Fuel Cells - Proton-Exchange Membrane Fuel Cells

Since proton-exchange membrane fuel cells (PEMFCs) are considered as alternative power devices for automotive applications, cold start-up ability is regarded as an important requirement. Low-temperature polymer fuel cells operating under humid conditions produce water-freezing effects and can cause severe problems. This article gives an overview starting with basic processes occurring during freezing/thawing in the layered structure of membrane, electrode, gas-diffusion layer (GDL) and flow field up to ice blockages in a fuel cell system. Resulting degradation effects of the fuel cell and their influence on transient operation behavior are as well introduced as mitigation strategies by means of optimized operating conditions and fuel cell system architecture. Today operation of PEMFCs and systems under freezing conditions is still a challenge but it is by far not anymore a knockout criterion for commercialization.