Investigation of metal foam porosity and wettability on fuel cell water management by Electrochemical Impedance Spectroscopy

ABSTRACT

Metal foam, as a potential alternative to conventional flow fields in proton-exchange membrane fuel cells (PEMFCs), has been adequately proven to possess high gas uniformity and water storage ability. In this study, various cathode flow fields including meatal foam and conventional parallel and serpentine flow fields are compared experimentally. Meanwhile, electrochemical impedance spectroscopy (EIS) is also used to characterize the impedances as a further evidence of water management capacity for different flow fields. The results indicate that the cell with metal foam can achieve up to over 80% power density than that of the serpentine flow field with one third pressure drop. The porosity selection of metal foam is dependent on the inlet relative humidity (RH) to reduce the polarization loss and maximize the cell performance. The inlet relative humidity is also an important factor to the PTFE loading strategy for effective water removal.

KEYWORDS:

• PEMFCs
• flow field
• metal foam
• eis
• water management

Highlights

Cell performances with different cathode flow fields are experimentally investigated.

Metal foam cell shows a better performance as well as a lower pressure drop.

Metal foam with high porosity reduces the dependence on the inlet humidity.

Proper PTFE coating for metal foam should be chosen for better water management.

Acknowledgments

This research is supported by the China–UK International Cooperation and Exchange Project (Newton Advanced Fellowship) jointly supported by the National Natural Science Foundation of China (Grant No. 51861130359) and the UK Royal Society (grant No. NAF\R1\180146), and the National Natural Science Foundation of Tianjin (China) for Distinguished Young Scholars (Grant No. 18JCJQJC46700).

Additional information

Funding

This work was supported by the the China-UK International Cooperation and Exchange Project (Newton Advanced Fellowship) jointly supported by the National Natural Science Foundation of China and the UK Royal Society [51861130359,NAF\R1\180146]; the National Natural Science Foundation of Tianjin (China) for Distinguished Young Scholars [18JCJQJC46700].