Influence of the Sintering of Electrocatalysts and Decrease of Proton Conductivity on the Current-Voltage Performance in the High-Temperature Proton Exchange Membrane Fuel Cells (HT-PEMFC)

The relevance of the sintering of electrocatalysts and voltage drops of HT-PEMFC was theoretically evaluated under the non-humid conditions at 150 °C, 170 °C and 190 °C. The degree of agglomeration of electrocatalysts over time simulated by three-dimensional kinetic Monte Carlo method was compared and quantitatively agreed with experimentally measured Transmission Electron Microscopy (TEM) results. Agglomeration of electrocatalysts leads to the loss of the electrochemically active surface area. It was found to be occurred more severe as temperature increased. Decreasing rate of the proton conductivity was calculated based on the tortuosity of the proton pass. The more the phosphoric acid was evaporated, the more tortuous the proton path became. A theoretical breakdown of the voltage drops indicated that the deterioration of electrocatalysts impacted on the earlier several hundreds of hours. The decrease in the voltage at the latter stage was due to mainly the decrease in the proton conductivity.