Two-Stage Microporous Layers with Gradient Pore Size Structure for Improving the Performance of Proton Exchange...

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Proton exchange membrane fuel cells (PEMFCs) require efficient gas diffusion layers (GDLs) for optimal performance.
• Controlling the pore structure of microporous layers (MPLs) is crucial for managing water and gas transport within GDLs.

Purpose of the Study:

• To prepare and characterize GDLs with gradient pore size structures using varying amounts of sodium bicarbonate (NaHCO3) as a pore-making agent.
• To investigate the impact of two-stage MPLs and their gradient pore structures on PEMFC performance.

Main Methods:

• Fabrication of GDLs with controlled pore structures in MPLs using NaHCO3.
• Evaluation of GDL properties including conductivity and water contact angle.
• Analysis of pore size distribution and capillary pressure.
• Performance testing of PEMFCs with the developed GDLs under various humidity conditions.

Main Results:

• The developed GDLs exhibited excellent conductivity and hydrophobicity.
• Introducing NaHCO3 modified pore size distribution, increasing capillary pressure and improving water/gas transmission stability.
• The GDL03 sample showed a significant increase in maximum power density (37.1% at 40% humidity, 38.9% at 60% humidity, 36.5% at 100% humidity) compared to a commercial GDL.
• The gradient MPL design facilitated a smooth transition in pore size, enhancing water and gas management.

Conclusions:

• Gradient pore size structures in MPLs are effective in improving PEMFC performance.
• Optimized GDLs with gradient pore structures offer enhanced water and gas management, leading to higher power density.
• This approach presents a promising strategy for developing advanced GDLs for fuel cell applications.