Boosting Bulk Oxygen Transport with Accessible Electrode Nanostructure in Low Pt Loading PEMFCs

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Polymer electrolyte membrane fuel cells (PEMFCs) offer a sustainable energy solution but face challenges in cost and oxygen transport.
• Sluggish oxygen transport in cathode catalyst layers (CCLs) limits PEMFC performance and efficiency.

Purpose of the Study:

• To investigate the impact of pore size distribution on bulk oxygen transport in PEMFCs.
• To optimize CCL structure for enhanced oxygen diffusion and fuel cell performance.

Main Methods:

• Utilized nano calcium carbonate with varying particle sizes as pore-forming agents.
• Performed physicochemical characterizations and in situ electrochemical measurements.
• Employed Lattice Boltzmann method (LBM) simulations to model oxygen transport.

Main Results:

• Effective oxygen diffusivity initially increases and then decreases with increasing most probable pore size.
• A "sphere-pipe" model was developed to explain bulk oxygen transport mechanisms.
• Both secondary pore size and primary pore number significantly influence oxygen transport.

Conclusions:

• Controlling pore size distribution is crucial for improving bulk oxygen transport in PEMFC CCLs.
• The proposed "sphere-pipe" model provides insights into optimizing CCL architecture for better fuel cell performance.