Yu. G. Chirkova,z and V. I. Rostokinb
aFrumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
bNational Research Nuclear University “Moscow Engineer Technical Institute,” Moscow, Russia
Received September 8, 2011
Abstract—The active layer of the cathode of a fuel cell with polymer electrolyte (Nafion) is considered. The
optimum carbon support structure is constructed using computer simulation: its carbon “skeleton” possesses
the maximum outer surface area and provides electronic conductivity of the grains, support cubes, along the
three coordinate axes. Nafion is absent in the support grain, so that the grain is capable of participating only in
the transport of oxygen molecules, it possesses no proton conductivity. An estimate of all parameters of an opti-
mum support grain is provided; in particular, the value of the effective Knudsen diffusion coefficient of oxygen
is established. After this, effective proton conductivity and effective Knudsen diffusion coefficient are calcu-
lated already on the whole active layer scale, according to the model of equally sized cube grains of three types.
In conclusion, the overall current in the active layer of a cathode with a polymer electrolyte was calculated for
the percolation cluster consisting only of Nafion grains and the Knudsen diffusion of oxygen created only by a
combined gas percolation cluster consisting of void grains and all support grains. The overall current value for
t = 80C and pressure of p* = 101 kPa proved to be low, hundreds of mA/cm2. The current value can apparently
be increased to several A/cm2 if the support grains are developed that would simultaneously possess both proton
conductivity and ability to sustain oxygen diffusion.
Keywords: fuel cell with polymer electrolyte, active layer, computer simulation, model of equally sized grains of
three types, optimum structure of the carbon support grain, combined percolation cluster, Knudsen diffusion
DOI: 10.1134/S1023193513020055
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