In Situ Fuel Cell Water Metrology at the NIST Neutron Imaging Facility

2010 ◽  
Vol 7 (2) ◽  
Author(s):  
D. S. Hussey ◽  
D. L. Jacobson ◽  
M. Arif ◽  
K. J. Coakley ◽  
D. F. Vecchia
Keyword(s):  
Fuel Cells ◽  
Water Content ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Neutron Imaging ◽  
Three Dimensions ◽  
Neutron Optics ◽  
Imaging Beam ◽  
Exchange Membrane

Neutron imaging has been demonstrated to be a powerful tool to measure the in situ water content of commercial proton exchange membrane fuel cells (PEMFCs) in two and three dimensions. The National Institute of Standards and Technology neutron imaging facility was designed to produce a high intensity, highly collimated neutron imaging beam to measure the water content of operating fuel cells. The details of the neutron optics and neutron detection are discussed in terms of the random uncertainty in measuring the liquid water thickness that is typical of operating PEMFCs.

scholarly journals Experimental Study on Critical Membrane Water Content of Proton Exchange Membrane Fuel Cells for Cold Storage at −50 °C

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4520
Author(s):  
Xiaokang Yang ◽  
Jiaqi Sun ◽  
Guang Jiang ◽  
Shucheng Sun ◽  
Zhigang Shao ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Water Content ◽  
Cold Storage ◽  
Proton Exchange Membrane ◽  
Membrane Resistance ◽  
Charge Transfer Resistance ◽  
Proton Exchange ◽  
Freezing Damage ◽  
Transfer Resistance ◽  
Exchange Membrane

Membrane water content is of vital importance to the freezing durability of proton exchange membrane fuel cells (PEMFCs). Excessive water freezing could cause irreversible degradation to the cell components and deteriorate the cell performance and lifetime. However, there are few studies on the critical membrane water content, a threshold beyond which freezing damage occurs, for cold storage of PEMFCs. In this work, we first proposed a method for measuring membrane water content using membrane resistance extracted from measured high frequency resistance (HFR) based on the finding that the non-membrane resistance part of the measured HFR is constant within the range of membrane water content of 2.98 to 14.0. Then, freeze/thaw cycles were performed from −50 °C to 30 °C with well controlled membrane water content. After 30 cycles, cells with a membrane water content of 8.2 and 7.7 exhibited no performance degradation, while those higher than 8.2 showed significant performance decay. Electrochemical tests revealed that electrochemical surface area (ECSA) reduction and charge transfer resistance increase are the main reasons for the degradation. These results indicate that the critical membrane water content for successful cold storage at −50 °C is 8.2.

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