Advancement of Membrane Technology for Proton Exchange Membrane Fuel Cell (PEMFC) Application

摘要

Nafion? perfluorosulfonic acid (PFSA) copolymer is considered an industry standard membrane material for use in PEMFC applications. However, Nafion? membranes shows conductivity and physical properties limitations to withstand operational conditions under a wide humidity and temperature range as desired by fuel cell developers/ automobile manufacturers. Thinner membranes (<25 μm) are increasingly being used to reduce membrane resistance and hence achieve higher power density. Although, thin membranes offer substantial performance enhancement in fuel cells, but they inherently possess reduced mechanical strength. Under dynamic load cycling the thin membrane may break down due to its inability to handle frequent expansion and contraction cycles under wide ranges of humidity. This problem becomes more evident when low equivalent weight ("EW") PFSA ionomer is used to achieve higher fuel cell performance. Low EW ionomers possess higher concentrations of sulfonic acid and hence possess higher water uptake, leading to further decrease in mechanical properties of the membrane. Thus a low EW thin membrane may show very good performance, but their reduced mechanical strength limits their durability.