Highly Durable Membrane Electrode Assembly with Multiwalled Carbon Nanotubes/CeO₂‐Reinforced Nafion Composite Membrane by Spraying Method for Fuel Cell Applications

Abstract

membrane fuel cells (PEMFCs) use the chemical energy of both hydrogen and oxygen to generate electricity with high efficiency, zero pollution, and rapid start-up/shut-down at relatively low temperatures (<100 °C). [1,2] Because of these attractive characteristics, PEMFCs have considerable potential as power sources for diverse applications, particularly in automobiles; With the motivation, many manufacturers have successfully commercialized these applications. However, some critical issues, such as high cost, insufficient durability, and water management difficulty, still limit further commercialization of PEMFCs in the market. Therefore, to address these issues, novel technological breakthroughs are necessary. Accordingly, the United States (US) Department of Energy (DOE) has set 2025 technical targets for membrane electrode assembly (MEA) in fuel cells. The targets require almost two times prolonged fuel cell durability to 8000 h and reduced MEA cost by 15% compared to those of the current commercial achievement of 4100 h and $11.8 kW −1 . [3] MEA, which is the essential part of PEMFCs, where electrochemical reactions occur, comprises two catalyst layers (anode and cathode) and a proton exchange membrane (PEM).Generally, MEA is manufactured by two representative techniques, [4] i.e., decal transfer and direct coating methods. For the decal transfer process, catalyst ink or slurry is first coated onto the release films. Next, at high pressure and temperature above the glass transition temperature of the PEM, the coated films are transferred to the PEM which is prepared by casting the electrolyte ionomer to the backer film. For the direct coating process, catalyst inks are directly coated onto the PEM by spray coating or ink-jet printing. For these processes, membrane manufacturing and electrode-coating should be separately conducted, and different type of equipment is required for each process. To simplify manufacturing, direct membrane deposition (DMD) method has been extensively studied. [5][6][7][8][9][10] For the DMD process, without the free-standing membrane, PEM is directly coated onto the anode and cathode in which the catalyst layer is coated on a gas diffusion layer (GDL) via a single coating system (e.g., spray or ink-jet), and then layers are assembled after aligning membrane-coated For achieving economically viable polymer electrolyte membrane fuel cells (PEMFCs) in the commercial market, simplifying the fabrication process and manufacturing of robust membrane electrode assembly (MEA) are important. Herein, a single spray-coating method for developing a robust and freestanding reinforced Nafion composite membrane and electrodes is reported. By comparing the fabricated membrane's morphology under diverse process conditions including the nozzle-to-substrate distance and solution-loading rates, the optimized spray-coating for uniformly deposited spray-based membrane without any defects has been determined. To explain this optimized condition, a simple theoretical model based on the concept of the surfa...

Redesign of Anode Catalyst for Sustainable Survival of Fuel Cells

“…MEA Chemical Durability Test under Accelerated OCV Holding Condition: An accelerated OCV holding test was conducted for 120 h by supplying partially humidified H 2 and O 2 with the same flow rate of 300 sccm at 90 °C under RH 30 % condition. [34,64,76] After the OCV holding test, the drain water from the anode and cathode was collected to analyze the concentration of the total eluted fluorine ions. The I-V polarization curves, EIS, and linear sweep voltammetry (LSV) were measured before and after the protocol.…”

Oxygen Plasma-Mediated Microstructured Hydrocarbon Membrane for Improving Interface Adhesion and Mass Transport in Polymer Electrolyte Fuel Cells

“…EIS measurements were conducted under a constant current of 0.1 mA, with an amplitude of 0.01 mA over 1 MHz to 1 Hz by supplying fully humidified nitrogen gas at 70 °C. The membranes’ in-plane conductivities were calculated using the measured EIS resistance and the following equation: σ = L italicRA where L (cm), R (Ω), and A (cm 2 ) represent the distance between the electrodes, resistance of the membrane, and cross-sectional area of the membrane, respectively. The chemical states of the membranes were examined using X-ray photoelectron spectroscopy (XPS) (Kratos, United Kingdom).…”

“…Apertures. The fabrication process of a polymeric stencil has been described in detail in the previous paper 26 and is summarized here. First, to prepare a polydimethylsiloxane (PDMS) mold with microsized pillar arrays (diameter 20 μm), a curing agent and base (Sylgard 184 kit, Dow Corning) were mixed in a weight ratio of 1:10 and poured onto the prepared silicon master with microsized holes (diameter 20 μm) and cured at 80 °C for 1 h. A flat PDMS mold was prepared similarly on a flat silicon master.…”

All sprayed fluorine-free membrane electrode assembly for low-platinum and low-humidity proton exchange membrane fuel cells

“…30,31 Previous studies have shown that a tight attachment between the membrane and catalyst is conducive to improving the catalyst utilization efficiency of the MEAs. [32][33][34] We here systematically studied the effect of Pt loading on the single-cell performance of the two MEAs. Fig.…”