bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
(Invited) Compositionally Engineered Ceria-Nickelate Composite Electrodes as Oxygen Electrodes in SOFCs and SOECs
Authors: Banner Jane , Akhtar Ayesha , Gopalan Srikanth
Published: December 2020

Composite electrodes comprising a rare-earth nickelate phase and a doped rare-earth ceria phase with a high level of rare-earth doping have been studied as oxygen electrodes. While rare-earth nickelates have shown great promise as oxygen electrodes in both solid oxide fuel cells (SOFC) and solid oxide electrolysis cells (SOECs), they become unstable in contact with rare-earth doped ceria. In this work we describe a strategy to eliminate this instability and enable the use of these electrodes as stable high performance oxygen electrodes in both SOFC and SOEC applications. The performance of such composite electrodes is explored using a symmetrical cell approach, and through the electrical conductivity relaxation (ECR) method and compare it to state-of-the-art oxygen electrodes comprising strontium doped lanthanum manganite (LSM) – yttria stabilized zirconia (YSZ) composite electrodes. The symmetrical cell tests which reveal the stabilized nickelate-ceria electrodes to be superior, are also well-correlated with the results of testing complete cells in both SOFC and SOEC modes. Based on these results we make the case for deploying these stabilized nickelate-ceria composite electrodes as oxygen electrodes in reversible SOFC-SOEC systems.
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.
Chromium Tolerant, Highly Active and Stable Electrocatalytic Internal Surface Coating for Cathode of Commercial SOFCs
Authors: Song Xueyan , Chen Yun
Published: December 2020

Intermediate temperature solid oxide fuel cells (IT-SOFCs) employing chromium-forming alloy interconnect requires the development of cathode not only with high electrochemical activity but also with the high resistance or tolerance towards Cr deposition and poisoning. In this work, the nanostructure origin of the performance degradation of the LSM/YSZ cells induced by Cr contamination was investigated. Meanwhile, we developed a surface coating layer on the commercial SOFC LSM/YSZ cathode backbone using atomic layer deposition. The ALD coating dramatically increases cell power density by 250 %. Meanwhile, upon cell operation in the high Cr environment, the LSM/YSZ cathode with ALD coating shows significant improvement of its resistance towards Cr poisoning. The degradation rate of the cell is reduced to 0.054 V per 1000 h, in comparing that of 1.68 V per 1000 h for the baseline cell.
Quantifying the Kinetics of Electron Transfer on Commercial Porous Carbon Electrodes
Authors: Chen Qing , Yang Shida
Published: December 2020

Commercial porous carbon electrodes (e.g. carbon paper and felt) remain indispensable parts in redox flow batteries. The three-dimensional porous structures provide ample sites for electrochemical reactions and permeable paths for electrolyte flow. On the other hand, the structures raise a great challenge in quantifying the kinetics of electrochemical reactions, a key task in engineering both the electrodes and the electrolyte for high power. Classic simulation of cyclic voltammetry (CV) does not apply to these electrodes, whereas electrochemical impedance spectroscopy requires knowledge and assumptions of the pore geometry to allow the derivation of the rate constants. We tackle this challenge via two approaches. The first approach reduces the dimensionality of the electrodes by filing the pores with epoxy. Exposing a cross-section of the epoxy-filled electrode allows us to characterize it as a planar electrode. The second approach removes all the active-material containing electrolyte outside the pores to achieve diffusion-less thin-layer electrochemistry in the pores with slow scans of CV. The simulation of the two types of CV curves gives account for the kinetics of electron transfer of common redox couples including ferri/ferrocyanide, ferric/ferrious ions, and V4+/5+.
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.
Monte-Carlo Modeling of Plasmon-Mediated Ion-Ion Energy Transfer
Authors: Collins John , Sundstrom Nicholas , Mishra Kailash C
Published: December 2020

Energy transfer between donor and acceptor ions is an important phenomenon in phosphor applications. In a quantum electrodynamic formulation of the energy transfer process, the donor-acceptor interaction is mediated by photons. In the presence of a metal, however, donor-acceptor interactions may also be mediated by surface plasmons. For donor-acceptor pairs near a smooth planar metallic surface, the probability of surface plasmon-mediated transfer has been estimated, and depends on both the donor-acceptor distance and the distance of each ion from the metallic surface. With the goal of designing an experiment to directly observe surface plasmon-mediated energy transfer, we simulated plasmon-mediated energy transfer in a solid using Monte Carlo methods. Using MatLab, we constructed a solid doped with randomly placed acceptors and donors, simulated the energy transfer process, and plotted the donor decay curves. We show that the plasmon-mediated transfer rate can be comparable to the radiative decay rate, and that the shape of the donor decay curves in plasmon-mediated transfer differs greatly from those resulting from Foerster-Dexter energy transfer. Thus, for a well-designed experiment, it should be possible to unambiguously identify the role of surface plasmons in the energy transfer process.
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
Band Gap Engineering in Luminescence Thermometry – Pros and Cons
Authors: Sójka Małgorzata , Bolek Paulina , Kulesza Dagmara , Brites Carlos Delgado Sousa , Zeler Justyna , Jedoń Joanna , Carlos Luís D , Zych Eugeniusz
Published: December 2020

Luminescence thermometry and 2D imaging using luminescence thermometric phosphors are of growing interest as these non-contact and non-invasive techniques may offer important advantages in some applications. The requirements such thermometers have to fulfill depend on considered use. It is obvious that bio and medical applications points on different parameters than measurements in cryo-range and measuring high temperatures point on yet different needs. Nevertheless, high-sensitivity and low inaccuracy are always appreciated, as well as chemical stability in conditions the thermometers are to be used.

One of the limitations of known luminescence thermometers is their limited range of temperatures they may measure. Obviously, some applications do not need a broad range of thermometer usability. On the other hand, presenting a good performance over a wide range of temperatures would give a versatile “all-purpose” thermometer. This might open a door for truly broad usage of such a phosphor.

Trying to deliberately manage the performance of luminescence thermometers for a broad-range and accurate temperature measuring we paid attention to the bandgap engineering as a tool to achieve this goal. In this presentation, we shall focus on Lu2(Ge,Si)O5:Pr and Y3(Al,Ga)5O12:Pr powders with different Ge:Si and Al:Ga ratios, respectively. We shall discuss the advantages of bandgap engineering in luminescence thermometry and will point to possible complications this may cause. Among others, we shall show that managing the bandgap cause at the same time changes in phonons energies and these affect radiative and non-radiative processes, so important when luminescence over a broad range of temperatures is considered. Last but not least, a side effect of bandgap engineering is the change of the phosphor refractive index, also an important parameter for luminescence properties.

This research was supported by the Polish National Science Centre (NCN) upon the grants #UMO-2017/25/B/ST5/00824 and UMO-2018/29/B/ST5/00420 and the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by Portuguese funds through the Portuguese Foundation for Science and Technology (FCT)/MCTES. Financial support from FCT (PTDC/CTM-NAN/4647/2014, NANOHEATCONTROL - POCI-01-0145-FEDER-031469) is also acknowledged. E. Z. and L. D. C. are grateful to the Polish National Agency for Academic Exchange (NAWA) for support under the NAWA-Bekker #PPN/BEK/2018/1/00333/DEC/1 and NAWA-Ulam #PPN/ULM/2019/1/00077/U/00001 projects, respectively.

Figure 1
(Keynote) Enzymatic Bioelectrocatalysis for Electrosynthesis
Authors: Minteer Shelley D.
Published: December 2020

Electrosynthesis of commodity and fine chemicals is an emerging area. Bioelectrocatalysis has only recently been considered for this application. This talk will discuss the advantages of bioelectrocatalysis for electrosynthesis with examples ranging from ammonia production to pharmaceutical products and intermediates. In the last 5 years, there have been extensive studies and new materials designed for catalytic reduction of nitrogen to ammonia. This is a challenging reductive transformation for traditional electrocatalysts and photocatalysts, but nature can provide an inspiration. Nitrogenase is the only enzyme known to reduce nitrogen to ammonia. This talk will discuss electroanalytical techniques for studying nitrogenase electrochemistry, including both mediated bioelectrocatalysis and direct bioelectrocatalysis. Then, this talk will discuss electrode materials innovation for interfacing these complex proteins with electrode surfaces as well as using them for electrosynthesis of ammonia as well as other value-added products (i.e. chiral amines, chiral amino acids, etc.). Finally, this talk will discuss the use of enzyme cascades for enzymatic bioelectrosynthesis and synthetic biology for microbial bioelectrosynthesis of ammonia and other value-added products.
Study on Collided Ag or Pt Single Nanoparticle’s Current Peak Shape Changing Depending on Applying Potential
Authors: Kim Ki Jun , Kwon Seong Jung
Published: December 2020

Electrocatalytic amplification method was used for analyzing electrochemical properties about collided nanoparticles. Silver nanoparticles (Ag NPs) and platinum nanoparticles (Pt NPs)’s characteristics about hydrazine oxidation reaction were investigated. Those NPs have distinct electrocatalytic activation for hydrazine oxidation reaction. For detecting these NPs, gold (Au) ultramicroelectrode (UME) was used as working electrode which has appropriate catalytic activities comparing with both NPs. When applied potential was above 0 V, Pt NPs showed positive electrocatalytic characteristic, then collided Pt NPs produced amplified transient current signal. In contrast, Ag NPs produced decreased transient current signal when colliding onto Au UME applied above 0.25 V which potential range Ag NPs showed negative electrocatalytic characteristics. But the transient current signals by each collided NPs showed shape shifting as changing applied potential. When applying relatively low potential range, current signals produced by each NPs were staircase shape which means the collided NPs sustain stable state on Au UME after collision events. After changing high potential range, the current signals were shifting to blip or spike shape. As analyzing current peak shape changing phenomenon, electrocatalytic reaction mechanisms by each NPs could be understood by this method.
Sodium Stripping and Plating from Na-β"-Alumina Ceramics Beyond 1000mA/cm2
Authors: Landmann Daniel , Graeber Gustav , Heinz Meike , Battaglia Corsin
Published: December 2020

Dendrite formation limits the cycle life of lithium and sodium metal anodes and remains a major challenge for their integration into next-generation batteries, even when replacing the liquid electrolyte by a solid electrolyte. Recent studies have pointed out that lithium and sodium metal creep rather than lithium and sodium diffusion is the primary mechanism for replenishing the voids forming in solid metal anodes at the interface to a solid electrolyte upon stripping. Void formation upon stripping causes current constrictions upon plating, promoting dendrite formation. Here we investigate plating and stripping of liquid sodium metal from a ceramic Na-β"-alumina electrolyte at 250 °C, thereby eliminating mass transport limitations due to creep. Employing a porous carbon electrode coating to (1) prevent dewetting of plated liquid sodium from and (2) to supply liquid sodium upon stripping to the sodiophobic Na-β"-alumina surface, we demonstrate extremely high current densities above 1000 mA/cm2 and cumulative plated capacities of 10 Ah/cm2 without dendrite formation [1]. These values are two orders of magnitude larger than the corresponding values measured at room temperature [2]. We further show that liquid sodium occupies 60% of the porosity of the carbon coating, while excess sodium accumulates on top of the coating. Increasing the thickness of the carbon coating from 50 μm to 200 μm does not affect the Coulombic efficiency, but reduces the constant current rate capability due to the increased flow resistance for liquid sodium in the porous coating. Our results confirm that eliminating void formation is effective in suppressing dendrite formation.

[1] D. Landmann, G. Graeber, M. V. F. Heinz, C. Battaglia, Materials Today Energy, in press

[2] M.-C. Bay, M. Wang, R. Grissa, M. V. F. Heinz, J. Sakamoto, C. Battaglia, Adv. Energy Mater. 2019, 201902889
Improving Energy Storage and Ion Transport of Soft Nanostructured Complexes Using Regulated Crystallization
Authors: Chen Jihua
Published: December 2020

Electron and Ion transport systems often rely on a balanced hierarchical boundary structure that spans from millimetre to nanometer scales. Systematically varied polymers and organic crystals are used to fine-tune the growth of soft nanostructured complexes. (1-2) The underlying intermolecular interactions between crystallization mediator and small molecule crystals can lead to thin films of largely enhanced performance for charge transport and energy storage purposes. In this work, controlled solution deposition was used to self-assemble a number of novel organic capacitors and solid electrolyte systems based on semicrystalline polymers, whose capacitance and ion conductivity are examined as a function of the resultant nanostructures and regulated crystallization conditions. Electrochemical impedance measurements, equivalent circuit modelling, as well as Vogel-Tamman-Fulcher relations are performed in light of microscopy studies including low-dose TEM to provide insights on capacitance enhancement and ion transport mechanism.(3)

References:

1. J. Chen et al., Chem. Mater. 25 (21) 4378

2. S.Bi, J.Chen et al, J. Polym. Sci. B, 53 (20) 1450

3.This research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

(*** This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).)
High-Throughput Screening of Na-Ion Cathodes
Authors: McCalla Eric
Published: December 2020

In the search for better performing battery materials, high-throughput approaches have the potential to screen large composition spaces in a short period of time and thereby greatly accelerate the development of advanced materials. The challenges are numerous both in terms of synthesis which is often done at much smaller scale than in commercial settings (e.g. milligrams) and in terms of characterization. Herein, we develop high-throughput synthesis of Na-ion cathodes in the Na-Mn-Fe-O pseudo-ternary system. The sol-gel approach is adapted to high-throughput and shows that single-phase materials are made whereas co-precipitation does not yield sufficiently intimate mixing of the cations and phase separation occurs. The samples made by sol-gel are further characterized using both X-ray diffraction and cyclic voltammetry (both in high-throughput) and yield results that match up very well with those obtained by making bulk amounts of the samples. This demonstrates scale-up of the combinatorial results will be possible. Preliminary data on the entire Na-Mn-Fe-O pseudoternary system will be shown for the first time revealing the structure-property relations taking place in this important system. This work will serve as both a screening tool and also help guide future research in the design of Na-ion cathodes.
The Development of High-Throughput Methods in the Study of All-Solid Li-Electrolytes
Authors: Jonderian Antranik , McCalla Eric
Published: December 2020

High-throughput experimentation is a fast and efficient methodology for materials discovery, screening, and optimization. It has, therefore, garnered a lot of attention from battery researchers as a potential way to accelerate the development of next-generation Li-ion batteries and battery systems beyond Li-ion. However, its successful use in battery materials discovery has been extremely limited due to a variety of challenges including: (i) difficulties in synthesizing mg-scale samples that are comparable to bulk samples made by industrial methods, (ii) limited high-throughput characterization acting like a bottleneck even after high throughput synthesis is developed, and (iii) high cost of commercially available high-throughput instrumentation. Here, we develop high throughput techniques for solid-state electrolytes.

First, a novel synthesis approach is used to make 64 mg-scale solid electrolytes simultaneously. The powder samples are prepared by a citrate sol-gel method using an automated dispensing system. These powders were formulated into sixty-four pellets using a home-made high-throughput pellet press die. The samples are then sintered at high temperature to yield the solid electrolytes. The proof of concept here is performed on the Li-La-Ti-O pseudo-ternary system that includes the perovskites Li3xLa2/3-x‰1/3-2xTiO3, considered candidates for solid-state electrolytes for high energy lithium-ion batteries. Given that vacancies and other defects play an essential role in ionic conductivity, the screening of complete phase diagrams has the potential to reveal phases with optimized defect contents and thus yield improved solid electrolytes.

We have therefore developed a high-throughput characterization suite for solid electrolytes. First, we use a high throughput X-ray diffractometer capable of producing Rietveld quality patterns for mg-scale samples in 10 min such that 64 patterns can be obtained in under 12 h. This system is readily used to produce structural phase diagrams in ternary or even quaternary systems. Next, a high throughput electrochemical impedance spectrometer is used to map the ionic conductivities onto the phase diagrams. Finally, high throughput electrochemistry is used to determine the stability window of the electrolytes. All aspects of this workflow are demonstrated on the Li-La-Ti-O system. This now permits the synthesis and full characterization of approximately 192 compositions per week with one researcher only. This approach is well suited to determine the structure-property relations in complex composition spaces.

The complete ternary Li-La-Ti phase diagram synthesized at 1200 °C with slow cooling was determined and will presented in detail. The bulk and total conductivities of the phase diagram was mapped by electrochemical impedance spectroscopy. Quenching was performed to verify that transformations during slow cooling are moderate in this system. Consequences for the development of other solid electrolytes will also be discussed.
Self-Assembled Hybrid of Microwave-Exfoliated V2O5 Nanoribbons and Reduced Graphene Oxide Nanosheets As a Sustainable Electrode Material for Zinc Ion Batteries
Authors: Muthukumar Kamalambika , Ya Chen , Leban Levon A , Li Jun
Published: December 2020

Rechargeable aqueous zinc ion batteries are an emerging topic in the battery research due to its high volumetric capacity (5855 mAh/cm3), low cost, environmental friendliness and safety. But the development of the zinc ion batteries have been seriously hindered by the slow insertion/extraction kinetics of the multivalent Zn2+ ions in the host structure. Two-dimensional (2D) transition metal oxides are intensely studied for various energy storage applications such as batteries and supercapacitors but controlled synthesis and tunable nanoscale properties are still a challenge. Herein we present and discuss the self-assembly of a hybrid material of microwave-exfoliated Vanadium pentoxide (V2O5) nanoribbons (NRs) on graphene oxide (GO) nanosheets as a potential host for zinc ion storage. Vanadium pentoxide have several advantages such as high discharge capacity (294 mAhg-1) and large abundance but suffers from low electrical conductivity and poor stability. Using a thermal treatment, the GO template is converted to reduced graphene oxide (rGO) which improves the electrical conductivity of the hybrid. Multiple divalent cations such as Zn2+ and Mn2+ have been used in the self-assembly process to bind the negatively charged V2O5 NRs and GO nanosheets to improve the stability of the hybrid and accommodate the intercalation/deintercalation of the Zn2+ ions. Incorporation of 0.0357 M Mn2+ along with 0.10 M Zn2+ in the assembly process has been found to form a stoichiometric composition of Mn0.15Zn0.08V2O5 by XPS, which provides the high specific capacity of 295 mAh g-1 at 0.5 A g-1 and a high stability with the capacity retention of ~81.3% after 500 cycles at 4 A g-1.
Next Generation of Separator Coatings Beyond Ceramics for Fast Charging
Authors: Roumi Farshid , Liu Jingjing
Published: December 2020

High rates of charge or discharge generates extensive heat, which gets trapped inside the battery, creating hot spots and leading to premature failure when the battery is used for long periods of time. Today’s solutions to this problem involve coating the separator with an aluminum oxide, or alumina coating – which increases melting temperature and improves safety. This has been one of the major breakthroughs in the battery industry over the past several decades. However, ceramic-coated separators do not provide enough thermal performance needed for fast charging and high power applications specially in large cell where the heat dissipation is challenging.

To address that problem, stating 2012, we have been developing a new class of separators coating, carbon-based coating, that is comparable in cost to ceramic coated separator but has 10 times the thermal conductivity and is safer – increasing the separator melting temperature by 100 deg C. This enhanced thermal conductivity will remove more heat during cycling, reduces hot spots and results in cell temperatures as much as 11 deg C lower during operation. PCS’s ability to remove heat will result in longer cycle life for EV batteries. The increased thermal performance means that PCSTMis safer than ceramic-coated separators, but the more important difference is the x10 thermal conductivity, which means that PCSTMfacilitates heat removal from the center of the cell substantially more than other separators. The benefit is likely to be increased cycle life and higher rate capability.

Figure 1
Quantitative Analysis of Electrode Gaps in Prismatic Format Lithium-Ion Cells
Authors: Spray Ryan , Cai Zhuhua , Goodman Johanna
Published: December 2020

Inside a lithium-ion cell, many layers of positive and negative electrodes are separated by an electrolyte-soaked separator. The positive and negative electrodes are engineered to be parallel so that the current distribution is uniform between each set of electrodes. This uniform current density further leads to uniform and predictable operation of the cell. During manufacturing, gaps can be introduced between the electrode layers. This is especially prevalent in prismatic cells because the cell manufacturing process involves inserting the pliable cell windings into a rigid cell housing and applying vacuum during electrolyte filling. These electrode gaps lead to non-uniform current densities, resulting in adverse effects such as incomplete lithiation, electrolyte degradation and possibly lithium plating.

One method of non-destructively visualizing internal cell features is computed tomography (CT) scanning. Collecting data via this method is relatively fast with a typical cell scan takes ~1 hr and multiple cells being scanned at once. The output is commonly a set of 16-bit .tiff images that can be loaded and analyzed by a variety of software packages, with Volume Graphics Studio and Avizo being two common programs. These programs can be used to make a variety of measurements on individual datasets, but they lack the ability to conduct high-throughput analysis of many datasets.

In this work, we have collected computed tomography data on prismatic cells cycled at a series of temperatures throughout their cycle life of up to 500 cycles. This data is analyzed for electrode gap features using a python code written to extract the number of gaps, gap locations, and gap volume for each dataset. This data is then aggregated for all datasets and analyzed for macroscopic trends. One finding from the study is that cells cycled at lower temperatures showed less expansion/contraction because of kinetics and less capacity passed overall, while cells cycled at higher temperatures showed increased gap volume due to material growth between layers. Additional findings and opportunities for future work will be presented.

Image upload:

Horizontal mapping of gap locations in individual cells from the three different temperature groups, where the size of the bubble correlates to the size of the gap. (0 Cycles: yellow, 100 & 200 cycles: blue, 500 cycles: purple)

Figure 1