Fuel cell failure

In situ cell resistance measurement, ac impedance, gas permeability, postmortem analysis using optical microscopy, SEM, TEM, NMR, IR, X-ray, neutron techniques, and chemical stmctural analysis have been used to investigate fuel cell failure mechanisms. 

Diagnosis of Catalyst Layer Degradation Fuel Cell Failure Analysis... 

Ft (platinum) catalysts supported on a conductive matrix, such as carbon, to provide electron conduction and (3) a hydrophilic agent, such as polytet-rafluoroethylene (PTFE) to provide sufficient porosity and adjust the hydro-phobicity/hydrophilicity of the CL for gaseous reactants to be transferred to active sites [2,3]. With each of those elements optimized to provide the best overall performance, the CL functions as a place for electrochemical reactions. The processes occurring in a CL include mass transport of the gaseous reactants, interfacial reactions of the reactants (e.g., H2 at anode and O2 at cathode) at the electrochemically active sites, proton transport in the electrolyte phase, and electron conduction in the electronic phase. When contaminants are present in the reactant streams, one or more of the above processes can be adversely affected, causing degradation in fuel cell performance or even fuel cell failure. 

The dissociative adsorption of hydrogen sulfide has been shown to occur in the gas phase according to the above reactions at elevated temperatures [49]. Although the conductivity of the solid electrolyte membrane can increase due to oxidation of the adsorbed SH and H2S (i.e., reaction (5.16)), the formation of a stable platinum sulfide film can lead to fuel cell failure [38]. 

Membrane degradation can result in loss of the electrolyte, loss of separator functionality, and severe fuel cell failure. In following sections, three membrane degradation modes—chemical, mechanical, and thermal—are introduced. 

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