流道脊表面微结构可嵌入气体扩散层的复合双极板研究

Aiming at the current state that there is no mass production of bipolar plates both domestically and abroad, which hinders commercialization of proton exchange membrane fuel cell stacks, and in order for acquiring low surface contact electric resistance with gas diffusion layers (GDL) and high electric conduction, a structurally novel graphite/resin composite bipolar plate on top of its flow-field lands standing up a layer of carbon fiber whiskers is proposed. By means of the new structure, composite bipolar plates are explored to be made, welded and treated on their flow-field lands using industrially automatic techniques being intended to achieve mass production abilities of bipolar plates. Researches will be focused on influences of the flow-field land surface microstructure and the whole plate structure on properties of the bipolar plate and properties of their single cell and stacks. Plastics forming, liquid honing and thermal welding, the readily available techniques in industry, will be investigated to prepare the novel bipolar plate and its cell and stack assembly. The carbon fiber whisker layer on the flow-field land will be able to embed into surface of the GDL, forming a transition carbon fiber layer between the plate and GDL. The transition layer can not only significantly reduce the contact resistance between the plate and the GDL, but also enhance transmission rates of electrons, ions and gas reactants. The enhancement can largely prevent the catalyst layer from disconnecting and falling and microstructure of the three-phase reaction area from altering inside the membrance electrode assembly due to the electrode wriggling and, therefore, increase efficiency and lifetime of the fuel cell stack. Uses of low price and low density materials and automatic techniques allow bipolar plates and their cell stacks to be of high power density and low cost.

针对国内外双极板尚无批量化生产能力这一制约燃料电池堆商业化瓶颈的现状，以降低双极板与气体扩散层接触电阻和降低复合双极板电阻为出发点，提出一种流道脊表面带有碳纤维绒毛的石墨/树脂复合双极板。通过该新型结构，探索双极板成型、流道脊表面处理以及热熔焊接的自动化技术。重点研究流道脊表面微结构和双极板整体结构对双极板性能以及由该双极板组成的单电池和电堆性能的影响；探索将工业上成熟的热塑性树脂成型技术、液体珩磨技术和热塑焊接技术用于研制可热熔焊接的复合双极板。所提出的流道脊表面微结构能够嵌入气体扩散层表层，在二者之间形成碳纤维过渡层，不仅可以显著降低二者之间的接触电阻，而且能够提高电池内电子、离子和气体反应物的传递速度，减少由于电极蠕动而造成的催化剂脱节、掉落和三相反应区域微结构的变化，从而提高燃料电池效率和寿命。价格低、密度小的原材料和自动化技术对提高电池的功率密度和降低成本具有重要意义。

本课题以降低双极板制备成本、储备双极板自动化生产技术为宗旨，研究了一种流道脊表面富含碳纤维绒毛的新型结构的复合双极板，并探索了将工业上成熟的热熔成型技术用于该双极板的制备。研究内容含四个部分：（1）碳纤维增强的高导电石墨/树脂复合材料的制备与原材料优化，（2）表面富含碳纤维绒毛的复合材料制备与性能研究，（3）双极板流场结构优化及其对质子交换膜燃料电池性能的影响。研究结果表明，经过原材料和制备参数优化的石墨/碳纤维/聚丙烯复合材料的导电性和机械强度满足要求，复合材料的表面碳纤维绒毛能够明显降低其表面接触电阻，经过流场结构优化的双极板提高了质子交换膜燃料电池的性能。研究成果包括申请发明专利1项，发表学术论文6篇，其中SCI检索论文3篇，EI检索论文2篇，北大中文核心期刊1篇，研究工作具有的理论意义和潜在的应用价值。