Analysis on the PEM fuel cells after accelerated life experiment

After 500 h accelerated lifetime test on an automotive PEM (proton exchange membrane) fuel cell stack, the performance of the cells at the stackʹs foreside is the worst. The electrochemical surface area, internal resistance, particle size and hydrophobic nature of catalyst are measured based on the electrochemical methods, electronic-lens and dropped water test. The results show that the internal resistance increases to double and the average particle diameter increases to 3 times when electrochemically active area surface coefficient decreases to one-fifth. The open circle voltage of the worst cell is 0.7 V and its maximum current density is 200 mA/cm2. Especially, the performance of part at air-outlet is the worst, followed by the part at air-inlet, hydrogen-outlet, and hydrogen-inlet. The phenomenon mentioned above at the inlet of stack is the most serious among all the cells in the stack.