Open Circuit Voltage OCV of the PEMFC

For an electrochemical cell, the electrical work, We, is equal to the change in the Gibbs free energy, AG between products and reactants  

In general, the electrical work (We) produced by the electrochemical reaction is the product of the charge (Q) and the cell voltage ( )  

The total charge transferred in this electrochemical reaction can be calculated according to Equation 21.3  

The fuel cell voltage at an open circuit condition is called the open circuit voltage (OCV). This OCV is defined as the difference between the standard potentials of the cathode (.E ) fhe anode (E ), and its value is 1.229 V at standard conditions. Note that this OCV is strongly dependent on the temperature and pressure. If the fuel cell is loaded with an electrical current, the cell voltage will be lower than the OCV due to the electrode polarizations (or electrode overpotentials). 

In Equations 21.10 and 21.11, as defined before, E and El are the standard cathode and anode potentials, respectively. El is a temperature-dependent constant 

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