Effects of open-circuit operation on membrane and catalyst layer degradation in proton exchange membrane fuel cells

Abstract

Durability issues have been attracting a great deal of attention in hydrogen/air proton exchange membrane (PEM) fuel cell research. In the present work, membrane electrode assembly (MEA) degradation under open circuit (OC) conditions was carried out for more than 250 h. By means of several on-line electrochemical measurements, the performance of the fuel cell was analysed at different times during the degradation process. The results indicate that structural changes in the PEM and catalyst layers (CLs) are the main reasons for the decline in performance during OC operation. The results also show that degradation due to platinum oxidation or catalyst contamination can be partially recovered by a subsequent potential cycling process, whereas the same cycling process cannot recover the membrane degradation.Crown

Degradation of a polymer exchange membrane fuel cell stack with Nafion® membranes of different thicknesses: Part I. In situ diagnosis

“…Also, from this degradation trend we can see that for all the MEAs with membranes of different thicknesses, the voltage degradation is partially recoverable after an interruption. This is in agreement with our previous degradation tests under idle conditions [26] and OC operation [15].…”

“…For Cell 1 and Cell 2 with thicker membranes, the degradation rate during the first 200 h was much higher than those during the subsequent periods. This phenomenon was also observed in our previous OCV experiment [15], and can be explained by the size effect of the catalyst. At the beginning of degradation, the nano-scale catalyst particles are facile to grow at a relatively high speed under these accelerated conditions.…”

“…Open circuit (OC) operation has also been recognized as an effective stressor for accelerated testing and the accelerated effects of OC operation on the degradation of PEM fuel cell components, including the PEM and catalyst layers, have been investigated [11][12][13][14][15]. The increased gas crossover due to zero reactant consumption under OC conditions was believed to be the major reason for the high degradation rate of the membrane [16].…”

“…Although there has been extensive research into membrane degradation, further understanding is still needed. Previously, we looked at performance degradation of a single cell under open circuit voltage (OCV) [15] and a six-cell stack under idle conditions [26]. In this study, we will report our preliminary results of a four-cell stack degradation using Nafion membranes of different thicknesses, including N117, N115, NR212, and NR211.…”

Degradation aspects of water formation and transport in Proton Exchange Membrane Fuel Cell: A review

“…Others like [70] suggested reducing RH, temperature and hydrogen pressure during PEMFC operation to suppress the hydrogen cross-over mechanism. The influence of fuel and oxidant starvation [71], open circuit operation [72], excessive air bleeding [73], humidity cycling [74,75], load-on/off cycling [76], and freeze/thaw cycling [77] on structural changes of the membrane was also demonstrated. A more detailed analysis of the effect of the operating conditions on the PEMFC durability can be found in [78].…”