大分子交联型碱性膜内微相分离结构的构筑及其对膜性能的影响机制研究

As the core component, anion exchange membrane (AEM) has always been the focus and difficulty in the development of anion exchange membrane fuel cell (AEMFC), which faces two severe challenges: 1) the low hydroxide conductivity and poor chemical stability; 2) the conflict between ionic exchange capacity (IEC) and mechanical properties. In an attempt to resolve these problems, we are going to construct hydrophilic/hydrophobic micro-phase separation structure in the macromolecular crosslinked AEM, which is realized by introducing a flexible alkyl chain between polymer backbone and ionic conductive group. In this novel AEM, the micro-phase separation structure can improve the conductivity significantly; meanwhile the macromolecular crosslinking network will suppress the swelling of AEM under high IEC, and give rise to high flexibility, toughness and chemical stability in the assistance of micro-phase separation structure. The project will start from the preparation of AEMs. The formation mechanism and property-regulation mechanism of the micro-phase separation structure in the macromolecular crosslinked AEM will be studied by controlling the fabrication conditions and structure parameters of the membrane. On the basis of controllable preparation, performance evaluation and theoretical simulation are employed to investigate the relationship between micro-phase separation structure and performances of the macromolecular crosslinked AEM. The expected results will provide experimental support and theoretical guidance on the design of high-performance AEM, promoting the development and application of AEMFCs.

作为碱性膜燃料电池（AEMFC）的核心部件，碱性膜（AEM）的开发一直是该领域研究的重点与难点，它面临两方面的严峻挑战：1）低的OH-离子电导率和差的化学稳定性；2）离子交换容量（IEC）与机械性能之间此消彼长的矛盾。对此，本项目拟在大分子交联型AEM的聚合物骨架与离子传导基团之间接入柔性烷基长链，构建膜内的微相分离结构，以显著提高膜的OH-离子电导率，同时大分子交联网络能够在高IEC下限制膜的溶胀，并结合微相分离结构的优势赋予膜优良的机械性能与化学稳定性。本项目将从膜的制备入手，通过改变制备条件和膜结构参数，研究大分子交联型AEM中微相分离结构的构建与调控机制。在此基础上，通过性能评价与理论计算，探究微相分离结构对膜宏观性能的影响机制。本项目的完成将在分子水平上为高性能AEM的开发提供实验依据和理论指导，促进AEMFC的发展和应用。

构建交联结构和亲水-憎水微相分离结构是提高阴离子交换膜性能的有效途径。在本课题组前期开发的聚苯并咪唑（PBI）交联的聚乙烯苄基氯（PVBC）交联膜（PBI-PVBC）基础上，本项目首先使用N-甲基哌啶为季铵化试剂，制备了N-甲基哌啶修饰的PBI-PVBC阴离子交换膜，其氢氧根离子电导率可达84 mS/cm（80℃），且具备优良的尺寸稳定性、机械性能和耐碱稳定性。随后，制备了基于三乙烯二胺（DABCO）的环状双季铵离子修饰的PBI-PVBC阴离子交换膜，其表现出了微相分离结构，在最优条件下，氢氧根离子电导率超过90 mS/cm（80℃），且具备优良的尺寸稳定性、机械性能和耐碱稳定性。进一步地，将季铵化聚乙烯亚胺取代PVBC制备了大分子交联膜，其氯离子电导率可超过40 mS/cm（80℃），但耐碱稳定性欠佳。此外，作为与本项目相关的研究方向，课题组开展了碱性析氢催化剂方面的研究，研究了硫化过程中Ni-Co双金属碱式碳酸盐结构的变化，对所得硫化物的催化性能和反应机理开展了系统研究。