Improved Pt-utilization efficiency of low Pt-loading PEM fuel cell electrodes using direct membrane deposition

Breitwieser, Matthias; Klingele, Matthias; Britton, Benjamin; Holdcroft, Steven; Zengerle, Roland; Thiele, Simon

doi:10.1016/j.elecom.2015.09.006

Cited by 55 publications

(45 citation statements)

References 16 publications

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“…In general, the ACLJS method offers excellent performance in terms of both current density at 0.7 V and peak power density, with 1.9 A/cm 2 [38][39][40] However, it should be noted that RSDT is very expensive to implement on the laboratory scale (∼$150,000 USD) and has a significant number of adjustable parameters, which may limit its widespread application in a university or R&D setting, though it remains promising at larger scales. By comparison, the ACLJS is a fairly economic process, where only a small amount of electricity and nitrogen gas are consumed.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of High Performing PEMFC Catalyst-Coated Membranes with a Low Cost Air-Assisted Cylindrical Liquid Jets Spraying System

Peng

Omasta

Rigdon

et al. 2016

J. Electrochem. Soc.

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In this work, a low cost air-assisted cylindrical liquid jets spraying (ACLJS) system was developed to prepare high-performance catalyst-coated membranes (CCMs) for proton exchange membrane fuel cells (PEMFCs). The catalyst ink was flowed from a cylindrical orifice and was atomized by an air stream fed from a coaxial slit and sprayed directly onto the membrane, which was suctioned to a heated aluminum vacuum plate. The CCM pore architecture including size, distribution and volume can be controlled using various flow parameters, and the impact of spraying conditions on electrode structure and PEMFC performance was investigated. CCMs fabricated in the fiber-type break-up regime by ACLJS achieved very high performance during PEMFC testing, with the top-performing cells having a current density greater than 1900 mA/cm 2 at 0.7 V under H 2 /O 2 flows and 700 mA/cm 2 under H 2 /Air at 1.5 bar (absolute) PEMFCs have long been considered to be among the most promising next-generation energy conversion systems for portable devices and transportation vehicles due to their zero or low pollution, high power density and low temperature operation.1-3 However, the widespread commercialization of PEMFCs remains challenged by the high cost of cell assembly and the requirement of durable performance. In the last decade, significant efforts have been launched to make the technology cost competitive and to improve the cell performance by developing new electrocatalysts and lowering the noble metal loading. 4,5 However, the catalyst composition is not the only factor to consider when creating high-performance, low cost PEMFC electrodes.The electrode pore structure plays a critical role in determining PEMFC performance, and it is a direct result of the application method. The electrode porosity and pore size distribution impact reaction kinetics and mass-transport processes, including water management and electron/proton conduction.6-8 Structural optimization can be decisive in reducing performance losses, particularly at low catalyst loading and high current density. 9 In general, the catalyst coated membrane (CCM) method has been found to be superior to the gas diffusion layer (GDL) coating process because CCM fabrication avoids catalyst particles penetrating into the pore network of the GDL, lowering resistance at the interface with the electrolyte. For the CCM method, the catalyst ink can be applied onto the polymer membrane by brushing, screen printing, spraying, reactive spray deposition as well as roll-to-roll methods.6,10-14 Among them, spraying has been commonly employed for CCM fabrication. 11,15,16 However, the effects of spraying conditions on the electrode structure and PEMFC performance are poorly understood in many systems, including the air-assisted cylindrical liquid jets spraying (ACLJS) system.The objective of this work is to investigate the influence of spraying parameters on CCM structure and performance, with a particular focus on the ACLJS system because of its ability to produce very high performance CCMs at...

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Section: Resultsmentioning

confidence: 99%

Fabrication of High Performing PEMFC Catalyst-Coated Membranes with a Low Cost Air-Assisted Cylindrical Liquid Jets Spraying System

Peng

Omasta

Rigdon

et al. 2016

J. Electrochem. Soc.

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“…This MEA fabrication method enables very low membrane resistances below 13 mU cm 2 and therefore high fuel cell power densities beyond 4.0 W/cm 2 with H 2 /O 2 as feed gases at 300 kPa abs and beyond 1.3 W/cm 2 under stoichiometric 1.2/2.0 H 2 /air operation at 300 kPa abs . The high performance was linked to a very low membrane thickness of about 12 mm and an improved interface between catalyst layer and the membrane itself [1,2]. Despite the high power densities another significant difference was identified compared to conventionally cast membranes: The cell polarization measurements in the work of Klingele et al [1] reveal that the ionic resistance increased only slightly at low humidification.…”

Section: Introductionmentioning

confidence: 94%

“…1b) was tightened with a torque of 1 Nm. A detailed description of the sample preparation including the printing process was published previously [1,2]. As reference, we used an N-112 Nafion ® membrane, coated with catalyst layers of identical Pt loading i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 4 1 ( 2 0 1 6 ) 1 1 4 1 2 e1 1 4 1 7 and stacked between the same gas diffusion media (Paxitech SAS).…”

Section: Sample Preparation and Fuel Cell Operationmentioning

confidence: 99%

Water management in novel direct membrane deposition fuel cells under low humidification

Breitwieser

Moroni

Schock

et al. 2016

International Journal of Hydrogen Energy

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Direct membrane depositionNeutron radiography Water management Back diffusion a b s t r a c t Polymer electrolyte membrane fuel cells (PEMFCs) fabricated by direct membrane deposition (DMD) were shown to work even at dry conditions without significant deterioration of the membrane resistance. Here, in situ neutron radiography is used to investigate the water management in those fuel cells to uncover the phenomena that lead to the robust operation under low humidification. A constant level of humidification within the membrane electrode assembly (MEA) of a DMD fuel cell is observed even under dry anode operation and 15% relative humidity on the cathode side. This proves a pronounced back diffusion of generated water from the cathode side to the anode side through the thin deposited membrane layer. Over the entire range of polarization curves a very high similarity of the water evolution in anode and cathode flow fields is found in spite of different humidification levels. It is shown that the power density of directly deposited membranes in contrast to a 50 mm thick N-112 membrane is only marginally affected by dry operation conditions. Water profiles in through-plane direction of the MEA reveal that the water content in the DMD fuel cell remains steady even at high current densities. This is in contrast to the N-112 reference fuel cell which shows a strong increase in membrane resistance and a reduced MEA water content with raising current densities. Thus this new MEA fabrication technique has a promising perspective, since dry operation conditions are highly requested in order to reduce fuel cell system costs.

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“…In this article, we have demonstrated that this resistance is a mass-transport resistance (MTR), which follows a diffusion-type mass 9 dependence. Furthermore, it is shown how a facile hydrogen-pump experiment can be easily employed to quantify this effect, thereby ruling out activation processes, water production, oxide effects, possible peroxide formation, and enhanced heat generation during oxygen limiting-current experiments at low potentials.…”

Section: Resultsmentioning

confidence: 99%

“…[1] Regrettably already for loadings below 0.10 mg Pt /cm² at the cathode side, the performance suffers quite drastically due to a poorly understood local resistance, which is thought to be related to an increased local mass-transport resistance (MTR), although other causes have been proposed as well. [2][3][4][5][6][7][8][9][10][11][12][13] In terms of physical interpretation, the MTR represents the local resistance of a reactant molecule towards reaching an active reaction site, which becomes more significant as the number of reaction sites decrease but the desired overall reaction rate remains the same.…”

Section: Introductionmentioning

confidence: 99%

Polarization loss correction derived from hydrogen local-resistance measurement in low Pt-loaded polymer-electrolyte fuel cells

Freiberg

Tucker

Weber

2017

Electrochemistry Communications

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The reduction of platinum-loading on the cathode side of polymer-electrolyte fuel cells leads to a poorly understood increase in mass-transport resistance (MTR) at high current densities.This local resistance was measured using a facile hydrogen-pump technique with dilute active gases for membrane-electrode assemblies with catalyst layers of varying platinum-loading (0.03-0.40 mg Pt /cm²). Furthermore, polarization curves in H 2 /air were measured and corrected for the overpotential caused by the increased MTR for low loadings on the air side due to the reduced concentration of reactant gas at the catalyst surface. The difference in performance after correction for all resistances including the MTR is minor, suggesting its origin to be diffusive in nature, and proving the meaningfulness of the facile hydrogen-pump technique for the characterization of the cathode catalyst layer under defined operation conditions.

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Improved Pt-utilization efficiency of low Pt-loading PEM fuel cell electrodes using direct membrane deposition

Cited by 55 publications

References 16 publications

Fabrication of High Performing PEMFC Catalyst-Coated Membranes with a Low Cost Air-Assisted Cylindrical Liquid Jets Spraying System

Fabrication of High Performing PEMFC Catalyst-Coated Membranes with a Low Cost Air-Assisted Cylindrical Liquid Jets Spraying System

Water management in novel direct membrane deposition fuel cells under low humidification

Polarization loss correction derived from hydrogen local-resistance measurement in low Pt-loaded polymer-electrolyte fuel cells

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