The role of water formation has bee

The role of water formation has been considered to fall into the‘aging’ category as the loss of Pt active surface area and ionomer dissolution of the MEA happen interchangeably. A similar classification applies to the effect of water retention, accumulation andtransport where changes in MEA and GDL properties including membrane swelling, porosity, corrosion of carbon catalyst support and metallic bipolar plates occur during the life-time of PEMFC. Only two factors, such as the formation of cell residual water into ice at subfreezing temperatures and the access of foreign contaminants by external humidification, are classified as catastrophic. These factors can lead to serious consequences such as membrane poisoning and catalytic combustion which cause an immediate termination of the PEMFC operation.