bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimizing the Interface of a Bipolar Membrane Fuel Cell: An Experimental Study
Authors: Park Andrew Michael , Neyerlin K.C. , Bender Guido , Long Hai , Pivovar Bryan S 
Published: February 2020

Bipolar membrane fuel cells (BMFCs) have been discussed in the past few years as a potential game-changer for the fuel cell community (1). In the most favorable alignment for fuel cell operation, BMFCs comprise an acidic anode (HOR) and an alkaline cathode (ORR), where protons and hydroxide ions are formed, respectively. The ions migrate through a proton or anion exchange membrane to the bipolar junction, where they combine to form water. Optimizing this interfacial reaction is critical to a high performance cell, but outside of recent modeling work (2, 3), few studies have paid specific attention to it.
In this study, a series of BMFC membrane electrode assemblies (MEAs) were fabricated where the proton exchange side comprised a Nafion 211 membrane and ionomer, and the alkaline membrane/ionomer were varied. All MEAs contained platinum on carbon electrode catalysts and were investigated via polarization curves and impedance. Initial MEAs made with several different AEM polymers exhibited an exorbitant cell resistance, attributed to the bipolar interface. To reduce cell resistance, bipolar membrane fabrication conditions were altered to study parameters that impact observed performance. Altering fabrication conditions resulted in nearly a 3x reduction in overall resistance, translating to large gains in BMFC performance. These fabrications methods will be summarized with results presented, which should help inform rational design and future work for BMFCs.
References
1. M. Ünlü, J. Zhou and P. A. Kohl, The Journal of Physical Chemistry C, 113, 11416 (2009).
2. K. N. Grew, J. P. McClure, D. Chu, P. A. Kohl and J. M. Ahlfield, J. Electrochem. Soc., 163, F1572 (2016).
3. Q. Li, J. Gong, S. Peng, S. Lu, P.-C. Sui, N. Djilali and Y. Xiang, J. Power Sources, 307, 358 (2016).
Figure 1. Example polarization curves for BMFC MEAs in H2/O2 at 60°C with and without membrane pretreatment.

Figure 1
Material-Process-Performance Relationships of Roll-to-Roll Coated Fuel Cell Electrodes
Authors: Mauger Scott A , Neyerlin K.C. , Yang-Neyerlin Ami C. , Ulsh Michael 
Published: February 2020

Roll-to-roll (R2R) coating is the most economical and highest throughput method for producing fuel cell electrodes. R2R coating encompasses many different methodologies to create uniform films on a moving web substrate (Figure 1a). One of the methodologies, gravure coating, uses rollers patterned with grooves or wells that fill with liquid, which is then transferred from the gravure roller to the substrate when the come into contact, creating a film (Figure 1b). Here, we present our work that utilized gravure coating to create highly uniform proton exchange membrane fuel cell electrodes on diffusion media. In addition to X-ray fluorescence, we utilized an in-line reactive impinging flow technique, developed by NREL, to characterize electrode uniformity.1

Additionally, we explored the materials-process-performance relationships associated with R2R coating of PEMFC electrodes. Lab-scale fabrication of electrodes sequentially builds up the thickness of the electrode through spraying multiple layers of a dilute dispersion to create a homogenous electrode. In contrast, with gravure coating a concentrated dispersion is coated, forming a thick, wet film that dries to form the electrode. Using several electrochemical diagnostic techniques2,3and electron microscopy, we explored the foundational relationships between ink formulation, coating physics, drying conditions, and substrate to understand how parameters such as ionomer-to-carbon ratio, solvent blend, and diffusion media porosity influenced electrode morphology, concentration gradients of materials, and critical MEA performance parameters such as surface area, activity, and oxygen transport (Figure 1c).
Figure 1 (a) NREL’s roll-to-roll coating station, (b) illustration of the gravure coating processes, and (c) polarization curves and electrochemical impedance spectra comparing spray-coated and roll-to-roll coated electrodes.
Acknowledgements: This work was supported by the U.S. Department of Energy under Contract No. DE-AC36-08GO28308 with the National Renewable Energy Laboratory. Funding provided by U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Fuel Cell Technology Office, program manager Nancy Garland. S.A.M. would also like to thank Guido Bender and Brian Green for assistance with reactive impinging flow measurments.
1. Zenyuk, I. V., Englund, N., Bender, G., Weber, A. Z. & Ulsh, M. Reactive impinging-flow technique for polymer-electrolyte-fuel-cell electrode-defect detection. J. Power Sources
332,372–382 (2016).
2. Thompson, E. L. & Baker, D. Proton Conduction on Ionomer-Free Pt Surfaces. ECS Trans.
41,709–720 (2011).
3. Neyerlin, K. C. et al. New Insights from Electrochemical Diagnostics Pertaining to the High Current Density Performance of Pt-Based Catalysts. 230th ECS Meeting Abstracts (2016).

Figure 1
Conflicting Roles of Nitrogen Doping in Carbon Nanotubes As Anode and Cathode Catalyst Support for Direct Methanol Fuel Cells
Authors: Gan Lin , Du Hongda , Lv Ruitao , Li Jia 
Published: February 2020

Nitrogen doping in carbon nanotubes (CNTs) is of great interest because it endows the inherently inert surface of CNTs with a variety of chemical functionalities. For instance, nitrogen-doped carbon nanotubes (NxCNTs) have been shown a promising electrode catalyst support for polymer electrolyte membrane fuel cells because the doped nitrogen atoms can promote a high dispersion of the metal catalyst nanoparticles on the NxCNT surface, which is essential for achieving a high utilization and thus high catalytic performance. However, beyond the role in nanoparticle dispersion, how nitrogen doping affects the catalytic performance in the anode and in the cathode of a realistic membrane-electrode-assembly (MEA), still remains elusive.
In this report, we performed a comparative study of NxCNTs at three different N doping levels as the anode and cathode catalyst support in both rotating disk electrode (RDE) and realistic direct methanol fuel cell (DMFC) test. Our results show that nitrogen doping can play significantly conflicting roles in the anode and cathode performance: (i) A very low doping level (1at.%) is sufficient to induce a homogenous distribution of both anode (PtRu) and cathode (Pt) catalyst nanoparticles. (ii) In RDE test, while nitrogen doping can substantially increase the specific activity of the anodic methanol oxidation, it brings no specific activity enhancement in the cathodic oxygen reduction reaction (ORR), suggesting that nitrogen doping can hardly affect the ORR electrocatalysis on the Pt surface. (iii) In MEA test, a low nitrogen doping level at 1 at.% in NxCNTs as anode catalyst support resulted in a higher power density compared to non-doped CNT support at both 30 and 60°; increasing nitrogen-doping content decreased the power density, likely due to a decreased electron conduction. In contrast, at the cathode, NxCNTs support mainly showed a lower power density, particularly at 60°, which is rationalized by the increased hydrophicility and thus unflavored removal of the water. Taken together, our results provide important guidelines for application of NxCNT support at the appropriate electrode of DMFCs.
A Core-Shell Fibrillar Electrocatalyst for the PEMFC Cathode By Microwave Accelerated Galvanic Displacement of Nickel with Platinum
Authors: Ercolano Giorgio , Farina Filippo , Cavaliere Sara , Rozière Jacques , Jones Deborah J. 
Published: February 2020

Currently Pt/Ni alloy [1] and de-alloyed [2] Pt/Ni nanoparticles, and the 3M nanostructured thin film catalyst of de-alloyed Pt/Ni films on whiskers [3] are some of the few to have met the DoE 2020 mass activity target of 0.44 A/mg Pt at 0.9 VIR free. The origin of the extraordinary activity shown by the Ni/Pt system is attributed to a delicate balance between a thin Pt shell and the sub-surface Ni content [1]. One approach to the preparation of highly active Ni/Pt electrocatalysts is by galvanic displacement of Ni from nanofibres with platinum [4]. We have recently found that is possible to reduce significantly the reaction time for Pt-Ni galvanic displacement by using a microwave-assisted procedure on Ni nanofibres, which leads to high mass activity catalysts (>0.5 A/mg Pt) in only 2 minutes. The shell thickness and density are controlled by extent of Ni/Pt displacement (Pt loading), itself controlled by the concentration of Pt ions in solution. By tuning the Pt content, Pt/Ni core/shell electrocatalysts were prepared that do not require electrochemical etching of surface Ni or de-alloying before utilisation. In addition the nickel core can be leached leaving chemically stable Pt4Ni thin tubular structure.
References:
[1] V. R. Stamenkovic, B. Fowler, B. S. Mun, G. Wang, P. N. Ross, C. A. Lucas and N. M. Marković, Science 315 493–497 (2007).
[2] P. Strasser and S. Kühl, Nano Energy 26 1–12 (2016).
[3] M. K. Debe, R. T. Atanasoski and A. J. Steinbach, ECS Trans. 41 937–954 (2011).
[4] S. M. Alia, Y. S. Yan and B. S. Pivovar, Catal. Sci. Technol. 4 3589–3600 (2014).
Acknowledgement: This project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking under grant agreement No 700127 INSPIRE. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme.
Influence of Methanol Crossover on Cathode Catalyst in Direct Methanol Fuel Cell
Authors: Komárková Zuzana , Fiala Roman , Matolin Vladimir 
Published: February 2020

The crossover effect is in the case of direct methanol fuel cell (DMFC) much more significant in comparison with PEMFC. Proof that the methanol crossover is a big issue in this field is a fact that there exist lots of publications describing the innovative procedures how to diminish this phenomenon [1-4].
In this work we present the investigation of influence of methanol crossover on the cathode catalyst. The durability of cathode catalyst exposed by methanol is studied. Moreover, the regenerative behavior after exposition has been found.
The comparison of commercial catalyst with our own sputtered Pt, Pt-Co and Pt-Ru thin film as a catalyst is presented. Additionally, the technic enabling measurement of the crossover in DMFC using micro-reactor and mass-spectrometry is introduced.
[1] ARICÒ, Antonino S., et al., Membranes, 2015, 5.4: 793-809.
[2] SUDAROLI, B. Mullai; KOLAR, Ajit Kumar.. Energy, 2016, 98: 204-214.
[3] MEENAKSHI, S., et al. Electrochimica Acta, 2013, 89: 35-44.
[4] WAN, Nianfang, et al.. Journal of power sources, 2007, 163.2: 725-730.
Ni-Based Hydrogen Oxidation Reaction Electrocatalysts for Alkaline Anion-Exchange Membrane Fuel Cells: Systematic Study on the Doping Effect
Authors: Davydova Elena S. , Dekel Dario R. 
Published: February 2020

Recent developments in hydroxide conducting anion exchange membranes have contributed to the growing interest in alkaline anion exchange membrane fuel cells (AEMFC) which has the potential to be the next fuel cell generation as in principle this technology allows to replace platinum-based catalysts for affordable metal catalysts. Until now, there are a few research studies describing initial development of hydrogen fueled AEMFC [1], and practically no work done on completely platinum group metal (PGM)-free catalysts for AEMFC. Though some progress was made in the development of low cost electrocatalysts for oxygen reduction reaction (ORR) in base media [2], much less attention was paid to the electrocatalysis for hydrogen oxidation reaction (HOR) in alkaline solutions. Attempts to move away from the use of PGMs results in prohibitively large voltage losses on the anode in the base media (Fig. 1).
This work provides an extensive literature review on both theoretical and experimental advances in HOR electrocatalysts for AEMFCs. In addition, this work provides new insights into new Ni-based electrocatalysts for the HOR in alkaline medium that are being developed in our group at the Technion, including RDE, XRD, XPS, TPD/TPR/TPO, SEM results and some aspects of DFT calculations.
[1] H.A. Miller et al. Angew. Chem. Int. Ed. 55 (2016) 6004.
[2] M.R. Tarasevich et. al. Russ. J. Electrochem. 52 (2016) 193.
[3] E.S. Davydova et. al. (2017), in preparation.
[4] Zhuang Z. et al. Nat. Commun. 7 (2016) 10141.
[5] Zheng J. et. al. Sci. Adv. 2 (2016) e1501602.
[6] http://www.infomine.com/
Acknowledgements. This work was partially funded by the Grand Technion Energy Program (GTEP), by the European Union's Horizon 2020 research and innovation programme under grant agreement No 721065, by the Ministry of Science, Technology & Space of Israel through the M.era-NET Transnational Call 2015, NEXTGAME project grant 3-12948, by the Ministry of National Infrastructure, Energy and Water Resources of Israel, and by the 2nd Israel National Research Center for Electrochemical Propulsion (INREP2-ISF).

Figure 1
Which LiVOPO4 Phase Works Best for Two Li Cycling?
Authors: Hidalgo Marc Francis Villarojo , Lin Yuh-Chieh , Omenya Fredrick , Chernova Natasha , Ong Shyue Ping , Whittingham M. Stanley 
Published: February 2020

Vanadyl phosphates show promise as cathode materials in Li-ion batteries due to the ability to hold multiple Li-ions per redox center. Specifically, the V5+/V4+ and V4+/V3+ couples allow for the material to hold up to two Li-ions per vanadium. The great structural diversity of this family, producing seven VOPO4 and three LiVOPO4 polymorphs, raises a question on which of them would work the best as a Li-ion battery cathode. The electrochemical performance of some of the polymorphs was reported in the literature, but the comparison is complicated by differences is materials morphologies, electrode preparation methods, current densities, and voltage windows used. Here we use LiVOPO4-2H2O as the precursor to synthesize all three LiVOPO4 phases: α1 (layered, tetragonal), β (orthorhombic), and ε (triclinic), and compare their electrochemical performances under the same conditions. The transformation between phases and their relative stabilities are studied using x-ray diffraction and differential scanning calorimetry. The role of oxygen partial pressure in phase stability is discussed based on the experimental data and first-principle calculations results. The electrochemical performance of each phase is evaluated using galvanostatic discharge-charge between 1.5 to 4.5 V at various current rates. The lithium diffusion coefficients are calculated using cyclic voltammetry and galvanostatic intermittent titration technique. These tests reveal that all the three phases can work as multi-electron cathodes; the Li transport details specific to each phase are discussed in conjunction with the structures.
This research is supported as part of the NorthEast Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0012583.
LiNi0.8Mn0.1Co0.
1O2 Cathode Materials with High Physicochemical Stability By Addition of Binding Oxides
Authors: Kang Beomhee , Koo Yehyun , Hong Soonhyun , Kim Chunjoong 
Published: February 2020

Lithium-ion batteries are expanding beyond the power sources of conventional small-sized appliances, and as power sources for electric vehicles and hybrid electric vehicles. However, in order to expand them to the power source of medium and large-sized devices, it needs more improved energy density and stability than existing lithium ion batteries. As a cathode with high energy density, nickel-rich layered oxide in lithium nickel cobalt manganese trivalent oxide (LiNi1-2xMnxCoxO2, NMC) has attracted great attention. In particular, nickel-rich NMC material showed excellent initial discharge capacity compared with Ni low NMC, but the secondary particle intergranular fracture of aggregation occurs during the charging/discharging process, resulting in mechanical deterioration of the material. As a result, capacity decreased due to the increase of charge and mass transfer resistance of battery.
In this study, the metal hydroxide is synthesized by co-precipitation with the addition of oxide materials, which acts as a binding agent in the primary particles. The addition of binding oxides improves the physical and chemical bonding of LiNi0.8Mn0.1Co0.1O2 (NMC811) Particles particles through the control at the precursor stage and it aims at securing the stability of the structure by preventing the crack formation, which is attributed to the mechanical stress of the primary particle phases during repeated cyclings. SEM and XRD analysis were performed to confirm the morphology, size and crystallinity of the powder and spherical particles with a layered structure (space group R-3m) were identified. In order to quantitatively analyze the local position and metal composition ratio of the binding oxide material and lithium in the particles, we studied the NMC811 and the binding oxide through EDS and ICP analysis. The electrochemical analysis was aimed to maintain the capacity over 90% at the lifetime characteristics (0.2 C, 100 times charge/discharge) and the energy density of the cathode material with the binding oxide. In addition, electrochemical characteristics and physical stability were evaluated by observing changes in real time surface characteristics by charging/discharging process using surface analysis such as in-line XPS.
Single Electrode Entropy Change for LiCoO2 Electrodes
Authors: Richter Frank , Gunnarshaug Astrid , Burheim Odne Stokke , Vie Preben J. S. , Kjelstrup Signe 
Published: February 2020

Heat effects and temperature are known to be of great importance to a Li-ion battery’s performance and lifetime expectancy. In this context the reversible heat effects, i.e. effects that are associated with charge transfer and electrode reaction entropy, play an important role [1, 2]. These effects are however scarcely investigated, especially with respect to the single electrode reaction entropy. These values can be obtained when measuring a symmetric cell under a temperature gradient, i.e. two similar electrodes at zero current and at different temperatures [3-4]. We report values of the thermoelectric potential of the symmetric cell consisting of two identical LiCoO2electrodes separated by an electrolyte:
Al(s,T) | Li(1-x) CoO2
(s,T) | EC, DEC, LiPF6(diss) | Lix CO2(s,T + ΔT) | Al(s,T+ ΔT)

The electrodes are commercial LiCoO2 electrodes on an aluminium current collector, each kept at temperatures; T and T + ΔT. The electrolyte is 1 M lithium hexafluorophosphate (LiPF6) in a EC DEC mixture (1:1, volume wise) soaked in a separator. The cell is assembled as a pouch cell, and the electrodes are thermostatted to the specified temperatures.
We show that there are two significant contributions of opposite sign to the thermoelectric signal relative to the temperature difference; commonly known as the Seebeck coefficient. The contribution from the Peltier heat is obtained from the steady state value after 3-5 days. The second contribution, which manifests itself within hours, is a Soret effect. From these results, we report the transported entropy of Li+ and estimate the heats of transfer for the electrolyte components.
The attached figure shows a cross section of the cell used in these measurements, where one side is heated by hot water and the other cooled by cold water. The pouch cell is sandwiched between these two sides and layers of copper containing thermocouples, so that the actual temperature difference on the surfaces of the pouch cell is known and uniform.
References;

Takano, K., et al., Entropy change in lithium ion cells on charge and discharge. Journal of Applied Electrochemistry, 2002. 32(3): p. 251-258.

Viswanathan, V.V., et al., Effect of entropy change of lithium intercalation in cathodes and anodes on Li-ion battery thermal management. Journal of Power Sources, 2010. 195(11): p. 3720-3729.

S. K. Ratkje, M. Ottøy, R. Halseid, M. Strømgård, Thermoelectric power relevant for the solid-polymer-electrolyte fuel cell, Journal of membrane science 107 (1995) 219–228.

S. Kjelstrup, P. J. S. Vie, L. Akyalcin, P. Zefaniya, J. Pharoah, O. S. Burheim, The seebeck coefficient and the peltier effect in a polymer electrolyte membrane cell with two hydrogen electrodes, Electrochimica Acta 99 (2013) 166-175.

Figure 1
Silicon Nanoparticles/Carbon Composites as Anodes for High-performance Lithium-ion Batteries
Authors: Xiao Lisong , Sehlleier Yee Hwa , Dobrowolny Sascha , Schulz Christof , Wiggers Hartmut 
Published: February 2020

Silicon has emerged as the most promising anode candidate for next-generation lithium-ion batteries (LIBs) owing to its high theoretical specific capacity of 3579 mAh/g combined with a relatively low working potential and its natural abundance. However, the practical application of pristine Si in anodes is seriously hindered by its low intrinsic electrical conductivity and the large volume variation during charging and discharging. The resulting mechanical stress causes rapid pulverization of the silicon, and isolation and disconnection of the active materials from the current collector. These failure events mostly cause a rapid degeneration of the Si electrodes.
In this study, Si nanoparticles (Si-NPs) were synthesized in a hot-wall reactor using monosilane as precursor. This process enables producing high purity Si NPs with a large production rate of up to 1 kg/h. Particle size, morphology, and crystallinity of the Si-NPs can be tuned towards optimized properties for battery applications by adjusting the synthesis parameters. In order to overcome the above mentioned failure scenarios of Si-NP-based anodes, Si/carbon nanocomposites such as Si-CNT, Si/graphene, Si-CNT/porous carbon, and Si-CNT/graphene composites have been developed to improve mechanical as well as electrical properties. As a highly promising product, the Si-CNT/ graphene nano-heterostructure demonstrates a high reversible initial capacity of 1665 mAh/g and very stable cycling performance over 500 cycles with a capacity decay of only 0.02% per cycle. Besides, the composite exhibits also a high-rate capability of 755 mAh/g (45.3% retention) at 10 C. These superior results imply that Si/carbon nano-heterostructures can be used for the development of high-performance lithium-ion batteries for durable and high-rate uses.