Solvent Effects on the Catalyst Ink and Layer Microstructure for Anion Exchange Membrane Fuel Cells

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• High-performance anion exchange membrane fuel cells (AEMFCs) require optimized catalyst layer (CL) microstructures.
• Solvent effects on ink formulation critically influence CL morphology and fuel cell performance.

Purpose of the Study:

• To investigate the impact of binary solvent systems (water/isopropyl alcohol) on ink and CL microstructures.
• To understand how solvent properties influence ionomer-particle interactions and CL formation.
• To correlate CL microstructure with AEMFC performance.

Main Methods:

• Fabrication of catalyst inks using varying water/IPA ratios with anion exchange ionomer and Pt/C catalyst.
• Characterization of ink and CL microstructures (e.g., pore size, porosity, ionomer distribution).
• Analysis of solvent properties (dielectric constant, solubility parameter) and their correlation with observed microstructures.

Main Results:

• IPA-rich inks lead to large Pt/C-ionomer aggregates and mesopores in the CL.
• Water-rich inks promote a 3D ionomer network, resulting in smaller pores, higher porosity, and homogeneous CLs.
• Solvent dielectric constant and solubility parameter influence particle interactions and surface tension, dictating CL microstructure.

Conclusions:

• Solvent engineering is a key strategy for controlling CL microstructure in AEMFCs.
• Optimized water content in inks leads to improved CL morphology and potentially enhanced AEMFC performance.
• This study provides insights for rational design of AEMFC components.