bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Growth Parameters on Optical and Electrical Properties of Nanostructured Ceria Thin Films Obtained By Spray Pyrolysis
Authors: García Sánchez Mario Fidel , Malagón García José Francisco , Romero Ibarra Issis Claudette , Santana Rodriguez Guillermo 
Published: February 2020

Recently, it has been demonstrated that nanostructured materials increase the transport properties of oxides used as electrolytes in solid oxide fuel cells (SOFC) [1-2]. However, the physical basis of this phenomenon it is not fully understood yet [3,4]. In thin films, electrical properties depend on the technique used and the growth conditions. In this work, nanostructured ceria thin films have been prepared by ultrasonic spray pyrolysis using cerium acetylacetonate as metallo-organic precursor dissolved in anhydrous methanol. The influence of flow rate and substrate temperature in the structural, optical and electrical properties of films was studied. The morphology, structure, optical and electrical properties were studied using scanning electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and impedance spectroscopy (IS). The influence of thermal annealing at 900 ºC on the structural properties of films was studied. The substrate temperature were optimized for obtaining smooth, dense, uniform and homogeneous nanocrystalline films with grains sizes smaller than 20 nm. The flow rate modified the morphology and the grain size of prepared films. By XPS were demonstrated the presence of Ce3+, even in treated films. The Ce3+ concentration do not depend on the grown temperature. The different signals observed in PL after the thermal annealing are associated to the presence of defects induced by levels in the band gap created by the Ce3+ atoms. The low values of total conductivity and activation energy measured by IS are related to the nanometric grain size.
The authors acknowledge financial support for this work from IPN with projects 20181399 and 20181907; CONACyT under project PN 1373 and “Red Temática de Almacenamiento”; and SECITI 095-2017.
References

M. F. García-Sánchez, J. Peña, A. Ortiz, G. Santana, J. Fandiño, F. Cruz, Solid State Ionics, 179 (2008) 243.

M. F. García-Sánchez, A. Ortiz, G. Santana, M. Bizarro, F. Cruz Gandarilla, M. A. Aguilar-Frutis, J. C. Alonso, J. Am. Ceram. Soc. 93 (2010) 155.

J. L. M. Rupp Solid State Ionics 207 (2012) 1.

A. Benítez-Rico, M. F. García-Sánchez, M. Picquart, B.M. Monroy-Peláez, G. Santana-Rodríguez, J. Nanomaterials 2015 (2015) 692648.
Advancements in Performance and Durability of Metal-Supported Solid Oxide Fuel Cells
Authors: Dogdibegovic Emir , Wang Ruofan , Lau Grace , Byrne Conor , Tucker Michael C 
Published: February 2020

Metal-supported solid oxide fuel cells (MS-SOFC) display a number of advantages over conventional all-ceramic SOFCs, including low-cost structural materials (e.g. stainless steel), mechanical ruggedness, excellent tolerance to redox cycling, and extremely fast start-up capability. These properties make MS-SOFCs ideally suited for range extenders in vehicles due to tolerance to thermal fluctuations following load changes or intermittent fuel flow. Directly fueled with ethanol or ethanol-water mixture, MS-SOFCs provide promising alternative for mobile applications.
In this talk, the recent progress on performance and durability of symmetric MS-SOFCs, pioneered at LBNL, will be addressed. The development of new electrolyte, new cathode and anode catalysts, optimized cell configuration, and processing techniques will be discussed. The catalyst infiltration technique allows for flexible and layered electrode composition, depending on the system applications and fuels. Our current state-of-the-art MS-SOFCs achieve power density of ≥1.5 W/cm2 at 700 °C and ≥2.85 W/cm2 at 800 °C when fueled with humidified hydrogen which is, to the best of our knowledge, the highest performance reported in the literature for stainless steel MS-SOFCs. However, catalyst coarsening and Cr deposition from the stainless steel metal support are known to occur1, and the primary degradation mechanisms are elucidated and tackled to improve the durability. The cell area specific resistance (ASR) of <0.144 W∙cm2 at 700 °C meets the projected requirements for commercialization in vehicles. Initial studies on button cells fueled with ethanol/water mixture are investigated and further efforts towards increasing power density and durability are addressed.

1M.C. Tucker, Journal of Power Sources, 369, 6-12, Nov. 2017.
Acknowledgments
The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency – Energy (ARPA-E), U.S. Department of Energy under work authorization number 13/CJ000/04/03. This work was funded in part by the U.S. Department of Energy under contract no. DE-AC02-05CH11231.

Figure 1.
(a) Illustration of a symmetric MS-SOFC configuration developed at LBNL, and (b) the highest cell performance obtained so far on the stainless steel MS-SOFCs.

Figure 1
Pr3+ Luminescence to Improve the Range, Accuracy and Sensitivity of Temperature Measurement
Authors: Brites Carlos Delgado Sousa , Fiaczyk Karolina , Ramalho Joao Filipe Candeias Baptista , Sójka Małgorzata , Carlos Luís D , Zych Eugeniusz 
Published: February 2020

For years, various contact techniques were used to measure temperature. Development of novel and evolving technologies raised the interest in elaboration of non-contact thermometry. Nowadays, this is radiation pyrometry which is the method of choice for such purposes. Yet, it has important limitations – sensitivity to stray light or reflected radiation as well as sensitivity to flame interferences. Also accuracy of temperature measurement, which is not better than ~2 K, is not always satisfactory. Today technologies do not fulfill the needs of temperature sensing in microelectronics, microoptics, photonics, microfluidics, nanomedicine and they require alternative solutions.
Among promising approaches, overcoming the limitations of other techniques, luminescent methods are of great interest. While the idea is not new [1], a real breakthrough using this technique was not yet achieved. Combining a high sensitivity and accuracy as well as broad range of temperature usability within one temperature sensor appeared challenging [2,3].
In this presentation we shall prove that Pr3+ luminescence characteristics may offer a lot in this field. While in some compositions this ion generates only 4f®4f luminescence due to relaxation of the higher 3P0 and lower 1D2 levels, in some others also 5d®4f luminescence may take place. We explored the possibility to use all these three luminescent components to sense the temperature accurately and in a broad range. The main argument for that is that all the three emissions are characterized by different mechanisms of their thermal quenching. Furthermore, temperature strongly affects the non-radiative relaxation between the three levels. Our presentation will show first results of the approach presented above using data for Sr2GeO4:Pr and will prove a validity and potential of this new attitude. Figure 1 presents profound changes in emission spectra of Sr2GeO4:Pr in the range of 17-600 K.
[1] P. Neubert, US2085508 A, 1937.
[2] L. D. Carlos, F. Palacio, Thermometry at the Nanoscale: Techniques and Selected Applications, Royal Society of Chemistry, Oxfordshire 2016.
[3] C. D. S. Brites, P. P. Lima, N. J. O. Silva, A. Millán, V. S. Amaral, F. Palacio, L. D. Carlos, Nanoscale 2012, 4, 4799.

Figure 1
Fabrication and Phase Transition of La2-X
Lu
x
Zr2O7 Transparent Ceramics
Authors: Wang Shiwei , Wang Zhengjuan , Zhou Guohong 
Published: February 2020

Materials with A2B2O7 formula have been drawing the attention of researchers for a diversity of applications, such as fast-ion conductors, photocatalysts, thermal barrier coatings, matrices for immobilization of highly active radionuclides from nuclear wastes and host materials for scintillators. A2B2O7 materials have three crystal phases decided by the ionic radius ratios (r
A/r
B). According to the rule of Subramanian et al
[1], pyrochlore phase was favored when r
A/r
B lay within the range of 1.46~1.78. Defective fluorite phase is stable for r
A/r
B < 1.46, whilst the monoclinic phase is stable for r
A/r
B > 1.78. In this study, a new series of La2-x
Lu
x
Zr2O7 (x = 0~2.0) transparent ceramics [2] with high density and average atomic number, which are hoped to be scintillator matrix, were fabricated by vacuum sintering and an interesting phenomenon was found. As Lu content increased, the crystal phase gradually transformed from pyrochlore to defective fluorite phase with the existence of a two-phase region (x = 0.6 ~ 1.2) (Figure 1). The appearance of a two-phase region illustrated that Subramanian’s theory is not available when there is large difference in ionic radii of the elements that occupy at Ln position (r
La
3+ = 1.160 Å, r
Lu
3+ = 0.977 Å). In addition, the grain growth of pyrochlore phase was inhibited due to the appearance of defective fluorite phase. Grain sizes of samples dominated by pyrochlore phase were 11~14 μm. Samples with two phases (x = 0.6~1.2) have much smaller grain sizes (< 3 μm), while samples dominated by defective fluorite phase have larger grain sizes (82~60 μm). All the samples (except for x = 0) are transparent and the highest in-line transmittance is reached to 72.4% (1100 nm) at x = 1.2 though two phases coexist. To verify that the two-phase region was not an accident, we fabricated LaLuZr2O7 powder by combustion method instead of solid state reaction and sintered in the same way. From XRD results, two phases are observed in both the synthesized powder and ceramic. Also, With 2 ~ 3 μm average grain size, the LaLuZr2O7 ceramic reaches high transparency with an in-line transmittance of 73.4% at 1100 nm, which is slightly higher than that made by solid state reaction method, showing the advantage of combustion method in synthesizing good powder. Rayleigh-Gans-Debye scattering theory was used to explain the high transmittance of the ceramics with two phases. When the refractive indices of the coexisting two phases are close to each other and the average grain size is smaller than 10 μm, the two phases have little influence on transparency of the ceramics.
[1] Subramanian MA, Aravamudan G, Subba Rao GV. Oxide pyrochlores-A review. Prog Solid State Chem 1983, 15: 55-143.
[2] Z.J. Wang, G.H. Zhou, X.P. Qin, F. Zhang, J.P. Ai, P. Liu, S.W. Wang. Fabrication and phase transition of La2-xLuxZr2O7 transparent ceramics. J Eur Ceram soc 2014, 34: 3951–3958.

Figure 1
Interfacial Stability of Argyrodite-Based Solid Electrolytes in All-Solid-State Batteries
Authors: Strauss Florian , Bartsch Timo , Kim A-Young , Janek Jürgen , Hartmann Pascal , Brezesinski Torsten 
Published: February 2020

All-solid-state batteries (ASSBs) are currently attracting much attention as next generation energy storage systems, with potentially both higher energy and power densities than state-of-the-art lithium-ion batteries (LIBs). The latter may be realized by combining layered Ni-rich oxide cathode materials such as Li1+x
(Ni1
–

y

–

z
Co
y
Mn
z
)1
–

x
O2 (NCM) and thiophosphate-based solid electrolytes (SEs). As for SEs, in particular argyrodites, Li6PS5X (X = Cl, Br), show great promise since they exhibit sufficient Li-ion conductivity (~2 mS/cm) and because of the simplicity of preparation.1 However, their practical implementation is hindered by poor electrochemical stability at the interface, in particular with positive electrode materials.2,3 In order to pave the way for rational interface design, processes occurring between cathode and electrolyte need to be better understood. Following these guiding principles, we herein report our recent efforts in implementing various in situ and ex situ techniques (X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, differential electrochemical mass spectrometry etc.) to gain mechanistic insight into interfacial SE degradation when in direct contact with NCM622 (60% Ni). We reveal the potential resolved formation of degradation products, which are found to be responsible in part for irreversible capacities and performance decay of ASSB cells. However, we also demonstrate that by using protective oxide coatings such as LiNbO3, these detrimental side reactions can be suppressed to a large extent. In summary, we reveal the importance of developing in situ characterization techniques in the area of ASSBs and provide valuable insight into the cathode/SE interfacial chemistry.
References:
[1] Bachman, J. C.; Muy, S.; Grimaud, A.; Chang, H.-H.; Pour, N.; Lux, S. F.; Paschos, O.; Maglia, F.; Lupart, S.; Lamp, P.; et al. Inorganic Solid-State Electrolytes for Lithium Batteries: Mechanisms and Properties Governing Ion Conduction. Chem. Rev.
2016, 116 (1), 140–162.
[2] Richards, W. D.; Miara, L. J.; Wang, Y.; Kim, J. C.; Ceder, G. Interface Stability in Solid-State Batteries. Chem. Mater.
2016, 28 (1), 266–273.
[3] Auvergniot, J.; Cassel, A.; Ledeuil, J.-B.; Viallet, V.; Seznec, V.; Dedryvère, R. Interface Stability of Argyrodite Li6PS5Cl toward LiCoO2, LiNi1/3Co1/3Mn1/3O2 , and LiMn2O4 in Bulk All-Solid-State Batteries. Chem. Mater.
2017, 29 (9), 3883–3890.
Impact of Cathode Material Particle Size and Applied Pressure on the Cycling Performance of All-Solid-State Batteries
Authors: Bartsch Timo , Strauss Florian , Kim A-Young , Janek Jürgen , Hartmann Pascal , Brezesinski Torsten 
Published: February 2020

All-solid-state batteries (ASSBs) containing solid electrolytes (SEs) are considered promising for use as next-generation energy storage devices in electric vehicles and portable electronics. Apart from safety benefits, in principle, they offer both higher energy and power densities than conventional lithium-ion batteries (LIBs) using a liquid carbonate-based electrolyte. However, ASSBs will only become competitive in the near future if some major problems are solved. These concern mainly technical functionality aspects, SE conductivity, and the stability of the electrode-solid electrolyte interface. The latter is not only crucial in terms of enabling the use of a Li-metal anode, but also at the cathode side, where a stable and robust contact between the SE and the cathode active material (CAM) is vital for long-term cycling performance. For example, this is the case when using layered Ni-rich oxide CAMs such as Li1+x
(Ni1-y-z
Co
y
Mn
z
)1-x
O2 (NCM) with high specific capacity and thiophosphate-based solid electrolytes.
Here we report on the strong impact of both CAM particle size and external applied pressure on the capacity of bulk-type ASSBs. Our model cell system comprised compacted pellets of NCM622 (60% Ni) as CAM, ß-Li3PS4 or Li6PS5Cl as SE, and In-metal as anode. In particular, we demonstrate the benefit of using small-size cathode particles (≤ 5 μm) to achieve virtually full theoretical specific capacity at low external pressure. This finding is rationalized through complementary galvanostatic cycling and X-ray diffraction on operating cells (in situ) as well as on harvested CAM/SE composites (ex situ). Besides, we reveal the significance of considering electrochemically inactive CAM in ASSBs, the proportion of which is equally increased for large particles and low applied pressure. Using charge transport measurements, we provide evidence that the presence of inactive CAM is due to a lack of electronic contact; ionic percolation seems not to be an issue for the two-phase cathode composites employed here. Overall, the results emphasize the importance of using size-tailored CAM, allowing for good electronic percolation, and thus conductive additives, which may cause SE degradation upon cycling, can be avoided.

Figure 1
Enhancement of Bifunctional Effect of NO3
- Anion By Using Glyme-Based Dual Solvent Electrolytes for Li-Air Batteries
Authors: Ishii Shunya , Yamada Shinya , Ishikawa Taro , Fujinami Taichi , Hayashi Yoshiya , Otsuka Hiromi , Ito Kimihiko , Kubo Yoshimi , Saito Morihiro 
Published: February 2020

In recent years, non-aqueous type rechargeable Li-air (O2) batteries (LABs) have attracted much attention as large-scale energy storage devices for electric vehicles because of the high energy density over 5 times larger than that of the conventional Li-ion batteries (LIBs) [1]. However, there are some problems to be solved for the practical use such as smooth deposition/decomposition reaction of Li2O2 at air electrode and suppression of Li dendrite growth at Li metal negative electrode (NE). To address these problems, we selected 1.0 M LiNO3/tetraglyme(G4) electrolyte and added acetonitrile (AN) or dimethyl sulfoxide (DMSO) with both high dielectric constant ε and low viscosity η to enhance the Li salt dissociation and lowering the electrolyte viscosity. Namely, the NO3
- anion was reported to work as a mediator to decompose the Li2O2 product at air electrode [2] and to form Li2O layer on the surface of Li metal NE to suppress the Li dendrite growth [3,4] and extra electrolyte decomposition. In this study, we investigated the bifunctional effects of NO3
- anion and its enhancement by using the dual solvent system for electrolyte. As a reference, 1.0 M LiOTf/G4 was also examined in the same way.
Figure 1 shows the η values for 1.0 M LiNO3/G4+X and 1.0 M LiOTf/G4+X (X= DMSO, AN) electrolytes. The both η values decreased with an increase in the content of mixed solvents especially for AN because of one tenth lower η (0.37 mPas) than G4. As a result, the σ value was drastically improved (Fig. 2). For the addition of DMSO, the decrease in the η was not so big. However, the σ value effectively increased as well as those for the AN. This indicates that the relative high ε (47) of DMSO enhanced to dissociate the Li salts and improved the σ value by increasing the number of carrier ions. In fact, the effect was confirmed by Raman spectra and Walden plots. Figure 3 shows the discharge/charge curves for the LAB cells using the dual solvent electrolytes at the applied current of 0.20 mA cm-2. By mixing DMSO, the overpotential was drastically reduced especially during discharge process. This effect was enhanced at a higher rate operation. In addition, Li deposition/dissolution tests using Li foil | Cu mesh cell also exhibited improved performances for the 1.0 M LiNO3/G4 electrolytes. The effects for the dual solvent system will be reported in more detail at the meeting.
This study was supported by JST Project “ALCA-SPRING”, Japan.
[1] P. G. Bruce et al., Nature materials, 11, 19 (2012).
[2] D. Sharon, et al., ACS App. Mater. & Int., 7, 16590 (2015).
[3] J. Uddin, et al., J. Phy. Chem. Lett., 4, 3760 (2013).
[4] M. Saito et al., J. Electrochem. Soc., 164(12), A2872 (2017).

Figure 1
Composite of Vn/Carbon Nanofibers As a Protective Layer on Cathode for High Performance Li-S Batteries
Authors: Kim Han-Byeol , Ngo Duc Tung , Park Chan-Jin 
Published: February 2020

With increasing demand for large scale energy storage systems (ESS), Li-S battery is regarded as a potential candidate for ESS, due to its high theoretical energy density and natural abundance of the cathode material. However, for conventional Li-S batteries, sulfur cathode has suffered from many issues such as low intrinsic electrical conductivity and instability leading to the insufficient utilization of sulfur. In particular, the dissolution of polysulfide intermediates into electrolyte results in the rapid capacity fading of the batteries. Therefore, for the development of the highly efficient Li-S battery, it is essential to improve the conductivity of the sulfur based cathode and maintain/reuse the soluble polysulfide within the cathode structure. To address these issues, some researchers used protective layer composed of carbon, metal oxides or polymers on the sulfur cathode. According to previous studies, carbon based materials as a protective layer on cathode reduced the charge transfer resistance of the sulfur cathodes by acting as an upper conducting network and localized the soluble polysulfides during cycling. This strategy is regarded as a simple and effective solution to make high capacity rechargeable Li-S batteries. In addition, other group demonstrated that Pt as an electrocatalyst could help to convert polysulfide deposits back into soluble long-chain polysulfide, and hence enhanced reaction kinetics and retained high Coulombic efficiency. Catalytic role of vanadium nitride, VN resembles that of more precious Pt. VN has desirable advantages for a sulfur cathode: (1) strong chemical adsorption of polysulfides on it, leading to suppressing the shuttle effect, (2) its high electrical conductivity, and (3) good catalytic activity for enhancing red-ox reaction kinetics.
In the present work, we fabricated a composite of VN/carbon nanofibers (VN/CNFs), as a protective sulfur electrode on cathode for Li-S cell, using electrospinning method. The morphology and chemical composition of electrospun VN/CNFs were characterized by SEM, TEM, and XPS, respectively. The Li-S cell with VN/CNFs protective layer exhibited excellent electrochemical performance in terms of specific capacity, cyclability, and rate capability. Owing to the strong and synergic polysulfides anchoring effect of the VN/CNFs, a high initial discharge capacity of 1,480 mAh g-1 and a Coulombic efficiency of ~98% were measured at a rate of C/2, when used in Li-S cell. Further, the Li-S cell exhibited a long-term cyclability: 82% capacity retention even after 200 cycles.

Figure 1
Correlating Molecular-Level Environments of Chloroaluminate Species with Electrochemical Behavior in Rechargeable Aluminum-Graphite Batteries
Authors: Xu Jeffrey , Turney Damon , Messinger Robert J. 
Published: February 2020

Aluminum metal has long been envisioned as an electrode for high-performance rechargeable batteries due to its high global abundance, low cost, non-flammability, and high volumetric capacity. Graphite has recently been shown to pair as a cathode with aluminum anodes when using chloroaluminate-containing ionic liquid electrolytes, exhibiting capacities that are stable at high charge/discharge rates and over long cycle lifetimes. However, there are presently unanswered questions related to the intercalation of sterically bulky chloroaluminate anions (e.g. AlCl4
-), structural changes of the cathode after prolonged cycling, and more generally, the relationship between the local structures of different graphitic materials and their electrochemical properties.
Here, we report on the investigation of charge storage and ion transport mechanisms in graphitic cathodes and their implications on bulk electrochemical behavior. Three types of graphites (pyrolytic, natural and synthetic) were studied. Solid-state 27Al magic-angle-spinning (MAS) NMR measurements on intercalated graphitic cathodes reveal the presence of chloroaluminate anions in different local environments and with different mobilities that evolve as a function of state-of-charge. Cyclic voltammetry experiments at varying scan rates were conducted to yield insights into ion transport phenomena and to disentangle the Faradaic and capacitive contributions to the total discharge capacity. Additionally, the surface area and porosity of the cathode materials, which affect the number of accessible sites for ion electrosorption, were quantified and correlated to the observed capacitance and overall energy density. Our findings reveal molecular-level insights into the intercalation processes and redox mechanisms of graphitic cathodes that can be collectively used to better understand and optimize aluminum-graphite battery performance.

Figure 1