bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Reformed Gas Components on the Operation of HT-PEMFC Stacks
Authors: Cremers Carsten , Bürger Stefan , Groß Martin Florian 
Published: December 2020

Due to still existing limitations in logistic and some risk in handling of compressed gases hydrogen is not a suitable fuel for all applications which can profit from the use of fuel cells. In such cases the use of a downstream reformer to generate hydrogen from another fuel is a viable option. Fuel cell which can tolerate the impurities contained in the reformed gas will avoid the need of sophisticated gas clean-up. Such tolerance is obtained by increasing the operation temperature. BASF has already shown that their Celtec® MEA can tolerated substantial CO and H2S concentration1 which was confirmed by us for MEA of other manufacturers2,3. Here, the effect of impurities on the operation of HT-PEMFC stacks is investigated.
In this contribution investigations of the effect of impurities typically found in fuel gas obtained by auto thermal reforming of jet fuels is reported. Tests were conducted on Serenergy S165L-35 stacks with 35 cells of 165 cm2 geometric electrode area. Investigated were in detail the effect of dilution of hydrogen with nitrogen or CO2, the effect of fuel gas humidity and the effect of percent level CO and ppm level H2S impurities.
It was found that the performance of the stack at an anode stoichiometry of 1.4 is strongly influenced by hydrogen dilution (cf. fig 1a and b). Thereby no difference is found between dilution with N2 or CO2 (cf. fig. 2) indicating that no relevant reversed water gas shift reaction does occur. High levels of humidification with anode feed dew point exceeding about 60 °C also reduce the stack performance (cf. fig 3). This effect can again be correlated to the dilution with hydrogen (cf. fig. 4). However, after longer test with high due points stack performance is irreversibly reduced (cf. fig 5). Adding CO or H2S to diluted hydrogen further reduces the performance as expected. Unexpectedly the impact of the addition of CO is higher than that of H2S (cf. fig 6). Finally adding CO and H2S has a combined effect (cf. fig 7) though not as strong a described by Schmidt and Baurmeister1.
In the contribution further analysis of the different effects e.g, on cell voltage distribution will be given as well as the determination and validation of a suitable operating point for a jet fuel surrogate reformate.
The work was financial supported by the European Defence Agency (EDA) through the Ad-Hoc project “IAPUNIT” Contract B 1490 GEM 3 GP, jointly financed by the Federal Republic of Austria, the Federal Republic of Germany, the Kingdom of the Netherlands, the Republic of Slovenia and the Kingdom of Sweden.
References

T. J. Schmidt and J. Baurmeister, ECS Trans., 3(1), 861 – 869 (2006)

C. Cremers, M. S. Rau, A. Niedergesäß, K. Pinkwart, and J. Tübke, ECS Trans., 75(14), 919 – 929 (2016).

M. Rau, A. Niedergesäß, C. Cremers, S. Alfaro, T. Steenberg, H.A, Hjuler, Fuel Cells, 16(5), 577 – 583 (2016).

Figure 1
Design and Characterization of Porous Graphite Bipolar Plates for Water Management in PEM Fuel Cells
Authors: Pitchiya Aswin Prathap , Krishnan Sitaraman 
Published: December 2020

Proton exchange membrane fuel cells (PEMFCs) are promising power-generation sources for mobile, stationary, and emergency backup power applications. Proper water management within the cell is crucial for the optimum performance and durability of PEMFCs. Excessive water leads to the flooding of the cathode compartment, while dehydration of the membranes results in increasing resistive losses. Therefore, water management is critical to the successful implementation of PEMFCs. To optimize the water balance, various designs have been proposed and tested. These approaches include the use of more complex diffusion media and microporous layers, liquid water injection, wicking of liquid water, and the use of different flow-field pathways1. The latter two approaches seek to enable self-humidification of the PEMFCs system, thereby decreasing the cost and parasitic power losses of external components such as humidifiers.
In this study, a porous hydrophilic bipolar plate with different pore structures were designed and characterized. Methods and compositions to produce fuel cell bipolar plates, with a porosity tailored for the desired up-take of water produced during fuel cell operation through capillarity, while offering sufficient resistance to permeability and leakage of gaseous fuel, are reported. The plates were composites of graphite (of different shapes and sizes) and polymer and were produced by a combination of powder or paste mixing, followed by compression molding and curing. Pore formation was engineered by adding a pore-forming agent2. Additionally, the pore surface was chemically modified using several surface modification methods.
A competitive plate design and fabrication technique is adopted in order to develop a low-cost, and light weight bipolar plates with improved mechanical and electrical conductivity and with exceptional hydraulic permeability and gas breakthrough pressure. The microporous bipolar plates developed in this research are promising for making water-management in PEMFCs simpler. The results of these studies will be presented and discussed.
References:

Wang, Y.; Diaz, D. F. R.; Chen, K. S.; Wang, Z.; Adroher, X. C., Materials, technological status, and fundamentals of PEM fuel cells–a review. Materials Today 2020,
32, 178-203.

Krishnan, S.; Harrington, M.; Pitchiya, A. P.; Putnam, Z.; Orlowski, D., Material Compositions And Methods For Porous Graphite-Polymer Composite Bipolar Plates. U.S. Patent Application 16/558,857: 2020.
(Invited) Curing Fuel Cell’s Alzheimer’s with Carbon Coatings for Stainless-Steel Bipolar Plates and a Healthy Lifestyle
Authors: Proch Sebastian Karl , Novalin Timon , Eriksson Björn , Bexell Ulf , Moffatt Claire , Westlinder Jörgen , Lagergren Carina , Wreland Lindström Rakel , Lindbergh Göran 
Published: December 2020

Membrane/ionomer degradation in proton exchange membrane (PEM) fuel cells caused by Fenton-reaction of Fe and Cu species with hydrogen peroxide is not unlike the development of Alzheimer’s in the human body. Stainless-steel dissolution under fuel cell-relevant conditions takes place via passive-transpassive-passive transitions (Figure 1) [1]. Moreover, rapid load cycling and concomitant global hydrogen starvation during the New European Driving Cycle (NEDC) [2] are very likely to create such transitions. In their presence, metal-stained carbon-coated bipolar plates lead to significant contamination of the MEA with Fe and Ni. In contrast, the mitigation of global fuel starvation in the NEDC makes it possible for the same plates to exhibit trace-metal contamination of the MEA as low as a pure graphite current collector. However, during both runs the carbon coating ensures a constant and low contact resistance between bipolar plates and gas diffusion layers (GLDs). To take the Alzheimer’s analogy a step further, these experiments show that the way the fuel cell is run can be more important than the quality of the components. In other words, lifestyle might beat genetics.
At SMT we strongly believe in the power of carbon for electrochemical energy conversion due to its sustainability, low cost, high stability, high conductivity, and the absence of oxide film formation, thus, maintaining low contact resistance. We, therefore, offer (non-metal stained) carbon-precoated stainless steel for bipolar plates produced in a roll-to-roll fashion.

Figure
1
. Transient dissolution behavior of a typical stainless steel, e.g., 304L, 316L, 904L, considered are only Fe and Cr species for simplification. In a potential step from OCP (+0.7 V vs. RHE), where Fe and Cr species are insoluble, to ±0 V vs. RHE, where the Fe species is soluble, Fe is preferentially leached (red trace in the transpassive part) until an all-Cr passive film has been reestablished, which takes about 100 s. The red and blue traces correspond to the Fe and Cr signal of an ICP-AES coupled to a flow cell with a stainless steel sample [1].
[1] Li X, Zhou P, Ogle K, Proch S, Paliwal M, Jansson A, et al. Transient stainless-steel dissolution and its consequences on ex-situ bipolar plate testing procedures. Int J Hydrogen Energy. 2020;45:984-95.
[2] Tsotridis G, Pilenga A, De Marco G, Malkow T. EU Harmonised Test Protocols for PEMFC MEA Testing in Single Cell Configuration for Automotive Applications. Petten (The Netherlands): EU; 2015.

Figure 1
Comparison of Novel 1,1-Diphenylethylene Alternating Copolymer and Polystyrene Based Anion Exchange Membranes
Authors: Briem Musashi , Trant Carrie , Park Sungmin , Bae Chulsung , Lee Sangwoo 
Published: December 2020

This research investigates 1,1-diphenylethylene as a monomer in polymeric ion exchange membranes through the synthesis of a novel alternating copolymer functionalized for ion transport and analysis of mechanical and conductive properties. This will further the development of cost effective and high-performance ion exchange membranes, enabling energy systems that employ ion-transporting membranes, like fuel cells and electrolyzers, to become more economically viable, which in turn would lead to cleaner and more sustainable energy production.
The goal of the project is to develop an understanding of chemical structure-physical property relationships to make self-assembling ion-conducting channels in ionomers which have physical properties that prevent the excess swelling that leads to the mechanical failure of membranes. In this vein, anion exchange membranes (AEMs) based on 1,1-diphenylethylene were synthesized and their ion conducting properties and physical state were characterized. Poly(1,1-diphenylethylene-alt-butadiene) alternating copolymer was synthesized via anionic polymerization, then selectively hydrogenated to eliminate double bonds in the polymer backbone. The pendant aromatic rings of the selectively hydrogenated poly(1,1-diphenylethylene-alt-butadiene) were then subjected to quantitatively controlled functionalized by super acid catalyzed Friedel-Crafts bromoalkylation, then aminated with trimethylamine. AEMs spanning a wide range of ion exchange capacities (IECs), 0.39-1.99 milliequiv./gram (meq./g), were made. Conductivity increased with IEC and temperature. Polystyrene based AEMs of similar IECs, 0.38-2.14 meq/g, were synthesized as a standard to compare the 1,1-diphenylethylene based copolymers. The 1,1-diphenylethylene based copolymers had favorable conductivities compared to polystyrene membranes of similar IEC. The glass transition temperature, water uptake, and dimensional swelling were investigated to explain the difference in conductivities between the two species.

Figure 1
Pore-Filled PEMs from Poly(Phenylene Sulfonic Acid)s and Electrospun Poly(Phenylene Sulfone) Fiber Mats
Authors: Wycisk Ryszard , Hossain M. , Shang Z. , Pintauro Peter N. 
Published: December 2020

Novel, composite, non-PFSA-based fuel cell membranes have been fabricated using a pore filling technique. The membranes consist of a mechanically stabilizing skeleton from an electrospun poly(phenylene sulfone) (PPSU) fiber mat and a thermally crosslinkable poly(phenylene sulfonic acid) (cPPSA) proton conducting ionomer that fills the interfiber voids. The work builds on two prior studies carried out in the labs of Prof. M. Litt and Prof. P.N. Pintauro demonstrating: (1) Exceptionally high proton conductivity, even at very low RH (down to 20% RH), of cPPSA solution cast films, and (2) Excellent durability of electrospun perfluorosulfonic acid (PFSA) ionomers/PPSU composite membranes, exceeding that of the pristine PFSA. Unfortunately, the high proton conductivity of cPPSA films, especially at low relative humidity, was offset by their significant brittleness, which made handling of those materials, including fabrication of membrane-electrode-assemblies, extremely difficult. The proposed pore-filling strategy should alleviate the brittleness problem leading to a robust, low RH-conductive PEM that is a true competitor to PFSA membranes and suitable for commercial applications.
Experiments focused on optimizing the cPPSA/PPSU ratio to achieve the desired balance of tensile strength and proton conductivity, and on minimizing membrane thickness to obtain area specific resistance (ASR) lower than 0.02 S/cm in the 40-90% RH range at 80oC. cPPSA copolymer was synthesized using Ullmann coupling copolymerization of 4,4′-dibromobiphenyl 3,3′-disulfonic acid with 1,4-dibromobenzene-2,5-disulfonic, followed by grafting certain fraction of backbone sulfonic acid groups with biphenyl linker [1]. The PPSU fiber mat was electrospun from NMP/acetone solution. Pore-filling was carried out by pouring a solution of cPPSA in methanol over the framed mat, followed by heating at 70oC to evaporate solvent. The cPPSA was crosslinked by an additional heating step, in a vacuum oven at 210oC for 1-2 hours. The resultant membranes had excellent proton conductivity, 5-10 times greater than that of Nafion® 211 in the 40-90% RH range at 80oC. Details of the membrane fabrication and characterization work will be presented in this talk.
[1] M. Litt and R. Wycisk, Poly(Arylenesulfonic Acids) with Frozen-In Free Volume as Hydrogen Fuel Cell Membrane Materials, Polymer Reviews, 55, 307 (2015).
Kinetics of Lithium Insertion and Plating on Basal and Edge Planes of Graphite
Authors: Schnabel Manuel , Kostecki Robert 
Published: December 2020

Lithium-ion batteries (LIBs) with graphitic anodes dominate the energy storage market1, 2, and it is of interest to accelerate charging of LIBs for a number of applications, especially electric vehicles. A common issue upon fast charging is that parts of a graphitic anode are polarized to negative voltages vs Li/Li+, leading to lithium plating3. The reversibility of Li plating on graphitic anodes is poor, and Li plating leads to exothermic reactions with standard electrolytes, and can lead to dendrite growth and shorts in the cell3. It is therefore of interest to understand the onset of Li plating, and the maximum current that can be sustained without plating.
In commercially relevant cells such measurements are complicated by the three-dimensional porous composite nature of the anode and its interaction with an electrolyte whose lithium concentration at the interface with the graphite varies as a function of depth within the electrode during fast charging4, 5. The goal of our work is to determine the fundamental kinetics of Li intercalation and plating at edge and basal plane graphite surfaces by performing fast charging experiments using highly oriented pyrolytic graphite (HOPG) samples.
HOPG consists of a stack of graphite planes, with in-plane grain sizes on the order of 0.1 mm, enabling such measurements at a well-controlled current density. We confirm that Li intercalation occurs almost exclusively at edge planes, and show that current densities above 1 mA/cm2 can be sustained at pristine edge surfaces (see figure, which shows potential as a function of linearly increasing current density). We also show that Li plating can nucleate on both edge and basal planes with an overpotential below 0.1 V, and explore the differences in Li insertion rate and plating overpotential for different stages of graphite.
Funding was provided by the U.S. DOE Office of Vehicle Technology Applied Battery Research and Extreme Fast Charge Program (XCEL).

T. Placke, R. Kloepsch, S. Dühnen and M. Winter, Journal of Solid State Electrochemistry, 2017, 21, 1939-1964.

N. Nitta, F. Wu, J. T. Lee and G. Yushin, Materials Today, 2015, 18, 252-264.

Q. Liu, C. Du, B. Shen, P. Zuo, X. Cheng, Y. Ma, G. Yin and Y. Gao, RSC Advances, 2016, 6, 88683-88700.

A. M. Colclasure, A. R. Dunlop, S. E. Trask, B. J. Polzin, A. N. Jansen and K. Smith, Journal of The Electrochemical Society, 2019, 166, A1412-A1424.

A. M. Colclasure, T. R. Tanim, A. N. Jansen, S. E. Trask, A. R. Dunlop, B. J. Polzin, I. Bloom, D. Robertson, L. Flores, M. Evans, E. J. Dufek and K. Smith, Electrochimica Acta, 2020, 337, 135854.

Figure 1
(Invited) Anthraquinone on Carbon: Is There Any Way to Get It Working?
Authors: Zhu Yachao , Deschanels Mathieu , Le Vot Steven , Fontaine Olivier , Favier Frederic 
Published: December 2020

Grafting redox active moieties, including anthraquinone, on large surface area carbons has been for long considered has a good opportunity to increase the energy density of electrochemical capacitors. From the CVs, usually looking like the merging of redox and capacitive signals, the storage capability obviously takes benefit from both contributions. Unfortunately, performances are not fully met: when increasing the anthraquinone loading above 10-15 w%, the double layer contribution decreases because of pore clogging. Cyclability is also poor: during the first few hundreds of cycles (often less), the capacity is progressively fading down because of either physisorb anthraquinone molecules being washed away from the carbon surface and molecule degradation.
Various approaches have been considered to address these limits. This paper is an introduction to two of those we have explored. The first one consists in the covalent grafting of an anthraquinone propargyl molecule by a Diels Alders reaction using carbon surfaces as dienophyl. For the second, anthraquinone molecules are first simply adsorbed at the carbon surface. In a second step, flakes from exfoliated MXene are deposited on top of the anthraquinone film by dip-coating. This carbide shell provides the resulting composite some extra electronic conductivity while allowing the electrolytic species to reach both anthraquinone and carbon thanks to its open structure. Attractive electrochemical characteristics have been obtained from electrodes based on these two different materials. These are discussed based on the compositions and morphologies of the prepared composite materials.

References

Brousse, T.; Cougnon, C.; Bélanger, D., Grafting of Quinones on Carbons as Active Electrode Materials in Electrochemical Capacitors. Journal of the Brazilian Chemical Society
2018,
29, 989-997.
Pognon, G.; Brousse, T.; Demarconnay, L.; Bélanger, D., Performance and stability of electrochemical capacitor based on anthraquinone modified activated carbon. Journal of Power Sources
2011,
196 (8), 4117-4122.
The Effect of Ball-Milling on the Oxygen Reduction Reaction Activity of Iron and Nitrogen Co-Doped Carbide-Derived Carbon Catalysts in Acid Media
Authors: Ratso Sander , Sougrati Moulay-Tahar , Käärik Maike , Kook Mati , Merisalu Maido , Rähn Mihkel , Kisand Vambola , Kikas Arvo , Paiste Päärn , Sammelselg Väino , Leis Jaan , Jaouen Frederic , Tammeveski Kaido 
Published: December 2020

Storing renewable energy to complete the energy cycle is a crucial challenge in the movement from a fossil fuel-based economy to a circular one. In the hydrogen cycle, stored hydrogen is converted back to usable energy in a fuel cell. The biggest issue in proton exchange membrane fuel cells (PEMFC) is the replacement of noble metal catalysts with a non-precious metal catalysts (NPMC). Iron and nitrogen doped nanocarbon materials are among the most promising alternatives.
In our previous works on iron and nitrogen doped carbide-derived carbons (CDC) we discovered that ball-milling of CDCs has a crucial effect on their porosity and the final activity of the catalyst.1,2 In this work,3 we study the effect of ball-milling conditions and compositions of catalyst precursors comprising a silicon carbide-derived carbon (SiCDC) on the properties of the final catalysts, most importantly their activity toward the oxygen reduction reaction (ORR). Ball-milling rates from 100 to 800 rpm were investigated with 400 rpm proving to be the optimum value. The effect of 1,10-phenanthroline-to-iron ratio in the precursor mixture was also studied, with a 12-1 molar ratio leading to the highest activity. Finally, ZnCl2 addition to the precursor mixture was explored as a pore former during pyrolysis. A ZnCl2-to-CDC mass ratio of 1 resulted in the highest ORR activity. 57Fe Mössbauer spectroscopy confirmed that most of the iron was atomically dispersed as Fe-Nx moieties (Figure 1, left). The most active catalyst showed a kinetic current density of 4.6 mA cm-2 at 0.8 V in rotating disk electrode tests and a current density of 18.6 mA cm-2 at 0.8 V in a single-cell proton exchange membrane fuel cell (Figure 1, right).

References

Ratso, N.R. Sahraie, M.T Sougrati, M. Käärik, M. Kook, R. Saar, P. Paiste, Q. Jia, J. Leis, S. Mukerjee, F. Jaouen, and K. Tammeveski, J. Mater. Chem. A, 6, 14663–14674 (2018).

Ratso, M. Käärik, M. Kook, P. Paiste, J. Aruväli, S. Vlassov, V. Kisand, J. Leis, A. M. Kannan, and K. Tammeveski, Int. J. Hydrogen Energy, 44, 12636–12648 (2019).

Ratso, M. T. Sougrati, M. Käärik, M. Merisalu, M. Rähn, V. Kisand, A. Kikas, P. Paiste, J. Leis, V. Sammelselg, F. Jaouen, and K. Tammeveski, ACS Appl. Energy Mater., 2, 7952–7962 (2019).

Figure 1
Alternative Me-N-C Based Carbon Foams As Fe-Free and Non-PGM Electrocatalysts
Authors: Suzuki Shoyo , Mufundirwa Albert , Sasaki Kazunari , Hayashi Akari , Lyth Stephen Matthew 
Published: December 2020

There is a demand for reducing the environmental load of automobiles to solve the current environmental problems. Fuel cell electric vehicles (FCEVs) which use hydrogen as fuel emit no carbon dioxide, and have already been commercialized. platinum-based materials are widely used as oxygen reduction reaction (ORR) catalysts. However, their high cost and limited durability impedes large-scale implementation. Until now, non-platinum group metal (non-PGM) Fe and N doped carbon (Fe-N-C) catalysts have achieved promising ORR activity [1]. However, these Fe-N-C catalysts still suffer from poor durability, due to the formation of reactive peroxide radicals as a side reaction during the ORR. Meanwhile, the use of Co species avoids the production of such radicals, potentially preserving the electrocatalyst [2]. Therefore, in this study we investigate the dependence of ORR activity on a variety of different metal ions by synthesizing alternative Me-N-C carbon foam electrocatalysts (Me = Co, Ni, Sn).
Pt-free electrocatalysts were synthesized from nitrogen-doped carbon foams (N-C) and various metal salt and small molecule precursors. Porous nitrogen-doped carbon foams with large surface area were made in-house. These were adsorbed with metal acetate and then heated in inert atmosphere, followed by acid washing to remove metallic phases. Finally, heat treatment under ammonia was performed. The effect of heat treatment temperature and metal loading on the microstructure and porosity was evaluated. The resulting catalysts were evaluated for catalytic activity using rotating-ring disk electrode voltammetry (RRDE) in acid.
For Co-N-C electrocatalysts it was found that heat treatment of the nitrogen-doped carbon foam support has a significant effect on catalyst performance, largely due to changes in surface area and porosity. The metal loading also has a strong effect on the performance, with an optimum Co loading of 0.1 wt% resulting in an onset potential of 0.8 VRHE and a half-wave potential of around 0.65 VRHE. Different metal ions were also systematically investigated, and it was found that Sn is highly promising as an alternative to Fe in non-PGM electrocatalysts.

References

[1] Albert Mufundirwa et al., Journal of Power Sources, 2018, 375, 244-254.
[2] Qingqing Cheng et al., Nano Energy, 2018, 52, 485-493.