Unexpected Performance of Inkjet‐Printed Membrane Electrode Assemblies for Proton Exchange Membrane Fuel Cells

Abstract

The effect of the deposition substrate on the performance of inkjet-printed membrane electrode assemblies (MEAs) is investigated. MEAs are fabricated from inkjet-printed catalyst-coated membranes (CCMs), gas diffusion electrodes (GDEs), and a bilateral sandwich of a CCM and a GDE. All MEAs are tested in proton exchange membrane fuel cells (PEMFCs). When a hot-pressing step is included in the MEA construction, the power density achieved with the GDE-based MEA is 1.067 W cm À2 , exceeding that achieved with the CCM-based MEA (0.579 W cm À2 ), and the bilateral sandwich MEA (0.792 W cm À2 ). The origin of the superior performance of the inkjet-printed GDE-based MEAs is investigated through electrochemical impedance spectroscopy and analysis of the microstructure of the printed membranes and electrodes. Atomic force microscopy and energy dispersive X-ray spectroscopy suggest that the greater surface and interfacial areas of the GDE-printed catalyst layer may drive the unexpectedly high performance of the GDE-based MEA as compared with its CCM and bilateral sandwich counterparts. These results provide new insights into the connections between the substrate, inkjet-printed catalyst layer microstructure, and catalyst utilization.

Challenges and Opportunities in Understanding Proton Exchange Membrane Fuel Cell Materials Degradation Using In‐Situ Electrochemical Liquid Cell Transmission Electron Microscopy

“…[42] Composition and physical/chemical properties of the above discussed electrode components, as well as electrodes' microstructure are some of the main factors governing the performance of the PEMFCs. Characterization of the fuel cell components has been used extensively by PEMFC researchers [43] to establish structure-property-performance relationships, including scanning electron microscopy (SEM), [44][45][46] transmission electron microscopy (TEM), [46] X-ray computed tomography (XCT), [45] atomic force microscopy (AFM), [47] X-ray photoelectron spectroscopy (XPS), [48] X-ray absorption spectroscopy (XAS), [49] Raman spectroscopy, infrared (FTIR) spectroscopy, [50] small-angle X-ray scattering (SAXS), X-ray absorption spectroscopy (XAS), [51,52] and on-line induced coupled plasma-mass spectroscopy (ICP-MS). [53] Specifically, TEM and scanning-TEM (STEM) techniques have proven to be of high interests to study catalysts and catalyst layers on a nanometer scale due to their sub-atomic spatial resolution in imaging and diffraction.…”

Longitudinal strand ordering leads to shear thinning in Nafion

“…6 Currently, the creation of CLs and PEMs involves a variety of ink based deposition methods such as electrospray deposition, 8 ultrasonic spraying, 9 screen printing, 10 brush printing, 11 gravure, 12 doctor blading, 13 slot dying, 14 and ink-jet printing. 15 In all of the above cases, either the catalyst ink is deposited on a solid material (PEM or GDL) or the PEM solution is deposited on the CL. 16 Deposition often involves shearing of the material, but the influence of the involved flow on the resulting structure and properties of the deposited material remains largely elusive.…”

Effect of Dispersion Solvents and Ionomers on the Rheology of Catalyst Inks and Catalyst Layer Structure for Proton Exchange Membrane Fuel Cells

“…Notably, the conventional CL is usually prepared from catalyst ink comprising the catalyst, ionomer, and solvent. The catalyst ink is first deposited on the substrate via solution deposition techniques, including ultrasonic spraying, 10 slot-die coating, 11 inkjet printing, 12 electrostatic spraying, 13 and gravure coating, 14 then evaporated, and dried to fabricate a CL. The deposition process of catalyst inks regulates the structure of the CL, including the three-phase interface, 12 pores, 14 Pt utilization rate, 13 and ionomer distribution, 15 thereby affecting the performance of MEAs.…”