Electrochemical and thermodynamic modeling of PEM electrolyzer performance: A comparative study with and without diffusion overpotential

In this paper, a mathematical model is developed, combining thermodynamic and electrochemical models. It was
used to study the effect of operating parameters, such as membrane thickness and operating temperature on the
performance of PEM electrolzer cell. The effect of ion diffusion through the membrane on the cell potential was
also studied. In addition, an analyze of energy and exergy efficiencies is carried out by studying the variation in
electrical energy required to operate the PEM electrolyzer cell. This is directly proportional to the efficiencies.
Moreover, a thermal energy due to heat produced by overpotentials is analyzed for different parameters.
Comparing the two scenario (with and without diffusion), the results show that the diffusion overpotential increases
with current density and leads to higher cell potential, which therfore requires more electricity to operate
the electrolyzer. As results, the efficiency of the electrolyzer decreases, as more energy is required to overcome
these overpotentials, and additional irreversible heat losses generated.