Preparation, <i>ex situ</i> and <i>in situ</i> Characterization of Gas Diffusion Media Containing and Non‐Containing Carboxymethylcellulose for PEM Fuel Cells

Latorrata, Saverio; Stampino, Paola Gallo; Cristiani, Cinzia; Dotelli, Giovanni

doi:10.1002/fuce.201400054

Cited by 5 publications

(10 citation statements)

References 39 publications

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“…Figure 9 shows polarization and power density curves, at each operating condition, of FEP-12 and of CMC-treated GDM with the same FEP content (hereafter named CMC-FEP-12). In this figure, it is evident that the presence of CMC on the MPL surface (which has been inferred by observing CMC thermogravimetric analysis, reported in Figure S3, Supplementary Materials) is effective in improving slightly electrical performance at low cathodic RH, both at 60 • C and 80 • C. This was also an important finding of authors' previous works [53,55] which used CMC as a rheological controller of PTFE-based inks for MPLs deposition. Such behavior at low RH may be ascribed to the hydrophilic nature of CMC which acts as a water reservoir leading to a better hydration of the polymeric membrane; accordingly, a higher proton conductivity and a lower ohmic resistance are obtained.…”

Section: Accelerated Stress Tests (Asts)supporting

confidence: 68%

“…On the basis of previous works by the authors [53,54], MPLs were prepared from inks containing, as carbonaceous phase, both carbon black (Vulcan XC72R from Cabot Italiana S.p.A., Ravenna, Italy) and multi-wall carbon nanotubes (CNTs, NTX1 (Nanothinx S.A., Patras, Greece)) [28]. The latter (10% by weight) were used to make final coatings more conductive [5] than those based on the unique pure carbon black (CB) [5].…”

Section: Preparationmentioning

confidence: 99%

“…Energies 2017, 10, 2063 3 of 16 these new GDMs following the procedure developed in [53] and then they were electrochemically tested and compared to FEP-based samples.…”

Section: Preparationmentioning

confidence: 99%

“…Constant phase elements (CPE) were used instead of pure capacitances to consider the capacitive losses [5] due to porosity of electrodes [12,47]. Moreover, carboxymethylcellulose (CMC) (Lamberti S.p.A., Albizzate, Italy), a well-known rheology controller and wettability modulator, which has already been used in this field [53,55,56], was also employed to consolidate surface layers improving adhesion between MPL and GDL and to enhance durability of the best performing FEP-based MPLs. Accordingly, the prepared MPL was additionally surface-treated with a CMC (0.75% by weight) solution, which was sprayed onto the MPL side (i.e., the one facing the electrode within the fuel cell), followed by a drying process at 120 °C for 30 min.…”

Section: Characterizationmentioning

confidence: 99%

“…The latter is a carbon-based hydrophobic film which is directly deposited onto the GDL. In the scientific literature, it is well-established that its use leads to a following the procedure developed in [53] and then they were electrochemically tested and compared to FEP-based samples.…”

Section: Introductionmentioning

confidence: 99%

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Performance Evaluation and Durability Enhancement of FEP-Based Gas Diffusion Media for PEM Fuel Cells

et al. 2017

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Nowadays, micro-porous layers (MPLs) for polymer electrolyte membrane fuel cells (PEMFCs) are commonly deposited onto gas diffusion layer (GDL) substrates starting from hydrophobic carbon-based dispersions. In this work, different quantities of fluorinated ethylene propylene (FEP), a fluorinated copolymer proven to be superior to polytetrafluoroethylene (PTFE) for a proper water management, were used to make both GDL and MPL hydrophobic. After the identification of the optimal amount of FEP, carboxymethylcellulose (CMC) was also added to gas diffusion media (GDM) to reduce overall ohmic resistance of the whole device and adhesion of MPLs to GDLs. Ex-situ chemical and mechanical accelerated stress tests (ASTs) were carried out to accelerate degradation of materials aiming to assess their durability. The highest quantity of FEP in GDMs led to the best electrochemical and diffusive properties. The presence of CMC allowed reducing overall ohmic resistance due to a better electrolyte hydration. A satisfactory durability was proven since the fundamental properties related to gas diffusion medium, such as wettability, ohmic and mass transport resistances, revealed to be quasi-stable upon ASTs.

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Section: Accelerated Stress Tests (Asts)supporting

confidence: 68%

Section: Preparationmentioning

confidence: 99%

“…Energies 2017, 10, 2063 3 of 16 these new GDMs following the procedure developed in [53] and then they were electrochemically tested and compared to FEP-based samples.…”

Section: Preparationmentioning

confidence: 99%

Section: Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Performance Evaluation and Durability Enhancement of FEP-Based Gas Diffusion Media for PEM Fuel Cells

et al. 2017

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Optimization of the Perturbation Amplitude for Impedance Measurements in a Commercial PEM Fuel Cell Using Total Harmonic Distortion

2016

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Abstract:One of the most important measurement parameters in electrochemical impedance spectroscopy (EIS) is the perturbation amplitude. The optimum perturbation amplitude value corresponds with a balance between the signal-to-noise ratio improvement and the reduction of the harmonic generation due to nonlinear effects: Therefore, the optimum perturbation amplitude is the maximum amplitude that ensures a linear response of the system. Two strategies were considered in this work: a constant amplitude strategy and a frequency dependent amplitude strategy. On the one hand, for the constant amplitude strategy, the optimum perturbation amplitude for EIS measurements of an individual cell of a commercial PEM fuel cell stack was determined. In order to fulfill this aim, the impedance spectra (at different DC currents) of the individual cell of the commercial PEM fuel cell stack were measured using different perturbation amplitudes. The total harmonic distortion of the recorded voltage signal was determined in each case, applying a FFT based method. The optimum amplitude for each DC current corresponds to the amplitude that minimizes the critical total harmonic distortion value. On the other hand, for the frequency dependent amplitude strategy, the optimum amplitude at each frequency for EIS measurements of an individual cell of a commercial PEM fuel cell stack was determined.

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A 3D Simulation of Single-Channel High-Temperature Polymer Exchange Membrane Fuel Cell Performances

et al. 2019

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The fuel cell is an electrochemical energy converter that directly converts the chemical energy of the fuel into electrical current and heat. The fuel cell has been able to identify itself as a source of clean energy over the past few decades. In order to achieve the durability and stability of fuel cells, many parameters should be considered and evaluated Therefore, in this study, a single-channel high-temperature polymer exchange membrane fuel cell (HT-PEMFC) has been numerically simulated in three-dimensional, isothermal and single-phase approach. The distribution of the hydrogen and oxygen concentrations, as well as water in the anode and cathode, are shown; then the effect of different parameters of the operating pressure, the gas diffusion layer porosity, the electrical conductivity of the gas diffusion layer, the ionic conductivity of the membrane and the membrane thickness are investigated and evaluated on the fuel cell performance. The results showed that the pressure drop in the cathode channel was higher than the anode channel, so that the pressure drop in the cathode channel was higher than 9 bars but, in the anode channel was equal to 2 bars. By examining the species concentration, it was observed that their concentration at the entrance was higher and at the output was reduced due to participation in the reaction and consumption. Also, with increasing the operating pressure, the electrical conductivity of the gas diffusion layer and ionic conduction of the membrane, the performance of the fuel cell is improved.

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Preparation, ex situ and in situ Characterization of Gas Diffusion Media Containing and Non‐Containing Carboxymethylcellulose for PEM Fuel Cells

Cited by 5 publications

References 39 publications

Performance Evaluation and Durability Enhancement of FEP-Based Gas Diffusion Media for PEM Fuel Cells

Performance Evaluation and Durability Enhancement of FEP-Based Gas Diffusion Media for PEM Fuel Cells

Optimization of the Perturbation Amplitude for Impedance Measurements in a Commercial PEM Fuel Cell Using Total Harmonic Distortion

A 3D Simulation of Single-Channel High-Temperature Polymer Exchange Membrane Fuel Cell Performances

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