22 février 2009
NEUTRONS FOR ANALYZING WATER DISTRIBUTION IN FUEL CELLS
Contact: Gérard Gebel

Closed cell. In the centre, 3 slots for the neutron beam.

Water management is a key issue for optimizing fuel cell operations. A dry polymer membrane induces a drop in performance due to low proton conductivity. An excess of water induces a flooding of the electrodes. A specific fuel cell has been built in collaboration within CEA-LITEN which is transparent to neutrons. The experiments conducted with this cell have answered a crucial question: where is the water within the cell during the operation?

 

The experiments were performed at the Laboratoire Léon Brillouin (Saclay). Water concentration profiles across membrane thickness have been determined as a function of the key operating parameters: Temperature, gas hydration, cycles, cell architecture, stoichiometry…

 

Interior side of a collecting plate showing the gas flow channel

Among the numerous results, the experiments revealed significant differences in the membrane hydration within the cell, for example close to the gas inlets and outlets, or in front of the channels used for gas distribution and the ribs on the current collectors.  It was also possible to separate the contribution of the different processes involved in the mass transport, such as the electro-osmosis (water transported by the protons) or the back diffusion under the concentration gradients between electrodes. These results will be used to validate and optimize the mass transport models used for the optimization of the water management during fuel cell operation.

 

Further reading: G. Gebel, et al., Journal of Power Sources 179 (2008) 132

 

Maj : 20/02/2014 (982)

 

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