Solvent effect on the Nafion agglomerate morphology in the catalyst layer of the proton exchange membrane fuel cells
By Kim, Tae-Hyun; Yi, Jae-You; Jung, Chi-Young; Jeong, Euigyung; Yi, Sung-Chul
Published in International Journal of Hydrogen Energy
2017
Abstract
Abstract In this work, we investigated the influence of the solvents used in the catalyst ink on performance of the proton exchange membrane fuel cells (PEMFCs). The mobility of the polymeric chains in 2.5 wt% Nafion dispersion is measured by fluorine-19 nuclear magnetic resonance after the use of different organic solvents including isopropyl alcohol (IPA), dimethyl sulfoxide (DMSO) and N-Methyl-2-pyrrolidone (NMP). Subsequently, the electrochemical properties, e.g., direct-current polarization and electrochemical impedance spectra, are characterized. As a result, the catalyst layer fabricated from the solvents with high main-chain mobility created more intimate contact at triple-phase boundary, enlarging the electrochemically available surface area and reducing the charge-transfer resistance, mainly due to a strong interaction between solvent molecule and Nafion ionomer. It is demonstrated that the use of the membrane electrode assemblies (MEAs) fabricated from NMP- and DMSO-based catalyst inks enable a H2/O2 {PEMFC} to yield 100% and 33% higher power densities at 0.6 V, respectively, as compared to the {MEA} fabricated from IPA-based catalyst ink.