Active layer of the oxygen cathode in a fuel cell with Nafion and platinum: The role played by the diffusion and ohmic restrictions and the selection of the working thickness of the active layer

Abstract

The basic parameters that characterize the operation of the active layer of a cathode with Nafion are the effective coefficient of the diffusion of oxygen, the effective ionic conductance, and the thickness of the active layer. One of the deficiencies intrinsic to the fuel cells containing Nafion is their extreme sensitivity to the heat and moisture exchange. Nafion demands an optimum degree of humidification. Upon thoroughly draining the active layer of a cathode with Nafion, its effective ionic conductance substantially lowers, and large diffusion restrictions arise following the flooding of pores in the active layer. The goal of this work is to perform a comparison of values of some dimensional characteristics pertaining to the flooded and thoroughly drained active layers of a cathode with similar indicators of an active layer in its optimum (normal) state. It is demonstrated how one should perform the selection of the working thickness of an active layer that would provide for the efficiency of its functioning.