Review of gas diffusion layer for proton exchange membrane-based technologies with a focus on unitised regenerative fuel cells

Omrani, Reza; Shabani, Bahman

doi:10.1016/j.ijhydene.2018.12.120

Cited by 90 publications

(46 citation statements)

References 301 publications

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“…The expected future depletion of fossil fuels together with the growing attention to environmental issues has been leading to a considerable development of alternative forms of energy. Polymer electrolyte membrane fuel cells (PEMFCs) are one of the most promising clean‐energy generators for both portable and non‐portable devices, due to their high efficiency, low working temperature and zero pollutant emissions . In order to make such systems completely competitive with other forms of energy generators, costs of materials have to be reduced, overall durability enhanced and some technical issues solved.…”

Section: Introductionmentioning

confidence: 99%

Innovative Perfluoropolyether‐Functionalized Gas Diffusion Layers with Enhanced Performance in Polymer Electrolyte Membrane Fuel Cells

et al. 2020

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In this work, perfluoropolyether (PFPE) functionalization was used as hydrophizing treatment for gas diffusion layers (GDLs) in polymer electrolyte membrane fuel cells (PEMFCs), instead of standard PTFE coatings, aiming to enhance the hydrophobicity of the gas diffusion media and to reduce the mass transfer limitations in the final device. Carbon cloth diffusion layers and carbon black were functionalized by decomposition of a PFPE peroxide. PFPE-functionalized carbon black was employed in the preparation of an ink suitable for obtaining microporous layers (MPLs) by deposition onto macroporous backing layers. Dual-layer gas diffusion media showing superhydrophobic behavior due to different hydrophobizing treatments were compared with conventional PTFE-based materials, by testing in a single PEMFC working at two different temperatures and at low and high relative humidity conditions. Such tests demonstrated improved performances over conventional GDLs for pure PFPE-based samples in terms of both overall electrical performance and reduced diffusive limitations in high current density conditions. The maximum output power achieved with the novel PFPE-based compounds was 460 mW cm -2 at 80°C and relative humidity (RH) 100% while the best improvement (10%) with respect to conventional GDLs was realized at 80°C and RH 60%.

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Section: Introductionmentioning

confidence: 99%

Innovative Perfluoropolyether‐Functionalized Gas Diffusion Layers with Enhanced Performance in Polymer Electrolyte Membrane Fuel Cells

et al. 2020

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“…On the other hand, liquid water accumulated at the anode side, can flood the gas diffusion layer (GDL) and hinder the transfer of reactants from the flow fields to the active area . The accumulation of water and nitrogen within the anode channel may result in nonuniform utilisation of the active area and local hydrogen starvation, causing the carbon corrosion in the cathode catalyst layer and hence fuel cell degradation .…”

Section: Introductionmentioning

confidence: 99%

“…20,21 On the other hand, liquid water accumulated at the anode side, can flood the gas diffusion layer (GDL) and hinder the transfer of reactants from the flow fields to the active area. 22,23 The accumulation of water and nitrogen within the anode channel may result in nonuniform utilisation of the active area and local hydrogen starvation, causing the carbon corrosion in the cathode catalyst layer and hence fuel cell degradation. 24,25 In order to prevent these issues, in DEA mode operation, an anode periodic purging arrangement is required to remove impurities from the anode and recover the cell voltage as well as avoiding early stage fuel cell degradation.…”

Section: Introductionmentioning

confidence: 99%

PEMFC purging at low operating temperatures: An experimental approach

et al. 2019

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SUMMARY In this paper, the effect of operating temperature on optimal purge interval for maximum energy efficiency in a proton exchange membrane fuel cell (PEMFC) with dead‐ended anode (DEA) was experimentally investigated. The study was conducted with a focus on challenges associated with operation at temperatures lower than the recommended designed temperature. With DEA, gradual voltage drop happens due to the accumulation of water and impurities such as nitrogen. Hence, periodic purging of the anode side is required to remove excess water and impurities that are accumulated at the anode side over time. Short purge intervals increase hydrogen loss that translates into low fuel utilisation, whereas long purge intervals result in voltage drop due to high water and impurity accumulations. Therefore, an optimal purge strategy should be implemented to maximise the stack energy efficiency. Depending on the operating conditions and loads, there are instances that a fuel cell stack operates at temperatures lower than its recommended designed temperature. Considering the temperature effect on the cell water management, operating temperature is an important factor to consider for optimising the purge strategy in PEMFCs. At lower operating temperatures (ie, below 50°C), more water is formed in liquid form, which makes the optimisation of purge strategy more challenging. For a stack temperature of 40°C, it was observed that with an increase in stack current from 0.25 to 0.45 A cm−2, the optimal purge interval decreases from 90 seconds to around 45 seconds, respectively. Increasing the stack temperature from 40°C to 50°C resulted in an increase in the optimal purge interval to 120 seconds and 90 seconds for stack currents of 0.25 (ie, low current density) and 0.45 A cm−2, respectively. At lower operating temperatures, more frequent purging schedules are needed accordingly to remove the liquid water from the cell. These results indicated that at lower operating temperatures, water accumulation at the anode side becomes more dominant compared with higher operating temperatures.

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“…Sintered metal fibres or powders are of particularly high interest due to their strong mechanical properties that make them suitable for providing mechanical support for other components in applications such as high-pressure water electrolysis [6,9,12]. Sintered metal powders provide porosities lower than 50% [13,14], which is suitable for electrolyser applications [15]; on the other hand, sintered metal fibres can provide porosities higher than 50% that is suitable for applications such as PEMFCs or URFCs [16,17]. In these kinds of applications, the electrical conductivity plays a major role in the performance as higher conductivity translates into lower ohmic losses, and hence higher efficiency.…”

Section: Introductionmentioning

confidence: 99%

Gas Diffusion Layers in Fuel Cells and Electrolysers: A Novel Semi-Empirical Model to Predict Electrical Conductivity of Sintered Metal Fibres

Omrani

Shabani

2019

Energies

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This paper introduces novel empirical as well as modified models to predict the electrical conductivity of sintered metal fibres and closed-cell foams. These models provide a significant improvement over the existing models and reduce the maximum relative error from as high as just over 30% down to about 10%. Also, it is shown that these models provide a noticeable improvement for closed-cell metal foams. However, the estimation of electrical conductivity of open-cell metal foams was improved marginally over previous models. Sintered porous metals are widely used in electrochemical devices such as water electrolysers, unitised regenerative fuel cells (URFCs) as gas diffusion layers (GDLs), and batteries. Having a more accurate prediction of electrical conductivity based on variation by porosity helps in better modelling of such devices and hence achieving improved designs. The models presented in this paper are fitted to the experimental results in order to highlight the difference between the conductivity of sintered metal fibres and metal foams. It is shown that the critical porosity (maximum achievable porosity) can play an important role in sintered metal fibres to predict the electrical conductivity whereas its effect is not significant in open-cell metal foams. Based on the models, the electrical conductivity reaches zero value at 95% porosity rather than 100% for sintered metal fibres.

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Review of gas diffusion layer for proton exchange membrane-based technologies with a focus on unitised regenerative fuel cells

Cited by 90 publications

References 301 publications

Innovative Perfluoropolyether‐Functionalized Gas Diffusion Layers with Enhanced Performance in Polymer Electrolyte Membrane Fuel Cells

Innovative Perfluoropolyether‐Functionalized Gas Diffusion Layers with Enhanced Performance in Polymer Electrolyte Membrane Fuel Cells

PEMFC purging at low operating temperatures: An experimental approach

Gas Diffusion Layers in Fuel Cells and Electrolysers: A Novel Semi-Empirical Model to Predict Electrical Conductivity of Sintered Metal Fibres

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