Which mechanism triggers degradation in polymer electrolyte membrane fuel cells operating at high humidity?

💡 Explanation

When exposed to high temperatures and humidity, the polymer electrolyte membrane undergoes hydrolytic scission because water molecules attack the ester bonds in the polymer backbone, cleaving the polymer chains and reducing mechanical strength. Therefore hydrolytic scission results, rather than catalyst poisoning, electrode delamination or channel blockage which arise by different mechanisms.

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