Reduced anode reactant pressures

The measured cell voltage of 0.8 V, which serves as a performance benchmark, can be resolved into the various contributions of anode and cathode overpotential, Nemst corrections for gaseous reactants under non-standard conditions, and IR losses in the separator, anode and bipolar plate (Table 2). The open circuit potential (Fig. 2) is calculated to be 1.12 V at the reduced CO2 partial pressure resulting from Boudouard corrosion at 750°C. From this we subtract first the 100 mV polarization required to bring the anode into the potential regime of the C/ CO2 electrode. 

The membrane has two functions. First, it acts as the electrolyte that provides ionic conduction between the anode and the cathode but is an electronic insulator. Second, it serves as a separator for the two-reactant gases. Some sources claim that solid polymer membranes (e.g., sulfonated fluorocarbon acid polymer) used in PEMFC are simpler, more reliable, and easier to maintain than other membrane types. Since the only liquid is water, corrosion is minimal. Pressure balances are not critical. However, proper water management is crucial for efficient fuel cell performance [6]. The fuel cell must operate under conditions in which the by-product water does not evaporate faster than it is produced, because the membrane must be hydrated. Dehydration of the membrane reduces proton conductivity. On the other hand, excess of water can lead to flooding of the electrodes. 

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