bluuebunny/crossref_metadata_2025 huggingface dataset:
AuCo3O4/C – Different Fabrication Methods and Application for Fuel Cell Reactions
Authors: Kepeniene Virginija , Stagniūnaitė Raminta , Vaičiūnienė Jūratė , Jasulaitienė Vitalija , Tamašauskaitė-Tamašiūnaitė Loreta , Norkus Eugenijus
Published: December 2020

Nanoscale materials are very important in many industries. There are many various synthesis methods such as adsorption, electroless deposition, galvanic displacement or microwave irradiation methods which let to fabricate nanomaterials. Lately, microwave irradiation is used as a rapid convenient method which gives excellent yields and higher purity of the products than conventional methods. Nanoparticles-based catalysts are usually heterogeneous catalysts broken up into metal nanoparticles in order to speed up the catalytic process. Metal nanoparticles have a higher surface area so there is increased catalytic activity because more catalytic reactions can occur at the same time. Nanoparticles catalysts can also be easily separated and recycled with more retention of catalytic activity than their bulk counterparts. Nanoparticles of gold are attractive for their interaction with other compounds and property to attract catalytic active groups.

In this work, we investigated the influence of synthesis method to the electrocatalytic activity of catalyst. Therefore, Au nanoparticles were deposited on the Co3O4/carbon (Co3O4/C) substrate using microwave irradiation AuCo3O4/C-1, AuCo3O4/C-2 and impregnation AuCo3O4/C-3 methods. The composition, morphology and structure of the prepared catalysts were characterized using Inductively Coupled Plasma Optical Emission Spectroscopy, Field Emission Scanning Electron Microscopy, Transmission Electron Microscopy, X-ray Photoelectron Spectroscopy and X-ray diffraction. The electrocatalytic properties of prepared catalysts were investigated towards ethylene glycol electro-oxidation and oxygen electro-reduction reactions in an alkaline medium. Electrochemical analysis was performed using a rotating disc electrode and the Autolab electrochemical workstation.

It has been determined, that in all cases modification of Co3O4/C catalyst by gold improved the electrocatalytic properties of synthesized AuCo3O4/C catalysts. As-prepared AuCo3O4/C catalysts showed an enhanced electrocatalytic activity towards the electro-oxidation of ethylene glycol and electro-reduction of oxygen in an alkaline medium compared with that obtained for the Co3O4/C or Au/C catalysts. The AuCo3O4/C catalysts prepared by microwave irradiation heating demonstrated up to 3 times higher electrocatalytic activity towards the electro-oxidation of ethylene glycol and up to 2 fold higher electrocatalytic activity towards electro-reduction of oxygen compared with that of the AuCo3O4/C catalyst prepared using impregnation.
Welcome Remarks - I01E: Polymer Electrolyte Fuel Cells & Electrolyzers 20 (PEFC&E 20) - Materials for Alkaline Fuel Cells and Direct-Fuel Fuel Cells
Authors: Mustain William
Published: December 2020

Welcome to I01E: Polymer Electrolyte Fuel Cells & Electrolyzers 20 (PEFC&E 20) - Materials for Alkaline Fuel Cells and Direct-Fuel Fuel Cells! Take a moment to listen to welcome remarks from the lead organizer, William Mustain.
pH-Controlled Growth of Ni-Fe Layered Double Hydroxide Electro-Catalyst for Water Oxidation with Exceptional Operational Stability
Authors: Mehdi Muhammad , Cho Hyun-Seok , Cho Won-Chul , Kim Sang Kyung , Kim MinJoong , Kim Chang-Hee
Published: December 2020

Ni-Fe layered double hydroxide (LDH) is a potential OER electro-catalyst in water electrolysis due to its layered open structure, rapid diffusion of reactant, good anion exchange and excellent hydroxyl adsorption. Its OER activity has been well reported at constant applied voltage. However, the water electrolyser utilizes renewable energy due to which it suffers irregular power supply that consequently affects its electrode activity. Therefore, the development of a stable Ni-Fe LDH under dynamic operation conditions is required. Herein, we performed pH-controlled growth of NiFe LDH (1:1) on Fe substrate in nickel sulfate solution by oxygen sparging. The prepared LDH requires a low OER overpotential of ~270 mV vs. Hg/HgO at 200 mA/cm2 in 1M KOH solution. Considering the potentiodynamic polarization curve of Ni-Fe LDH, its OER region is above 0.5 V (vs. Hg/HgO) and shutdown region is below 0.3 V (vs. Hg/HgO). The voltage fluctuation between both regions may result in phase change and structural distortion. Therefore, three stability regimes are important to consider for an actual operational stability test; upper OER regime I (constant 0.75 V (vs. Hg/HgO)), one-minute lower to upper OER regime II (0.5 to 0.75 V (vs. Hg/HgO)) and one-minute on-off regime III (0.3 to 0.75 V (vs. Hg/HgO)). The electrochemical characterization before and after each 12 hours regime showed no degradation and steady kinetics (38 mV/dec). The morphological and surface analysis using SEM, XRD, TEM and XPS confirmed that the LDH structure remained preserve after each regime.

Fig. 1: Operational stability test of Ni-Fe LDH prepared by pH-controlled growth under three regimes and embedded IR-corrected polarization curve after each regime.

Figure 1
Electrocatalytic Hydrogen Evolution Reaction with Multilayer Graphene-Covered Ni Particles Synthesized by Microwave-Assisted Catalytic Methane Decomposition
Authors: Kodera Fumihiro , Yoshida Narumi , Inoue Mitsuhiro , Umeda Minoru , Miyakoshi Akihiko
Published: December 2020

It is known that the type of electrocatalysts used in the hydrogen evolution reaction (HER) are critical for energy technologies such as water splitting and hydrogen fuel cells. Thus, in recent years, increasing attention has been paid to the development of noble metal-free electrocatalysts. It has recently been reported that Ni–C-based catalysts exhibit HER activity comparable to that of Pt in an acidic medium. Moreover, we have recently developed a new metal–carbon powder, which contained multilayer graphene-covered Ni particles as the main component, synthesized by multimode microwave-assisted catalytic CH4 decomposition using a multimode microwave reactor. Thus, in this study, we investigated the electrocatalytic HER over the Ni–C powder using a digital potentiostat equipped with a potential sweep unit. Figure 1 shows the current–potential curve in the presence or absence of dissolved oxygen in an aqueous H2SO4 solution; the curve was obtained using a carbon paste electrode filled with the Ni–C powder. A reduction current based on HER was observed from approximately 0.0 V (referred vs. SHE), while the onset potential was shown to be slightly affected by the presence or absence of dissolved oxygen. Therefore, the Ni–C powder can be used as a noble metal-free electrocatalyst to implement the HER with excellent electrochemical performance in acidic medium.

*Figure 1. Linear sweep voltammograms with the carbon paste electrode (Φ = 3 mm) filled with the Ni–C powder, synthesized by a multimode microwave-assisted process in an acidic solution under different atmospheres. SR = 10 mV/s.

Figure 1
Atom-Scale Dispersed Palladium in a conductivePd0.1TaS2 Lattice with a Unique Electronic Structurefor Efficient Hydrogen Evolution
Authors: Wang Xin , Wang Dong , Lu Yue , Song Changsheng , Pan Jie , Li Chilin , Sui Manling , Zhao Wei , Huang Fuqiang
Published: December 2020

Noble metal catalysts have extraordinary catalytic activity but suffer from high cost; therefore single atom catalysis attracts tremendous attention. Here, we propose atom-scale dispersed palladium (Pd) in a layered TaS2 lattice to form new compounds of PdxTaS2, whose crystal structure was resolved by powder X-ray diffraction. The electrical conductivity of metallic Pd0.1TaS2 (1.36 * 104 S m-1) is twice as large as that of TaS2 (6.18 * 103 S m-1). This compound applied as a new electrocatalyst for the hydrogen evolution reaction (HER) exhibits excellent catalytic performance with an onset overpotential of 77 mV, superior to those of other catalysts such as TaS2 (295 mV) and Pd-loaded TaS2 (114 mV). Density functional theory calculations reveal that the interaction of Pd-4d and Ta-5d orbitals results in the upshift of the Fermi level (TaS2 versus Pd0.1TaS2) to decrease the barrier height for the HER. Furthermore, the hybridization of Pd-4d and S-3p orbitals builds up pathways along the c axis to improve the conductivity and promote HER performance. It is noted that the amount of Pd used in Pd0.1TaS2 is only 4 wt%, compared with 20 wt% in commercial Pd/C catalysts, which is beneficial for its practical application.
Local Measurement of Anode Current Collector Potential in a PEM Water Electrolyzer
Authors: Becker Hans , Castanheira Luis , Smith Graham , Dickinson Edmund J. F. , Hinds Gareth
Published: December 2020

The current collector (CC) components (bipolar plate and porous transport layer) of a polymer electrolyte membrane water electrolyser (PEMWE) comprise one of the highest proportion of the cost of the stack [1]. It is widely accepted that the PEMWE CC material needs to withstand the relatively high potentials encountered at the anode electrode, with ex situ qualification testing typically carried out at an applied potential of at least 2 V vs the standard hydrogen electrode (SHE). As a result, platinum-coated titanium is the common material of choice. However, we offer a counter hypothesis that it is unlikely that the corrosion potential of the anode CC is equal to that of the anode electrode due to the very low ionic conductivity of the pure water phase separating the two components.

In this work, an innovative in situ reference electrode consisting of a Nafion®/H2SO4 salt bridge connected to a reversible hydrogen electrode is used to measure the corrosion potential of the anode CC during PEMWE cell operation. Using this technique, we demonstrate for the first time that the corrosion potential of the anode current collector is effectively decoupled from that of the anode electrode [2]. Furthermore, we demonstrate that carbon paper can be applied as anode CC material without any noticeable corrosion taking place.

The implications of this work are that significantly cheaper materials such as carbon or carbon-coated stainless steel can be used for CC components, which could reduce the cost of PEMWE technology substantially. The key advance is the use of a thin porous spacer layer between the anode and the CC. Factors that may influence the implementation of this new concept are discussed, including the influence of spacer layer tortuosity and water conductivity on the corrosion potential of the CC.

References

[1] K. Ayers, N. Danilovic, R. Ouimet, M. Carmo, B. Pivovar, M. Bornstein, Perspectives on low-temperature electrolysis and potential for renewable hydrogen at scale, Annual Review of Chemical and Biomolecular Engineering 10 (2019) 219–239.

[2] H. Becker, L. Castanheira, G. Hinds, Local measurement of current collector potential in a polymer electrolyte membrane water electrolyser, Journal of Power Sources 448 (2020) 227563.

Figure 1
Towards a Generic Understanding of the Oxygen Evolution Reaction– Experimental Determination of Reaction Mechanism and Kinetic Parameters
Authors: Schuler Tobias , Kimura Taro , Schmidt Thomas J. , Buechi Felix N.
Published: December 2020

In polymer electrolyte water electrolysis (PEWE) kinetic overpotentials are the governing loss category when employing thin membranes. To guide the rational design of highly efficient catalysts in order to increase cell efficiency, the knowledge about oxygen evolution reaction (OER) mechanism as well as rate determining step and reaction intermediates is indispensable. Despite intensively theoretical as well as experimental analysis based on DFT modelling1 and RDE measurements2, 3, the valid reaction mechanism is still controversially discussed in literature for state-of-the-art OER catalyst IrO2
4.

To elucidate the reaction mechanism (Fig. 1) and rate determining step based on IrO2/TiO2 OER catalyst in absence of potential catalyst deactivation induced by gas agglomeration in liquid environment5, a novel methodology based on gas fed PEWE is applied allowing for controlled variation of water activity. For the first time the reaction order can be determined in order to probe and identify the valid reaction mechanism proposed in literature. The full characterization of kinetic parameters and comparison of gaseous as well as liquid fed PEWE kinetics enables the generic deduction of OER overpotential and current density relation6.

References

J. Rossmeisl, Z. W. Qu, H. Zhu, G. J. Kroes and J. K. Nørskov, Journal of Electroanalytical , 2007, 607, 83-89.

M. Kroschel, A. Bonakdarpour, J. T. H. Kwan, P. Strasser and D. P. Wilkinson, Electrochim Acta, 2019, 317, 722-736.

S. M. Alia, B. Rasimick, C. Ngo, K. C. Neyerlin, S. S. Kocha, S. Pylypenko, H. Xu and B. S. Pivovar, Journal of The Electrochemical Society, 2016, 163, F3105-F3112.

T. Reier, H. N. Nong, D. Teschner, R. Schlögl and P. Strasser, Advanced Energy Materials, 2017, 7,1601275.

H. A. El-Sayed, A. Weiß, L. F. Olbrich, G. P. Putro and H. A. Gasteiger, Journal of The Electrochemical Society, 2019, 166, F458-F464.

T. Schuler, T. Kimura, T.J. Schmidt, F. N. Büchi, Energy and Environmental Science, manuscript accepted 27th of May 2020

Figure 1
The Effect of Material Priorities on Oxygen Evolution Activity and Assessing Half-Cell Screening As a Predictive Tool in Electrolysis
Authors: Alia Shaun M , Manco Judith , Anderson Grace C. , Hurst Katherine E. , Capuano Christopher
Published: December 2020

While hydrogen as a chemical commodity is used today in transportation and agriculture, it is a relatively small contributor in overall energy pathways. Hydrogen produced by electrochemical water splitting has further been limited by cost. Electrolysis, however, when coupled directly with low-cost intermittent power has an opportunity for expanded use in the future in grid storage and offloading curtailed inputs to other sectors. Expanded use will require reduction in the power input and capital cost, and will likely involve component development.

Within catalysis in proton exchange membrane electrolysis, this includes reductions in the platinum group metal loading and materials development to improve: performance to lessen load requirements; or stability to mitigate durability losses. Ex-situ testing, or rotating disk electrode half-cells, are commonly used to screen materials in the early stages of catalyst development. Understanding the limitations of the approach, however, is critical to predicting device-level performance and better guiding development efforts.

In this effort, several iridium- and ruthenium-based catalysts were studied for oxygen evolution activity and stability in half-cell tests. Electrochemical surface area measurements were used to separate surface area from specific activity as well as approximate contributions for metals and oxides. Generally, catalysts with higher iridium metal and ruthenium composition tended to produce higher activity. Changes were observed following extended exposure to high potential, and the dissolution rates and surface area losses for iridium metal and ruthenium were typically higher. Catalyst options, however, were found that provided an optimum in activity and stability, and additional characterization was used to evaluate morphology, crystallinity, and alloying as potential contributors. Device-level examinations further assess the ability rotating disk electrodes as a predictive tool and test the approach across different material sets, compositions, and morphologies.

Figure 1
High Surface Area IrOx Synthesis By Glycine-Assisted Adams Fusion Method for Improved Electrocatalysis of Oxygen Evolution Reaction
Authors: Baik Chaekyung , Lee Seung Woo , Pak Chanho
Published: December 2020

As renewable energy generation increases, the storage of intermittently excess electricity is becoming an important challenge due to the instability of photovoltaic and wind generation. Among many approaches, hydrogen production through water electrolysis features the advantages of long-term large-scale storability [1]. Especially, proton exchange membrane water electrolysis (PEMWE) has benefits at high current operation and gas purity compared to the alkaline water electrolysis. Iridium oxide (IrO2), which is the most widely using catalysts for PEMWE at present, were developed intensely to overcome the sluggish oxygen evolution reaction (OER) kinetics and unsatisfied stability under acidic conditions [2-3]. Recent studies demonstrated amorphous IrOx have higher OER activity than rutile IrO2 owing to IrIIIOOH species. Despite the high OER activity, amorphous IrOx has issues in high Ir dissolution rate during OER which is critical for OER stability. In this study, high surface area IrOx was synthesized by Adams fusion method with glycine as an additive (denoted by IrOx (G)) to enhance OER activity and stability. From the XRD analysis, IrOx was observed with crystallite of 2.4 nm calculated from (101) by Scherrer equation. XPS results show positive peak shifts at Ir 4f and higher Oads/Olatt ratio of O 1s peak compared to rutile IrO2 which is well-known features of hydrated amorphous IrOx [4]. The specific surface areas of IrOx (G) obtained by BET equation were 385 m2 g-1 which is 170 % larger than IrO2 prepared by the common Adams fusion method (225 m2 g-1, denoted by Adams-IrO2). The result shows that glycine acts as a pore-forming agent and also prevent the development of rutile IrO2 during thermal treatment. The amorphous structure and high specific surface area of IrOx (G) are the main reasons which increase OER activity and stability. IrOx (G) exhibited 305 mV overpotential at 10 mA cm-2 which is a significantly lower overpotential than Adams-IrO2 (340 mV). Also, no significant change occurred during 6 hours of chronopotentiometry at 10 mA cm-2 which implies excellent stability at OER.

References

E. Hosseini, M.A. Wahid, Renew. Sust. Energy Rev., 57, 850 (2016).

Faustini, M. Giraud, D. Jones, J. Rozière, M. Dupont, T.R. Porter, S. Nowak, M. Bahri, O. Ersen, C. Sanchez., Adv. Energy Mater., 9, 1802136, (2019).

Li, S. Li, M. Xiao, J. Ge, C. Liu, W. Xing, Nanoscale, 9, 9291, (2017).

F., Abbott, D., Lebedev, K., Waltar, M., Povia, M., Nachtegaal, E., Fabbri, C., Copéret, T. J., Schmidt, Chem. Mater., 28, 6591, (2016).
First Principles Analysis of Oxygen Cycle Electrocatalysis: Multifunctional Materials and Reactivity Trends
Authors: Zeng Zhenhua , Dionigi Fabio , Wang Lei , Markovic Nenad M , Wang Chao , Strasser Peter , Greeley Jeffrey
Published: December 2020

Water splitting to generate O2 and H2 fuel is an ongoing focus of (photo)electrochemical energy storage and conversion efforts. While water oxidation to generate O2 through the oxygen evolution reaction (OER) accounts for the majority of energy loss in this process, water reduction to generate H2 through the hydrogen evolution reaction (HER) in alkaline is also sluggish, with over two orders of magnitude less activity than in acid. For OER, NiFe layered double hydroxides have attracted significant interest due to their comparable performance with precious metal-based RuO2 and IrO2 catalysts. In spite of extensive study, however, the 3D crystal structure of the active phase under catalytic oxygen evolution reaction conditions remains unclear, and the lack of atomic-scale details concerning the crystal structure makes it challenging to choose appropriate structural models for first principles-based mechanistic studies. Similarly, for alkaline HER, ultrathin (oxy)hydroxide films on precious metal substrates have shown impressive activity improvements compared to pure Pt, but the films’ structure and stability are still largely unknown, and the catalytic mechanism remains unclear.

In this presentation, we will begin by showing our recent efforts to elucidate the catalytically active phase and OER mechanism on NiFe layered double hydroxides by combining electrochemical measurements, operando experiments, DFT calculations, and ab initio molecular dynamics simulations. Next, for HER, we will turn to monolayer Ni (oxy)hydroxide films, wherein we will demonstrate that these ultrathin films can be dramatically stabilized with respect to the corresponding bulk analogs and that the bifunctional interface provides ideal sites for water activation. Finally, if time permits, we outline our recent work on oxygen reduction reaction electrochemistry, discussing both tunable intrinsic strain in two-dimensional transition metal electrocatalysts for the ORR, as well as recent developments in the study of stability of PGM-free electrocatalysts.
Grid Scale Energy Storage: Modeling of Electrolyzer-Fuel Cell Combination and Comparison with Flow Batteries
Authors: Motupally Saagar , Pasaogullari Ugur
Published: December 2020

Abstract:

Grid-scale renewable energy installations are gaining traction around the world. The addition of these intermittent resources onto the energy grids is resulting in challenges that need to be addressed [1]. The challenge with the mismatch between supply and demand has accelerated the need for grid-scale energy storage technologies. The viability of some of these technologies from a future technical and economic requirements standpoint is being studied widely [2].

Though today over 95% of the energy stored is in the form of pumped hydro, many other technologies spanning the broad areas of Mechanical (flywheel, compressed air, etc.), Thermal (molten salt, thermal dams, etc.), Batteries (lithium-based, flow batteries, etc.) and Hydrogen (electrolysis, fuel cells, etc.) are actively under development with a focus on future requirements [1-5].

In this paper, we will investigate the viability of Hydrogen electrolyzer and fuel cell technologies for long duty cycle and steep ramp frequency regulation applications. We will compare the characteristics of Polymer Electrolyte Membrane (PEM) and Solid Oxide (SO) Electrolyzer Fuel Cell (EFC) combinations with Flow Batteries. The techno-economic comparison will be in the areas of (a) Levelized Cost of Energy (LCOE) and (b) Transient Capability.

The LCOE models will consider round trip efficiency, equipment capital costs, storage costs, operating costs, and system durability/reliability. The key input data/parameter set for the LCOE calculations will be obtained by extrapolating real-life performance information from key Electrolyzer, Fuel Cell, and Flow Battery suppliers [3-5]. Whereas the transient capability models will be based on applicable charge and discharge duty cycle regimes as well as the transient response to a full range of variation in loads. The transient modeling will be obtained by fitting real-life electrochemical data to simple lumped parameter models [2,5].

References:

D. Timmons et al., “The Economics of Renewable Energy,” GDAE, Tufts University, Medford MA, 02155.

R. Darling et al., Energy Environ. Sci., 2014, 7, 3459.

S. Satyapal, H2@Scale R&D Consortium Kickoff Meeting H2@Scale Overview Chicago, IL – August 1, 2018.

B. Pivovar, 2019 DOE Hydrogen and Fuel Cells Program Review, April 30, 2019.

M. Pellow et al., Energy Environ. Sci., 2015,8, 1938-1952.
(Invited) Oxygen Electrocatalysis By Transition Metal Spinel Oxides
Authors: Xu Zhichuan J
Published: December 2020

Exploring efficient and low-cost oxygen electrocatalysts for ORR and OER is critical for developing renewable energy technologies like fuel cells, metal-air batteries, and water electrolyzers. This presentation will present a systematic study on oxygen electrocatalysis (ORR and OER) of transition metal spinel oxides. Starting with a model system of Mn-Co spinel, the presentation will introduce the correlation of oxygen catalytic activities of these oxides and their intrinsic chemical properties. The catalytic activity was measured by rotating disk technique and the intrinsic chemical properties were probed by synchrotron X-ray absorption techniques. It was found that molecular orbital theory is able to well-explain their activities. The attention was further extended from cubic Mn-Co spinels to tetragonal Mn-Co spinels and it was found that the molecular theory is again dominant in determining the catalytic activities. This mechanistic principle is further applied to explain the ORR/OER activities of other spinels containing other transition metals (Fe, Ni, Zn, Li, etc.). The talk further gives insight on surface reconstruction on spinel oxides and how the bulk properties affect such reconstruction during OER. In addition, the talk will also discuss the possibility of the spin-selected charge transfer during oxygen electrocatalysis through transition metal oxides
Simulation of a Double-Sided Cathode SOFC Comparing Different Electrochemical Reaction Kinetics
Authors: Zhang Xiaoqiang , Espinoza-Andaluz Mayken , Li Tingshuai , Qi Yuanxin , Andersson Martin
Published: December 2020

A 3D symmetric double-sided cathode SOFC model is constructed considering coupled electrochemistry, fluid dynamics, gas diffusion, heat transfer as well as mechanical properties. The cell geometry constructed is based on the prototype SOFC model tested at Ningbo Institute of Material Technology and Engineering (NIMTE) in China (1). The detailed geometry is shown in Figure 1 (a). In this study, different kinetics expressions for anode and cathode reaction are compared. For anode, the oxidation of hydrogen comprises of different elemental reactions which include adsorption/desorption and charge transfer steps, but for cathode the reaction is simpler, e.g., the reduction of oxygen (2). In this paper, the current density, temperature distribution as a function of different kinetics will be presented. Moreover, the stress distributions will also be carefully analyzed.

Preliminary results of electrode current density, temperature and von Mises stress distribution is showed in Figure 1 (b ~ c). Detailed comparation of different distribution in 2D as well as line graph will be extracted with different kinetics. This work will lay foundation for further modelling work when considering different electrochemical kinetics.

Figure 1 (a) Model geometry; (b) Electrode current density distribution; (c) Temperature distribution; (d) von Mises stress distribution.

References:

1. W. Liu, Z. Zou, F. Miao, X. Li, J. Wang, J. Yang, J. Wilson, X. Zhou, Z. Zhong, Q. Zhai and W. Guan, Energy Technology, 7, 240 (2019).

2. H. Zhu, R. J. Kee, V. M. Janardhanan, O. Deutschmann and D. G. Goodwin, Journal of The Electrochemical Society, 152 (2005).

Figure 1
A Bayesian Approach to Autonomous Analysis of Electrochemical Impedance Spectra
Authors: Huang Jake , Papac Meagan , Zakutayev Andriy , O'Hayre Ryan
Published: December 2020

Electrochemical impedance spectroscopy (EIS) is a valuable characterization tool for a wide variety of materials due to its ability to probe transport and reaction pathways over a broad range of timescales. Recently, developments in experimental techniques have increased the use of EIS in high-throughput materials characterization. However, extraction of meaningful insight from high-volume EIS data streams is often stymied by the complexity of processing and analyzing impedance spectra. To address this challenge, we present a framework for fully autonomous analysis of EIS data leveraging Bayesian methods to obtain both the distribution of relaxation times (DRT) and equivalent circuit fits.

The predominant quantitative method for EIS analysis is equivalent circuit modeling, which requires careful selection of equivalent circuit elements to represent physical processes in the system under study. However, the last decade has seen increasing interest in the DRT, which enables detailed EIS analysis without a priori construction of equivalent circuits. Deconvoluting the DRT is an ill-posed problem which may be tamed by imposing constraints upon the solution (regularization), but the solution is highly sensitive to the nature and severity of such constraints, which are challenging to calibrate. We demonstrate the application of Bayesian inference to determine the optimal regularization level and accurately deconvolute the DRT. The Bayesian approach identifies both smooth features (e.g. dispersed ZARCs) and sharp features (e.g. RC and Gerischer elements) in the DRT, is highly robust to noise, and is self-calibrating. We also explore the connection between the DRT and equivalent circuit modeling, illustrating how well-calibrated estimates of the DRT can both enable empirical selection of equivalent circuit models and provide initial parameter estimates for complex non-linear least squares fitting of these models. We apply these methods to both synthetic spectra and experimental data from high-throughput characterization of fuel cells and batteries to demonstrate their validity and utility. The software is published in an open-source Python package to enable broad usage and further development.

Acknowledgments:

This work was supported by the Advanced Research Projects Agency-Energy (ARPA-E) through the REFUEL program (Award No. DE-AR0000808) and the Army Research Office under Grant No. W911NF-17-1-0051.
(Invited) Applications of Protonic Ceramics for Electrochemical Energy Conversion and Storage
Authors: O'Hayre Ryan , Duan Chuancheng , Zhu Liangzhu , Cadigan Chris , Huang Jake , Papac Meagan , Zakutayev Andriy , Zhu Huayang , Karakaya Canan , Braun Robert J. , Ricote Sandrine , Pan Zehua , Kee Robert J. , Sullivan Neal P
Published: December 2020

Recent exciting advancements in proton-conducting ceramic materials and devices suggest that they are approaching a technology readiness level that rivals more well-established polymeric and oxygen-ion conducting counterparts. Because they can enable proton-mediated electrochemistry under both dry and wet environments at moderate temperatures, protonic ceramics provide unique opportunities to enhance or synergize a diverse range of complementary electrochemical and thermochemical processes. Because of this potential, significant efforts have been devoted to advancing numerous energy-related applications using these materials. Here, we will provide an overview of recent research efforts at the Colorado School of Mines focused on developing protonic ceramics for a number of applications, including:

Hydrocarbon-tolerant protonic ceramic fuel cells for electricity generation (PCFCs)

Protonic ceramic electrolyzers for fuel synthesis (PCECs)

Reversible protonic-ceramic electrochemical cells for energy storage (RePCECs).

Recent progress has lead to remarkably high-performance H2 and hydrocarbon-fueled PCFCs; exceptionally efficient (>97% LHV efficiency) PCECs for H2 production and for the co-conversion of steam and carbon dioxide to renewable methane; H2/H2O-based RePCECs with >75% round-trip efficiency (cell-level) for seasonal energy storage, and a reversible ammonia fuel cell for ammonia synthesis/power production. In addition, ongoing collaboration with industrial partners demonstrates promising scale-up and durability progress for protonic ceramic cells and stacks that underscores their potential for eventual commercial application.

Acknowledgements: This work was supported by the Advanced Research Projects Agency-Energy (ARPA-E) through the REFUEL (Award No. DEAR0000808) and REBELS programs (Award No. DE-AR0000493) and the Office of Fossil Energy (Award No. DE-FE0031716). Additional support was provided by the Army Research Office under Grant No. W911NF-17-1-0051, the Office of Naval Research via Grant No. N00014-16-1-2780, and faculty research funding from Kansas State University.
(Invited) Atomic Layer Deposition-Enabled Functionalization of 3D Nanostructures for Oxygen Electrocatalysis
Authors: Lee Min Hwan
Published: December 2020

Since the performance of a fuel cell is largely limited by the oxygen reduction kinetics, a rationale design and development of active and durable cathodes is very important. For catalysis per mass, catalysts with a maximized surface area are preferred. This is even more the case for low- and intermediate-temperature solid oxide fuel cells (SOFCs) where the even more sluggish cathodic kinetics should be addressed for commercially acceptable performance. However, electrodes with a high surface area is susceptible to thermal agglomeration during operation at elevated temperatures, leaving the long-term durability of the structure as a major concern.

In this talk, I will present our recent efforts to address this issue by atomic-/nano-scale surface treatment of both noble metal (Pt)-based electrodes and more SOFC-relevant cathode materials mainly by the use of atomic layer deposition (ALD). An ultrathin overcoat have proved highly effective in suppressing the sintering kinetics of the underlying electrode structure and thus enhancing the overall cell durability by a significant margin. I also present our recent study successfully demonstrating that even an angstrom-thick oxide overcoat improves thermal durability of high-surface-area electrodes by maintaining the morphology of nanoparticle-decorated (wet-impregnated) cathode structures. The benefits of the surface overcoat is not limited to the enhancement of thermal durability. A discussion on the underlying mechanism of the enhanced electrode kinetics will be also provided.

We acknowledge the support from the Korea Institute of Industrial Technology (KITECH) and U.S. National Science Foundation CAREER Award (DMR 1753383).
Parametric Optimization and High Resolution Fabrication of Freeform Gas Diffusion Layers
Authors: Torgersen Jan , Bock Robert
Published: December 2020

The gas diffusion layer (GDL) is a multifunctional part of a fuel cell governing reactant and product transport in opposing directions, thermal and electrical conductivity as well as mechanical stability. Its design and production are cumbersome and, for now, obtainable architectures are random networks with uncontrollable transport pathways. According to simulations, an optimized “designer GDL” architecture may lead to immediate benefits in conductivity and permeability by several orders of magnitude.1 This could result in an increase of the achievable current density and a reduction in transport losses. To realize transport optimized architectures, a fabrication method is required that can convert architectures with computer defined properties directly into physical models.2 Here we present our latest results on the fabrication of “designer GDLs” with high-resolution stereolithography of dimensionally stable photopolymers with high aromatic content. These polymers have the potential to be converted to amorphous carbon at predictable dimensional shrinkage retaining their CAD defined geometry. Particularly, we present the high-throughput fabrication of polyimide and SU-8 formulations. We present process parameters, tolerances achievable and show initial results on the carbonization of these formulations as well as absolute dimensions and tolerances obtainable. Our research may lead to a new toolbox for studying and fabricating the next generation of porous membranes for Polymer Electrolyte Membrane Fuel Cells (PEMFCs) and likely a variety of other electrochemical devices requiring effective transport characteristics.

D. Niblett, V. Niasar, and S. Holmes, J. Electrochem.
Soc., 167, 013520 (2019).

J. Torgersen et al., Adv. Funct. Mater., 23, 4542–4554 (2013).

Figure 1
(Invited) Solid Electrolytes As Thermally Activated Ionic Switches
Authors: Roberts Christine C. , Allcorn Eric , Benavidez Angelica D , Fleig Patrick F , Garzon Fernando H , Karulkar Mohan , Nemer Martin B , Rodriguez Mark
Published: December 2020

Inorganic solid electrolytes are naturally less ionically conductive at room temperature than at elevated temperatures where they can be superionic. This intrinsic Arrhenius-type behavior is useful for niche applications that require a thermally activated switch, for example in batteries with long room temperature storage lifetimes, geothermal batteries, or novel circuits. We seek electrochemically stable materials with poor room temperature ionic conductivities and high activation energies, starting with the lithium-stuffed garnet class of solid electrolytes (Li5+xM3N2O12+0.5x). To efficiently identify attractive dopants, we seeded a machine learning algorithm with attributes published in the available literature. This approach confirmed the lithium concentration and dopant electronegativities are important parameters in materials design. We then have explored these predicted relationships through garnet materials synthesis and electrochemical impedance spectroscopy measurements up to 400 oC.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.
(Invited) Increasing Biogas to Liquid Fuel Yield By Solid Oxide Co-Electrolysis of Biogas CO2 Fraction
Authors: Hartvigsen Joseph J. , Elangovan S. , Frost Lyman J.
Published: December 2020

OxEon Energy, LLC (OxEon) plans to demonstrate production of liquid hydrocarbon fuels using both the methane and CO2 generated in a food waste digester operated by the Environmental Products & Technologies Corporation (EPT). The EPT food waste digester in Burley Idaho sells produced biogas into a natural gas pipeline after separating and venting the bio-CO2. This project will convert the bio-methane to synthesis gas (syngas, as CO & H2) using a non-thermal plasma catalyzed autothermal reformer. To achieve high bio-carbon utilization, an OxEon high temperature solid oxide co-electrolysis (HTCE) system will electrochemically generate additional syngas from the bio-CO2 combined with steam raised by cooling the Fischer Tropsch (FT) reactor. Syngas from the reformed methane and co-electrolyzed CO2, will be converted to liquid fuels using an OxEon developed FT reactor. Each of the technology components have been field tested independently and will be combined for the first time in this project. The project outcome will be an engineering scale demonstration of liquid hydrocarbon bio-fuel production achieving > 50% conversion to liquids of the biogenic carbon in both CH4 & CO2 produced by an anaerobic digester.

Each of the three technology elements of the integrated engineering test incorporates numerous innovations. The plasma reactor is designed to be fuel flexible, sulfur tolerant, and economically scalable to small, distributed bio-gas resources. It is also very efficient using a low power non- thermal plasma. High temperature solid oxide electrolysis has demonstrated efficiency at the thermodynamic limit as shown by analysis and testing at DOE and NASA laboratories, and is unique in its ability to co-electrolyze steam and CO2 directly to syngas. The HTCE stacks use innovations proven for the NASA Mars 2020 project which required exceptional ruggedness and effective high temperature seals. The FT reactor enables economical fabrication of smaller size synthetic fuel plants designed to match the scale of distributed renewable biomass resources. This is achieved with large diameter standard piping combined with a novel internal thermal management structure.

The status of the technology elements and the planned engineering demonstration will be presented.

This work is supported by the Bioenergy Technologies Office of the US Department of Energy.
(Invited) Tailored Syngas Production Via High Temperature H2o-CO2 Co-Electrolysis
Authors: Marina Olga , Coyle Chris , Meinhardt Kerry , Holladay Jamelyn
Published: December 2020

Solid oxide electrolysis cells (SOEC) operating at 600 – 850°C are used to split water using excess renewable or nuclear electrical energy and convert it to chemical energy which is stored in H2 and O2. SOECs can also be used as electrochemical reactors for the co-electrolysis of steam and carbon dioxide. The two reactants, typically waste products in an industrial plant, could be turned into syngas (CO+H2), a valuable and very commonly used reagent in the chemical industry. Syngas is subsequently used to produce synthetic fuels, olefins or other liquid hydrocarbons via Fischer-Tropsch synthesis or for methanol synthesis and hydroformylation.

In this presentation we focus on CO2-H2O co-electrolysis, the simultaneous electrochemical reduction of carbon dioxide and steam, carried out on the porous Ni-based electrodes in high temperature SOECs. Experiments were conducted using multiple button cells. The rate of the electrochemical reactions was measured in the temperature range 700-850oC for varied reactant compositions: 10-98% CO2 and 5-50% H2O, also in the presence of some H2 and CO. Kinetics of electrochemical CO2 reduction were evaluated for different CO2/H2O ratios and compared to steam electrolysis. Product analysis was completed using gas chromatography. Long term electrochemical performance of multiple cells was recorded simultaneously for over 500 hours of continuous testing with occasional interruptions to obtain current-voltage characteristics and collect the impedance spectra. The ability to control H2 :CO ratios in generated syngas by varying the inlet H2O/CO2 ratios and cell potential was demonstrated. Thus, precise control of the H2 to CO ratios, a unique feature of electrochemical conversion can be used to optimize selectivity of the desired byproduct.
Ultrathin, Flexible, Solid Polymer Composite Electrolytes for High Performance and Safe Lithium Batteries
Authors: Wan Jiayu , Cui Yi
Published: December 2020

Safety issues in lithium-ion batteries have recently raised serious concerns. Replacing flammable liquid electrolytes, solid-state electrolytes (SSEs) are thought to address this issue and provide unmatched energy densities in Li-based batteries. Here, we demonstrated the design of a ultralightweight and fireproof polymer−polymer SSE. Strategies in enhancing ionic conductivity and Li dendrite suppression properties in ultrathin SSEs will be discussed. The whole SSE is made from organic materials, with a thin, tunable thickness (10−25 μm), which endorse the energy density at least comparable to conventional Li-ion batteries.
Operando Raman Spectroscopy and Impedance Spectroscopy, a Powerful Combination to Better Understand Fuel Electrodes in Solid Oxide Cells
Authors: Drasbæk Daniel Bøgh , Welander Märtha , Traulsen Marie Lund , Sudireddy Bhaskar Reddy , Holtappels Peter , Walker Robert A.
Published: December 2020

Solid oxide cells are based on an oxygen ion conducting ceramics and thus can be used to convert a large variety of fuels into electricity and vice versa. As solid oxide fuel cells, hydrocarbon fuels such as methane can be converted to electricity forming water and carbon dioxide. However, the reversed reaction the reduction of water and carbon dioxide to hydrogen and carbon monoxide (the so called syngas) is also of interest e.g. for the synthesis of high value fuels in subsequent methanation or Fischer-Tropsch reactions. The state-of-the-art electrode for both solid oxide fuel cells and electrolysis cells are so called Nickel cermet electrodes, which are prone to carbon formation due to the high amount of Ni (usually above 33vol%).

An alternative fuel electrode concept is based on an electronically conducting ceramic and using infiltrated metals as electrocatalytically active elements. This concept is versatile as it allows the use of various electrocatalysts, not limited to Ni. Based on a comparative study, Fe, Co in addition to Ni have been identified as promising electrocatalyst materials and have been investigated as regards their behavior in carbon containing gas atmospheres [1]. Raman spectroscopy in combination with impedance spectroscopy and especially during operation of the cell is a powerful tool to investigate electrodes in solid oxide cells [2,3].

In this study Raman spectroscopy has been applied either in-situ (at open circuit voltage) or operando (under load in fuel cell mode) to investigate carbon formation and electrochemical performance. The results show a clear decrease in carbon formation when Co was present in the electrode. In-situ experiments confirmed in general an electrode deactivation when carbon was built up, while operando studies revealed an electrode activation when carbon was observed. This latter effect is tentatively attributed to an improvement of the electrical contact within the ceramic electrode. The influence on the impedance as well the detailed impact of operation parameters will be discussed.

References:

[1] D.B Drasbæk et al. Electrochimica Acta 2019, 327, 135004.

[2] J. Kirtley et al., J. Phys. Chem. C 2013, 117, 49.

[3] D.B. Drasbæk et al., Fuel Cells 2019, 19, 484.
Recent Advancements in Solid Oxide Fuel Cell Electrolysis Technology at Nexceris, LLC
Authors: Dogdibegovic Emir , Kopechek David , Wallace Anila , Harasyn Pamela , Arkenberg Gene , Kidner Neil J. , Swartz Scott , Seabaugh Matthew Mark
Published: December 2020

Increasing demand for long-term energy storage and reduced carbon emissions promotes solid oxide electrolysis cell (SOEC) technology. SOEC systems can achieve high hydrogen production rates with near 100 percent stack electrical efficiency while co-electrolysis of carbon dioxide and water leads to production of syngas. With over 25 years’ experience building and testing solid oxide fuel cell (SOFC) materials, components and stacks, Nexceris has a proven track-record of commercializing SOFC products to major OEMs. The established manufacturing platforms at Nexceris enable smooth expansion into SOEC applications.

In this talk, development of new SOEC electrode materials, stack components and stacks will be discussed. Over 50 down-selected air and fuel electrodes were electrochemically screened on 25 cm2 electrolyte-supported single cells and compared to baseline electrodes. Multiple electrode sets provided current density over -1.5 A/cm2 at 1.3 V and 800 °C with 75 percent steam/25% percent hydrogen fuel and air. The promising electrodes were implemented into short stacks with active cell area of 42 cm2. Stacks were operated continuously in SOEC mode at 1.3-1.4 V for ≥ 500 hours. The resulting short stack demonstrations show promising SOEC baseline performance and durability platform for future cell and stack development. Co-electrolysis and water electrolysis tests were also conducted and yielded comparable performance. Nexceris’ ChromLok coatings for bipolar plates were also integrated to stacks and tested under realistic conditions.