Investigation of Mass Transport Losses in Polymer Electrolyte Electrolysis Cells

In polymer electrolyte electrolysis cells different processes contribute to the losses with increasing current. While the contribution of the ohmic overpotential is well characterized and can easily be determined by measuring the high frequency resistance of the cell, the kinetic and mass transport losses are more difficult to characterize and understand. For determining the mass transport losses, also the kinetic losses need to be characterized, which needs careful analysis in particular when pressure varies over a wide range. The dependence of the mass transport losses is determined as function of the structures employed as current collectors, i.e., possible two-phase phenomena in the porous structures as well as for different operating conditions with respect to pressure and temperature. The results show that over a wide range of current densities a quite significant part of the voltage losses can to be attributed to mass transport.