bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating the Durability of Unsupported Pt-Alloy Aerogel Cathode
Authors: Henning Sebastian , Ishikawa Hiroshi , Kühn Laura , Herranz Juan , Eychmüller Alexander , Schmidt Thomas J. 
Published: February 2020

State-of-the-art polymer electrolyte fuel cells (PEFCs) require considerate amounts of carbon-supported platinum nanoparticle (Pt/C) catalysts (up to 0.4 mgPt/cm2
MEA) to catalyse the cathodic oxygen reduction reaction (ORR) [1]. To reduce overall PEFC costs, these excessive Pt-loadings must be reduced by enhancing the catalysts’ ORR activity and stability; e.g. by alloying platinum with other metals like Ni, Cu, Co [2] and by replacing or completely removing the carbon support that suffers from significant corrosion during the normal operation of PEFCs [3].
To overcome these activity and stability challenges, unsupported bimetallic Pt-alloy aerogels consisting of a 3D nanochain network (~ 30 m2
ECSA/gPt) were synthesized (see Figure 1 for a TEM image of Pt3Ni aerogel) [4, 5]. Both Pt-Ni and Pt-Cu aerogels meet the US Department of Energy ORR activity target for 2017 of 440 A/gPt at 0.9 VRHE[6] when tested in liquid half cells. Considering that this outstanding performance needs to be demonstrated in an actual PEFC, Pt-Ni and Pt-Cu aerogels were processed into membrane electrode assemblies (MEAs) and characterized in a differential PEFC [7].
In this contribution, we present the MEA optimization process for unsupported Pt-alloy aerogel ORR catalysts and compare cell performance and durability (start-stop cycles, load cycles) to a conventional Pt/C benchmark. To explain the outstanding stability of Pt-alloy aerogel catalysts for start-stop cycling (see Figure 1), catalyst layers were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) at beginning-of-life and end-of-life.
[1] F.T. Wagner, B. Lakshmanan, M.F. Mathias, J. Phys. Chem. Lett. 1 (2010), 2204-2219.
[2] H.H. Wang, Z.Y. Zhou, Q. Yuan, et al., Chem. Commun. 47 (2011), 3407-3409.
[3] C. Hartnig, T. J. Schmidt, J. Pow. Sourc. 196 (2011), 5564-5572.
[4] S. Henning, L. Kühn, J. Herranz, et al., J. Electrochem. Soc. 163 (2016), F998-F1003.
[5] S. Henning, L. Kühn, J. Herranz, et al., Electrochim. Acta 233 (2017), 210-217.
[6] O. Gröger, H.A. Gasteiger, J.P. Suchsland, J. Electrochem. Soc. 162 (2015), A2605-A2622.
[7] P. Oberholzer, P. Boillat, R. Siegrist, et al., Electrochem. Commun. 20 (2012), 67-70.
Assessment of Cathode Catalyst Characteristics to Enhance High Current Density Performance in PEMFCs
Authors: Mani Prasanna , Cimenti Max , Manolescu Dorina , Susac Darija , Jankovic Jasna , Sun Dennis , Habisch Aronne 
Published: February 2020

At AFCC continuous effort has been made to improve the power density of fuel cell stack for automotive application in the past decade*. The unique challenges in durability posed by the need for much higher power generation per catalyst loading, kW/mg-Pt is still a major driver and a minimum viable stack functionality for mass production. This presentation will focus on one of the ways to meet the above criterion using mature Pt/C technology (10 to 50 wt% Pt on a high surface area carbon) for oxygen reduction in the cathode. The catalysts were custom made by Tanaka Kikinzoku Kogyo K.K to maximize and stabilize the Pt nanoparticles activity during their life cycle. The graph shows the linear dependency of a mix of the above catalysts characteristics such as Pt surface area (CO Chemisorption), Pt crystallite size (XRD), and catalyst surface area (N2 BET) as a function of Pt wt% on Carbon.
With more in-depth analyses, preliminary optimization of catalyst layer for each of the above catalysts will be performed and the results will be discussed. These activities would facilitate the understanding of the effect of catalyst characteristics, catalyst structure (ionomer, catalyst layer thickness, EPSA, etc.), and electrode Pt loading (0.25 and 0.15 mg-Pt/cm2) on the high current density performance up to 3 A/cm2. Identifying the above parameters would leverage further development in maximizing the fuel cell functionalities and improving the stack durability.

*Reference:AFCC accomplishments, http://www.afcc-auto.com/company/about-us/

Figure 1
Anion Conducting Ionomers for Fuel Cell and Electrolyzer Applications
Authors: Huang Garrett , Liu Lisha , Ahlfield John M. , Kim Yunbum , Kaburagi Yuna , Tricker Andrew , Kohl Paul A 
Published: February 2020

Electrochemical devices, such as fuel cells and electrolyzers, which operate under alkaline conditions, are of interest because they have reduced platinum usage and certain performance advantages. New and improved anion conducting membranes (AEM) have been developed. It is desirable for AEMs to have high molecular weight and low oxygen or fuel permeability.
The anion conducting ionomers used to make the electrodes for fuel cells and electrolyzers share some properties with the membranes, such as chemical stability and high ionic conductivity. However, they differ from membranes in other areas such as oxygen or fuel permeability and molecular weight.
In this study, the performance of a variety of anion conducting ionomers was tested in alkaline fuel cells and electrolyzers. It was found that low molecular weight ionomers gave higher initial and long-term performance. The performance was correlated with materials properties and results from impedance spectroscopy.
Financial support from US Office of the Deputy Assistant Secretary of the Army for Defense Exports and Cooperation (DASA-DE&C) is gratefully acknowledged.
Investigating Non-Precious Metal Catalyst-Electrolyte Interface in Anodes for Alkaline Fuel Cells
Authors: Narvaez Villarrubia Claudia Wuillma , Serov Alexey , Dumont Joseph H , Atanassov Plamen , Kim Yu Seung 
Published: February 2020

Extensive research is being performed in renewable and sustainable energy to satisfy the world’s demand and reduce carbon dioxide emissions. Part of these efforts focuses on the development of energy conversion devices such as fuel cells. Alkaline membrane fuel cells (AMFCs) gained attention due to their good activities for oxygen reduction reaction (ORR) in high pH environments using non-precious metal catalysts.1 However, the hydrogen oxidation reaction (HOR) activities with non-precious metal catalysts are still low and poorly understood. Our previous research3,4 with Pt catalysts in alkyl ammonium and guanidinium alkali organic solvents indicated that the HOR activity of Pt is limited by cationic group adsorption at the surface of the catalyst, showing the performance of fuel cells rapidly degraded. In this presentation, we expand our investigation to the HOR interfacial behavior of non-precious Ni-based catalysts-quaternary ammonium functionalized ionomers using microelectrode set-up. Our data suggests that the time-dependent cationic group adsorption with the non-precious metal catalyst is less than that of the Pt catalysts, in spite of the much lower HOR initial activity of the non-precious metal catalysts. Here we will present the microlectrode and surface-FTIR mechanism studies of the interaction of non-precious metal catalyst and various quaternized alkaline polymer electrolytes and their impact on the kinetics of HOR under high pH conditions.

Acknowledgment

This work is supported by US Department of Energy, Energy Efficiency and Renewable Energy, Fuel Cell Technology Office.

References

[1] H. Meng, P. K. Shen, “Novel Pt-free catalyst for oxygen electroreduction,” Electrochem. Commun.
8, 588–594 (2006).
[2] W.C. Sheng, H.A. Gasteiger, Y. Shao-Horn, “Hydrogen Oxidation and Evolution Reaction Kinetics on Platinum: Acid vs Alkaline Electrolytes,” J. Electrochem. Soc., 157, B1529 (2010).
[3] S.-D. Yim, H. T. Chung, J. Chlistunoff, D.-S. Kim, C. Fujimoto, T.-H. Yang, Y. S. Kim, “A Microelectrode Study of Interfacial Reactions at the Platinum-Alkaline Polymer Interface,” J. Electrochem. Soc., 162, F499 (2015).
[4] H. T. Chung, Y.-K. Choe, U. Martinez, J. H. Dumont, A. Mohanty, C. Bae, I. Matanovic, Y. S. Kim, “Effect of Organic Cations on Hydrogen Oxidatin Reaction of Carbon Supported Platinum,” J. Electrochem. Soc., 163(14), F1-F7 (2016).
(Invited) Electrode Evolution in Solid Oxide Cells
Authors: Irvine John 
Published: February 2020

Fuel cells will undoubtedly find widespread use in this new millennium in the conversion of chemical to electrical energy, as they offer very high efficiencies and have unique scalability in electricity generation applications. The solid oxide fuel cell (SOFC) offers certain advantages over lower temperature fuel cells, notably its ability to utilise CO as a fuel rather than being poisoned and the availability of high-grade exhaust heat for combined heat and power or combined cycle gas turbine applications. Although cost is clearly a key barrier to widespread SOFC implementation, perhaps the most important technical barriers currently being addressed relate to the electrodes, particularly the fuel electrode or anode. In terms of mitigating global warming, the ability of the SOFC to utilise commonly available fuels at high efficiency, promises an effective and early reduction in carbon dioxide emissions and hence is one of the lead new technologies to improve the environment.In the longer term the ability to utilise waste derived fuels such as biogas will be of critical importance.
The electrochemical reactions in fuel cells and electrolysers occur at the interface between electrodes and electrolyte. Here we look at attempts to nanoengineer this interface to enhance performance and also probe the changes in local structure that relate to activation or ageing during operation.
References:
[1] “Switching on electrocatalytic activity in solid oxide cells”, J-H. Myung, D. Neagu, D.N. Miller & J.T.S. Irvine, Nature, 2016, doi:10.1038/nature19090
[2] “Evolution of the electrochemical interface in high-temperature fuel cells and electrolysers”. JTS. Irvine, D. Neagu, MC. Verbraeken, C. Chatzichristodoulou, C. Graves, MB. Mogensen. Nat. Energy. 2016, 1, 15014
(Invited) High Temperature Ionic Ceramics Fuel Cell to Power Unmanned Aerial Systems (UASs)
Authors: Chu Deryn 
Published: February 2020

Small unmanned aerial systems (SUASs) have a great potential for numerous applications. The SUASs are light-weight, man-portable, and capable of delivering commercial products. Currently, small UASs are powered by lithium-ion batteries, however, flight endurance is limited and requires frequent charging battery due to low capacity and energy density. Numerous research and development efforts have focused on alternative power sources. These alternative power sources include technologies such as solar cells and hydrogen based polymer electrolyte membrane fuel cells. In this presentation, we address a high temperature ionic ceramics fuel cell to power a ~20lbs unmanned aerial system for 8hrs (4x improvements over the competing battery technology).
Optimization of Anion Exchange Membranes Derived from Cross-linked Chitosan-Poly (diallyldimethylammonium chloride) for All-solid Electrochemical Capacitors
Authors: Wei Yanan , Ao Bei , Qiao Jinli , Lian Keryn 
Published: February 2020

Carbon dioxide can be formed in many ways, especially in combustion, it is one of the most important reasons lead to greenhouse effect and global warming. So many scientists devoted themselves to techniques that can reduce CO2 emissions. Among these promising techniques, electrochemical ways provide a efficient means, as it can convert carbon dioxide into fuels and other useful materials.[1,2] This way has many advantages: (a) the process is controllable by setting the temperature of electrode; (b) the system can take advantage of new energy resources and the production do not contaminate environment; (c) the system is compact and easily operated; (d) the experiment can be operated under normal atmospheric pressure and temperature.[3,4]

In this paper, Tin-Cu alloy was deposited on carbon paper by electrodeposition in aqueous solution, which was employed as a cathode for electrochemical reduction of CO2 to formate, and how to obtain big catalytic current density, high efficiency and high production rate of formate were explored and discussed. Tin-Cu alloys with different compositions were characterized by morphology, structure, and composition. The electrochemical behavior of the alloys was measured by EIS and CV analysis. In addition, FE, partial current density (PCD), and concentration of HCOO− on the alloys were investigated and compared with those on Sn and Cu electrodes.
References
[1] S. Rasul, D.H. Anjum, A. Jedidi, Y. Minenkov, L. Cavallo, K. Takanabe, Angew. Chem. Int. Ed., 54,2146(2015).
[2] Q. Lu, J. Rosen, Y. Zhou, G.S. Hutchings, Y.C. Kimmel, J.G. Chen, F. Jiao, Nat. Commun., 5,4242(2014).
[3] Q. Shen, Z.F. Chen, X.F. Huang, M.C. Liu, G.H. Zhao, Environ. Sci. Technol., 49,5828(2015).
[4] X.Q. Min, M.W. Kanan, J. Am. Chem. Soc., 137, 4701(2015).
Mechanical Characterization of SOFC Anode Support Materials at Operating Conditions
Authors: Stanley Patrick , Hays Thomas H , Wachsman Eric D. 
Published: February 2020

Solid-oxide fuel cells (SOFCs) rely on a good seal between the anode and cathode sides of the cell to function properly. This means that cells must be manufactured, assembled, and sealed in a manner that does not compromise the gas-tight separation of anode and cathode. The mechanical properties of the cell, specifically the anode support layer, must be able to withstand the stresses it is subjected to without cracking. While the specific material and processing conditions can affect the mechanical properties, so can the temperature and oxygen concentration, thus it is of interest to characterize the mechanical properties not only at ambient conditions, but also at elevated temperatures and under reducing environments.
To study these properties, flexural bend tests were performed on gadolinium doped ceria samples at various temperatures and oxygen partial pressures to study their flexural modulus and flexural strength. This was then compared with other characterization and mechanical testing techniques, such as scanning electron microscopy, X-ray diffraction, indentation and impulse excitation techniques, to evaluate what phenomenon are occurring under what conditions. From this work, it can be better understood how a SOFC must be designed and manufactured to be able to withstand stresses while under operating conditions.
Features of Molten Oxide Fuel Cells and Molten Oxide Membranes for Electrochemical Energy Conversion and Oxygen Separation
Authors: Belousov Valery 
Published: February 2020

Recently, the molten oxide fuel cell (MOFC) and molten oxide membrane (MOM) concepts have been proposed.1-4 MOFCs are a new class of intermediate temperature fuel cells combined the advantages of both solid oxide fuel cells, SOFCs (air as a cathode gas) and molten carbonate fuel cells, MCFCs (a highly conductive molten electrolyte) and could be used for electric power generation. MOMs are a new type of ion transport membranes which demonstrate competitive oxygen permeability and highest oxygen selectivity and could be used for ultrahigh purity oxygen separation from air. However, before MOFC and MOM technologies can gain a share of the energy market, important issues have to be addressed. These issues include the development of innovative molten oxide materials with enhanced performance and establishment of oxygen ion transport mechanisms in these materials. Understanding the oxygen ion transport mechanisms in molten oxides is important for the discovery of next-generation electrochemical materials that can enable the operation of MOFCs and MOMs efficiently. In this paper, we highlight the progress made in developing this understanding as well as the advances made in searching innovative electrochemical materials for MOFCs and MOMs.
References

V.V. Belousov. Next-Generation Electrochemical Energy Materials for Intermediate Temperature Molten Oxide Fuel Cells and Ion Transport Molten Oxide Membranes, Acc. Chem. Res., 2017, 50, 273.

V.V. Belousov, S.V. Fedorov. A Novel Molten Oxide Fuel Cell Concept, Fuel Cells, 2016, 16, 401.

V.V. Belousov, S.V. Fedorov. A Highly Conductive Electrolyte for Molten Oxide Fuel Cells, Chem. Commun., 2017, 53, 565.

V.V. Belousov, I.V. Kulbakin, S.V. Fedorov, A.A. Klimashin. Novel Molten Oxide Membrane for Ultrahigh Purity Oxygen Separation from Air, ACS Appl. Mater. Interfaces, 2016, 8, 22324.
Stabilization of Electrode-Electrolyte Interface By Conformal Passivating Layers on the Surface of Spinel Nanocrystals
Authors: Kwon Bob Jin , Key Baris , Dogan Fulya , Jokisaari Jacob , Kim Chunjoong , Klie Robert F , Cabana Jordi 
Published: February 2020

Stable cycling performance with high power density in lithium ion battery (LIBs) is required to meet the criteria for the power source such as electric vehicles. But generally, high power density is hindered by slow diffusion of lithium ions in micrometric electrode materials. [1] From this perspective, nanoparticle electrode materials can enhance the rate of lithium ions because of shortened diffusion pathway of lithium ion. Besides, high surface area of electrode induces facile access of charge via large contact area with electrolyte and conducting additives like carbon. In contrast, chemical degradation at electrode-electrolyte interface is also facilitated by large contact area with nanoparticle electrode. Unfavorable interfacial reactions such as dissolution of cathode species and decomposition of electrolyte mainly occur through energetically unstable surfaces of the active material. [2] In order to minimize side reactions that can negatively affect electrochemical performance, introducing electrochemically inactive ions on the surface of active materials can improve the interfacial stability. However, this substitution should take place as thin passivating layers on individual particles to preserve storage capacity. [3] A strategy toward the stabilization of electrode-electrolyte interfaces has been devised by introducing core-shell nanocrystals, consisting of electroactive lithium transition metal oxide cores and ultra-thin inactive epitaxial oxide shells on the surface. Spinel Li1+xMn2-xO4 nanocrystals were used as a core component, with an Al-rich shell as passivation layers to minimize unfavorable reaction on the surface of cathode particles. The electrochemical performance shows that Spinel Li1+xMn2-xO4 nanoparticle with conformal shell reveals improved capacity retention and rate capability even at elevated temperature, compared to a bare counterpart.
Reference
1. Isaac D. Scott, Yoon Seok Jung, Andrew S. Cavanagh, Yanfa Yan, Anne C. Dillon, Steven M. George, and Se-Hee Lee, Nano Letters, 414–418, 11 (2011).
2. Peter G. Bruce, Bruno Scrosati, and Jean-Marie Tarascon, Angew. Chem. Int. Ed, 2930-2946, 47 (2008).
3. Chunjoong Kim, Patrick J. Phillips, Linping Xu, Angang Dong, Raffaella Buonsanti, Robert F. Klie, and Jordi Cabana, Chem. Matter, 394-399, 27 (2014).
Enhanced Electrochemical Performance of Mechano-Activated Nanoparticles of the Low Temperature Orthorhombic Phase of Li2FeSiO4
Authors: Rasool Majid , Lu Xia , Chiu Hsien-Chieh , Voisard Frédéric , Gauvin Raynald , Jiang De-Tong , Zaghib Karim , Demopoulos George P. 
Published: February 2020

Lithium transition metal silicates Li2

M
SiO4 (
M
= Fe, Mn, Co, etc.) have been under intense research due to their high theoretical capacity of 330 mAh/g. However, most of the present work have been focused on the electrochemistry of the high temperature monoclinic phase (m-LFS), which shows clear phase transition to a thermodynamically stable low-temperature orthorhombic phase (o-LFS) during cycling. In this context we thought of interest to investigate the cycling behavior of the low-temperature o-LFS that we synthesized via hydrothermal processing. However, as synthesized o-LFS crystals have large ~1.5 µm size, which is undesirable for li-ion intercalation. Therefore, for particle size reduction, we used high energy planetary ball milling and obtained nanoparticles of ~50 nm. Interestingly, XRD results showed improved crystallinity during ball milling. Moreover, electrochemical performance of such mechanically activated nanoparticles showed improved capacity with increasing milling time. This intriguing (unusual) behavior could have significant implications to the development of high capacity LIB materials.
Keywords: Li2FeSiO4; Orthorhombic; Low temperature; Electrochemical performance; Li-ion battery
(Invited) Cation-Disordered Rocksalt Oxides for High-Capacity Positive Electrodes of Rechargeable Lithium/Sodium Batteries
Authors: Yabuuchi Naoaki 
Published: February 2020

In the past decade, lithium-enriched compounds, Li2MeO3 (Me = Mn4+, Ru4+ etc.), have been extensively studied for high-capacity positive electrode materials of lithium batteries. Although the origin of high reversible capacities was a debatable subject for a long time, recently it has been evidenced that charge compensation is partly achieved by solid-state redox of non-metal anions, i.e., oxide ions (anionic redox),[1] coupled with solid-state redox of transition metal ions (cationic redox), which is the basic theory used for classical lithium/sodium insertion materials. Competition between cationic and anionic redox reactions is often evidenced for the lithium-enriched materials because the energy level of oxygen 2p band is lowered by the presence of excess lithium ions with high ionic characters in the crystal lattice. Reversibility of anionic redox reactions is also influenced by ionic and covalent characters for chemical bonds of transition metal ions.[2, 3] In contrast, when the energy of metal 3d band is low enough than that of oxygen 2p, pure cationic redox is realized even for lithium-excess system.[4] In this presentation, we discuss the material design strategy with the concept of cationic and anionic redox reactions to develop new high-capacity lithium/sodium insertion materials for battery applications.
References
[1] M. Sathiya et al, and J.-M. Tarascon, Nature Materials, 12, 827 (2013).
[2] N. Yabuuchi et al., PNAS, 112, 7650 (2015).
[3] N. Yabuuchi et al., Nature Communications, 7, 13814 (2016).
[4] S. Hoshino, et al., and N. Yabuuchi, ACS Energy Letters, 2, 733 (2017).