensified proton transfer ability by optimizing the membrane microstructures and thus enhancing the multiscale synergistic effects. In this project, HPFCMs are employed as platform. More specifically, (1) the preparation and regulation mechanisms of HPFCMs will be investigated. Additionally, the influence of membrane materials and preparation conditions upon the physical structures of HPFCMs will be explored for elucidating the formation mechanism of the micro-nano pores, which in turn would assists to construct novel and controllable membrane structures; (2) the influence of interactions between fiber and filling material upon the chemical environments at the interfacial domains of HPFCMs will be investigated, which is then used to elucidate the formation mechanism of acid-base pairs and the induction mechanism of interfacial interaction upon the arrangement of functional groups; (3) the mechanisms of proton conduction and multiscale synergistic effects during proton migration will be elucidated by investigating the proton conduction property of HPFCMs. In such a way, the relationship between membrane microstructures and proton conduction properties will be proposed. Then, the general methods and theories on proton-transfer intensification will be obtained and high performance PEM will be prepared by optimizing the preparation process (e.g., method and conditions), which have important significance for hydrogen fuel cell. The hierarchical porous materials developed in this project can be utilized in other chemical processes, such as catalysis, absorption, and membrane separation. The results obtained in this project will be of great benefit to the rational design and controllable fabrication of proton conductors and porous materials.

开发高传导膜与膜材料是燃料电池技术的迫切需求。为获得新结构、高传导质子交换膜（PEM）并深化质子传递机理研究，提出“制备多级孔结构纤维复合膜，通过对膜微结构优化来强化多尺度协同作用，实现质子传递过程强化”的思路。项目以多级孔结构纤维复合膜为平台，着重考察：（1）多级孔结构纤维复合膜的制备和调控机制，探索膜材料与制备条件对膜物理结构的影响规律，揭示膜微/纳孔形成机制，创制新结构膜材料；（2）分析纤维与填充材料间作用力对界面处化学环境的影响规律，阐明酸—碱对形成过程及界面相互作用对基团排布的诱导机制；（3）测试膜质子传递性能，揭示质子传递机理及传递过程中多尺度协同作用机制，建立膜微结构与质子传导间的构效关系，丰富传递过程强化的一般性方法与理论，得到高性能PEM，促进氢燃料电池技术发展。项目开发的多孔材料还可应用于催化、吸附以及其它膜分离过程。项目将有助于质子导体及多孔材料的理性构建与可控制备。

质子交换膜作为质子交换膜燃料电池的核心组件，其性能直接决定电池的性能，因此开发高传导膜与膜材料是燃料电池技术发展的迫切需求。本项目结合软模板法和静电纺丝技术制备多级孔结构纳米纤维（HPNF），后填充高分子基质制备多级孔结构纳米纤维复合膜（HPFCM），通过优化膜微结构强化多尺度协同效应，构建三维质子传递网络，实现质子传递过程高效强化和燃料电池性能提升。具体如下：（1）选用疏水型离子液体[Cnmim][Tf2N]作模板，制备平均孔径为4-5 nm的磺化聚醚醚酮（SPEEK）HPNFs，后浇铸壳聚糖（CS）基质制备HPFCM。结果表明：CS上碱性基团诱导SPEEK上磺酸基团在界面处富集行成酸碱对传递通道，复合膜质子传导率显著提升；强烈的酸碱相互作用同时有效提高了膜的热稳定性、抗溶胀性等物化性能。（2）为验证方法通用性，采用离子液体[Cnmim][Tf2N]和Nafion制备HPNF，后填充CS基质制备HPFCM，并系统研究膜的传递各项异性特性。结果表明：在90 oC和100% RH下，HPFCM的垂直向传导率较NFCM提高了3.2倍，传递各向异性显著降低；同时，HPFCM表现出良好的物化性能。（3）利用[Cnmim][Tf2N]（n < 9）在水溶液中自组装形成的20-60 nm胶束，并以此为模板，以水溶性聚乙烯醇和聚乙烯亚胺为前驱体，制备具有大孔径（17-45 nm）和贯穿孔结构的HPNF，后填充SPEEK基质制备HPFCM。结果表明：大的孔径有利于基质均匀充分进入纤维纳米孔，贯穿的孔结构使得膜内行成了更加长程连续的垂直向质子传递通道；在80 oC和100％ RH下HPFCM的垂直向传导率达到561 mS cm-1，远高于传统的纳米纤维复合膜，同时，传递各项异性系数降低到1.08。此外还深入研究了界面相互作用对基团的诱导富集作用及质子在界面处的传导机制。项目的研究成果还有望直接应用于诸如吸附、催化和能量储存等领域相关产品的开发与制备。