Revelation of ink solvents influence mechanism in catalyst layer of proton exchange membrane fuel cells

The optimal catalyst layer microstructure is vital for the commercialization of proton exchange membrane fuel cells. Understanding catalyst ink is crucial for achieving this microstructure. This study investigates the effect of solvents on ionomer behavior to establish the relationship between catalyst ink and fuel cell performance. Molecular dynamics simulation results show that the water and n-propanol mixture (NPA-aq) solvent has a stronger binding interaction with the Pt surface compared to other solvents. NPA-aq solvent weakens ionomer adsorption on the Pt surface and creates a porous proton conduction network. The NPA-aq MEA exhibits lower mass transfer resistance than the Water MEA and EG-aq MEA. However, the results of dynamic light scattering show that NPA-aq ink particles aggregate and grow up over time, leading to an increase in the coverage degree of ionomer on Pt surface and reducing electrochemical active surface area. This work provides mechanistic analysis for the solvent selection of the ink with a targeted ionomer control, which is helpful to reduce the mass transfer loss and accelerate the commercialization of fuel cells.