燃料电池用聚合物质子交换膜的研究进展

Abstract

质子交换膜（PEM）是质子交换膜燃料电池的核心组件之一，具有隔绝阴阳极、提供质子传递通道和阻止燃料渗透的作用. 商业化应用的全氟磺酸PEM存在燃料渗透严重、高温条件下导电性差和成本高的问题，开发性能优良的聚合物PEM显得很有必要. 本文讨论了近年来聚合物PEM的研究进展，分别从聚合物的主链、支链和交联结构角度介绍了分子结构对薄膜相分离、质子导电性、稳定性和电池性能等性能的影响，并讨论了聚合物分子结构设计方面存在的问题，最后对燃料电池用聚合物PEM在未来的发展方向进行了展望.

Proton exchange membrane (PEM) is one of the key components in PEM fuel cells, which possesses the function of separating the cathode and anode, affording proton transport channels and preventing fuel permeability. The property of PEM significantly influences the performance and service life of fuel cells. Nowadays, the commercially used Nafion membranes have the shortcomings of serious fuel permeability, low proton conductivity at elevated temperature and high price, which limits the rapid development of PEM fuel cells. Therefore, it seems to be urgent to develop novel PEMs with low cost and good comprehensive properties. Polymeric proton exchange membrane is an important developing direction in the research field of PEMs. This review focuses on the recent progresses in polymeric proton exchange membrane from the perspective of molecular structure. The effects of main backbones, side chains and crosslinking networks on the membrane properties, such as phase separation, proton conductivity, stability and cell performance, are analyzed. The existing problems in molecular structure design of polymeric PEMs are also discussed. Finally, an outlook for future developing directions in polymeric proton exchange membrane applied in fuel cells is presented. By comparing the effect of different structures of polymeric PEMs on their properties, it is concluded that the property of polymeric PEMs can be improved by the following three strategies: (1) Preparing block copolymer or locally and densely sulfonated polymers. The method is beneficial for obtaining high proton conductivity by adjusting the structure of main backbones. (2) Grafting functional hydrophilic or hydrophobic side chains. By using the high mobility of side chains, obvious phase separation of PEMs can be obtained as well as high proton conductivity. Polymers containing hydrophobic side chains are widely utilized as anion exchange membranes, however, the studies in polymers containing hydrophobic side chains as PEMs are still few up to now. (3) Preparing fully crosslinking PEMs. The formed crosslinking networks guarantee high chemical and dimensional stabilities of PEMs, which is profitable for the long-time running of PEM fuel cells. The work aims to provide available guidance for the synthesis of novel polymeric PEMs and promote their practical applications.