In situ analysis of water management in operating fuel cells by confocal Raman spectroscopy

A fuel cell has been specially designed for the study of the water management in situ and operando by confocal micro-Raman spectroscopy. Water concentration profiles across the working Nafion® membrane have been extracted for different operating conditions. The characterisations performed in front of the gas distribution channel show an extreme sensitivity of the membrane water content to the local relative humidity. Electrochemical impedance spectroscopy measurements, carried out in parallel, reveal that these averaged values can be misleading when used to obtain information on the local membrane hydration state.

Research Highlights
► The water management in PEMFC has been studied operando by confocal micro-Raman spectroscopy.
► Water concentration profiles accross Nafion® membrane was recorded under different operating conditions.
► Transverse water profiles vary with temperature, current density and local relative humidity.
► Global resistance measurements can be misleading to obtain information on the local membrane hydration level.