Effect of extended short-circuiting in proton exchange membrane fuel cells

To decrease the cost of fuel cell manufacturing, the amount of platinum (Pt) in the catalyst layer needs to be reduced. In this study, ionomer gradient membrane electrode assemblies (MEAs) were designed to reduce Pt loading without sacrificing performance and lifetime. A two-layer stratification of the cathode was achieved with varying ratios of 28 wt. % ionomer in the inner layer, on the membrane, and 24 wt. % on the outer layer, coated onto the inner layer. To study the MEA performance, the electrochemical surface area (ECSA), polarization curves, and electrochemical impedance spectroscopy (EIS) responses were evaluated under 20, 60, and 100% relative humidity (RH). The stratified MEA Pt loading was reduced by 12% while maintaining commercial equivalent performance. The optimal two-layer design was achieved when the Pt loading ratio between the layers was 1:6 (inner:outer layer). This MEA showed the highest ECSA and performance at 0.65 V with reduced mass transport losses. The integrity of stratified MEAs with lower Pt loading was evaluated with potential cycling and proved more durable than the monolayer MEA equivalent. The higher ionomer loading adjacent to the membrane and the bi-layer interface of the stratified catalyst layer (CL) increased moisture in the cathode CL, decreasing the degradation rate. Using ionomer stratification to decrease the Pt loading in an MEA yielded a better performance compared to the monolayer MEA design. This study, therefore, contributes to the development of more durable, cost-effective MEAs for low-temperature proton exchange membrane fuel cells.

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Ionomer content effect on charge and gas transport in the cathode catalyst layer of proton-exchange membrane fuel cells

Journal of Power Sources ◽

10.1016/j.jpowsour.2021.229531 ◽

2021 ◽

Vol 490 ◽

pp. 229531

Author(s):

Yurii V. Yakovlev ◽

Yevheniia V. Lobko ◽

Maryna Vorokhta ◽

Jaroslava Nováková ◽

Michal Mazur ◽

...

Keyword(s):

Fuel Cells ◽

Proton Exchange Membrane ◽

Gas Transport ◽

Catalyst Layer ◽

Proton Exchange ◽

Cathode Catalyst ◽

Cathode Catalyst Layer ◽

Exchange Membrane

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Effects of flow distributor geometry and diffusion layer porosity on reactant gas transport and performance of proton exchange membrane fuel cells

Journal of Power Sources ◽

10.1016/j.jpowsour.2003.07.017 ◽

2004 ◽

Vol 125 (1) ◽

pp. 27-39 ◽

Cited By ~ 58

Author(s):

W.M. Yan ◽

C.Y. Soong ◽

Falin Chen ◽

H.S. Chu

Keyword(s):

Fuel Cells ◽

Diffusion Layer ◽

Proton Exchange Membrane ◽

Gas Transport ◽

Proton Exchange ◽

And Performance ◽

Exchange Membrane ◽

Flow Distributor ◽

And Diffusion

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Design Concepts for Directed Exit Flow in Micro Fuel Cells

2nd International Conference on Fuel Cell Science, Engineering and Technology ◽

10.1115/fuelcell2004-2477 ◽

2004 ◽

Cited By ~ 1

Author(s):

Wei Shi ◽

Sang-Joon Lee

Keyword(s):

Fuel Cells ◽

Proton Exchange Membrane ◽

Gas Diffusion ◽

Proton Exchange ◽

Operating Conditions ◽

Design Concepts ◽

New Concepts ◽

And Performance ◽

Electronic Load ◽

Exchange Membrane

Miniature and micro fuel cells continue to advance as promising alternatives for efficient and portable electric power. This paper presents a study of experimental modifications to the exit flow configuration of microchannels used in small proton-exchange-membrane fuel cells. New concepts for exit geometry are presented, which promote effective water removal and provide reactant back-pressure in an efficient and self-contained manner. Cell assembly is designed such that reactants must necessarily flow laterally through the gas diffusion electrodes near the exit, rather than simply pass over the free backside surfaces of these electrodes. Multiple prototypes were produced using microfabrication techniques with channel sizes of 100 and 200 microns, and performance was tested using a hydrogen-air test station with programmable electronic load. One of the new concepts in particular showed a marked improvement from 28 mW/cm2 peak power density under baseline conditions to 37 mW/cm2 for the modified design under similar operating conditions. The design offers an opportunity for higher performance in miniature fuel cells with low gas consumption and no additional cost.

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