bluuebunny/crossref_metadata_2025 huggingface dataset:
Boosting the Stability and Performance of SOFCs: A New Approach to Oxygen Storage Capacity Using Lanthanum-Doped Ceria Interlayer Technology
Authors: Nguyen Xuan Dong , Lee Seok hee , Lim Hyung Tae , Shin Tae Ho
Published: February 2024

Being carbon neutral is one of the world's most important objectives. More than 65 percent of the countries that emit harmful greenhouse gases have committed to achieving net-zero emissions by the middle of the century.[1] There are numerous essential ways to gather energy for worldwide missions, including fuel cells, solar power, wind power, etc. The growing marketplace of fuel cells is following the trend of green-energy demand. Solid oxide fuel cells (SOFCs) are gaining popularity in the next-generation energy industry due to their high energy conversion efficiency, fuel flexibility, and low emissions.[2]

The main challenges for the commercialization of SOCs that need to address are high performance, long-term durability, and effective cost. Stabilized zirconia such as Yttria-stabilized zirconia (YSZ) and Scandia-stabilized zirconia (ScSZ) is commonly used as a self-standing electrolyte support. The inability of zirconia-based electrolytes to react with Sr-rich cathode materials like LSC, LSCF, BSCF, etc. Therefore, the electrodes and the zirconia-based electrolyte must have the best-interlayered buffer structure. Optimizing interlayer microstructures to make them more effective at high-performance ESCs is of great interest. Several Rare-earth doped ceria (RDC) materials, including (Gd, Ce)O2, (Sm, Ce)O2, and (La, Ce)O2, have been used as efficient interlayers to lessen reactivity and preserve ionic conductivity in the interface. However, the difference in the thermal expansion coefficient (TEC) between the GDC and the YSZ poses a significant problem for starting and halting SOCs. In the present work, we focus on the commercial lanthanum-doped ceria (Ce0.6La0.4O1.8 - LDC) as a buffer layer between the YSZ electrolyte and the LSCF cathode because of its higher oxygen storage capacitance. The reactivity of the YSZ/GDC composite was higher than that of the YSZ/LDC composite. And the total conductivity of the LDC/YSZ composite is higher than GDC/YSZ composite even though LDC has lower conductivity than GDC. Moreover, the mismatching of TEC was reduced by replacing the GDC with the LDC bilayer.

Consequently, the maximum power density for the electrolyte-supported cell SOFC with LDC interlayer was ~0.55 W.cm−2 at 1073 K. A variety of additives (Co, Mn, and Cu) was added to the LDC buffer layer to examine the sintering properties. The addition of copper not only obtained the highest microstructural density but also improve mechanical stability under cost-effective processes.

References

[1] M. Meinshausen, N. Meinshausen, W. Hare, S.C. Raper, K. Frieler, R. Knutti, D.J. Frame, M.R.J.N. Allen, Greenhouse-gas emission targets for limiting global warming to 2 C, 458 (2009) 1158-1162.

[2] C. Graves, S.D. Ebbesen, S.H. Jensen, S.B. Simonsen, M.B.J.N.m. Mogensen, Eliminating degradation in solid oxide electrochemical cells by reversible operation, 14 (2015) 239-244.
(Invited) Boosting Solid Oxide Fuel Cell Performance through the Effect of of Interstitial Oxide Ion Supplying of Oxygen Storage Capacitance Materials at Cathodic Functional Layer
Authors: Shin Tae Ho , Xuan Dong Nguyen , Lee Sang Won , Kim Hye Young
Published: February 2024

Chemical compatibility between the hierachical interface components in solid oxide fuel cells (SOFCs) is an emerging critical issues that significantly impact the durability of SOFCs. However, there are several challenging issues to be solved: cost-effective manufacturing configuration, lowering the operating temperature, and durability. The creation of novel materials or long-lasting electrode/electrolyte interfaces that permit high activity (oxygen reduction or fuel oxidation) while maintaining long-term stability is one of the major barriers to the commercialization of the SOFC Rare-earth doped ceria (REDC) is commonly used to enhance durability and activity in solid oxide cells (SOCs) engineering, with Gd-doped ceria (GDC) being a popular choice for interlayer and additives in solid oxide fuel cells (SOFCs). However, the Ce diffusion into the lattice of ZrO2of YSZ-based electrolyte as a solid solution at high-temperature manufacturing still is remained to be solved. In this study, we conducted La-doped CeO2 (LDC), whose Ce-sites are highly occupied with La to avoid a solid solution of Ce-Zr, as a functionalized interlayer between YSZ-based electrolyte and cathode. When LDC (La-doped CeO2, LDC, Ce0.6La0.4O2−δ) or Bi doped Cerium Oxide buffer layer was optimized at lowering sintering temperature to prevent a La2Zr2O7 impurity reaction, the improved electrochemical performance was achieved at the maximum power density (MPD) of ~1.43 W cm-2 at 800 oC. The high substitution of La3+ into the ceria lattice improves the oxygen non-stoichiometry of LDC, leading to improve the oxide ion supplying of the cathode side during the high current operation. Consequently, we firstly propose that the larger oxygen storage or supplying capacitance (OSC) effect of the interdiffusion layer composition (La, Zr, Ce, Y)O2 in La-doped CeO2 (LDC) is responsible for the positive enhancement of the oxygen reduction reaction (ORR) at high current ranges through interstitial oxygen supply at the cathode/electrolyte interface rather than (Gd, Zr, Ce, Y)O2 in GDC. The OSC of the LDC is higher than that of the GDC, and it effectively enhances the electrochemical performance of the cathode interface in the SOFCs because it may be affected by the high oxygen carrier concentration of the LDC, the higher oxygen releasing, and storage capacitance. This revealed that the effect of oxygen releasing, and storage capacity of the buffer layer might be the cause of improved performance. Consequently, the cell containing the high OSC buffer layer fabricated at 1250 oC to avoid interfacial insulating layers, such as La2Zr2O7 impurities, successfully displayed a dramatically high-power density value.

Figure 1
Enhancing Electrochemical CO2 Reduction of La(Sr)Fe(Mn)O3 with Metal (Ru, Ni, Co, and Fe) Catalytic Additives for High-Temperature CO2 Electrolysis Cells
Authors: Lee Seokhee , Lee Sang Won , Shin Tae Ho
Published: February 2024

Solid oxide electrolysis cells (SOEC) have tremendous potential as highly efficient devices for high-temperature CO2 electrolysis. Commonly used Ni-based fuel electrodes experience inherent redox instabilities under direct CO/CO2 conditions. Therefore, the robust perovskite oxide La(Sr)Fe(Mn)O3 (LSFM) has been suggested as an alternative owing to its excellent coking resistance. However, LSFM electrodes are limited by their poor catalytic activity in CO2 reduction. To alleviate this problem, various metal additives have been added as catalysts to decrease the surface reaction barrier, which accelerates the chemical adsorption of CO2. In this study, the various metal catalysts (Ru, Co, Fe, and Ni) are deposited on the surface of LSFM electrode using the infiltration method. The distribution of the relaxation time (DRT) is investigated to confirm the catalytic activity for CO2 electrolysis. Consequently, when applied Fe catalyst in LSFM electrode, an electrolysis performance of 2.2 A cm-2 at 1.5 V in CO2 electrolysis was obtained at 1123 K.
Mixed Ionic-Electronic Conductivity in Oxygen-Free K2NiF4-Type Hydrides
Authors: Rodenburg Hendrik Pieter , Kyriakou Vasileios , Artrith Nongnuch , Ngene Peter
Published: February 2024

Hydride-ion conductors and mixed hydride-electronic conductors are promising materials for numerous applications, for example as catalysts, catalyst supports or promoters for hydrogenation reactions, especially ammonia or methanol production. They could also be used in (electro)chemical energy conversion and storage devices such as batteries, fuel cells and reversible hydrogen storage systems. Therefore, there is a major interest in hydride-ion conductors with high conductivity at moderate temperatures.

Many presently known hydride-ion conductors are oxyhydrides, of which a large number have the K2NiF4-type structure.[1-5] As oxide ions occupy part of an oxyhydride’s anion sublattice, not all anions participate in hydride-ion transport, thereby potentially limiting the ionic conductivity at moderate temperatures. In this presentation, the synthesis and electrochemical characterization of several different oxygen-free K2NiF4-type structured hydride-ion conductors, such as Rb2CaH4 and Cs2CaH4, will be discussed.

By electrochemical analysis, the materials are found to exhibit mixed ionic-electronic conductivity at moderate temperatures. Small instabilities in the conductivity and TPD results which show that the materials release hydrogen gas indicate that the ionic conductivity is related to the presence of hydride-ion vacancies. In addition, computational results show that the measured activation energies are close to the expected values for hydride-ion transport.

The total conductivities at 200 °C are around 10-6 S cm-1, a significant portion of this being due to hydride-ion transport. The discovery of mixed hydride-electronic conductivity in these materials opens up new possibilities to explore mixed hydride-electronic conductors in catalysis and low-temperature energy conversion and storage applications.

G. Kobayashi et al., Science
2016, 351, 1314-1317.

A. Watanabe et al., Electrochemistry
2017, 85, 88-92.

Y. Iwasaki et al., J. Mater.
Chem. A
2018, 6, 23457-23463.

F. Takeiri et al., Inorg. Chem.
2019, 58, 4431-4436.

F. Takeiri et al., Nat. Mater.
2022, 21, 325-330.

Figure: Illustration of one transport pathway that hydride-ions can take through K2NiF4-type structured materials. The path taken is informed by computational results.

Figure 1
Total Energy and Total Power for the SOEC: Critical Role of Area Specific Resistance in Hydrogen Production Rate
Authors: Williams Mark
Published: February 2024

This paper develops the governing Total Energy (TE) (kilowatt-hours per kilogram hydrogen) and Total Power (TP) equations for the SOEC. The TE equation includes heat input, exergetic flows, enthalpy of vaporization, pressurization, heat loss, area specific resistance (ASR), etc. The TE equation developed, as it would happen, correlates well with the Idaho National Laboratory (INL) proven SOEC performance of 45 kilowatt-hours per kilogram hydrogen at 20 bars and 725K. TE is the key performance equation necessary for designing, predicting, and planning for SOEC and SOFC performance and cost. The ASR has a critical role in SOEC TE and TP. The ASR and the targets for ASR necessary to meet important DOE performance targets are discussed.
(Invited) Mixed Ionic Electronic Conductors (MIECs): The Importance of Fast and Slow Processes
Authors: Kilner John Anthony
Published: February 2024

MIECs are ideal materials for use as electrodes in solid state ionic devices. They have found application in SOFCs, SOECs, and solid state battery devices. In this contribution we will focus on MIEC used in the SOFC/SOEC where oxygen is the mobile ion. Most of these materials are complex perovskite materials, for example La1-xSrxCoyFe1-yO3-δ (LSCF). The focus of experimental observation in these materials has been on the fast process of transport of the highly mobile oxygen ion and much is known about the effect of non-stoichiometry in determining the level of oxygen ion transport. Most of these materials are very good mixed conductors at temperatures above 600°C but the lattice oxygen transport drops off markedly at lower temperatures. Recently there have been attempts to improve the lower temperature behaviour by producing nanomaterials, usually in thin film form [1-3], with a high density of grain boundaries. These have been shown to introduce fast diffusion paths along the grain boundaries and have been shown to improve the electrochemical performance.

What has been neglected in the study of these materials is the evolution of the cation distribution in these complex oxides. The cation distribution has a marked effect upon the performance of an MIEC electrode, for example, the segregation of Sr to the surface which is detrimental to the oxygen exchange [4, 5], the development of defect clusters which can trap the oxygen vacancies, and the local chemistry of the grain boundaries [6], affecting transport in polycrystalline materials. Cation transport is a slow process but has importance during the short times and high temperatures during processing, and even more relevantly for the low temperatures but very long times associated with operation. This has implications for the durability of these devices. The contrast between these fast and slow processes will be discussed in this contribution and their relevance to different processing regimes and operational durability.

References

[1] A.M. Saranya, A. Morata, D. Pla, M. Burriel, F. Chiabrera, I. Garbayo, A. Hornes, J.A. Kilner, A. Tarancon, Chemistry of Materials
30 (2018) (16) 5621.

[2] A.M. Saranya, D. Pla, A. Morata, A. Cavallaro, J. Canales-Vázquez, J.A. Kilner, M. Burriel, A. Tarancón, Advanced Energy Materials
5 (2015) (11) 1500377.

[3] E. Navickas, T.M. Huber, Y. Chen, W. Hetaba, G. Holzlechner, G. Rupp, M. Stoger-Pollach, G. Friedbacher, H. Hutter, B. Yildiz, J. Fleig, Physical Chemistry Chemical Physics
17 (2015) (12) 7659.

[4] M. Kubicek, G.M. Rupp, S. Huber, A. Penn, A.K. Opitz, J. Bernardi, M. Stoger-Pollach, H. Hutter, J. Fleig, Phys Chem Chem Phys
16 (2014) (6) 2715.

[5] G.M. Rupp, H. Téllez, J. Druce, A. Limbeck, T. Ishihara, J. Kilner, J. Fleig, Journal of Materials Chemistry A
3 (2015) (45) 22759.

[6] M. Acosta, F. Baiutti, A. Tarancón, J.L. MacManus-Driscoll, Advanced Materials Interfaces
6 (2019) (15) 1900462.
(Invited) Chemical Intricacies of Mixed Ionic-Electronic Conducting Perovskite Oxides
Authors: Manthiram Arumugam
Published: February 2024

Mixed ionic-electronic conductors (MIEC) play a critical role in electrochemical devices, such as batteries and fuel cells. Ideally, both the electrodes (anode and cathode) should support a fast transport of electrons and the working ions to realize acceptable reaction kinetics and current density/rates. Crystal chemistry and the resulting chemical bonding control the MIEC properties and the device performances ensuing from them. This presentation will illustrate the richness and complexities displayed by perovskite-based MIECs, which are employed as electrodes in solid oxide fuel cells, oxygen separation membranes, etc., by taking a few basic fundamental materials parameters/factors:

By taking the ionic sizes of the A and B cations in ABO3 perovskite oxides, the presentation will show the ability to tune the electronic and ionic conductivities in MIECs. Specifically, for example, how the approach of B-O-B bond angle towards 180o by replacing the A cations with progressively increasing size can cause an increase in bandwidth, electron delocalization, and electronic conductivity, and eventually a semiconductor-to-metal transition.

By taking the size difference between the A cations in the double perovskite oxides, such as ALnCo2O6-
d (A = alkaline earth and Ln = lanthanide), how oxygen content (6-d) and hole concentration can be altered drastically under even identical synthesis conditions due to the preference of different coordination numbers for A and Ln ions, e.g., the preference of larger cations like Ba2+ for 12-fold coordination while smaller cations like Y3+ for 8-fold coordination.

By taking the coordination number of trivalent cobalt ions as an example, the presentation will illustrate how the low-spin to high-spin transition that has plagued the cobalt-containing perovskite oxides with huge thermal expansion coefficient can be eliminated by designing materials with tetrahedral-site cobalt ions instead of octahedral-site cobalt ions.

By taking the differences in the magnitude of the charge-transfer gap between the B3+/4+:3d band and the top of the O2-:2p band in ABO3 perovskite oxides, the presentation will explain how the oxygen flux in oxygen gas separation membranes can be altered due to the differences in the degree of covalence in the B-O bond.
(Invited) Proton Surface Exchange Kinetics and Stability of Thin-Film Triple Conducting Oxides for Protonic Ceramic Electrolysis Cells
Authors: Lee Jongmin , Buckner Haley H , Perry Nicola H.
Published: February 2024

Protonic ceramic electrolysis cells (PCECs) have been attracting attention due to their ability to operate in the intermediate temperature (300 - 500 ˚C) sweet-spot. These temperatures enable fast kinetics, inexpensive materials (no precious metals; stainless interconnects), and lower operating voltage for producing green hydrogen, without the accelerated degradation that may be observed at higher temperatures. The steam electrodes often support triple conduction and thereby host the proton exchange / oxygen evolution process at the surface, where steam is split. Steam electrode materials development is at a relatively early stage, with open questions around the relationships among bulk composition, evolving surface chemistry, kinetic quantities, and degradation mechanisms. We are investigating the proton exchange surface coefficient (k) and its evolution over time on model thin film electrodes in order to ultimately develop highly active and long-term stable steam electrodes for PCECs.

ABO3 perovskites with Ba on the A-site and nominally multivalent ions on the B-site are candidates for steam electrodes given the varied compositions in this class that can transport oxide ions, protons, and electronic species, and the lowering of hydration enthalpies by the basicity introduced by Ba. However, very few measurements of k exist for these materials, and the evolution of surface chemistry and thus k is poorly understood.

In this work, we fabricated and compared two perovskite triple conducting oxides by growing geometrically well-defined films of Ba(Pr,Y)O3-x (BPY) and Ba(Co,Fe,Zr,Y)O3-x (BCFZY) with pulsed laser deposition. We examined the proton surface exchange coefficients (k-values) using simultaneous in-situ optical transmission relaxation and electrical conductivity relaxation measurements upon switching pH2O at a temperature of 400 ˚C, and continued these switches as a function of time to assess stability. To our knowledge, this is the first use of an optical transmission method to probe elevated temperature steam splitting kinetics, and we interpret the optical (and electrical) changes as indicative of redox during the hydrogenation process. The k-values of BPY thin films were approximately ten times higher than those of the BCFZY thin films, and BPY also retained higher k-values over time. The bulk and surface chemical compositions of BPY and BCFZY thin films before and after relaxation measurements were compared using Rutherford backscattering spectrometry, angle-resolved X-ray photoelectron spectroscopy, and scanning transmission electron microscopy with spectroscopy. Pronounced Ba enrichment and Si contamination (from the quartz tube) were evident at the surface of BPY by both S/TEM-EDS and XPS, whereas for BCFZY these surface chemical features were only detectable by XPS and absent in S/TEM-EDS. Implications for materials design of steam electrodes will be discussed, considering efficiency and lifetime.
High Performance Protonic Ceramic Electrochemical Cells Operating at <500°C
Authors: Liu Fan , Deng Hao , Liu Bin , Duan Chuancheng
Published: February 2024

Protonic ceramic electrochemical cells (PCECs) can operate in both fuel cell and steam electrolysis modes for efficient power generation and green hydrogen production. Thanks to the low activation energy of proton conduction, PCECs are uniquely capable of operating at temperatures below 600°C. Although some intriguing demonstrations of intermediate-temperature (500-600°C) PCECs (IT-PCECs) have been made in the last decade, the operating temperature of PCECs is still too high to revolutionize ceramic electrochemical cell technology, which is ascribed to the high ohmic resistance and positive electrode polarization resistance. It has been also recognized the electrode polarization resistance dominates the total resistance at <500°C. These challenges suggest both the electrolyte and positive electrode should be redesigned to lower the PCEC operating temperature.

In this work, we present two main approaches to reducing electrolyte ohmic resistance, electrolyte-positive electrode contact resistance, and electrode polarization resistance, which enables PCECs operation at <500°C. First, by using the ultrasonic spray coating system to coat the electrolyte layer on a negative electrode substrate with low Ba-deficiency, a bamboo-structured, ultrathin, and chemically homogeneous electrolyte can be fabricated. Second, a newly in-situ formed composite positive electrode was developed, which enhances the interfacial bonding between the positive electrode and electrolyte, further reducing ASRo

, while improving both bulk oxygen-ion diffusion coefficient and surface oxygen exchange coefficientat <500°C.

The newly developed LT-PCECs attain outstanding power densities in fuel cell mode (as high as 0.77 W cm-2 at 450°C), and exceptional current densities in electrolysis mode (over -1.28 A cm-2 at 1.4 V and 450°C). Furthermore, reducing the temperature does not sacrifice the fuel flexibility of these ceramic fuel cells. We demonstrated that the PCECs can directly utilize ammonia and methane for power generation at <500°C. Exceptional durability has been also demonstrated in both fuel cell and electrolysis modes at <500°C.

These results further emphasize that through the PCEC scalable manufacturing processes and novel positive electrode materials presented here, PCECs can be employed for power generation and H2 production at <500°C, thereby transforming the architectures and removing previous operational constraints of ceramic electrochemical cells for scaled operation. PCECs can therefore be considered as one part of the growing hydrogen economy, while leveraging the existing fossil fuel infrastructure and achieving higher energy efficiency and lower CO2 emissions.
(Invited) Materials Stability in Anode-Supported Solid Oxide Cells
Authors: Barnett Scott A
Published: February 2024

Professor Anil Virkar has been a pioneer in the development and characterization of high-performance anode-supported solid oxide fuel cells, and in understanding degradation processes in such cells operated in electrolysis mode. This talk reviews methods for improving anode-supported cells, particularly for yielding high performance at reduced operating temperature. The understanding of degradation mechanisms occurring during solid oxide electrolysis cell operation will be discussed.
(Invited) Forming Multifunctional Ceramics with Different ZrO2 Polymorphs: Mixed Ion-Electron Conducting Properties of Zirconium Titanium Oxides
Authors: Walker Robert A. , Sinrud Joshua B. , McIntyre Melissa
Published: February 2024

Infiltrating porous electrodes with solution phase precursors is a strategy employed to improve performance, catalytic activity and longevity in high temperature electrochemical devices. For example, traditional Ni yttria-stabilized zirconia (Ni-YSZ) cermet anodes used in solid oxide fuel cells (SOFCs) are susceptible to carbon accumulation and to sulfur poisoning. To counter the effects of degradation, anodes have been infiltrated with secondary materials containing Sn, Ba, Al and a host of other constituents, typically at levels of 1-5% (by mass). Processing and preparing infiltrated electrodes, however, can lead to formation of new material phases that affect surface chemistry and electrode microstructure in unexpected ways.

In this work, XRD and Raman spectroscopy are used to investigate the formation of functional zirconium titanate secondary phases in Ti/Zr oxides. Different zirconia polymorphs (either pure or stabilized with small amounts of yttria (YSZ)) mechanically mixed with TiO2 and heated above 1000 ˚C in stagnant air react to form several secondary phases. For sintering temperatures > 1100 ˚C, mixtures of TiO2 and m-ZrO2 form a ZrTiO4 secondary phase while mixtures of TiO2 and 3YSZ or 8YSZ form Zr5Ti7O24. The extent of secondary phase formation is enhanced with both higher sintering temperature and yttria content. The Zr5Ti7O24 secondary phase formed from TiO2/8YSZ samples sintered at 1400 ˚C exhibits unexpected mixed ionic and electronic conductivity at 800 ˚C. These findings suggest that secondary phases intentionally integrated into electrode architectures can improve the performance of high temperature electrocatalyst systems.
Solid Oxide Electrochemical Cells for Nitrogen and Oxygen Production
Authors: Sun Xiufu , Mondi Francesco , Monich Patricia Rabelo , Pirou Stéven , Frandsen Henrik Lund , Hendriksen Peter Vang
Published: February 2024

Nitrogen and oxygen are both very important commodities with a wide variety of applications in industries, such as chemical, food and metallurgical plants as well as in the medical sector. Nowadays most of the nitrogen and oxygen are produced via air separation technologies such as cryogenic distillation (ASU) or pressure swing adsorption (PSA). Both ASU and PSA offer economical and mature ways for nitrogen and oxygen production at large (>100 ton/day) or medium scales (20-100 tons/day). If one can develop a technology for providing these gases in an energy efficient and cost effective way also at small scale, preferably driven by electricity only, this would enable new applications of the gases. Such a technology would match characteristics of the future green electricity system relying on small scale (few MWs) power generation and fluctuating production..

In this work we present an efficient electrochemical process for N2 and O2 production based on a solid oxide electrochemical cell technology by oxygen extraction from air. Cells with a 53 × 53 mm2 size were produced by a conventional tape casting method. They consist of a ca.10 μm CGO (Ce0.9Gd0.1O2-δ) electrolyte sandwiched between composite electrodes made from either LSCF (La0.6Sr0.4Co0.2Fe0.8O3-δ) - CGO, or LSF (La0.6Sr0.4FeO3-δ) - CGO. To boost performance at low temperature, the electrodes were infiltrated with Pr-oxide. The electrochemical performance with the different supports were characterized by obtaining current-voltage (iV) characteristics at different temperatures as well as through electrochemical impedance spectroscopy(EIS) with or without infiltration. For characterization, air was used as feed stock to the cathode compartment and air, or oxygen was used as sweep gas to the anode compartment. A voltage below 200 mV is needed to drive a current of 1 A/cm2 through the cell, which can provide a purity of 90% of N2 out at an operation temperature of 650 °C (see Figure 1a). The cells were demonstrated to operate for producing a 98% pure N2 stream without degradation over a 1500 h period (see Figure 1b).

Further analysis show that the specific power consumption calculated based on the power input and outlet gas flow rate for 90% N2 production is ca. 0.1 kWh/m3 and the specific power consumption for 96% and 98% N2 production is 0.21 and 0.31 kWh/m3, respectively. A 3-fold increase in required power is observed when going from a N2 purity from 90% to 98%.

Detailed electrochemical analysis and the electrochemical performance comparison between LSCF and LSF based mixed ionic electronic conductor (MIEC) electrodes will be presented. Factors limiting cell performance will as well as analysis of optimal point of operation in terms of energy consumption and reliability will also be discussed.

Acknowledgment

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 862482.

Figure 1
Managing the Scaling Relationship for Plasma-Activated Electrolysis Toward Nitrogen Fixation
Authors: Bera Susanta , Jung Myung-Jin , Kwon Se-Hun , Herrmann Anja , van de Sanden Richard , Tsampas Michail N.
Published: February 2024

To substitute fossil feedstock, storing renewable electricity in chemical bonds has become one of the tremendous and attractive approaches. This approach enables the transformation of base molecules (i.e., H2O, N2, CO2) into energy or chemical-rich molecules. The energy stored in the nitrogen-based compound is a critical biogeochemical cycle in nature due to its essential nutrient for living organisms in the forms of ammonia, nitrates, urea, amino acids, and DNA/RNA nucleotides as well as the high atmospheric volume of 78%. Artificial nitrogen fixation via a catalytic approach powered by sustainable renewables (e.g. wind, solar) provides an alternative as well as promising route to resource the value-added chemicals.

N2 is a nonreactive base molecule due to its non-polarity and a strong triple bond between the atoms. Subsequently, even with an active catalyst, a substantial amount of energy is needed to activate N2 [1]. This Account covers our group’s recent advances in solid oxide electrolysis cells (SOECs) for providing reacting species on catalysts in a controllable manner while a radio frequency (RF) plasma is used to increase the reactivity of nitrogen [2,3]. Using oxygen ion or proton conducting SOECs we can produce either ammonia or nitric oxide (via reacting with plasma-activated N2) by suppressing oxygen or hydrogen evolution, respectively. The spatial separation of nitrogen dissociation and catalytic formation of the target molecules provides true independent parameters to optimize the electrocatalytic reactions. In both cases, the concentration of products is orders of magnitude higher than equilibrium (in the absence of plasma) while very high selectivity to nitrogen fixation is observed.

To date most of the studies have focused on the material axis, however, recent theoretical studies have revealed that large-scale N2 fixation necessitates the rational design of the reactor, catalyst selectivity, reaction kinetics, and fluid dynamics and thus it keeps the processes far from the optimum performance. In this contribution, we investigate several aspects including flow dynamics, nature of the catalyst, activation energy of the catalytic process, catalyst surface-to-volume ratio, catalyst selectivity, and residence time of plasma-activated nitrogen to reach the catalyst surface, toward solving the aforementioned limitations.

References

[1] H. Ma, R. K Sharma, S. Welzel, M. CM van de Sanden, M. N Tsampas, W. F. Schneider, Nat. Commun. 13 (2022) 402.

[2] R. K. Sharma, H. Patel, U. Mushtaq, V. Kyriakou, G. Zafeiropoulos, F. Peeters, S. Welzel, M. CM van de Sanden, M. N. Tsampas, ACS Energy Lett. 6 (2020) 313.

[3] H. Patel, R. K. Sharma, V. Kyriakou, A. Pandiyan, S. Welzel, M. C.M. van de Sanden, M. N. Tsampas, ACS Energy Lett. 4 (2019) 2091.

Figure 1
Preparation of Textured Polycrystalline La2NiO4+
δ
Membranes and Their Oxygen-Transporting Properties
Authors: Escobar Cano Giamper Eliseo , Zhao Zhijun , Riebesehl Fabian , Stölting Oliver , Breidenstein Bernd , Feldhoff Armin
Published: February 2024

Due to its high chemical and thermal stability in CO2 atmosphere and its anisotropic crystal structure, the Ruddlesden-Popper phase La2NiO4+δ
has attracted considerable attention in the research field of oxygen-transporting membranes. The anisotropic properties of La2NiO4+δ
can be exploited in textured polycrystalline membranes to control the oxygen diffusion through this material. To fabricate textured La2NiO4+δ
membranes, powder mixtures consisting of fine-grained equiaxial La2NiO4+δ
matrix particles and large plate-like La2NiO4+δ
template particles in different mass ratios were uniaxially pressed and then sintered in air. For this purpose, the anisotropic template particles were synthesized by molten-flux method using NaOH as flux [1]. In the powder mixture, the La2NiO4+δ
template particles can be aligned perpendicular or parallel to the pressing direction, depending on the geometry of the pressing tool and the sample preparation. After the sintering process, textured La2NiO4+δ
membranes were obtained, which was verified by measuring X-ray diffraction patterns and pole figures. Further X-ray diffraction measurements together with the calculation of the Lotgering orientation factor revealed that an increasing content of the template particles in the ceramic materials leads to a stronger texturing. Scanning electron microscopy micrographs show some individual plate-like

La2NiO4+δ
grains well embedded in the matrix. Homogeneous distribution of lanthanum, nickel and oxygen in the ceramics was confirmed by energy-dispersive X-ray spectroscopy. Finally, the influence of the template particle content in the La2NiO4+δ
membranes on the oxygen permeation performance is discussed.

[1] Escobar Cano, G.; Brinkmann, Y.; Zhao, Z.; Kißling, P.A.; Feldhoff, A. Sol–Gel-Process-Based Molten-Flux Synthesis of Plate-like La2NiO4+

δ
Particles. Crystals
2022, 12, 1346. https://doi.org/10.3390/cryst12101346
Coating Effects of Sm0.2Ce0.78M0.02O2-
δ (M=Ni, Co, Pd, NiCo) Layer on Ni/YSZ Anode for Internal Dry Reforming in Solid Oxide Fuel Cells
Authors: Kim JunHo , Jung Hong Ryun , Yun Jeong Woo
Published: February 2024

Internal dry reforming of methane (DRM) in solid oxide fuel cells (SOFCs) has environmental advantages because CH4 and CO2 are considered as two major greenhouse gases causing global warming. Carbon coking, however, can be major drawback in the DRM via pyrolysis of methane and Boudouard reaction. In this study, Sm0.2Ce0.78M0.02O3-
δ (SCM, M=Ni, Co, Pd, NiCo) was investigated to minimize carbon coking and to improve the catalytic activity for internal DRM in SOFCs. Samarium doped ceria (Ce0.8Sm0.2O2-
δ) has been widely used in SOFCs due to the excellent ionic conductivity and the mixed ionic and electronic conductivity (MIEC). To improve the catalytic activity of Ce0.8Sm0.2O2-
δ, Ni, Co, Pd, and NiCo alloy were substituted into the Ce. The SCM phase was stable in internal DRM condition. The morphology and compositions are analyzed with XRD, SEM, TEM, XPS, etc. Sm0.2Ce0.78Ni0.01Co0.01O2-
δ(SCNC) showed excellent DRM results with over 90% in CH4 and CO2 conversion and close to 1 in H2/CO selectivity at 800oC. The carbon deposition of SCNC catalysts was minimized. In addition, power density of SCNC-coated Ni/YSZ anode was improved with 2.3 times higher in CH4/CO2 fuel conditions comparing to that of Ni/YSZ anode.
Modification of Fuel Electrode Microstructure for Protonic Ceramic Cells by the Infiltration of Various Metal Nanoparticles
Authors: Jo Jun Ho , Lim Hyung-Tae
Published: February 2024

Proton ceramic cells (PCCs) are promising eco-energy electrochemical energy conversion systems. Proton conducting perovskite oxide electrolytes of PCCs have high ion conductivity at intermediate and low temperatures because of their low activation energy. Most of electrode infiltration studies for fuel electrode supported PCCs were carried out on a thin air electrode layer rather than a thick fuel electrode. In the present study, various metallic nanoparticles (such as Ni, Pd and Pt) were infiltrated in fuel electrode scaffolds to increase the thriple phase boundary (TPB, electrode-electrolyte-gas phase). The fabricated fuel electrode supported PCC consisted of Ni-BaCe0.7Zr0.1Y0.1Yb0.1O3-ẟ cermet fuel electrode, BaCe0.7Zr0.1Y0.1Yb0.1O3-ẟ (BCZYYb) electrolyte, and BCZYYb-La0.6Sr0.4Co0.2Fe0.8O3-ẟ composite air electrode. SEM analysis results revealed that metallic nanoparticles can be infiltrated up to the fuel electrode functional layer and their distribution was uniform through the layer. The PCC with metal nanoparticle infiltrated fuel electrode exhibited higher power density and lower polarization resistance than that with bare fuel electrode. This study shows the electrochemical performance of fuel electrode supported PCCs can be further improved by the facile infiltration method.
Interface Modification of LATP-Based Solid-State Li Metal Batteries Using Composite Polymer Electrolyte and Li-in Alloy
Authors: Kim Min Joo , Kang DongJae , Lee Seok Hee , Lim Hyung-Tae
Published: February 2024

NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolyte attracts attention because of its stability in the air and water and its chemical stability with high-voltage cathode materials. However, LATP solid electrolyte has interfacial problems, such as limited contact area. Additionally, Li/LATP interface is deteriorated by structural collapse due to its reduction products. Herein, we modified the electrode interface using PEO based protecting layer (PL) and Li-In alloy anode. PEO based protecting layer (PL) was applied to suppress the Li/LATP interface side reactions and minimize the LiFePO4 (LFP) /LATP interfacial resistance. We applied two kinds of PLs, solid polymer electrolyte (SPE) and composite polymer electrolyte (CPE). A CPE was prepared using a ceramic filler of LLZTO in order to improve the ionic conductivity and long-term cycling stability of PL. As an anode material Li foil and In1.5Li foil were utilized. The symmetric and full cells were prepared with a PL coated on both sides of the electrolyte. The symmetric cell consisted of Li/PL/LATP/PL/Li and the full cell consisted of Li (or In1.5Li) /PL/LATP/PL/LFP. The symmetric cell and full cell with CPE exhibited stable cycling performance, compared to that with SPE. The symmetric cell utilizing In1.5Li foil showed higher overpotential during the initial cycles, but it showed improved cycling stability, compared to that with Li metal foil. XRD and TOF-SIMS results indicate that there were no structural and chemical changes in the LATP coated with PL. Therefore, the modification strategies of CPE protecting layer and Li-In alloy anode are effective for enhancing cycling performance in all-solid-state batteries.
Oxygen Electrode Surface Constructing for Reversible Protonic Ceramic Electrochemical Cells
Authors: Luo Shunrui , Kai Pei , Chen Yu , Arbiol Jordi
Published: February 2024

Reversible protonic ceramic electrochemical cells (R-PCECs) have great potential for energy conversion and storage at low-intermediate temperatures (400-700oC), which could enable the conversion of H2O into H2 in electrolysis (EL) mode, and inversely the production of electricity in fuel cell (FC) mode. However, the sluggish kinetics of oxygen reduction/evolution reaction (ORR/OER) at reduced temperatures, as well as undesired surface segregation and structural deterioration, have impeded the development of R-PCECs devices. In this presentation, we introduce a double-perovskite type oxygen electrode that has been optimized for enhanced reaction activity and surface stability using an efficient fluorite catalyst coating. Specifically, the oxygen electrode, PrBaCo2O5+δ (PBC), has been infiltrated with an active and durable shell, Pr0.1Ce0.9O2+δ (PCO). The obtained results show that PCO-PBC possess elevated oxygen vacancy concentration which would improve the surface exchange process, facilitate ion diffusion, and provide multiple active reaction sites, while simultaneously preventing Ba segregation during operation. Therefore, the fuel-electrode-supported single cell with a PCO-PBC oxygen electrode achieves high performance and a negligible degradation in EL and FC dual modes for 25 cycles and 100 h at 650 oC with 3vol.% H2O.
Non-Arrhenius Ionic Conductivity Behaviour in Antiperovskite Solid Electrolytes for Sodium Metal Batteries
Authors: Darminto Brigita D , Pasta Mauro , Lee Hyeon Jeong , Guo Hua , Rees Gregory , Cattermull John , Diaz-Lopez Maria , Hashi Kenjiro , Kuwata Naoaki , Goodwin Andrew
Published: February 2024

Solid-state sodium metal batteries have been proposed as an alternative to lithium-ion batteries (LIBs) for next-generation applications due to the high abundance and wide distribution of sodium resources.1 Sodium antiperovskites (Na3OX, X = Cl, Br, or BH4) have recently attracted great interest as solid electrolyte candidates due to the relatively low processing temperature (<500 oC), reasonable ionic conductivity (up to 4.4 x 10-3 S cm-1 at room temperature), and great chemical stability against sodium metal anodes.2,3 Typical solid-state ionic conductors have temperature-dependent ionic conductivity that follows Arrhenius behaviour over a broad range of temperatures, corresponding to a constant activation energy Ea. However, this is not the case in Na3OBr, and instead a phenomenon resulting in a higher ionic conductivity and lower activation energy is observed to occur at 255 oC. Similar non-Arrhenius ionic conductivity phenomenon has also been reported in the potassium antiperovskite K3OI. It has been proposed that this behaviour originated from anion disordering, but conclusive experimental evidence to support this claim has not been reported.4 An understanding of the origin of this behaviour could enable the synthesis route to be optimised such that higher ionic conductivities could be achieved.

In this work, we combined temperature-resolved bulk and local characterisation methods including Pawley and Rietveld refinements of synchrotron x-ray diffraction (XRD), pair distribution function (PDF), solid-state nuclear magnetic resonance (NMR) spectroscopy, and electrochemical impedance spectroscopy (EIS) to gain an insight into the origin of this non-Arrhenius behaviour. We found that this phenomenon does not originate from anion disordering, as previously speculated, because the lattice parameter of Na3OBr changed linearly with temperature and no major intensity changes were observed in the Na-Br and Na-O signals in the PDF patterns. Other supporting findings that lead us to this conclusion will be discussed in the presentation.

References

Wang, X. et al. Ultra-stable all-solid-state sodium metal batteries enabled by perfluoropolyether-based electrolytes. Nat. Mater.
21, 1057–1066 (2022).

Zheng, J., Perry, B. & Wu, Y. Antiperovskite Superionic Conductors: A Critical Review. ACS Mater. Au
1, 92–106 (2021).

Sun, Y. et al. Rotational Cluster Anion Enabling Superionic Conductivity in Sodium-Rich Antiperovskite Na3OBH4. J. Am. Chem. Soc.
141, 5640–5644 (2019).

Zheng, J. et al. Antiperovskite K3OI for K-Ion Solid State Electrolyte. J. Phys. Chem. Lett.
12, 7120–7126 (2021).
(Digital Presentation) Facile Fabrication of Nickel and Sc-Doped Zirconia Cermet Electrode Thin Film on YSZ Substrate Via Screen-Printing for Solid Oxide Electrochemical Cells
Authors: Macalisang Christine Mae , Cervera Rinlee
Published: February 2024

Solid oxide electrochemical cells (SOCs) operating as either solid oxide fuel cells (SOFCs) or solid oxide electrolysis cells (SOECs) are widely known as promising advancements in green energy technologies for storage and high-efficiency energy generation. This study used a single screen-printing deposition method to fabricate a porous Nickel – scandia-stabilized zirconia (Ni-ScSZ) cermet electrode on a dense YSZ solid electrolyte substrate. The precursor powders were prepared via the glycine-nitrate combustion process. To investigate the effect of ink slurry solvent on the quality, structure, and morphology of the deposited films, ethanol, and alpha-terpineol were used. The screen-printed films were sintered at 1300°C for 6h and reduced under an Ar/5% H2 gas environment at 700°C for 2h to form porous electrodes. X-ray diffraction (XRD) analysis showed that all sintered NiO-ScSZ films exhibited cubic peak structures of both NiO and ScSZ. Scanning electron microscopy (SEM) micrographs and elemental mapping revealed finer morphology with good dispersion of NiO and ScSZ phases for sintered NiO-ScSZ films with alpha-terpineol as solvent. After exposure to Ar/5% H2 gas environment, a complete reduction of NiO to Ni was revealed by XRD for all Ni-ScSZ electrodes. Moreover, SEM micrographs of as-reduced samples showed an increase in porosity as oxygen was removed from NiO. Electrochemical impedance spectroscopy was used to determine the conductivity of the reduced Ni-ScSZ electrode films under Ar/5% H2 gas environment. The obtained total conductivity values upon reduction are 9.54x10-5 S/cm and 4.75x10-5 S/cm for ethanol and alpha-terpineol as solvents, respectively.
(Digital Only Presentation) Effects of Ink Solvent on the Screen-Printing Fabrication and Morphology of LSM-YSZ Thin Films Deposited on YSZ Substrate for Solid Oxide Electrochemical Cells
Authors: Hablado Jessa , Cervera Rinlee
Published: February 2024

Screen-printing is a cheap and easy thin film deposition technique utilized in energy devices fabrication, specifically, in solid oxide electrochemical cells (SOCs). This technique offers simple set-up, film quality control and mass production. In this study, LSM-YSZ, a promising component material for SOCs application was deposited on YSZ electrolyte via screen-printing. Specifically, the study aimed to investigate the effect of the solvent used in screen-printing on the quality of the deposited film. LSM-YSZ precursor powders synthesized via glycine-nitrate combustion process (GNP) were screen-printed on YSZ substrate using different solvents, ethanol and alpha-terpineol. The structure, morphology, and conductivity values of the GNP LSM-YSZ thin films using two solvents were compared. Results showed that both solvents produced a uniform distribution of rhombohedral LSM and cubic YSZ thin films with porous morphologies but alpha-terpineol solvent exhibited more agglomerated particles. Despite having this morphology, alpha-terpineol is still preferred than ethanol due to its reproducibility and scalability as it is less volatile than the other one. Moreover, there was no significant difference between the measured total conductivities of the half-cells using two solvents with the values of 4.63e-3 S/cm and 2.07e-3 S/cm at 700°C, and activation energies of 0.374 eV and 0.483 eV from 500°C - 700°C, for ethanol and alpha-terpineol, respectively.
Development of Stabilized Organic Cathodes Via Grafting Redox-Active Molecules to Carbon in Aqueous Zinc-Ion Batteries for Energy Storage Systems
Authors: Baker Thomas James , Ibarra Espinoza Alejandra , Gourley Storm William D , Adams Brian D , Higgins Drew Higgins
Published: February 2024

Despite being in the early stages of development, aqueous zinc-ion batteries (ZIBs) show much promise for grid scale energy storage with their safe, simple design, and high theoretical volumetric energy density. One of the major bottlenecks of ZIB performance is their limited practical cathode specific capacity. Organic redox-active molecules are gaining attraction as alternative cathode active materials to the more standard metal oxides. The limited capacity of cathodes using organic compounds as active materials can be addressed by the versatile nature of redox capable organic cathode design. However, these cathodes are often plagued by capacity fade. We developed aqueous ZIB cathodes with organic molecules grafted to carbon substrate via a facile synthesis technique. Electrochemical and material analysis confirmed the presence of covalent grafting. This tunable grafting method anchored and stabilized the redox active molecules which could easily be incorporated into a ZIB cathode. By fixing the molecules, capacity fade was mitigated as the cells were charged and discharged. Additionally, using this flexible synthesis methodology the cathode composition and structure was translated from work done on lithium-ion batteries and optimized for ZIB performance. In this work, the tunable organic cathode synthesis methods employ the use of simple chemical modifications that avoids the utilization and waste of expensive and hazardous compounds. This methodology has the flexibility to apply inexpensive and sustainable precursors to improve ZIB sustainability not only for lab scale use but also for pilot scale production. This approach highlights the promise of grafted organic materials for next generation ZIB cathodes.