bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Epitaxial Thin Films of Solid-State Battery Material
Authors: Takada Kazunori , Ohnishi Tsuyoshi 
Published: December 2020

Solid-state batteries are regarded as next-generation batteries, which will play important roles in the coming low-carbon society; however, they have been suffering from their low power densities. Although low ionic conductivities of solid electrolytes had been the reason for the low power densities, intense studies have given solid electrolytes with high ionic conductivities: The highest conductivity exceeded 10−3 S cm−1 in 1990s and has reached 10−2 S cm−1 recently among sulfides. These conductivities are comparable to, or higher than, those of organic-solvent liquid electrolytes; however, even such high conductivities do not lead to high power densities without fast ionic conduction at the interfaces between the battery materials. In spite of the importance, studies on interfacial transport phenomena are still pioneering stage. For example, although high interfacial resistances between high-voltage cathodes and sulfide solid electrolytes have successfully reduced [1], mechanism of the high interfacial resistance is still in an argument; and although oxide systems have been suffering from high grain boundary resistance [2], origin of the grain boundary resistance is still unclear.
Thin-film systems are ideal for such fundamental studies on the interfaces owing to their simple geometry, in which the interface can be a plane, and the ionic conduction can be regarded as one-dimensional. The thin films should be single crystal with controlled crystal orientation in order to construct interfaces formed between defined crystal planes and free from any defects including grain and domain boundaries.
We have been focusing our attention on making such thin films by epitaxial growth. We have successfully formed some battery materials into single-crystal-like thin films with controlled crystal orientation [3–5]. An epitaxial film of perovskite-type solid electrolyte shows the influence of domain boundaries on ionic conduction, while anisotropic ionic conduction expected in LiCoO2 is clearly observed in a high-quality epitaxial film for the first time.
References
[1] N. Ohta, K. Takada, L.Q. Zhang, R.Z. Ma, M. Osada, and T. Sasaki, Adv. Mater., 18, 2226 (2006).
[2] Y. Inaguma and M. Nakashima, J. Power Sources, 228, 250 (2013).
[3] K. Nishio, T. Ohnishi, K. Akatsuka, K. Takada, J. Power Sources, 247, 687 (2014).
[4] T. Ohnishi, K. Mitsuishi, K. Nishio, and K. Takada, Chem. Mater., 27, 1233 (2015).
[5] K. Okada, T. Ohnishi, K. Mitsuishi, and K. Takada, AIP Advances, 7, 115011 (2017).
High Temperature Solid Oxide Cells for Power-to-X applications: Status, Materials, Challenges and Prospects
Authors: Amaya-Dueñas Diana-María , Riegraf Matthias , Lang Michael , Riedel Marc , Heddrich Marc P. , Costa Rémi , Friedrich K. Andreas K 
Published: December 2020

In the context of the energy transition, all sectors have the need to achieve the CO2 reduction goals and to use renewable energy as basis of their activity. In particular, a corner stone is to radically transform the chemical industry by integrating highly efficient electrochemical processes based on renewable power. This is a possibility to decarbonize the synthesis of chemicals, which was one aspect of the Power-to-X concept.
Due to the fast kinetic at high temperature (~ 800°C), Solid Oxide Cells (SOC) enable not only efficient conversion of steam into Hydrogen, but also simultaneous electrolysis of H2O and CO2 to produce in one step syngas (H2 + CO), which is one of the main feedstock for the production of valuable chemicals, e.g. via methanol.
In this contribution we report on state-of-the-art electrolyte supported cells operated in H2O-CO2 co-electrolysis mode in a range of temperature between 770°C and 860°C with different steam/carbon ratios for syngas production.
The electrochemical behavior of these cells is presented and discussed with regards of the specific thermodynamic of CO2 reduction. Additionally, the thermodynamic boundaries for carbon deposition are shown in order to identify safe operating regimes for cells and SOC stacks [1]. In this regard also ten-layer stacks with electrolyte supported cells were tested for 2000 h in exothermic steam and co-electrolysis mode at elevated pressures of 1.4 and 8 bar. The predominant increase of the ohmic resistance during operation was identified to be mainly responsible for the observed degradation of all three stacks whereas the increase of the polarization resistances played a subordinate role. Within the post-test analysis noticeably high Nickel depletion was observed for the stack operated at the highest pressure in steam electrolysis mode. When operated at high conversion for long time, i.e. typically 1000 hours, it is shown that the fuel electrode is affected by significant irreversible morphological changes due to silicon species originating very likely from the feed water, highlighting the needs in purified stream in order to keep degradation rates sufficiently low to enable sufficient lifetime of the systems. The important contributions by Mogens Mogensen with regard to steam electrolysis, co-electrolysis and degradation phenomena will be acknowledged.
Aiming at enhancing durability and flexibility in SOC operation, we report as well on the potential use of an alternative perovskite electrocatalyst La0.65Sr0.3Cr0.85Ni0.15O3-δ (LSCrN) as fuel electrode for reversible operation in which performance in fuel cell steam electrolysis and co-electrolysis operating modes are evaluated.
[1] Amaya Dueñas D. M, Riedel M., Riegraf M., Costa R., Friedrich K. A. (2020) High Temperature Co-electrolysis for Power-to-X, Chemie Ingenieur Technik 2020, 92, No. 1–2, 45–52, doi: 10.1002/cite.201900119
Current Status of Solid Oxide Fuel Cell Technology Research and Development at National Energy Technology Laboratory
Authors: Hackett Gregory A , Abernathy Harry , Lee Shiwoo , Kalapos Thomas 
Published: December 2020

The DOE Office of Fossil Energy Solid Oxide Fuel Cell (SOFC) Program is interested in the near-term commercialization of high-temperature SOFC and solid oxide electrolyzer cell (SOEC) technologies that are robust, reliable, and resilient. A recent report delivered to the United States Congress highlighted several development recommendations including the design of pilot-scale units, continued early stage research and development, increased industrial engagement, and the exploration of reversible operation of SOFC technology.
The National Energy Technology Laboratory (NETL) SOFC research group currently addresses most of these recommendations. NETL’s in-house research efforts focus on the characterization, simulation, and mitigation of high temperature degradation of fuel cell components. The capstone of these efforts is NETL’s SOFC degradation modeling framework, which uses NETL supercomputing facilities to simulate SOFC performance degradation of thousands of possible electrode configurations experiencing multiple simultaneous degradation modes under a broad array of relevant operating conditions. The models for the different degradation modes are based upon experimental data (1) generated in-house, (2) referenced from available scientific publications, and (3) shared from collaborations with other industrial, academic, and national laboratory partners within the SOFC Program. The team then employs techniques in data analytics to select optimal electrodes to maximize the SOFC performance for given operating conditions. These modeling efforts guide electrode engineering efforts in-house and through external collaborations by identifying (1) which degradation modes contribute the most to overall performance degradation for given operating conditions and (2) which electrode features will have the greatest impact on lowering cell degradation and system costs. Additionally, the development on non-invasive in situ high temperature fiber optic sensors for temperature and gas composition measurement provides valuable data for inclusion in degradation models as well as informing technology development at the commercial scale. Finally, the wealth of experience gained in development degradation models and materials for reducing the cost of SOFC technology is being readily applied to reducing the cost of SOEC technology.
NETL will report on its most recent progress in the field of SOFC and SOEC development, including degradation modeling, in situ fiber optic sensor development, electrode engineering, and relevant systems-level analyses.
Multi-Layer Processed 50×50mm2 Cathode-Supported Thin-Film Proton Conducting Electrolysis Cells Via Inverse Tape Casting
Authors: Kwati Leonard , Ivanova Mariya E. , Deibert Wendelin , Meulenberg Wilhelm A. , Ishiraha Tatsumi , Matsumoto Hiroshige 
Published: December 2020

Despite progress made with small scale laboratory type solid oxide proton-conducting electrolysis cells in recent years, a significant challenge has been upscaling robust and affordable planar type devices. The fabrication of such multilayered devices, usually via a tape casting process requires careful control of shrinkages of individual layers to prevent warping and cracks during sintering. In the present contribution, 5 × 5 cm2 planar cathode-supported protonic electrolysis half-cell consisting of Ba(Zr0.5Ce0.4)8/9Y0.2O2.9 electrolyte, NiO-SrZr0.5Ce0.4Y0.1O3-δ cathode functional layer and NiO-Ba(Zr0.5Ce0.4)8/9Y0.2O2.9 substrate were successfully processed using an inverse tape casting route. The sintering parameters of the half-cells were analyzed and adjusted to obtain defect-free half-cells with diminished warping. The smooth tri-layered green tapes produced yielded suitably dense and gas-tight electrolyte layers after co-sintering at 1350 ºC/5h. The low sintering behavior of the green tapes, as well as the obtained final microstructure, are direct results of careful control over some casting parameters. For example, slurry viscosities, thicknesses of individual layers, temperature, and time scheme for firing. Current-voltage characteristics and hydrogen evolution rates measured in the temperature range 500-600°C, using Ba0.5La0.5CoO3−δ as the anode, demonstrate excellent performance and durability. Cross-sectional view of the polished layered structured BZCY(54)8/92 complete cell post cell characterization were also analyzed. Preliminary results revealed well-adhered layers and delamination free even after steam electrolysis testing.
Acknowledgments
This work was supported by the JSPS Core-to-Core Program of Advanced Research Networks (Solid Oxide Interfaces for Faster Ion Transport), the Ministry of Economy, Trade, and Industry (METI), Grants-in-Aid for Scientific Research (KAKENHI), DAICHI and by the International Institute for Carbon-Neutral Energy Research (I2CNER) sponsored by the World Premier International Research Center Initiative (WPI), MEXT Japan.
Numerical Simulation of OXIDE-ION Blocking Effect in Hydrogen Permeable Metal-Supported Fuel Cell
Authors: Jeong SeongWoo , Aoki Yoshitaka , Habazaki Hiroki 
Published: December 2020

Protonic ceramic fuel cells (PCFCs) have been drawing considerable attentions because of their potential for high-power operating at intermediate temperature (IT), 400–600°C, which is a salient issue for their practical implementation. BaZr0.1Ce0.7Y0.2O3, popular proton-conducting ceramic electrolyte material, has notably high conductivity of 9 × 10−3 S cm−1 at 500°C [1], but vast majority of power outputs in current PCFC literature still lag far behind 1.0 W cm−2 at the IT regime. In general, PCFCs have structure of porous anode support composed proton-conducting ceramic electrolyte and metallic Ni. Meanwhile, a hydrogen membrane fuel cell (HMFC), which consist of a dense hydrogen-permeable metal anode and kindred electrolyte material, has achieved extraordinary performances of 1.4 W cm−2 at 600°C [2]. This is higher than any others ever reported to the best of our knowledge. However, what give rise to such high performance is obscure. Here, we simulated effect of oxide-ion blocking at anode/electrolyte on defect profile in HMFC and compared them with those of PCFCs to elucidate origins of the high performance.
The one-dimensional concentration profiles of three charged defect carriers: oxygen vacancy, proton, and oxygen hole at steady state were computed based on Nernst–Planck–Poisson model with defect thermodynamics of BaZr0.8Y0.2O3 [3]. In PCFC, membrane is equilibrated with O2, H2, and H2O gases. In HMFC, however, boundary conditions at the anodic surface are unknown since the surface is sealed by dense metal anode. We made an assumption that a flux of oxygen vacancy is kept at 0 inside the electrolyte membrane of HMFC [4].
Simulations confirm that oxide-ion blocking at an electrolyte/anode interface greatly modifies the defects’ distribution across the membrane. Positively charged oxygen vacancies are depressed near electrolyte/anode interface owing to the oxide-ion blocking, and thus, protonic defects are alternatively accumulated near the regions for the charge neutrality preservation, which results in the enhancement of local proton conductivity (Attached image). Accordingly, the superior performance of HMFC to PCFC is attributable the proton pumping by utilizing the oxygen chemical potentials.
References
[1] C. Zuo et al., Ba(Zr0.1Ce0.7Y0.2)O3 as an electrolyte for low-temperature solid-oxide fuel cells, Adv. Mater. 2006, 18, 3318.
[2] N. Ito et al., New intermediate temperature fuel cell with ultra-thin proton conductor electrolyte, J. Power Sources 2005, 152, 200.
[3] H. Zhu et al., Defect incorporation and transport within dense BaZr0.8Y0.2O3−
d
proton-conducting membrane, J. Electrochem. Soc. 2018, 165, F581.
[4] S. Jeong et al., Proton Pumping Boosts Energy Conversion in Hydrogen-Permeable Metal-Supported Protonic Fuel Cells, ACS Appl. Energy Mater. 2020, 3, 1222

Figure 1
Development of Protonic Ceramic Fuel Cells Using Yb-Doped BaZrO3 Electrolytes
Authors: Kuroha Tomohiro 
Published: December 2020

Acceptor-doped barium zirconate was used as the electrolyte material because it has CO2 stability. Previous studies have shown that yttrium-doped barium zirconate (BZY) has the highest proton conductivity. However, cells using BZY crack in the conventional ceramic tape-casting and firing process used to fabricate laminated ceramic electronic devices. This is because the NiO used for the anode reacts with BZY to form BaY2NiO5.
The reactivity between the acceptor-doped barium zirconate and NiO was examined at the 1500 °C firing temperature. Ytterbium-doped barium zirconate (BZYb) did not form the complex oxide with NiO. Using BZYb revealed no problems such as cell cracking. In the cell using BZYb, the maximum power density at 700 °C and 600 °C were 0.70 Wcm-2 and 0.49 Wcm-2, respectively. Electrochemical impedance spectroscopy of the cell showed that the ohmic resistance was 0.28 Wcm2, approximately three times larger than the resistance value calculated using the bulk conductivity of BZYb and electrolyte thickness. It seems to be due to the solid solution of Ni in the electrolyte. To improve performance, techniques to prevent Ni solid solution diffusion are necessary.
Characterizing SOFC Stack Electrochemical Performance at Elevated Pressure
Authors: Cadigan Chris , Chmura Christopher , Jensen Søren Højgaard , Braun Robert J. , Sullivan Neal P 
Published: December 2020

In this report, we present our work to characterize the electrochemical performance of solid-oxide fuel cell stacks under elevated-pressure operation. The effort is part of a five-year U.S. DoE ARPA-E INTEGRATE program to combine the high efficiency of solid-oxide fuel cells with the low-cost of reciprocating engines to demonstrate an advanced hybrid electric generator. Within this hybrid system, solid-oxide fuel cells (SOFCs) convert natural gas into electricity. Unconverted fuel leaving the SOFC stacks feeds a downstream natural-gas reciprocating engine that drives an electric generator. In this architecture, the stacks are hydraulically placed upstream of the engine, necessitating stack operation at elevated pressures of 2-5 barg. SOFC stack performance at elevated pressure has witnessed limited study. The team at the Colorado School of Mines is characterizing SOFC stack performance at elevated pressure through design and commissioning of the pressurized stack electrochemical test stand shown in the figure.
Reactive gases are regulated using mass flow controllers to simulate the reformate stream produced by a natural gas fuel processor. Such a fuel processor will be incorporated into the stand at a later stage of the research program. Reactants flow through a preheat furnace and into a pressure vessel to reach the solid-oxide fuel cell stack. The pressure within this vessel is matched to the operating pressure of the SOFC stack, minimizing pressure differentials between the internal flow channels of the stack and the surrounding environment. Following electrochemical conversion, exhaust gases exit the stack and the pressure vessel, and are cooled through a series of heat exchangers. Back-pressure regulators near the end of the flow stream regulate stack and vessel operating pressure.
The stand has been used to explore the impacts of elevated pressure operation on the electrochemical performance and degradation of Ceres SteelCell stacks. Additional parameters being explored include the effects of fuel composition, anode recycle, and internal fuel reforming. In this talk, we will present preliminary findings on the effects of these variables on stack performance, and their impact in achieving the aggressive performance targets of the SOFC-engine hybrid electric generator.

Figure 1
Transition Metal Ions for Solid State Lighting and Optical Thermometry
Authors: Brik Mikhail G. , Srivastava Alok M , Beers William W , Cohen William 
Published: December 2020

Different transition metal ions with 3d unfilled shells are used for applications in solid state lasers and phosphors. Among the whole 3d group the ions with the 3d3 configuration are of particular importance, due to their specific energy level scheme, which can lead to three kinds of photoluminescence spectra: i) sharp spin-forbidden 2E→4A2 emission; ii) broad spin-allowed 4T2→4A2 emission; iii) coexistence of both these emissions.
In the present work we review recent progress in the development of crystalline materials doped with the Mn4+ and Cr3+ ions.
The Mn4+ ions-doped hosts exhibit only sharp emission spectra in the range from 620 nm to ~700 nm, depending on the host [1]. The phosphors with emission between 620 nm and 650 nm (such as K2SiF6, Na2SiF6 etc) are suitable for applications in white LEDs to produce warm white light. The phosphors emitting at longer wave lengths (e.g. double perovskites Ba2LaNbO6, La2LiSbO6 etc) are used for applications in white LEDs for agriculture, to enhance plant growth [2].
In addition to several examples of tuning emission peak position by chemical composition, an important issue of dependence of the emission intensity on the local symmetry will be discussed in detail.
The Cr3+ ions can produce all three above-mentioned spectra, depending on the host material. For example, in ZnAl2O4 and MgAl2O4 sharp Cr3+ red 2E→4A2 emission transition is peaked at around 685 nm [3], whereas in LaSc3(BO3)4 and (Ce,Gd)Sc3(BO3)4 crystals broad infrared Cr3+ 4T2→4A2 emission band is centered at 960 nm and 1100 nm, respectively [4, 5].
An interplay of the strong and weak crystal field effects can produce redistribution of relative intensities of both 2E→4A2 and 4T2→4A2 emission transitions in the Cr3+-bearing phosphors. With increased temperature, the crystal field strength is decreased and the infrared 4T2→4A2 emission gains intensity. Ratio of intensities of these two transitions can be used for non-contact temperature measurements [6, 7]. Another potential application of such systems is pressure sensing. These examples justify recently renewed interest to the Cr3+ and Mn4+ ions.
References:
[1] M.G. Brik, A.M. Srivastava, J. Lumin. 133 (2013) 69-72.
[2] A.M. Srivastava, M.G. Brik, H.A. Comanzo, W.W. Beers, W.E. Cohen, T. Pocock, ECS J. Sol. State Sci. & Technol. 7 (2018) R3158-R3162.
[3] M.G. Brik, J. Papan, D.J. Jovanović, M.D. Dramićanin, J. Lumin. 177 (2016) 145-151.
[4] X.F. Long, G.F. Wang, T.P.J. Han, J. Cryst. Growth 249 (2003) 191-194.
[5] M.G. Brik, V.A. Lebedev, E.V. Stroganova, J. Phys. Chem. Solids 68 (2007) 1796-1804.
[6] J. Ueda, M. Back, M. G. Brik, Y. X. Zhuang, M. Grinberg, S. Tanabe, Opt. Mater. 85 (2018) 510-516.
[7] M. Back, J. Ueda, M. G. Brik, T. Lesniewski, M. Grinberg, S. Tanabe, ACS Appl. Mater. Inter. 10 (2018) 41512-41524.
Ultraviolet Light-Emitting Diodes Using Aluminium Indium Nitride Nanowire Structures
Authors: Velpula Ravi Teja , Jain Barsha , Bui Ha Quoc Thang , Nguyen Hieu Pham Trung 
Published: December 2020

Ultraviolet (UV) light-emitting diodes (LEDs) have various applications in the field of biochemistry, medicine, water/air purification, etc. To achieve efficient UV LEDs, researchers have essentially focused on the use of AlGaN alloys in the active region. However, the practical applications of AlGaN based UV LEDs are severely limited due to poor external quantum efficiency (EQE). Some reasons behind the low EQE in AlGaN based UV LEDs are efficiency droop, mostly due to electron leakage into the p-region, poor light extraction efficiency (LEE) which is mainly due to the total internal reflection and the absorption of UV light in the p-GaN contact layer. Identifying and developing the potential of alternative UV materials will be critical to make further progress in the development of deep UV emitters. In this regard, AlxIn1-xN alloy has not been widely studied even though it holds great potential applications in UV and visible light-emitting devices [1]. In this study, we have performed the epitaxial growth, electrical and optical properties of spontaneously grown AlInN nanowires on Si (111) substrate by molecular beam epitaxy (MBE) and demonstrated a high crystalline quality of AlInN nanowire LED structures with stable and strong EL emission at ~299 nm peak wavelength.
The AlInN nanowire LED structure, shown in Fig. 1(a), was spontaneously grown on n-Si (111) substrates under nitrogen rich conditions by a Veeco GEN II MBE system equipped with a RF plasma-assisted nitrogen source. The growth conditions for GaN nanowire segments include a growth temperature of ~ 770 °C, nitrogen flow rate of 1 sccm, and forward plasma power of ~ 400 W. The device active region consists of ~ 100 nm n-Al0.78In0.22N, 40 nm undoped Al0.75In0.25N well and 100 nm p-Al0.78In0.22N layers. Growth temperature of the active region was at ~ 670 ̶ 700 °C to increase the In incorporation in AlInN segments and the nitrogen flow rate was kept at 2.5 sccm, while the plasma power was fixed at 400 W. After being grown by MBE, the nanowire LED samples were fabricated using standard lithography method as reported elsewhere [2]. The device characterization was performed on LED with an area size of 500×500 µm2. Photoluminescence (PL) spectrum of the grown nanowire LEDs exhibits strong emission in the UV wavelength range as shown in Fig. 1(b). The peak emission at ~ 299 nm and ~ 280 nm is responsible for the emission from the AlInN quantum well and barriers, respectively. The AlInN nanowire UV LEDs have strong EL intensity with the peak wavelength at ~ 299 nm, as shown in Fig. 1(c). This work is being developed toward the achievement of high power AlInN nanowire UV LEDs, and the result will be presented.

Reference

R. T. Velpula, B. Jain, M. R. Philip et al., Sci. Rep., 10(1) 1-10 (2020).

R. T. Velpula, B. Jain, H. Q. T. Bui et al., Optical Materials Express, 10(2) 472-483 (2020)

Figure 1