Effect of Oxygen Concentration on Current Density Distribution in the Land-Channel Direction

Fundamental study of reactants and products distribution in a proton exchange membrane fuel cell (PEMFC) has always been focus of research. Baker at. el. applied limiting current density as a tool to predict the overall oxygen diffusion resistance from the channel to the catalyst layer. Their results showed that at high current densities operation (relatively wet condition) the oxygen diffusion resistance is much higher than the low current densities operation (relatively dry condition) [1]. However, this method is unable to determine the effect of land-channel geometry on the oxygen diffusion resistance. 

In our previous studies, we have measured the current density distribution in the land-channel geometry at 340 µm resolution and found that in a wet condition, current densities are higher in channel areas than in land areas [2-3].

In this work, we are going to present current density distribution as a function of oxygen concentration in the land-channel direction. This method can be used to obtain local polarization curves at 35 degree C and 100% RH (see attached Figure) under the land and channel. Subsequently, it will be used to measure local limiting currents and can be used to resolve oxygen diffusion resistance distribution in the land-channel direction. Similarly, using hydrogen pumping, in low hydrogen concentration effect of land-channel geometry on the current density distribution can be analyzed. 

References

1. D.R. Baker, D. Caulk, K.C. Neyerlin, M.W. Murphy. J. Electrochem. Soc., 156, B991 (2009).
2. U.N. Shrivastava, K. Tajiri. ECS Trans., 58, 1643 (2013)..
3. U.N. Shrivastava, K. Tajiri. Electrochemistry letters. Submitted.