Electro-thermal impedance spectroscopy applied to an open-cathode polymer electrolyte fuel cell

Engebretsen, Erik; Robinson, James B.; Obeisun, Oluwamayowa A.; Mason, Tom; Finegan, Donal P.; Hinds, Gareth; Shearing, Paul R.; Brett, Dan J. L.

doi:10.1016/j.jpowsour.2015.10.047

Cited by 27 publications

(23 citation statements)

References 17 publications

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“…Thermocouples can provide a crude measure of temperature inside fuel cells [15][16][17][18], but cannot provide high spatial resolution, and as they need to be inserted inside the fuel cell, this often requires design modifications which may affect reactant flow and fuel cell performance. Infrared thermal imaging can provide very high spatial and temperature resolution [19][20][21][22][23][24], but requires use of modified fuel cells with an infrared transparent window, and/or cells with open channels (such as open-cathode fuel cells [25][26][27][28]) or can only image the outer surface of a cell or stack [29,30]. Combined temperature and current mapping studies allow the impact and interactions of these two parameters on the overall performance to be assessed [17,20,[31][32][33].…”

Section: Current and Temperature Mapping In Fuel Cellsmentioning

confidence: 99%

Nitrogen Blanketing and Hydrogen Starvation in Dead-Ended-Anode Polymer Electrolyte Fuel Cells Revealed by Hydro-Electro-Thermal Analysis

Meyer

Ashton

Torija

et al. 2016

Electrochimica Acta

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Dead-ended anode operation has a number of practical advantages that simplify system complexity and lower cost for polymer electrolyte fuel cells. However, deadended mode leads to performance loss over time which can only be reversed by performing intermittent purge events. This work applies a combined hydro-electrothermal analysis to an air-cooled open-cathode fuel cell, presenting experimental functional maps of water distribution, current density and temperature. This approach has allowed the identification of a 'nitrogen blanketing' effect due to nitrogen crossover from the cathode and a 'bypass' effect where a peripheral gap between the gasket and the GDL offers a hydrogen flow 'short circuit' to the border of the electrode. A consequence of high local current density at the margin of the electrode, and resulting high temperatures, may impact the lifetime of the cell in dead-end mode. KeywordsDead-ended anode; bypass effect; neutron imaging; nitrogen blanketing; current and temperature mapping. IntroductionPolymer electrolyte fuel cells (PEFC) fuelled with hydrogen are among the most promising energy conversion technologies for a broad range of applications, including portable, stationary and automotive power delivery. Dead-ended anode operation enables significant design simplification, with the replacement of humidifiers, and flow controllers by pressure regulators [1]. However, it causes 3 reversible performance decay, and intermittent purging of the anode chamber is required to sustain effective operation. Greater insight into the mechanism of fuel cell operation during dead-ended mode is required in order to optimise the purging programme and ensure that irreversible degradation does not result. In-situ diagnostic techniques provide one of the most effective ways of studying the performance of fuel cells; combined mapping of current density, temperature and water distribution is applied here to give an unprecedented level of understanding into dead-ended fuel cell operation. Current and temperature mapping in fuel cellsInitiated by Cleghorn et al. 4 Combined temperature and current mapping studies allow the impact and interactions of these two parameters on the overall performance to be assessed [17,20,[31][32][33]. However, capturing the water content may provide insights on how the temperature and current density fluctuate, and therefore should ideally be measured at unison. Neutron imaging in fuel cellsNeutron imaging can identify water in the in-plane orientation (with the membrane plane parallel to the beam) and through-plane orientation (with the membrane plane perpendicular to the beam), enabling differentiation of water content in the cathode and the anode [34][35][36] Dead-ended anode operations in an air-cooled open cathode fuel cell.Dead-ended anode operation is a common mode for operating fuel cells as it can simplify the fuel cell system, potentially avoiding flow meters, humidifiers, and drastically reducing hydrogen losses (slippage). It employs a single pressure regulator befor...

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Section: Current and Temperature Mapping In Fuel Cellsmentioning

confidence: 99%

Nitrogen Blanketing and Hydrogen Starvation in Dead-Ended-Anode Polymer Electrolyte Fuel Cells Revealed by Hydro-Electro-Thermal Analysis

Meyer

Ashton

Torija

et al. 2016

Electrochimica Acta

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“…For example, the relationship between electrochemical performance and heat generation, using so-called electro-thermal impedance spectroscopy, has been reported [6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical pressure impedance spectroscopy applied to the study of polymer electrolyte fuel cells

Engebretsen

Mason

Shearing

et al. 2017

Electrochemistry Communications

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The development of novel in-situ diagnostic techniques allows new insight into the internal working of polymer electrolyte fuel cells (PEFCs) so that improved performance can be realised. Electrochemical impedance spectroscopy (EIS) is a widely used characterisation technique that takes advantage of the dynamic relationship between current and voltage to deconvolute critical mechanisms and sources of performance loss occurring with different time constants. Here, we apply electrochemical pressure impedance spectroscopy (EPIS) which examines the transfer function relating reactant gas pressure modulation to the electrical response of the fuel cell. A sinusoidally oscillating perturbation is applied to the cathode backpressure using an innovative loudspeaker arrangement and the resulting voltage 2 perturbation is monitored across a frequency range while the fuel cell is operated in galvanostatic mode. It is shown that the technique can be used to separate the explicit effect of water management from reactant starvation when a PEFC is operated under different reactant humidification conditions. KeywordsElectrochemical pressure impedance spectroscopy; polymer electrolyte fuel cell; backpressure; transfer function analysis; water management; mass transport limitation.

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“…Several studies have reported the efficiency of these polymeric electrolytes based on thermoplastic polymers and ILs for use in electrochemical devices . Peng et al .…”

Section: Introductionmentioning

confidence: 99%

“…used thermoplastic polyurethane and poly(vinylidene‐ co ‐hexafluoropropylene) with a lithium salt for construction of an electrolyte for batteries, obtaining an electrolyte with high conductivity, 6.62 × 10 −3 S cm −1 , and good mechanical stability at room temperature. Thermoplastic polyurethanes were also used to produce supercapacitors with high capacitance and high potential windows . A great drawback of using thermoplastic as polymer electrolytes is their working temperature range, which is limited to the melting point of the polymeric matrix.…”

Section: Introductionmentioning

confidence: 99%

New all solid‐state polymer electrolyte based on epoxy resin and ionic liquid for high temperature applications

Silva

Soares

2017

J of Applied Polymer Sci

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Flexible epoxy network loaded with high amount of ionic liquid (IL) 1‐decyl‐3‐methylimidazolium bromide ([DMIM]Br) has been reported by using a mixture of polyol amine as curing agent. The IL presents good electrochemical response even at 170 °C, as no evidence of redox reactions was observed. The incorporation of as high as 50 wt % of this IL within the epoxy matrix resulted in solid and flexible electrolyte with good thermal stability below 180 °C, as measured by thermogravimetric analysis and ionic conductivity of around 10−6 S cm−1 at room temperature and higher than 10−3 S cm−1 at high temperature. This electrolyte presented a prodigious potential for applications in electrochemical devices at high temperature like batteries and supercapacitors, and the flexibility of this solid electrolyte persist at low temperature because of its low glass transition temperature. Furthermore, leakage problems were not observed. Thereby, impedance spectroscopy and cyclic voltammetry were performed to characterize the electrochemical properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45838.

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Electro-thermal impedance spectroscopy applied to an open-cathode polymer electrolyte fuel cell

Cited by 27 publications

References 17 publications

Nitrogen Blanketing and Hydrogen Starvation in Dead-Ended-Anode Polymer Electrolyte Fuel Cells Revealed by Hydro-Electro-Thermal Analysis

Nitrogen Blanketing and Hydrogen Starvation in Dead-Ended-Anode Polymer Electrolyte Fuel Cells Revealed by Hydro-Electro-Thermal Analysis

Electrochemical pressure impedance spectroscopy applied to the study of polymer electrolyte fuel cells

New all solid‐state polymer electrolyte based on epoxy resin and ionic liquid for high temperature applications

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