Storage of DMFC MEA at Extreme Temperatures

This paper investigates the change in performance of DMFC membrane electrode assemblies (MEAs) after storage at −10°C and 60°C under different experimental conditions. It highlights the importance of methanol concentration, an MEA’s material properties such as membrane material and catalyst loading, as well as the reactivation procedure. Storage at 60°C and concentrations below 1M methanol had no negative effect on MEA performance while storage at 60°C in a 4 M methanol solution could cause a severe performance decrease. Application of a reverse current for 10 s to a MEA which was affected by such storage was found to reinstall original performance. The effect of storage at −10°C on MEA performance strongly depends on MEA properties. MEAs are grouped into three different categories with regard to suitability for low temperature storage: not affected, reversibly affected, and irreversibly affected. The reversibly affected MEAs could be instantly and completely reactivated by reverse current. MEA materials such as various hydrocarbon membranes and high catalyst loadings as well as the manufacturing methods CCM (catalyst coated on the membrane) and CCS (catalyst coated on the substrate) were found to be principally suitable to build MEAs tolerant to storage at −10° C.