Influence of the electrocatalyst layer thickness on alkaline DEFC performance

Area of Science:

• Electrochemistry
• Materials Science
• Energy Conversion

Background:

• Alkaline direct ethanol fuel cells (DEFCs) are promising for energy applications.
• Minimizing cost while maintaining electrochemical performance is crucial for DEFC commercialization.
• Layer thickness in gas diffusion electrodes (GDEs) significantly impacts fuel cell efficiency.

Purpose of the Study:

• To investigate the influence of anode and cathode layer thickness on DEFC performance.
• To determine the optimal layer thicknesses for enhanced ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR).
• To assess the impact of layer thickness on the overall resistance of the fuel cell.

Main Methods:

• Preparation and characterization of gas diffusion electrodes (GDEs) using scanning electron microscopy (SEM) for layer thickness.
• Electrochemical characterization in a half-cell configuration, including cyclic voltammetry and polarization curves.
• Single cell measurements and electrochemical impedance spectroscopy (EIS) to evaluate performance and resistance.

Main Results:

• Layer thickness significantly influences EOR and ORR activity and overall cell resistance.
• Optimal layer thicknesses were identified for Pt-free catalysts and membranes.
• High maximum power density of 120 mW cm⁻² was achieved with optimized layer thicknesses.

Conclusions:

• Simple half-cell GDE measurements can effectively simulate realistic reaction conditions.
• Optimized layer thicknesses are critical for cost-effective and high-performance DEFCs.
• The study successfully demonstrated the achievement of optimal layer thicknesses and high power density using Pt-free components.