质子交换膜燃料电池不锈钢双极板表面自修复聚苯胺/聚吡咯复合涂层的制备与机理研究

Proton-exchange membrane fuel cell (PEMFC) is a clean energy power system which has been expected to be the best and ultimate solution for atmospheric pollution and energy shortage. However, traditional graphite bipolar plates of PEMFC are brittle, low-strength, and their processing cost are very expensive. These defects are seriously restricting the mass production and business applications of PEMFC. Stainless steel has high conductivity, high strength, low cost, simple processing, which make it an ideal substitute material for the graphite bipolar plates. But in the acidic PEMFC environments, the oxide layers on stainless steel (SS) will increase the contact resistance and the metal ions penetrating into the proton exchange membrane will decline the conductivity. In the present project, a bilayer conducting composite coating composed of an inner layer of polypyrrole (PPY) and an external polyaniline (PANI) layer is synthesized on stainless steel by electropolymerization. The composite coating obtains self-healing properties and achieves long-term intelligent protection for SS bipolar plates by inhibitor doping. The adhesion, thermal stability, and chemical stability of the composite coating in the PEMFC enviroment are enhanced by the modification of the SS surface and electropolymerization process optimization. We will reveal the polymerization processes and the growth models of the composite coating, clarify the self-healing mechanism, and evaluate its service reliability in the PEMFC environment. This project is expected to lay a strong foundation for the application of the SS bipolar plates.

质子交换膜燃料电池（PEMFC）作为一种清洁能源动力系统有望成为人类解决大气污染和能源短缺的最佳和最终方案。然而，传统石墨双极板加工成本昂贵，脆性大，强度低，严重制约了PEMFC的批量生产和商业应用。不锈钢电导率高，强度高，加工简便且成本低，是替代石墨双极板的理想材料。但在PEMFC酸性环境中，不锈钢表面氧化物层会增加接触电阻；腐蚀产生的金属离子渗入质子交换膜将导致电导率下降。本项目采用电聚合方法在不锈钢表面制备聚苯胺（外层）/聚吡咯（内层）复合涂层，通过缓蚀剂掺杂，巧妙实现复合涂层的自修复特性及其对不锈钢双极板的长效、智能防护；通过不锈钢表面改性和电聚合工艺优化，提高涂层在PEMFC环境中的附着力、热稳定性和化学稳定性。本项目将揭示复合涂层的聚合过程和生长规律，阐明自修复机理，评估复合涂层在PEMFC环境中的服役可靠性，为不锈钢双极板的应用奠定基础。

为了解决不锈钢双极板在质子交换膜燃料电池（PEMFC）环境中长期服役易被腐蚀的技术难题，本项目采用电聚合技术在不锈钢双极板表面沉积PANI、PPY导电聚合物基复合防护涂层。通过特殊质子酸掺杂、纳米改性、与功能物质复合等技术，制备了磷钼酸再掺杂聚苯胺、聚苯胺-聚丙烯酸/聚乙烯亚胺、聚苯胺/氢氧化镍、聚吡咯/氧化石墨烯、聚苯胺/二氧化硅等多种智能、高效的导电聚合物基复合防腐蚀涂层，巧妙实现了导电聚合物复合涂层对不锈钢长效、稳定、智能防护。通过导电聚合物涂层在中性盐环境和酸性环境中的防腐蚀效果和失效机理研究，揭示了导电聚合物涂层的自修复机理。研究表明：PANI涂层中Ni(OH)2的引入可修复PANI自身的多孔缺陷，提高涂层的疏水性，增强涂层对腐蚀性物质的屏障作用。与此同时，Ni(OH)2的引入够降低PANI涂层的还原速率，使PANI的氧化态得以维持，促进涂层/金属界面钝化膜的形成，使涂层表现出优良的防腐蚀性能。本项目为导电聚合物防腐蚀涂层的实际应用尤其是在PEMFC金属双极板上的应用奠定了坚实基础。项目资助期间共发表SCI论文10篇，待发表2篇。项目投入直接经费20万元，支出153972.14元，各项支出基本与预算相符。剩余经费46027.86元，剩余经费计划将用于本项目后续研究。