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A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A5: Hydrogen Energy".

Deadline for manuscript submissions: closed (20 October 2020) | Viewed by 47254

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Special Issue Editors

Prof. Dr. Massimo Viviani

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Guest Editor

Istituto di Chimica della Materia Condensata e di Tecnologie per l’Energia (ICMATE)—Consiglio Nazionale delle Ricerche (CNR), c/o DICCA-UNIGE, Via all’Opera Pia 15, 16145 Genova, Italy
Interests: electroceramics; SOFC; solid state chemistry; impedance spectroscopy; nanomaterials

Dr. Antonio Barbucci

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Guest Editor

Department of Civil, Chemical and Environmental Engineering (DICCA), Università di Genova, Via all’Opera Pia 15a, 16145 Genova, Italy
Interests: electrochemistry; fuel cells; solid oxide cells; batteries; environmental electrochemistry; hydrogen storage; corrosion; corrosion protection

Prof. Dr. Maria Paola Carpanese

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Guest Editor

Department of Civil, Chemical and Environmental Engineering (DICCA), University of Genoa (UNIGE), 16145 Genova, Italy
Interests: solid state electrochemistry; impedance spectroscopy; SOFC/SOEC; processing; electroceramics

Prof. Dr. Sabrina Presto

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Guest Editor

Istituto di Chimica della Materia Condensata e di Tecnologie per l’Energia (ICMATE)—Consiglio Nazionale delle Ricerche (CNR), c/o DICCA-UNIGE, Via all’Opera Pia 15, 16145 Genova, Italy
Interests: electroceramics; processing; structural characterization; SOFC; solid state chemistry; impedance spectroscopy

Special Issue Information

Dear Colleagues,

We are inviting submissions to the Special Issue of the Energies Journal on the subject area of “Advanced Materials and Technologies for Fuel Cells”.

Fuel cells are considered the preferable candidate for replacing conventional energy technologies, thanks to their tremendous potential for improving efficiency and reducing CO₂/NO_x emissions. The potential applications of fuel cells systems range from transport to stationary power generation, and extend to renewable energy storage when they are used in reverse mode as electrolyzers. High-temperature fuel cells are also well suited for carbon capture and utilization (MCFC) and for power to gas processes involving the co-electrolysis of CO₂ and H₂O (SOFC–SOEC). Among low-temperature fuel cells, microbial cells are an excellent example of bio-compatible energy systems, and are a challenge for the near future.

Further advancements in fuel cell technology are strongly dependent on the improvement of materials properties. The improvement of the catalytic activity in both anodic and cathodic materials is the key factor enabling the use of different types of fuel (gas or liquid, hydrogen or hydrocarbons), as well as the extension of the SOFC lifetime, by lowering of the operative temperature. For advanced PEM, platinum-group-metal-free and/or nanostructured electrodes are highly recommended for use as biofuels and biogas.

This Special Issue welcomes contributions focused on experimental techniques and computational theories that can provide fundamental insights into the development of new electrode, electrolyte, interconnects, and sealing materials, as well as on the technological improvements ensured by the use of fuel cells.

Prof. Massimo Viviani
Prof. Antonio Barbucci
Prof. Maria Paola Carpanese
Prof. Sabrina Presto
Guest Editors

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Keywords

Co-electrolysis
High conductivity electrolyte materials
Innovative architectures
Nano-structured electrodes
Platinum-group-metal-free electrodes
Electro-catalysis
Interconnects and sealing
Internal fuel processing
Balance of Plant (BOP) components
Modelling at the cell-stack-plant level
Life cycle and thermoeconomic analysis.

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Published Papers (13 papers)

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Research

11 pages, 2600 KiB

Open AccessFeature PaperArticle

Investigation of the Fuel Utilization Factor in PEM Fuel Cell Considering the Effect of Relative Humidity at the Cathode

by Mojtaba Baghban Yousefkhani, Hossein Ghadamian, Keyvan Daneshvar, Nima Alizadeh and Brendy C. Rincon Troconis

Energies 2020, 13(22), 6117; https://doi.org/10.3390/en13226117 - 22 Nov 2020

Cited by 9 | Viewed by 4805

Abstract

This research consists of both theoretical and experimental sections presenting a novel scenario for the consumption of hydrogen in the polymer electrolyte membrane fuel cell (PEMFC). In the theory section, a new correction factor called parameter δ is used for the calculation of fuel utilization by introducing concepts of “useful water” and “non-useful water”. The term of “useful water” refers to the state that consumed hydrogen leads to the production of liquid water and external electric current. In the experimental section, the effect of the relative humidity of the cathode side on the performance and power density is investigated by calculating the parameter δ and the modified fuel utilization at 50% and 80% relative humidity. Based on the experimental results, the maximum power density obtained at 50% and 80% relative humidity of the cathode side is about 645 mW/cm² and 700 mW/cm², respectively. On the other hand, the maximum value of parameter δ for a value of 50% relative humidity in the cathode side is about 0.88, while for 80% relative humidity it is about 0.72. This means that the modified fuel utilization for 50% relative humidity has a higher value than that for 80%, which is not aligned with previous literature. Therefore, it is necessary to find an optimal range for the relative humidity of the cathode side to achieve the best cell performance in terms of the power generation and fuel consumption as increasing the relative humidity of the cathode itself cannot produce the best result. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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11 pages, 3047 KiB

Open AccessArticle

Ce_0.9Gd_0.1O_2−x for Intermediate Temperature Solid Oxide Fuel Cells: Influence of Cathode Thickness and Anode Functional Layer on Performance

by Visweshwar Sivasankaran, Lionel Combemale, Mélanie François and Gilles Caboche

Energies 2020, 13(17), 4400; https://doi.org/10.3390/en13174400 - 26 Aug 2020

Cited by 3 | Viewed by 2730

Abstract

The performances of Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC) anode-supported planar cells with a 10 cm² active surface were studied versus the combination of cathode thickness and the presence of an Anode Functional Layer (AFL). The temperature range was 500 to 650 °C, and Gd_0.1Ce_0.9O_2−x (GDC) was used as the electrolyte material, Ni-GDC as the anode material, and La_0.6Sr_0.4Co_0.2Fe_0.8O_3−d (LSCF48) as the cathode material. The power density, conductivity, and activation energy of different samples were determined in order to investigate the influence of the cathode thickness and AFL on the performance. These results showed an improvement in the performances when the AFL was not present. The maximum power density reached 370 mW·cm⁻² at 650 °C for a sample with a cathode thickness of 50 µm and an electrolyte layer that was 20 µm thick. Moreover, it was highlighted that a thinner cathode layer reduced the power density of the cell. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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19 pages, 2076 KiB

Open AccessArticle

2D Simulation for CH₄ Internal Reforming-SOFCs: An Approach to Study Performance Degradation and Optimization

by Emilio Audasso, Fiammetta Rita Bianchi and Barbara Bosio

Energies 2020, 13(16), 4116; https://doi.org/10.3390/en13164116 - 9 Aug 2020

Cited by 14 | Viewed by 2964

Abstract

Solid oxide fuel cells (SOFCs) are a well-developed technology, mainly used for combined heat and power production. High operating temperatures and anodic Ni-based materials allow for direct reforming reactions of CH₄ and other light hydrocarbons inside the cell. This feature favors a wider use of SOFCs that otherwise would be limited by the absence of a proper H₂ distribution network. This also permits the simplification of plant design avoiding additional units for upstream syngas production. In this context, control and knowledge of how variables such as temperature and gas composition are distributed on the cell surface are important to ensure good long-lasting performance. The aim of this work is to present a 2D modeling tool able to simulate SOFC performance working with direct internal CH₄ reforming. Initially thermodynamic and kinetic approaches are compared in order to tune the model assuming a biogas as feed. Thanks to the introduction of a matrix of coefficients to represent the local distribution of reforming active sites, the model considers degradation/poisoning phenomena. The same approach is also used to identify an optimized catalyst distribution that allows reducing critical working conditions in terms of temperature gradient, thus facilitating long-term applications. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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12 pages, 3930 KiB

Open AccessArticle

Glass-Ceramic Sealants for SOEC: Thermal Characterization and Electrical Resistivity in Dual Atmosphere

by Hassan Javed, Antonio Gianfranco Sabato, Mohsen Mansourkiaei, Domenico Ferrero, Massimo Santarelli, Kai Herbrig, Christian Walter and Federico Smeacetto

Energies 2020, 13(14), 3682; https://doi.org/10.3390/en13143682 - 17 Jul 2020

Cited by 12 | Viewed by 3453

Abstract

A Ba-based glass-ceramic sealant is designed and tested for solid oxide electrolysis cell (SOEC) applications. A suitable SiO₂/BaO ratio is chosen in order to obtain BaSi₂O₅ crystalline phase and subsequently favorable thermo-mechanical properties of the glass-ceramic sealant. The glass is analyzed in terms of thermal, thermo-mechanical, chemical, and electrical behavior. Crofer22APU-sealant-Crofer22APU joined samples are tested for 2000 h at 850 °C in a dual atmosphere test rig having reducing atmosphere of H₂:H₂O 50/50 (mol%) and under the applied voltage of 1.6 V. In order to simulate the SOEC dynamic working conditions, thermal cycles are performed during the long-term electrical resistivity test. The glass-ceramic shows promising behavior in terms of high density, suitable CTE, and stable electrical resistivity (10⁶–10⁷ Ω cm) under SOEC conditions. The SEM-EDS post mortem analysis confirms excellent chemical and thermo-mechanical compatibility of the glass-ceramic with Crofer22APU. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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10 pages, 2201 KiB

Open AccessArticle

Infiltrated Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ-Based Electrodes as Anodes in Solid Oxide Electrolysis Cells

by Xavier Majnoni d’Intignano, Davide Cademartori, Davide Clematis, Sabrina Presto, Massimo Viviani, Rodolfo Botter, Antonio Barbucci, Giacomo Cerisola, Gilles Caboche and M. Paola Carpanese

Energies 2020, 13(14), 3659; https://doi.org/10.3390/en13143659 - 15 Jul 2020

Cited by 9 | Viewed by 3148

Abstract

In the last decades, several works have been carried out on solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) technologies, as they are powerful and efficient devices for energy conversion and electrochemical storage. By increasing use of renewable sources, a discontinuous amount of electricity is indeed released, and reliable storage systems represent the key feature in such a future energy scenario. In this context, systems based on reversible solid oxide cells (rSOCs) are gaining increasing attention. An rSOC is an electrochemical device that can operate sequentially between discharging (SOFC mode) and charging (SOEC mode); then, it is essential the electrodes are able to guarantee high catalytic activity, both in oxidation and reduction conditions. Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) has been widely recognized as one of the most promising electrode catalysts for the oxygen reduction reaction (ORR) in SOFC technology because of its astonishing content of oxygen vacancies, even at room temperature. The purpose of this study is the development of BSCF to be used as anode material in electrolysis mode, maintaining enhanced energy and power density. Impregnation with a La_0.8Sr_0.2MnO₃ (LSM) discrete nanolayer is applied to pursue structural stability, resulting in a long lifetime reliability. Impedance spectroscopy measurements under anodic overpotential conditions are run to test BSCF and LSM-BSCF activity as the electrode in oxidation mode. The observed results suggest that BSCF is a very promising candidate as an oxygen electrode in rSOC systems. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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14 pages, 1272 KiB

Open AccessArticle

Eulerian Two-Fluid Model of Alkaline Water Electrolysis for Hydrogen Production

by Damien Le Bideau, Philippe Mandin, Mohamed Benbouzid, Myeongsub Kim, Mathieu Sellier, Fabrizio Ganci and Rosalinda Inguanta

Energies 2020, 13(13), 3394; https://doi.org/10.3390/en13133394 - 2 Jul 2020

Cited by 41 | Viewed by 6544

Abstract

Hydrogen storage is a promising technology for storage of renewable energy resources. Despite its high energy density potential, the development of hydrogen storage has been impeded, mainly due to its significant cost. Although its cost is governed mainly by electrical energy expense, especially for hydrogen produced with alkaline water electrolysis, it is also driven by the value of the cell tension. The most common means of electrolyzer improvement is the use of an electrocatalyst, which reduces the energy required for electrochemical reaction to take place. Another efficient means of electrolyzer improvement is to use the Computational Fluid Dynamics (CFD)-assisted design that allows the comprehension of the phenomena occurring in the electrolyzer and also the improvement in the electrolyzer’s efficiency. The designed two-phase hydrodynamics model of this study has been compared with the experimental results of velocity profiles measured using Laser Doppler Velocimetry (LDV) method. The simulated results were in good agreement with the experimental data in the literature. Under the good fit with experimental values, it is efficient to introduce a new physical bubble transfer phenomenon description called “bubble diffusion”. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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13 pages, 8761 KiB

Open AccessArticle

A Paper-Based Microfluidic Fuel Cell Using Soft Drinks as a Renewable Energy Source

by Jaime Hernández Rivera, David Ortega Díaz, Diana María Amaya Cruz, Juvenal Rodríguez-Reséndiz, Juan Manuel Olivares Ramírez, Andrés Dector, Diana Dector, Rosario Galindo and Hilda Esperanza Esparza Ponce

Energies 2020, 13(10), 2443; https://doi.org/10.3390/en13102443 - 13 May 2020

Cited by 13 | Viewed by 3536

Abstract

The research aims were to construct an air-breathing paper-based microfluidic fuel cell (paper-based

μ

FC) and to evaluated it with different soft drinks to provide energy for their prospective use in portable devices as an emergency power source. First, in a half-cell configuration, [...] Read more.

The research aims were to construct an air-breathing paper-based microfluidic fuel cell (paper-based

μ

FC) and to evaluated it with different soft drinks to provide energy for their prospective use in portable devices as an emergency power source. First, in a half-cell configuration, cyclic voltammetry showed that glucose, maltose, and fructose had specific oxidation zones in the presence of platinum-ruthenium on carbon (PtRu/C) when they were individual. Still, when they were mixed, glucose was observed to be oxidized to a greater extent than fructose and maltose. After, when a paper-based

μ

FC was constructed, PtRu/C and platinum on carbon (Pt/C) were used as anode and cathode, the performance of this

μ

FC was mostly influenced by the concentration of glucose present in each soft drink, obtaining maximum power densities at room temperature of 0.061, 0.063, 0.060, and 0.073 mW cm

^{- 2}

for Coca Cola

^{®}

, Pepsi

^{®}

, Dr. Pepper

^{®}

, and 7up

^{®}

, respectively. Interestingly, when the soft drinks were cooled, the performance was increased up to 85%. Furthermore, a four-cell stack

μ

FC was constructed to demonstrate its usefulness as a possible power supply, obtaining a power density of 0.4 mW cm

^{- 2}

, using Coca Cola

^{®}

as fuel and air as oxidant. Together, the results of the present study indicate an alternative application of an

μ

FC using soft drinks as a backup source of energy in emergencies. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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19 pages, 6666 KiB

Open AccessArticle

Single-Cell Tests to Explore the Reliability of Sofc Installations Operating Offshore

by Nelson Thambiraj, Ivar Waernhus, Crina Suciu, Arild Vik and Alex C. Hoffmann

Energies 2020, 13(7), 1624; https://doi.org/10.3390/en13071624 - 2 Apr 2020

Cited by 5 | Viewed by 2447

Abstract

This paper studies the robustness of off-shore solid oxide fuel cell (SOFC) installations and the nature and causes of possible cell degradation in marine environments. Two important, cathode-related, impediments to ensuring SOFC reliability in off-shore installations are: cathode degradation due to salt contamination and oxygen depletion in the air supply. Short-term and long-term tests show the effect of salt contamination in the cathode feed on cell performance, and reveal the underlying cause of the degradation seen. SEM/X-ray Diffraction/(XRD) analyses made it possible to identify salt taken up in the cathode microstructure after the short-term testing while the macroscopic cell structure remained intact after the short-term tests. The long-term degradation was found to be more severe, and SEM images showed delamination at the cathode/electrolyte interface with salt present, something that was not seen after long-term testing without salt. The effect of oxygen depletion on the performance was also determined at three different temperatures using I-V curves. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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14 pages, 2902 KiB

Open AccessArticle

In Situ High Pressure Structural Investigation of Sm-Doped Ceria

by Cristina Artini, Sara Massardo, Maria Maddalena Carnasciali, Boby Joseph and Marcella Pani

Energies 2020, 13(7), 1558; https://doi.org/10.3390/en13071558 - 27 Mar 2020

Cited by 7 | Viewed by 2205

Abstract

As a result of the lattice mismatch between the oxide itself and the substrate, the high-pressure structural properties of trivalent rare earth (RE)-doped ceria systems help to mimic the compressive/tensile strain in oxide thin films. The high-pressure structural features of Sm-doped ceria were studied by X-ray diffraction experiments performed on Ce_1−xSm_xO_2−x/2 (x = 0.2, 0.3, 0.4, 0.5, 0.6) up to 7 GPa, and the cell volumes were fitted by the third order Vinet equation of state (EoS) at the different pressures obtained from Rietveld refinements. A linear decrease of the

\ln B_{0}

vs.

\ln (2 V_{a t})

trend occurred as expected, but the regression line was much steeper than predicted for oxides, most probably due to the effect of oxygen vacancies arising from charge compensation, which limits the increase of the mean atomic volume (

V_{a t}

) vs. the Sm content. The presence of RE₂O₃-based cubic microdomains within the sample stiffens the whole structure, making it less compressible with increases in applied pressure. Results are discussed in comparison with ones previously obtained from Lu-doped ceria. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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11 pages, 3133 KiB

Open AccessArticle

Transport Properties and High Temperature Raman Features of Heavily Gd-Doped Ceria

by Cristina Artini, Sabrina Presto, Sara Massardo, Marcella Pani, Maria Maddalena Carnasciali and Massimo Viviani

Energies 2019, 12(21), 4148; https://doi.org/10.3390/en12214148 - 30 Oct 2019

Cited by 9 | Viewed by 2768

Abstract

Transport and structural properties of heavily doped ceria can reveal subtle details of the interplay between conductivity and defects aggregation in this material, widely studied as solid electrolyte in solid oxide fuel cells. The ionic conductivity of heavily Gd-doped ceria samples (Ce_1−xGd_xO_2−x/2 with x ranging between 0.31 and 0.49) was investigated by impedance spectroscopy in the 600–1000 K temperature range. A slope change was found in the Arrhenius plot at ~723 K for samples with x = 0.31 and 0.34, namely close to the compositional boundary of the CeO₂-based solid solution. The described discontinuity, giving rise to two different activation energies, points at the existence of a threshold temperature, below which oxygen vacancies are blocked, and above which they become free to move through the lattice. This conclusion is well supported by Raman spectroscopy, due to the discontinuity revealed in the Raman shift trend versus temperature of the signal related to defects aggregates which hinder the vacancies movement. This evidence, observable in samples with x = 0.31 and 0.34 above ~750 K, accounts for a weakening of Gd–O bonds within blocking microdomains, which is compatible with the existence of a lower activation energy above the threshold temperature. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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13 pages, 2848 KiB

Open AccessFeature PaperArticle

A Comprehensive Study of Custom-Made Ceramic Separators for Microbial Fuel Cells: Towards “Living” Bricks

by Jiseon You, Lauren Wallis, Nevena Radisavljevic, Grzegorz Pasternak, Vincenzo M. Sglavo, Martin M Hanczyc, John Greenman and Ioannis Ieropoulos

Energies 2019, 12(21), 4071; https://doi.org/10.3390/en12214071 - 25 Oct 2019

Cited by 26 | Viewed by 3820

Abstract

Towards the commercialisation of microbial fuel cell (MFC) technology, well-performing, cost-effective, and sustainable separators are being developed. Ceramic is one of the promising materials for this purpose. In this study, ceramic separators made of three different clay types were tested to investigate the effect of ceramic material properties on their performance. The best-performing ceramic separators were white ceramic-based spotty membranes, which produced maximum power outputs of 717.7 ± 29.9 µW (white ceramic-based with brown spots, 71.8 W·m⁻³) and 715.3 ± 73.0 µW (white ceramic-based with red spots, 71.5 W·m⁻³). For single material ceramic types, red ceramic separator generated the highest power output of 670.5 ± 64. 8 µW (67.1 W·m⁻³). Porosity investigation revealed that white and red ceramics are more porous and have smaller pores compared to brown ceramic. Brown ceramic separators underperformed initially but seem more favourable for long-term operation due to bigger pores and thus less tendency of membrane fouling. This study presents ways to enhance the function of ceramic separators in MFCs such as the novel spotty design as well as fine-tuning of porosity and pore size. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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16 pages, 4626 KiB

Open AccessArticle

Suitability of Sm³⁺_-Substituted SrTiO₃ as Anode Materials for Solid Oxide Fuel Cells: A Correlation between Structural and Electrical Properties

by Saurabh Singh, Raghvendra Pandey, Sabrina Presto, Maria Paola Carpanese, Antonio Barbucci, Massimo Viviani and Prabhakar Singh

Energies 2019, 12(21), 4042; https://doi.org/10.3390/en12214042 - 24 Oct 2019

Cited by 8 | Viewed by 3352

Abstract

Perovskite anodes, nowadays, are used in any solid oxide fuel cell (SOFC) instead of conventional nickel/yttria-stabilized zirconia (Ni/YSZ) anodes due to their better redox and electrochemical stability. A few compositions of samarium-substituted strontium titanate perovskite, Sm_xSr_1−xTiO_3−δ (x = 0.00, 0.05, 0.10, 0.15, and 0.20), were synthesized via the citrate-nitrate auto-combustion route. The XRD patterns of these compositions confirm that the solid solubility limit of Sm in SrTiO₃ is x < 0.15. The X-ray Rietveld refinement for all samples indicated the perovskite cubic structure with a

P m \bar{3} m

space group at room temperature. The EDX mapping of the field emission scanning electron microscope (FESEM) micrographs of all compositions depicted a lower oxygen content in the specimens respect to the nominal value. This lower oxygen content in the samples were also confirmed via XPS study. The grain sizes of Sm_xSr_1−xTiO₃ samples were found to increase up to x = 0.10 and it decreases for the composition with x > 0.10. The AC conductivity spectra were fitted by Jonscher’s power law in the temperature range of 500–700 °C and scaled with the help of the Ghosh and Summerfield scaling model taking ν_H and σ_dc T as the scaling parameters. The scaling behaviour of the samples showed that the conduction mechanism depends on temperature at higher frequencies. Further, a study of the conduction mechanism unveiled that small polaron hopping occurred with the formation of electrons. The electrical conductivity, in the H₂ atmosphere, of the Sm_0.10Sr_0.90TiO₃ sample was found to be 2.7 × 10⁻¹ S∙cm⁻¹ at 650 °C, which is the highest among the other compositions. Hence, the composition Sm_0.10Sr_0.90TiO₃ can be considered as a promising material for the application as the anode in SOFCs. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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13 pages, 3566 KiB

Open AccessArticle

A Transient Behavior Study of Polymer Electrolyte Fuel Cells with Cyclic Current Profiles

by Yan Shi, Holger Janßen and Werner Lehnert

Energies 2019, 12(12), 2370; https://doi.org/10.3390/en12122370 - 20 Jun 2019

Cited by 12 | Viewed by 3869

Abstract

This paper reports on the effects of different load profiles on the transient behavior of a polymer electrolyte fuel cell (PEFC). A protocol of six tests, each with different current density ramps, was conducted. The corresponding cell voltage, pressure drop response, and ohmic resistance were then experimentally investigated. The time-dependent voltage profiles were applied to represent the cell performance. The cathodic pressure drop and ohmic resistance were utilized to analyze the water dynamic behavior inside the cell. The voltage overshoot and undershoot behavior were observed throughout the experiment. It was found that with an increase of the current change rates, the magnitude of voltage over/undershoots also increased. When the holding time at the constant current density was zero, the overshoot or undershoot behavior disappeared. The results of the pressure drop analysis showed that the load ramp did not have a significant effect on the average pressure drop in the tests. During the load cyclic operation in each test, the two-phase flow tended to reach equilibrium in the cell. Impedance analysis showed that the ohmic resistance changed with the change in the current density; however, the difference between the tests was not obvious. Full article

(This article belongs to the Special Issue Advanced Materials and Technologies for Fuel Cells)

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