(53b) Component Degradation and Its Mitigation In Polymer Electrolyte Fuel Cells

Two primary degradation modes that currently limit fuel cell stack lifetime and considerably increase stack cost due to the required over-engineering are: 1) the corrosion of electrocatalyst support during transient operating modes (e.g. start-up / shut-down) resulting in electrode thinning and loss of electrocatalytic activity, and 2) the free-radical-induced oxidative degradation of the electrolyte membrane during PEFC operation, resulting in membrane thinning and pin-hole formation. This talk will provide a brief overview of each degradation mode, explaining how they can led to catastrophic stack failure, and will then present the advances made in our laboratory to offer effective and novel solutions to these seemingly intractable problems.

To mitigate support corrosion, a new class of mixed-metal-oxide supports have been synthesized, characterized, and evaluated in our laboratory. Testing both at IIT and at an automotive OEM has confirmed the exceptional corrosion resistance of this class of supports. To mitigate electrolyte degradation, a novel in-situ-fluorescence-spectroscopy-based technique has been developed in our laboratory to monitor, for the first time, the rate of reactive oxygen species (ROS, specifically OH* and OOH*) formation within the electrolyte of an operating PEFC. Remarkably effective regenerative free radical scavengers have been synthesized and evaluated in our laboratory; these materials, when added to the polymer electrolyte, have lowered the macroscopic rate of oxidative polymer electrolyte degradation by close to 2 orders of magnitude.