Influence of Ionomer Adhesion Ratio of Catalyst Layer on Electrode Characteristics of Polymer Electrolyte Fuel Cell

Abstract

Optimization of the catalyst layer structure is necessary to realize high performance and low cost of a polymer electrolyte fuel cell (PEFC). The catalyst layer is normally composed of Pt/C powder and an ionomer. The adhesion state of ionomer to Pt/C powder not only changes the proton transport route but also influences the microstructure of the electrode, which is an important factor in controlling cell performance. In this study, in order to investigate the adhesion state of ionomer, we developed the new measurement technique of the specific surface area of catalyst layer. The measurement method was based on the gas adsorption method (N 2), and the adhesion ratio of the ionomer was determined from the ratio of the specific surface area before and after removal of the ionomer in the catalyst layer. In addition, the electrode characteristics of the catalyst layer were also measured, and the relationship between the ionomer adhesion ratio and the cell performance was discussed. As a result, it was found that the adhesion ratio of ionomer was correlated with electrode characteristics, meaning that the adhesion ratio of ionomer should be an important parameter for improving cell performance.

Effect of carbon nanotube-based catalyst layer surface roughness on polymer electrolyte membrane fuel cell performance

“…We have reported that a PBI layer coated on the carbon surface facilitated Nafion adsorption and enabled homogeneous ionomer distribution in the CL, 62 thus we consider that ionomer distribution in the MEAs is homogeneous throughout the CL. The ionomer content was evaluated using TGA according to a reported procedure, 55 in which the sheets were heated from 30 to 550 °C under a N 2 flow, followed by isothermal heating at 550 °C for 10 min to allow complete decomposition of the Nafion ionomer. Finally, the sample was heated from 200 to 900 °C under an air flow to decompose the CNTs (Fig.…”

“…The sample was then heated to 900 °C at an air flow rate of 300 mL min −1 and a heating rate of 10 °C min −1 . 55 Transmission electron microscopy (TEM) was performed using a JEM-2010 microscope (JEOL, Tokyo, Japan) operated at 120 kV. X-ray photoelectron spectroscopy (XPS) was performed using an AXIS-ULTRA DLD spectrometer (Shimadzu, Kyoto, Japan).…”

Effect of Surface Roughness of Carbon Nanotube-based Catalyst Layer for Polymer Electrolyte Membrane Fuel Cell Performance

“…for 24 h at 25 °C to incorporate ionomer into the sheets, ionomer content was evaluated using TGA according to the reported procedure 55 , in which the sample was heated from 30 °C to 550 °C under N2 flow, followed by isothermal heating at 550 °C for 10 minutes to allow complete decomposition of Nafion ionomer. Finally, the sample was heated from 200 °C to 900 °C under air flow to decompose the CNTs (Figure S5a).…”