Fuel Cell Degradation
Authors:Randy Hughes, Gabriel Jurado
Mentor:Timothy Usher, Doctorate Professor of Physics, Cal State San Bernardino
Fuel cells have become increasingly applicable. A device responsible for providing power for human associated infrastructure must have limits to its operating conditions known. Fuel cells have an advantage of operating reliably until failure. Degradation of reliability is not a gradual decrease, but a catastrophic drop off. This problem is the focus of current research. We approach this problem by running various tests on differently damaged Nafion membranes. A group of six undamaged Nafion membranes, with six degraded Nafion membranes, are tested under various electrical based methods. The first test is a voltage/current graph. This method collects data expressed as voltage vs. current and voltage vs. time. The current interrupt method, which interrupts the constant current, collects data representing current vs. time. Electro impedence spectroscopy, (EIS), runs the fuel cells through a frequency sweep. The sweep ranges from 1Hz through 200kHz. This data is plotted initially with Bode plots, frequency vs. gain, and frequency vs. phase. The Bode plots showed minute differences between treated and non-treated membranes, thus the data was graphed into a Nyquist plot. Under the Nyquist plot the data is displayed with real and imaginary axes, x being real, y being imaginary. Under this representation the differences between damaged and non-damaged membranes are spatially clearer. Initially, on the y-axis, damaged membranes ranged from -15 to -17(ohms) ending at approximately -9, while peaking between 20 and 25 on the x-axis. Non-damaged membranes ranged from -17 to -20, on the y-axis, and peaked between 20 and 30, on the x-axis. These results indicate non-damaged membranes, which have been run over 20 times more than other non-damaged membranes, yield data similar to damaged membranes. Further research will go into determining a relationship between the numbers of trials a non-damaged membrane endures, and how similarly it relates to damaged membranes.