Experimental Study on OC PEMFC Performance Improvement and MEA Parameter Optimization Under Water Shortage Conditions

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Optimizing membrane electrode assembly (MEA) structure is critical for open-cathode proton exchange membrane fuel cells (OC PEMFCs) performance, especially under water-scarce conditions.
• Gradient ambient temperature significantly impacts MEA performance by affecting cathode catalyst layer hydration, proton conduction, and three-phase boundary formation.
• Increased ohmic and cathode activation resistance, identified through polarization curves and electrochemical impedance spectroscopy (EIS), lead to reduced stack voltage output.

Purpose of the Study:

• To investigate the impact of MEA structural parameters on OC PEMFC performance under simulated water shortage conditions.
• To identify optimal cathode catalyst layer I/C ratio and thickness, as well as gas diffusion layer (GDL) properties, for enhanced fuel cell efficiency.
• To understand the relationship between MEA structure, hydration, and electrochemical performance.

Main Methods:

• Orthogonal experimental design was employed to systematically vary cathode I/C ratio (0.74-0.9) and catalyst layer thickness (8, 12 μm).
• Gas diffusion layer (GDL) thickness (185-324 μm) and pore structure were characterized using mercury intrusion porosimetry (MIP) and Brunauer-Emmett-Teller (BET) analysis.
• Performance evaluation involved polarization curve analysis and electrochemical impedance spectroscopy (EIS) under controlled indoor temperature and humidity.

Main Results:

• An I/C ratio of 0.86, a medium GDL pore structure, and a catalyst layer thickness of 12 μm demonstrated superior performance.
• Optimal MEA configuration achieved a notable output of 700 mA/cm² at 0.62 V for the OC PEMFC.
• Sensitivity analysis confirmed the significant influence of catalyst layer characteristics and GDL properties on overall cell voltage.

Conclusions:

• The study successfully identified key MEA structural parameters that enhance OC PEMFC performance under water-limited scenarios.
• Optimized MEA design, particularly catalyst layer properties and GDL structure, is crucial for mitigating performance degradation due to hydration issues.
• The findings provide valuable insights for designing more robust and efficient OC PEMFCs for applications facing water scarcity.