高稳定高兼容性离子凝胶型高温质子交换膜的构筑机理及性能研究

The proton exchange membrane based on ionic liquids (ILs) is a hot research point for high temperature proton exchange membranes, which are core part of high temperature proton exchange membrane fuel cells (HT-PEMFC). However, two problems including ILs incompatibility with Pt-based catalysts and poor retention of ILs in the membranes should be solved. Protic ammonium ILs (PAILs) with controllable structure are constructed on molecular level, which are compatible with Pt-based catalysts. Further, the PAILs are anchored in the silicon gels with three-dimensional network structure to fabricate ionogels-based proton exchange membranes by sol-gel reaction on nanoscale, which show high stability and compatibility. The microstructure, electrochemical characterization and cell performance of composite membranes are researched by modern spectroscopy, electrochemical technology and single cell test. Moreover, combined with density functional theory, the mechanism of compatibility between ILs-based proton exchange membranes and Pt-based catalysts is investigated, and the mechanism of proton conducting and structure-performance relationship are also elucidated. Based on this project, theoretical guidance and experimental support will be developed for high temperature proton exchange membranes with high performance.

高温质子交换膜是高温质子交换膜燃料电池（HT-PEMFC）的核心部件，基于离子液体的高温质子交换膜是其研究热点，但该类膜存在与Pt基催化剂兼容性及离子液体保留能力差的缺陷。本项目首先拟在分子水平上设计结构可控且同Pt基催化剂兼容的质子型铵盐离子液体，并在纳米尺度上通过溶胶-凝胶反应将其“锚定”在三维网络结构的硅凝胶骨架内，形成离子凝胶型复合膜，以提高膜的兼容性和稳定性。然后，利用现代谱学显微技术、电化学方法及单电池测试手段，研究复合膜的微观结构、电化学特性及电池性能；并通过理论计算，阐明离子液体基高温质子交换膜与Pt基催化剂的兼容性机理、质子传导机理及材料构效关系，为开发高性能的HT-PEMFC电解质膜提供理论指导与实验依据。

高温质子交换膜是高温质子交换膜燃料电池（HT-PEMFC）的核心材料，基于离子液体的复合膜是其研究热点之一。本项目首先在分子尺度上设计和合成结构可控的离子液体，并且研究其与Pt基催化剂的兼容性；其次采用溶胶-凝胶法在纳米尺度上制备稳定的离子液体/SiO2离子凝胶复合膜，探索其制备规律，并对其进行物理化学表征。循环伏安法表明离子液体的阳离子对其与Pt的兼容性起决定作用，相比于咪唑和吡啶阳离子，季铵阳离子毒化作用最小，其次CF3SO3-阴离子也具有较低的毒化作用，因此我们重点制备了与Pt具有良好兼容性及优异热稳定性和高电导率的二乙基甲基铵三氟甲基磺酸盐（[dema][TfO]）；研究表明TMOS/HCOOH/[dema][TfO]三者的比例决定了凝胶时间、复合材料的物理化学性质；优化后的离子凝胶复合膜具有良好的热稳定性，可应用于高温质子交换膜燃料电池；质子在复合膜中主要以Grotthuss 跳跃机理传导，100 -200 oC，复合膜电导率可达10-3 S cm-1以上，且具有良好的稳定性。本项目的开展为拓展离子液体基质子交换膜在高温燃料电池中的应用提供了新的思路。此外，在项目基础上也拓展进行了与离子液体具有更好兼容性的非铂催化剂的系统研究。