bluuebunny/crossref_metadata_2025 huggingface dataset:
High Performance Anode Material for Solid Oxide Fuel Cells: Ni Exsolution on a-Site Deficient La0.4Sr0.4Sc0.9Ni0.1O3
Authors: Gao Yang , Ciucci Francesco
Published: February 2020

Highly efficient and environment-friendly devices for energy transformation are in urgent demand for the sustainable production of power. Solid oxide fuel cells (SOFCs) are among the most efficient systems that can convert chemical energy directly into electricity. Currently, Ni/yttria-stabilized ZrO2 (YSZ) is the state-of-the-art SOFC anode material (or the cathode material of solid oxide electrolysis cells), due to its relatively high mechanical strength, high performance, and low cost. However, the Ni/YSZ anode still has several limitations including Ni agglomeration at high temperature, sulfur poison, and carbon coking.  While perovskite-type materials have been used as SOFC anodes to overcome many of these challenges, their catalytic activity is typically poor. Recently, exsolution of catalytic nanoparticles on the surface of perovskites has drawn great research interest because of the potential enhancement in electrochemical activity. Irvine and collaborators have shown that A-site deficient perovskites allow easier and more controllable exsolution, and several materials capable of growing nanoparticles in-situ have been developed. However, the catalytic activity delivered by A-site deficient perovskites with exsolved nanoparticles is still not comparable to that of state-of-the-art SOFC anode materials. There are still many opportunities for materials development and improvement, since most of the recent studies have focused on La0.5Sr0.5TiO3 or NbTiO4
related materials. Perovskites based on other non-easily-reducible metals may be used to deliver even better activity.

In this work, we report a novel Sc-based A-site deficient perovskite La0.4Sr0.4Sc0.9Ni0.1O3-δ (LSSN), synthesized as an anode material for solid oxide fuel cells. LSSN is reduced in hydrogen at 900 oC for 15 hours to form a highly active and stable anode. Spherical Ni nanoparticles (~100 nm in diameter) with well-defined boundaries are exsolved on the surface after reduction. the reduced LSSN (rLSSN) show high electrochemical catalytic activity, with the area specific resistances as low as 0.055 Ω cm2 at 800 °C in humid H2. Our work introduces a new anode material with potential to enhance electrochemical catalytic activity and suggests a new series of A-site deficient perovskites for SOFC anodes.
Developing Low-Intermediate Temperature Fuel Cells for Direct Conversion of Methane to Methanol Fuel
Authors: Torabi Alireza , Barton Joseph , Willman Carl , Ghezel-Ayagh Hossein , Li Na , Poozhikunnath Abhinav , Maric Radenka , Marina Olga A
Published: February 2020

The direct conversion of methane to liquid fuels and chemicals is highly sought, especially at low-scale to more effectively utilize remote natural gas resources. The objective of this project is development of a durable, low-cost, and high performance  Low Temperature Solid Oxide Fuel Cell (LT-SOFC) for direct conversion of methane to methanol and other liquids, characterized by: a) Operating temperature < 500oC, b) Current density of > 300 mA/cm2,  in fuel cell mode  and > 100 mA/cm2 in liquid hydrocarbon production mode, c) continuous operation of > 100 h, d) cell area > 100 cm2, e) cell cost  per rate of product output < 100,000/bpd, f) process intensity of > 0.1 bpd/ft3, g) product yield  and carbon efficiency > 50%, and h) volumetric output per cell > 30 L/day
(Invited) Materials Challenges in Advanced Water Splitting Technologies
Authors: Miller Eric Lars , Randolph Katie , Peterson David , Sutherland Erika , Rustagi Neha , Studer Sarah , Klahr Benjamin
Published: February 2020

The US Department of Energy’s (DOE) Fuel Cell Technologies Office (FCTO) has made significant progress in hydrogen and fuel cell technology advancement and cost reduction.  With the rollouts of fuel-cell vehicles by major automotive manufacturers underway, enabling technologies for the widespread production of affordable, renewable, low carbon footprint hydrogen becomes increasingly important. FCTO’s Hydrogen Production Program supports a broad range of H2 production pathways, ranging from nearer-term to longer term technologies.  Advanced water splitting (AWS), including electrolysis, photoelectrochecmical and thermochemical routes, is one of the more versatile pathways and can play a significant role. A general overview of FCTO’s H2 Production Program with a focus on advanced water splitting technologies will be provided.

Fundamental materials challenges remain which limit conversion efficiency and durability of AWS H2 production pathways, therefore limiting large-scale technoeconomic viability.  Expensive materials are commonly required.  Innovations are needed in the development of functional materials and interfaces which address the thermodynamic and kinetic limitations to performance and lifetime at the macro-, meso- and nano-scales.  Catalytic advances, especially with respect to low- and non-platinum group metal (pgm) hydrogen and oxygen evolution catalyst materials in both acidic and basic environments, are needed for low temperature electrolysis operation. Examples of ongoing electrolysis and photoelectrochemical R&D will be discussed.
A Pt-Free, Activated Carbon Nanotube Cathode, PEM Water Splitting Electrolyzer
Authors: Das Rajib Kumar , Vasilyeva Svetlana V. , Pulido Ramon M , Pucher Ilaria , Turiansky Mark , Rinzler Andrew G.
Published: February 2020

Anticipated increases in worldwide energy consumption, the reality of ultimately limited hydrocarbon fuels, as well as their contribution to global warming, have all encouraged the development and commercialization of renewable, carbon neutral, energy technologies. An issue for renewable energy sources like solar, wind and wave energy is their intermittency. An efficient means to overcome this intermittency is to build excess capacity into the generating plants and to use that excess capacity to produce high energy density hydrogen fuel via water electrolysis for on demand reconversion to electrical energy in fuel cells. A major impediment to this solution is that commercial water splitting electrolyzers use scarce and costly precious metal catalysts which make such an energy storage/recovery scheme prohibitively expensive. Alternative, earth-abundant, non-precious metal catalysts are highly desired.

We recently demonstrated that purified single wall carbon nanotubes (SWNT), and select layered graphitic materials, activated by a simple electrochemical process, provide an exceptional non-precious metal electrocatalyst for the hydrogen evolution and the hydrogen oxidation reactions in both acidic and near neutral pH. [1] Here we validate this result for hydrogen evolution in a single-cell PEM electrolyzer. The MEAs studied used Nafion 115 and an IrRuOx anode. Three distinct cathodes were tested: 1) commercially available Pt loaded (3.0 mg/cm2) Vulcan X-72 carbon (for a point of comparison); 2) non-activated SWNTs; and 3) activated SWNTs. In all cases I-V measurements were performed at 80oC. The commercial Pt loaded MEA exhibited the high gas production rates expected from engineered Pt, converting 1.0 A/cm2 at 1.67 V. The non-activated SWNTs yielded very low gas production rates requiring 1.89 V for a current of only 0.040 A/cm2. The activated SWNTs demonstrated a performance completely comparable, at all potentials, with that of the commercial Pt electrode (see Figure), attaining 1.0 A/cm2 at 1.64 V. Ninety hours of operation showed no degradation in the cathode performance.

It has been estimated that a 50% reduction in the cathode Pt used would result in a 15% electrolyzer cost reduction. [2] Our entirely Pt–free electrode using only earth abundant carbon could nearly double that cost saving.

Acknowledgements.

This work was supported by Nanoholdings, LLC.

References:

[1] R. K. Das, Y. Wang, S. V. Vasilyeva, E. Donoghue, I. Pucher, G. Kamenov, H.-P. Cheng, A. G. Rinzler, ACS Nano, 8 (8), 8447–8456 (2014)

[2] K. E. Ayers, E. B. Anderson, C. B. Capuano, B. D. Carter, L. T. Dalton, G. Hanlon, J. Manco, and M. Niedzwiecki, ECS Transactions, 33 (1), 3-15 (2010)

Figure 1
Metal Oxides Supported on Carbon Nanotubes As Bifunctional Electrocatalysts for Reversible Alkaline Membrane Fuel Cells
Authors: Zhao Shuai , Rasimick Brian , Mustain William E , Xu Hui
Published: February 2020

Carbon nanotubes (CNTs) have received much research interest for energy conversion and storage due to their inherent extraordinary electrical and mechanical properties. Modified CNTs could be used as electrocatalyst supports for the oxygen reduction reaction (ORR) in fuel cells and for the oxygen evolution reaction (OER) for water electrolyzers. Here we present metal oxides supported on CNTs as bifunctional catalysts for reversible alkaline membrane fuel cells.

In order to introduce more active sites and further optimize both the ORR and OER activity in alkaline media, growing transition metal oxides, such as cobalt and nickel oxides, along pre-oxidized CNTs is a state-of-the-art technique. However, in this study, we have discovered that the oxidation degree of the support CNTs (i.e., different oxidizing agents and length of oxidation time) may lead to variable proportions of oxygen functional groups or defective sites, which can further influence the size of metal oxides and their distribution on the CNTs.

As shown in Fig. 1a and b, the support CNTs were pre-oxidized by KMnO4 and concentrated HNO3, respectively, resulting in different densities of metal oxide particles along the tubes. Comparing different length of oxidation time in Fig. 1b and c, the CNTs oxidized by concentrated HNO3 for 0.5 h (Fig. 1c) have much fewer particles anchored than the ones with 6 h oxidation (Fig. 1b).  All of these feature changes would have a huge impact on the activity and durability of the bifunctional catalysts. 

This work may provide novel perspectives for design of CNTs as support materials in electrochemical applications.

Acknowledgement:The project is financially supported by the Department of Energy’s Fuel Cell Technology Office under the Grant DE-EE0006960.

Figure 1.  Metal oxide particle growth along CNTs based on various oxidation degrees

Figure 1
Design of Electrocatalysts for Oxygen Evolution Reaction
Authors: Serov Alexey , Maes Ashley M , Blair Sarah , Artyushkova Kateryna , Atanassov Plamen
Published: February 2020

Nanostructured materials are widely used in different energy applications: fuel cells, electrolyzers, supercapacitors, Li-ion batteries, etc [1, 2]. Several synthetic approaches can be used for the preparation of CNTs, graphene, etc, such as CVD, exfoliation and other. Herein we report the adopted sacrificial support method (SSM) developed at UNM group [3-4] as a powerful tool for synthesis of materials for oxygen evolution from alkaline solutions.

Several types of 3D structured materials such as carbon nanotubes, oxides, bi- and tri-metallic nickel-based alloys were synthesized by modified SSM. The morphology control was achieved by variation of silica and precursors type, as well as the ratio of silica to the precursor. After successful synthesis of those materials, the sacrificial support (SiO2) was leached using concentrated HF or by 7M KOH. Figure 1 represents a schematic synthesis of CNT-based materials by Sacrificial Support Method.

Figure 1. Schematic view of CNT-based materials synthesis by Sacrificial Support Method.

Different materials with controlled morphology were characterized by XRD, SEM, TEM, BET and XPS methods. Electrochemical performance in the reactions of oxygen reduction, oxygen evolution, was found to be promising for substitution of existing state-of-the-art platinum group metals catalysts.

References:

[1] N. I. Andersen, A. Serov, P. Atanassov “Metal Oxides/CNT Nano-Composite Catalysts for Oxygen Reduction/Oxygen Evolution in Alkaline Media”, Appl. Catal. B: Environmental, 163 (2015), 623-627.

[2] A. Serov, M. Padilla, A. J. Roy, P. Atanassov, T. Sakamoto, K. Asazawa, H. Tanaka "Anode Catalysts for Direct Hydrazine Fuel Cells: From Laboratory Test to an Electric Vehicle", Angewandte Chemie Int. Ed. 126 (39) (2014), 10419–10715.

[3] A. Serov, K. Artyushkova, N. I. Andersen, S. Stariha, P. Atanassov "Original Mechanochemical Synthesis of Non-Platinum Group Metals Oxygen Reduction Reaction Catalysts Assisted by Sacrificial Support Method", Electrochim. Acta (2015) doi:10.1016/j.electacta.2015.02.108

[4] A Zalineeva, A Serov, M Padilla, U Martinez, K Artyushkova, S Baranton, C Coutanceau, Plamen B Atanassov, "Glycerol electrooxidation on self-supported Pd1Sn1-x nanoparticules", Appl. Catal. B: Environmental, 176 (2015), 429–435.

Figure 1
Cobalt-Molybdenum Carbide Hybrids As Efficient Oxygen Evolution Reaction Catalysts for Alkaline Water Electrolysis
Authors: Kim MinJoong , Song DongHoon , Oh SeKwon , Cho EunAe
Published: February 2020

Increasing demand for clean energy have triggered researches on alternative energy sources and devices to reduce use of fossil fuel. Hydrogen has been considered as one of the most promising energy source for future due to its high energy density and no air pollutant emission. Splitting water into hydrogen and oxygen is an environmentally friendly method for producing hydrogen gas. This technology can store excess electric energy in the form of chemical bonds of hydrogen, which can resolve an issue about surplus electric power of present renewable energy systems caused by irregular energy source such as airflow and sunlight.

Water electrolysis reaction is divided into two half reactions; hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). High overpotential of both HER and OER is the most significant problems to hamper reaction rate and overall efficiency of water electrolysis, especially OER has much higher overpotential than HER. Therefore, recently major efforts have been devoted to exploring active catalysts for the OER in water electrolysis cell.

Among many kinds of candidate materials for OER catalyst, cobalt (Co) and various Co based materials, including nanostructured Co3O4, CoSe2, Co based perovskites, CoP, CoB and Co/N-doped carbon, have drawn much attention for use in the alkaline water electrolysis system. These Co based catalysts have low OER ovepotential in alkaline media comparable with precious metal based catalysts, such as IrO2 and RuO2. However, previous studies has focused mainly on the exploring desirable composites for high OER activity without careful mechanistic study. OER mechanism on Co based catalysts and descriptors for designing more efficient catalysts have been unclear yet.

Herein, we report novel hybrid type catalysts, which composed of Co and molybdenum carbide (Mo2C), as efficient OER catalysts for alkaline water electrolysis, and evaluate the OER mechanism by investigating the effects of surface acidity of the catalysts on the OER activity in alkaline media. Mo2C has very similar electronic structure with platinum (Pt) group metal. So, it can be promising candidate as an efficient electrocatalyst for water electrolysis system. We synthesized Co-Mo2C hybrids using facile solution based process. Synthesized Co-Mo2C hybrids exhibit enhanced activity and durability compared with Co and ruthenium dioxide (RuO2) catalysts in alkaline media (0.1 and 1 M KOH). This result is ascribed to increase in surface acidity by formation of Co-Mo bimetallic surface on the Co-Mo2C hybrids. Increase in surface acidity leads to increase in hydroxide ion (OH-) adsorption on the catalyst surface, which can promote the OER kinetics in alkaline media.

Fig. 1. XRD patterns of Co-Mo2C hybrids.

Fig. 2. OER activities of Co-Mo2C hybrids, Co, RuO2 and Mo2C in 0.1 M KOH solution.

Figure 1
Electrodeposition of Binary and Ternary Ag-Tl-Se Thin Films and Its Possible Application in Photoelectrochemical Conversion of the Solar Energy
Authors: Lucas Francisco Willian de Souza , Mascaro Lucia Helena
Published: February 2020

Solar energy is inexhaustible, has renewable characteristics, and is considered to be a clean energy source. One of the main energy sources of the future is linked to the efficient utilization of the solar energy by conversion into electric energy (photovoltaic conversion) or for hydrogen fuel producing (photoelectrochemical water splitting). According to our knowledge, the study of the applicability of the binary and ternary Ag-Tl-Se films in solar energy conversion has not been reported, as well as, the fabrication of these films by electrodeposition. In light of this, the present work describes the pulsed- and co-electrodeposition of the binary and ternary Ag-Tl-Se (ATSe) thin films and its applicability in the photoelectrochemical hydrogen production by water splitting. For this, studies of cyclic voltammetry (CV), SEM, EDX, NIR-UV-vis spectroscopy, XRD, Mott-Schottky, and photocurrent were performed. Electrochemical experiments were carried out in a 3-electrode configuration electrochemical cell. Mo-plate (1 cm2) was the working electrode; a Pt-plate was used as the auxiliary, and an Ag/AgCl/Cl-
(sat. KCl) served as the reference electrode (RE). The measurements of comparative photocurrent were performed in 0.5 H2SO4 at -0.60 V and using a solar simulator with AM 1.5G lens, where the light intensity incident on the electrode was adjusted to 100 mW cm-2 (1 sun).   From electrochemical behavior characterized by CV, they were chose the deposition potentials of 0.1, -0.15 and -0.4 V vs. RE for ATSe films obtaining. The optimized electrolytic bath was constituted of 0.1 mM AgNO3, 3 mM Tl2SO4, 1 mM SeO2, and 0.5 M Na2SO4/H2SO4, pH = 2. The codeposition (CD) and potential pulsed deposition (PP) were used for study the method effect on the films properties. For CD, the bath temperatures were 25 and 50º C and for PP, 22 factorial experiments were done at 25º C; with pulse duration (2 or 10 min) and number of potential pulses (2 or 3 potentials) as variables. Ten (10) different films were obtained and, from them, it was possible to conclude that the properties are strongly dependent of the deposition potential, bath temperature, growing method and pulse duration. All films were p-type, showed band gap energy from 0.89 to 1.06 eV and presented Ag-Se, Ag-Tl-Se or Tl-Se phases. Interesting results were obtained from photocurrents studies, it was observed that the films composed of a mixing of cubic TlSe and tetragonal Tl2Se phases had higher photocurrent intensity (0.92 mA cm-2) associated the hydrogen production during photoelectrochemical water splitting. Such films were obtained by the CD method, using 1h of electrodeposition at the potential of -0.4 V vs. RE and bath temperature of 50º C. Thus, these studies could help us to observe the potentiality of the Tl-Se films for efficient solar energy conversion, which will be shown.
Tungsten Carbide-Based Catalysts for Oxygen Evolution Reaction in Alkaline Media
Authors: Song DongHoon , Kim MinJoong , Cho EunAe
Published: February 2020

Hydrogen produced by electrolysis is one of the promising means by which to store electricity coming from renewables and to address its intermittency. With the growing global electricity share from renewable energy sources, large-scale storage systems are required. Alkaline electrolysis can be a sustainable solution for the large-scale energy storage system. However, high overpotential and slow kinetics particularly of the oxygen evolution reaction (OER) still remains as a hurdle to limit efficiency of the system. To enhance efficiency of alkaline electrolysis cells, catalysts which have high electrocatalytic activity for OER should be developed.

 Platinum-like behavior of Tungsten carbide in surface catalysis was first reported by Levy and Boudart in 1973[1]. In addition, tungsten carbide was reported to have Pt-like electronic structure by Colton in 1975[2]. After that, tungsten carbide has been studied widely and expected to substitute noble metal catalysts which are used in many electrochemical reactions. Here, we studied tungsten carbide as a support for 3d-transition metals and make bi-metallic surfaces for developing a high activity OER catalyst.

 First, WC-Co was synthesized by heat treatment. Carbon nitride (g-C3N4) and tungsten chloride were used as a carbide precursor and cobalt acetate was also used for helping carbonization of tungsten. After heat treatment, acidic leaching process was followed to eliminate cobalt. Through additional mixing with Nickel precursor and heat treatment, Ni/WC was synthesized and to compare electrocatalytic activity Ni/C was also prepared. In addition, many different Ni/WC which have different Ni to WC ratios were synthesized and measured in electrochemical way. Finally, the optimal ratio was determined and it show better electrocatalytic activity than precious catalysts and any other non-noble catalysts.

 Cyclic voltammetry was measured to evaluate OER activity in 1 M KOH in potential range from 1 to 1.8 V. Figure 1 shows that pure WC and Ni/C have 394 mV and 413 mV overpotentials at 10 mA∙cm-2 respectively. In Metal/WC cases, Cobalt/WC shows only 417 mV. But Nickel/WC shows 340 mV overpotential at 10 mA∙cm-2 and higher electrocatalytic activity for OER than RuO2 in alkaline media.

 

η
@ 10 mA cm-2 (mV)

Ni/C
394

WC
413

Co/WC
417

Ni/WC
340

RuO2

355

Table1. Activities for OER at 10 mA cm-2

References

[1] R. B. Levy, M. Boudart, Science, New series, Vol. 181, No. 4099 (1973) 547-579

[2] Richard J. Colton, Jan-Tsyu j. Huang, J.Wayne Rabalais, Chemical Physics Letters, Vol. 34, No. 2 (1975) 337-339

Figure1. Cyclic voltammetry for the oxygen evolution reaction in 1 M KOH of Ni/C, WC, Co/WC, Ni/WC, RuO2

Figure 1
Electrochemical Synthesis of Hydrogen with Depolarization of the Anodic Process
Authors: Skatkov Leonid , Tulskiy Gennadiy , Tulskaya Alena , Bayrachniy Vladimir , Gomozov Valeriy , Deribo Svetlana
Published: February 2020

World experience defines hydrogen as the most perspective energy carrier. Producing hydrogen by electrolysis helps effectively solve the problem of peak loads and failures arising from the different structure of energy consumption during the day .

Thermoelectrochemical cycles of producing hydrogen are intensively studied in Kharkov Polytechnic Institute, Kharkov, Ukraine. Further development of  hydrogen production by electrolysis of water associated with implementation of Hybrid Sulfur cycle  or "Westinghouse cycle") [1]. It is a two–step process, first a low–temperature electrochemical step (1):

2H2O + SO2 H2 + H2SO4                 (1)

and second a high temperature (2):

H2SO4 H2O + SO2 + 0,5 O2                  (2)

   The clear advantage of the Hybrid Sulfur Cycle process is that the standard reversible voltage E0 of the net cell reaction (2) is only 0.17 V. For comparison, conventional water electrolysis requires E0 = 1.23 V. In laboratory–scale tests, the realized cell voltage of SO2 depolarization electrolysis has been 0.5¼1.3 V, depending on the current density and other operational parameters compared with the 1.8¼2.0 V of commercial alkaline water electrolysis. Thus, SO2 depolarization electrolysis would require 25¼60 % of the electrical energy required for direct water splitting by conventional electrolysis. The electrochemical process is far from technical implementation and intensively studied in recent years.Hybrid Sulfur cycle was intensively studied for practical implementation with using platinum, gold and palladium anodes . Further investigation is connected with using more affordable anode materials. According to the E–pH diagram, ruthenium, molybdenum, tungsten and their oxides are defined to be most perspective catalytic materials.

 Active porous anode was obtained by covering the graphite basis by active carbon, Pt, MoO3, RuO2, WO3. Covering with active carbon was prepared by impregnating the graphite basis in sugar solution, followed by drying and thermal decomposition. The other composite coatings were prepared by impregnating a sugar solution and brine H2[PtCl6], (NH4)6Mo7O24·4H2O, (NH4)4W5O17, followed by drying and thermal decomposition at 600...650 K. The cylindrical anodes have diameter 20 mm and thickness 5 mm.

          They were inserted into a special current source, consisting of a current–conducting tubes with welded sample holder (Fig. 1). Samples were fixed in a holder nut. Current supply material – titanium coated PTFE. Current–voltage measurements were carried out in plastic cell with anode and cathode separation space cation exchange membrane. Electrode potentials were measured relative to a mercury sulfate reference electrode and converted to the normal hydrogen electrode.
Nanostructured Nickel Iron Sulfide Grown on Nickel Foam for Highly Active and Durable Water Splitting Electrocatalyst in Alkaline Electrolyte
Authors: Shanmugam Sangaraju , Ganesan Pandian
Published: February 2020

The increasing demand for the energy and environmental concerns has induced global efforts to find and explore alternative energy sources for fossil fuels. As an ideal candidate, hydrogen produced from water splitting is an attractive next generation energy conversion device [1]. The noble metals are the most active in catalyzing the water electrolysis to produce pure hydrogen, but the high cost and elemental scarcity greatly hinder their widespread applications. The development of low-cost, efficient, and robust electro-catalysts (both oxygen evolution (OER) and hydrogen evolution (HER) catalysts) for water splitting is a crucial step toward the conversion and storage of sustainable energy resources such as solar energy. Not only the catalysts need to be composed of inexpensive elements, they are also desirable to be prepared at low energy cost [2,3,4].

   Here, we have investigated the inexpensive synthesis of electrochemically depositing the nickel iron sulfides on nickel foam for the highly efficient bi-functional water splitting to meet the current demand. Nickel iron sulfide on nickel foam (NiFeS/NF) showing the low over-potential about 230 mV for OER and 205 mV for the HER. This bi-functional catalyst also showing robust durability about 200 hours. The high performance and also the facile synthesis with strong coating on nickel foam make it commercial viable catalyst. The NiFeS/NF catalyst for large scale with highly efficient and durable bi-functional catalyst for water splitting outperform the noble metals such as IrO2, RuO2electrocatalysts. The details of direct synthesis, characterization of new transition metal sulfides on metallic substrates will be discussed in this presentation.

References:

[1] N. Jiang, L. Bogoev, M. Popova, S. Gul, J. Yanob, Y. Sun, J. Mater. Chem. A, 2014, 2,19407–19414.

[2] P. Ganesan, M. Prabu, J. Sanetuntikul, S. Shanmugam, ACS Catal., 2015, 5, 3625-3637.

[3] X. Long, G. Li, Z. Wang, H. Y. Zhu, T. Zhang, S. Xiao, W. Guo, S. Yang, J. Am. Chem. Soc.    

   2015, 137, 11900−11903.

[4] C. Tang, Z. Pu, Q. Liu, A. M. Asiri, X. Sun, Electrochimica Acta. 2015, 153, 508–514
Catalysts, Nickel Phosphide (Cathodic) and LiCoO2 (Anodic), for Electrolysis of Water
Authors: Hwang Shinjae , Porter Spencer H , Laursen Anders B. , Gardner Graeme , Li Mengjun , Manichev Viacheslav , Amarasinghe Voshadhi , Taghaddos Elaheh , Safari Ahmad , Greenblatt Martha , Garfunkel Eric , Dismukes Gerard Charles
Published: February 2020

Choice catalysts are required to lower the activation barriers for both the oxidative and reductive half reactions associated with electrolysis of water. Using models provided by natural systems, such as the Ca-Mn cubane motif in the water oxidizing complex of photosystem II and the Ni-S active site of hydrogenase, we have developed LiMO2 (M = Transition metal) 1 and Ni-P compounds which mimic their chemistry2. Thin films of the oxygen evolving reaction (OER) catalyst, cubic LiMO2 (M = Co), and the hydrogen evolving reaction (HER) catalyst, NixPy, are a potentially cost-effective and electrically efficient catalysts for water splitting. Thin films of both the OER and HER catalysts on a transparent conductive oxide substrate and on a light absorbing substrate [Si (100)] have been produced. We shall report the structural, surface, and atomic characterization of these films via x-ray photoelectron spectroscopy, atomic force microscopy, helium ion microscopy, x-ray diffraction, and Rutherford backscattering. These results aid in explaining the (photo-)electro-catalytic properties observed. The cathode and anode can be combined to create a monolithic device that splits water and is discussed in a complementary talk in section I07 titled: “Efficient Solar Water Splitting via Tunable Photoanode-Photocathode-Catalyst Interface Devices”.

References

Gardner, G. P.; Go, Y. B.; Robinson, D. M.; Smith, P. F.; Hadermann, J.; Abakumov, A.; Greenblatt, M.; Dismukes, G. C. Angew. Chem. Int. Ed.
2012, 51, 1616.

Laursen, A. B.; Patraju, K. R.; Whitaker, M. J.; Retuerto, M.; Sarkar, T.; Yao, N.; Ramanujachary, K. V.; Greenblatt, M.; Dismukes, G. C. Energy Environ. Sci.
2015, 8 (3), 1027.

Figure 1
Conditions Causing Edge Corrosion in Flow-Battery Stacks
Authors: Darling Robert M. , Shiau Huai-Suen , Weber Adam Z , Perry Mike L.
Published: February 2020

Conventional redox-flow batteries (RFBs), like all-vanadium, contain reactors with many individual cells stacked in series electrically and in parallel fluidically.  Because the positive and negative electrolytes are conductive (> 10 S/m), shunt currents flow in the fluidic manifolds connecting the individual cells.  This is a long recognized source of inefficiency in RFBs and in some fuel-cell [1, 2] and electrolyzer [3] stacks with circulating liquid electrolytes.  These undesirable shunt currents are typically managed by designing the manifold and port regions of the cell stacks to have large enough resistances to yield acceptable efficiency without causing excessive pressure drop [1, 4].  Equivalent-circuit models with resistor elements for the manifold and port are normally used to model the shunt and port currents when analyzing these tradeoffs (e.g., [2, 5]).

Considerably less attention has been paid to the electrochemical reactions that support the shunt currents.  For example, at the positive electrodes at the positive end of an all-vanadium RFB cell stack at open circuit, V(V) is discharged to V(IV) in the active area (drain current), while V(IV) is converted to V(V) in the vicinity of the port to support the shunt current.  The simultaneous occurrence of the V(IV)/V(V) reaction in the anodic and cathodic directions on the same electrode leads to interesting potential and current profiles.  More importantly, it is possible to develop large overpotentials at the junction between the edge of the electrically-conductive bipolar plate and the insulating port region that can cause deleterious reactions like carbon corrosion.

In this talk, steady-state and transient numerical simulations of an all-vanadium RFB stack with two cells will be presented.  The impact of the port and manifold resistances on the overpotential at the junction between the more positive bipolar plate and the adjacent insulating port will be discussed.  Figure 1 shows a nonlinear relationship between port resistance and overpotential at the junction.  High overpotentials, probably sufficient to cause carbon corrosion, are observed when the port resistance is low. The governing relationships and design criteria will be introduced.

References

C. Reiser, U.S. Patent 3,634,139 (1972).

M. Katz, J. Electrochem. Soc., 125, 515 (1978).

I. Rousar, J. Electrochem. Soc., 116, 676 (1969).

Q. Ye, J. Hu, P. Cheng, and Z. Ma, J. Power Sources,
296, 352 (2015).

E. A. Kaminski and R. F. Savinell, J. Electrochem. Soc., 130, 1103 (1983).

Figure 1
Effect of Ti(IV) Ion on Mn(III) Stability in Ti/Mn Electrolyte for Redox Flow Battery
Authors: Kaku Hirokazu , Dong Yong-Rong , Hanafusa Kei , Moriuchi Kiyoaki , Shigematsu Toshio
Published: February 2020

Renewable energies such as wind power and solar power are now rapidly introduced worldwide. Energy storage systems, especially large-scale batteries become more necessary than ever for stabilizing the electric power fluctuations caused by renewable energies. Redox flow battery (RFB) is one of the strong candidates for this application, because of its easiness to scaling up and monitoring of state of charge, long cycle life, and safety. To accelerate the commercialization of RFB, reducing the cost of the battery system is one of the most important issues.

   Nowadays, vanadium (V) electrolyte is generally utilized for commercial RFB. Because the electrolyte is one of the key and expensive components in RFB system, many alternative electrolytes are developed to decrease the cost of RFB system. We have investigated various metal ions as active materials that are abundant and common for industrial use. In our research, titanium/manganese (Ti/Mn) RFB system has good potential, which use the redox reactions of Mn2+/Mn3+ and Ti4+/Ti3+ as positive and negative side, respectively. We have already reported that the cell voltage and the energy density of Ti/Mn system are comparable to those of V system [1].

    One of the challenges in Ti/Mn system is to improve the stability of Mn3+ ion in the positive electrolyte at charged state. Mn3+ ion can easily disproportionate to Mn2+ and MnO2, which leads to degradation of battery performance due to the precipitation of MnO2 particles. We reported that mixing Ti4+ ion in the positive electrolyte makes redox reaction of Mn2+/Mn3+ more reversible and prevents the precipitation of MnO2 particles. Ti4+ ion in the positive electrolyte also changes the color of the electrolyte with Mn2+ ion and the potential of positive electrolyte during charging, which strongly suggests the Ti4+ion interacts with Mn ion.

    This time we investigated the effect of Ti4+ ion in the positive electrolyte with various ratios of Ti to Mn. The effect of the ratio of Ti4+ ion on the electrochemical properties and MnO2 morphologies will be closely discussed.

References

[1] Y. R. Dong, et.al., 228th ECS Meeting, 120 (2015)
Study of Aqueous Zinc Nickel Flow Battery with High Energy Density
Authors: Wang Yan , Liu Jin
Published: February 2020

The escalation of power system promotes the development of battery technologies with its huge application market. Redox flow batteries (RFBs) are very attractive to customers in the energy grid system, and their noticeable technological innovations in the past decades have driven them to gradually replace the conventional energy storage methods under certain circumstance. Portable batteries used in electronics and fully electric vehicles ought to be designed to fulfill the growing desires on supplying energy quicker and longer. Therefore, many significant improvements have been achieved on battery manufacture and mechanism optimization. Here, the first fully-flow-able zinc–nickel flow battery (ZNFB) is studied, whose performance is supposed to be suitable for various scales. Through using semi-solid fuel cell (SSFC) technology, we incorporate the beneficial features of aqueous Zn/Ni chemistry (essentially sustainable, eco-friendly and deposit-abundant) into RFB structure to make a “hybrid” flow battery system with nano-size carbon network. Basic electrochemical properties of ZNFB are reported, and its suspension and electrode characters have been studied and improved.
The Advantages of the Use of Porous Metal Fiber Media in Different Alloys As Gas Diffusion Layer in Various Energy Storage Systems
Authors: Goossens Davy , Synhaeve Kris , De Baerdemaeker Jérémie
Published: February 2020

Large scale energy storage systems are a possible alternative to buffer the variability and the intermittency of electricity generated from renewable sources such as solar and wind. The main requirements of such energy storage systems are high efficiency, good rate capability, long life and low cost.

The electrodes in these large energy storage systems like e.g. Electrolysers and Redox Flow batteries are becoming more and more important attributers to the cost and performance drivers in the BOP. As the working environment in the different available system vary significantly, an optimization of the structure and material use in the electrodes is clearly needed.

In this study, different metal fiber media which can be used as porous electrode, produced in a variety of different metals and structures were evaluated on the performance drivers needed to achieve an improved energy storage system. The different materials are compared with alternative technologies on a variety of parameters like corrosion resistance, conductivity, permeability, mechanical strength, … and evaluated on the performance in an electrochemical cell.

This talk will give an overview on the progress of each of the different drivers.
Elastic Properties of Freeze-Cast La0.6Sr0.4Co0.2Fe0.8O3
Authors: Zou Ying , Araki Wakako , Balaguer Maria , Malzbender Jürgen
Published: February 2020

Elastic parameters, namely Young’s, shear and bulk moduli and Poisson’s ratio, of freeze-cast La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) envisaged as porous substrate for the application of dense LSCF oxygen transport layers were investigated at room temperature by a quasi-static hysteresis compression test. The nonlinear stress-strain behavior of LSCF results in continuously changing elastic parameters. The evolution of these elastic parameters was studied as a function of the longitudinal strain. The elastic parameters showed extrema due to ferroelastic domain switching. Young’s and shear moduli revealed minimum values while bulk modulus and Poisson’s ratio demonstrated maximum values, due to the transverse strain contributed by ferroelastic domain switching. Bulk modulus shows relatively constant values before and after the domain switching process. Young’s modulus shows similar values as in literature and the Young’s modulus from bending tests is close to the lowest values evaluated continuously from nonlinear stress-strain curves. The apparent fractures stress in a compressive mode along the pore direction is much higher than the bending strength of porous LSCF with isotropic pore structure. It appears to benefit from its large, long, oriented pore structure, which not only provides large porosity but also relatively high mechanical stability along the pore direction.

Figure 1
Cr Poisoning of (La,Sr)(Co,Fe)O3 SOFC Cathodes at the Micrometre to Nanometre Scale
Authors: Ni Na , Skinner Stephen J. , Jiang San Ping , Wang Cheng Cheng
Published: February 2020

For developing solid oxide fuel cells (SOFCs) operating at intermediate temperatures, metallic materials have become a preferential choice for the interconnect due to their low cost and excellent physical and chemical properties. However the presence of chromium in all commonly used metallic alloys has been found to cause poisoning of the cathode leading to rapid electrochemical performance degradation of the cathodes including one of the most promising (La,Sr)(Co,Fe)O3-δ (LSCF) perovskite oxides [1-4]. Despite the extensive research on the chromium deposition and poisoning processes, careful microstructural studies at multi-scale lengths are rare, which can provide valuable information for the fundamental understanding of the Cr poisoning mechanisms required for developing Cr tolerant cathode materials.   

In this paper, we examine the Cr poisoning mechanisms in LSCF materials by correlating the bulk electrochemical properties of the cell with their structural and chemical change at multi-scales down to the nanometer level. Cells with LSCF cathodes were prepared, and the effect of Cr poisoning on the electrochemical behavior of the cell was assessed by electrochemical impedance spectroscopy. The change in nano/microstructure and chemistry due to poisoning were studied in parallel by a combination of several advanced electron microscopy techniques including focus ion beam (FIB) tomography, high resolution and analytical (scanning) transmission electron microscopy ((s)TEM). Our results show that apart from change at the micrometer level, Cr poisoned samples with an increase in the total polarization resistance by one order of magnitude exhibit subtle nanoscale changes such as formation of nanometer size Cr rich phases, Cr segregation at LSCF grain boundaries and alternation of LSCF bulk stoichiometry. This nanoscale evolution correlates well with the impedance results obtained from the same samples, which shows that the area specific resistance of poisoned sample increased due predominantly to the increase of the oxygen reduction component related with a decrease both in the oxygen exchange rate at the LSCF internal surface and the oxygen diffusion in the electrode.

References

[1]        M.C. Tucker, H. Kurokawa, C.P. Jacobson, L.C. De Jonghe, S.J. Visco, J. Power Sources
160 (2006) (1) 130.

[2]        S.P. Jiang, X.B. Chen, Int. J. Hydrog. Energy
39 (2014) (1) 505.

[3]        S.N. Lee, A. Atkinson, J.A. Kilner, J. Electrochem. Soc.
160 (2013) (6) F629.

[4]        B. Wei, K. Chen, C.C. Wang, Z. Lü, S.P. Jiang, Solid State Ion.
281 (2015)  29.
Study on Solid Oxide Fuel Cell with Porous Scaffold Electrode Manufactured By Tape Casting Process
Authors: Bae Joongmyeon , Jang Young-hoon
Published: February 2020

Solid oxide fuel cell (SOFC) is energy conversion device which can converts chemical energy of hydrogen and oxygen to electrical energy. Conventional SOFC is fabricated by preparing anode support and coating electrolyte and cathode by spin coating or screen printing. One alternative way to fabricating SOFC is making porous scaffold on electrolyte support by same material with electrolyte and infiltrating electrode catalyst in porous scaffold. By this procedure, nano-sized catalyst network can be distributed in electrode and microstructure of electrode become easy to control and gas diffusion in electrode can be enhanced. However, conventional scaffold type SOFC has high ohmic resistance because of thick electrolyte support. To enhancing the performance of scaffold type SOFC, electrolyte thickness should be reduced. Moreover, there is problem that connectivity of electrolyte support and porous backbones is increased but porosity of scaffold is decreased as sintering temperature is increased. For solving these problems, tape casting process was applied to fabricate SOFC. By laminating tapes of each layers and co-sintering process, both connectivity and porosity can be obtained in high temperature sintering process.

 In this study, performance of scaffold electrode was compared with thick film electrode and SOFC single cell with porous scaffold electrode was fabricated by tape casting process. First, performance of scaffold electrode was compared with thick film electrode by electrochemical impedance spectroscopy analysis. La0.4Sr0.6Ti0.4Mn0.6O3-δ was infiltrated to porous scaffold as electrode catalyst and symmetric cells of scaffold electrode and thick film electrode were prepared. Area specific resistance (ASR) of scaffold electrode was 0.6 Ω·cm2 and ASR of thick film electrode was 3.4 Ω·cm2 at 800℃. SOFC single cell with porous scaffold electrode was fabricated by tape casting process. 8 mol % Yttria-stabilized Zirnocia (8YSZ) was used as electrolyte material. Electrolyte slurry and porous scaffold slurry with pore former were prepared and sequentially casted to make thin electrolyte and anode support. Cathode backbone tape was laminated on the sample by hot pressing. By sintering at 1400℃, thin electrolyte and porous scaffold were fabricated. La0.4Sr0.6Ti0.4Mn0.6O3-δ and La0.8Sr0.2MnO3 were infiltrated as anode catalyst and cathode catalyst, respectively. Open circuit voltage of the sample was 1.09V at 800℃, indicating that thin and dense electrolyte was formed. And the effects of porous scaffold were also investigated with respect to different porosity and different catalyst loading amount.

Figure 1
Simultaneously Coupled Mechanical-Electrochemical-Thermal Simulation of Lithium-Ion Cells
Authors: Santhanagopalan Shriram , Zhang Chao , Sprague Michael A. , Pesaran Ahmad
Published: February 2020

Understanding the combined electrochemical-thermal and mechanical response of a system has a variety of applications.  For instance, such behavior is characterized routinely in reactor design to understand structural failure of components from electrochemical fatigue.  In energy storage, the potential induced changes to properties of materials (e.g., swelling or surface oxidation induced fracture) have often been categorized as reliability concerns.  For lithium ion batteries, there is the added concern over safety of the system in the event of mechanical failure of the cell components.

                In this work, we study different mechanical test conditions and examine the interaction between mechanical failure and electrochemical-thermal responses, by developing a simultaneously coupled model. We begin with a model system to demonstrate the steps involved in building the coupling framework and proceed to model a pouch-format cell with explicit representations for each individual component such as the active material, current collector, separator, etc. Anisotropic constitutive material models are presented to describe the mechanical properties of active materials and separator. Some initial results are shown in Figure 1.  The model predicts accurately the force-strain response and fracture of battery structure, simulates the local failure of separator layer, and captures the onset of short circuit for lithium-ion battery cell under different test conditions. The difference in the electrochemical response and the implications for follow on chemical reactions under these test conditions are discussed.

 Acknowledgement

                 This study was supported by Computer Aided Engineering for Batteries (CAEBAT) project of the Vehicle Technologies Office, Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy. The research was performed using computational resources sponsored by the Department of Energy's Office of Energy Efficiency and Renewable Energy, located at the National Renewable Energy Laboratory.

Figure 1
(Invited) Modeling the Chemically Induced Stress in Lscf Oxygen-Separation Membranes
Authors: Euser Bryan , Zhu Huayang , Berger John , Kee Robert J.
Published: February 2020

Strontium- and iron-doped lanthanum cobaltite perovskites (La1-xSrxCo1-yFeyO3-δ) are used for a number of electrochemical applications, including solid oxide fuel cells (SOFCs), oxygen separation membranes, chemical sensors, and catalysts.  This paper focuses specifically on La0.6 Sr0.4Co0.8Fe0.2O3-δ, LSCF6482.  The material is a mixed ionic and electronic conductor (MIEC), with good oxide-ion conduction.  The electronic conduction is via small polarons associated with reduced and oxidized states of cobalt.  An important aspect of the present study is to understand the coupled effects of defect transport and stress, especially in oxygen-separation membranes.  Varying the environmental oxygen pressure on the membrane surfaces induces spatially transient responses of the charge-carrying-defect concentrations, electrostatic potential, and hydrostatic stress.  The stress is the result of atomic-scale strain and distortion within the crystal lattice structure.  Sufficiently high stress, especially tensile stress, can cause material degradation or failure. 

 A Nernst–Planck–Poisson (NPP) model is extended to account for the coupled effects of defect transport and chemically induced stress.  In addition to the effects of concentration and electrostatic-potential gradients, the Nernst–Planck fluxes include the influence of hydrostatic-stress gradients.  The stress model is based on the elastic response of a thin plate, including the effects of oxide-ion vacancy concentrations.  The material properties for LSCF6482, including mechanical properties, thermodynamic parameters for the defect chemistry, and charged-defect diffusivities, are obtained by interpreting previously published experimental data.  The model is formulated as a system of partial differential equations and solved computationally, predicting transient profiles of defect concentrations, electrostatic potential, and hydrostatic stress.