bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionic Permeability within Thermally-Activated Batteries
Authors: Humplik Thomas , Stirrup Emily K. , Wesolowski Dan Edward , Allen Ashley Nicole , Grant Richard P. , McKenzie Bonnie B. , Roberts Christine C. , Roberts Scott A. , Mondy Lisa Anne , Grillet Anne M.
Published: February 2020

Thermally-activated (or molten salt) batteries utilize high melting temperature (> 300 ºC) salts as the electrolyte. Since the electrolyte is solid at room temperature, an advantage of these types of batteries is that there is no self-discharge prior to activation, which significantly increases the shelf life compared to conventional electrochemical batteries. To activate the battery, a heat source (usually an internal pyrotechnic) is required to melt the electrolyte and enable current flow. During the melting/activation process, the separator in each cell thins until the oxide binder supports the cell compaction force. An open question is what becomes of the melted electrolyte within the separator and electrodes during activation. The transport and infiltration of the electrolyte into the electrodes can reduce the internal impedance of the cell; however, excess electrolyte could cause shortage and failure of the battery. Therefore, an improved fundamental understanding of the governing transport properties of the electrolyte is needed to better predict the performance of thermal batteries during activation.

In this work, we performed a series of fundamental studies to probe the ionic mobility and conductivity of the electrolyte.  First, by utilizing a series of single cells frozen at various activated times, we performed electron probe microanalysis (EPMA) on the cell cross-sections to quantify the transport of bromine tracers. Through the use of image analysis techniques, we mapped out of the concentration of bromine throughout each cell and elucidated the complex process of electrolyte diffusion and flow. Next, using a custom-built pressure vessel cell, we quantified the permeability of the electrolyte through the oxide binder during and after activation. Furthermore, we investigated the effects of compaction pressure on both the permeability and internal impedance of the separator. Collectively, these experimental studies provide quantitative transport information about the electrolyte, which can be used to inform predictive models for battery activation and improve the understanding of the impact of separator compaction on electrolyte transport properties. 

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
Boron Subphthalocyanines and the Exploration of Other p-Block Metal Phthalocyanines for Use in Organic Electronics
Authors: Bender Timothy P
Published: February 2020

For some time our group has been focused on the design and synthesis of derivatives of boron subphthalocyanine (BsubPc) for application in organic electronics. In most cases, organic electronic devices utilize the prototypical BsubPc, chloro boron subphthalocyanine (Cl-BsubPc). We have shown that by using facile chemical transformations we can tailor the nature of the BsubPc to a dye, sublimate, engineered crystal or polymer. Early on in our research program we showed that peripheral functionalization of the BsubPc moiety had detrimental effects on the electrochemical behavior/stability. We therefore focused on chemical derivatization of the boron metal centre while maintaining the hydrogen periphery. The chemical transformations we have found most successful rely on the oxo-philicity of the boron metal centre.

In this presentation I will outline examples of each type of BsubPc, the chemistry we used to achieve each derivative, in addition to presenting their application in organic electronic devices including organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs).

I will also highlight our group’s recent interest in expanding our methodology to other p-block metal phthalocyanines (M-Pcs) including Pcs of aluminum, silicon, germanium and phosphorous. In each case the metal was chosen due to its abundance and its ability to participate in our previously established oxo-philic based chemistry. Preliminary organic electronic device data will also be presented.

Coauthors will be cited as appropriate throughout the presentation.

Leading References:

(1) “Pentafluorophenoxy Boron Subphthalocyanine (F5BsubPc) as a Multifunctional Material for Organic Photovoltaics.” Morse, G.E.; et al. ACS Appl. Mat. Inter., 2014, 6 (3), 1515–1524.

(2) “Utilizing the π-Acidity of Boron Subphthalocyanine to Achieve Novel Solid-State Arrangements.” Paton, A.S.; et al. Crystal Growth & Des., 2013, 13 (12), 5368–5374.

(3) “Halogen bonds can direct the solid state arrangement of phenoxy-boron subphthalocyanines.” Virdo, J.D.; et al.CrystEngComm, 2013, 15, 3187-3199.

Figure 1
The Synthesis and Porperties of Metallotriphyrins
Authors: Xue Zhaoli , Wang Yemei
Published: February 2020

Triphyrins are analogues of porphyrinoids that contain only three pyrrole or isoindole rings linked by meso-sp2 carbon atoms. The first synthesis of tribenzosubporphyrins was reported by Osuka’s group in 2006 with very harsh conditions. From then on, lots of subporphyrin analogues have been reported. However, almost all of these reported subporphyrins existed only as bowl-shaped boron complexes and the yields are typically very low. In 2008, we reported a facile synthesis of meso-aryl-substituted [14]benzotriphyrin(2.1.1) compounds based on a modified Lindsey condensation method in moderate yields up to 35%. These compounds represent as the first example of near planar core-free contracted porphyrinoids with 14-π-electron aromatic systems containing only the standard pyrrole and isoindoline moieties. X-ray diffraction analysis revealed that the triphyrin core is near planar. During the metallization with transition metals we found that [14]benzotriphyrin(2.1.1) is good tridentate monoanionic ligand for octahedral coordination. Till now, nine kinds of [14]BenzoTriphyrin(2.1.1)-metal complexes have been synthesized and characterized including Ag(I), Mn(I), Fe(II), Re(I), Rh(I), Ru(II), Pd(II), Pt(II) and Pt(IV).
Kinetic Studies of Reactions of Hydroxyporphyrins on Silicate Surface
Authors: Mizutani Tadashi
Published: February 2020

Construction of the monolayer film of semiconductive and redox-active porphyrins on the metal oxides such as silicate or titanates attracts interests for possible applications of the process in fabricating organic electronic devices, organic catalysts, and organic-inorganic hybrid materials. Porphyrins bearing linker functional groups such as hydroxy or bromo groups in the peripheral meso-phenyl groups were reacted with the surface silanol groups of silicate glass at 80 to 240 oC in a solid-solid reaction to obtain the monolayer film of porphyrin on the silicate glass. The rates of the reaction were determined by visible spectroscopic studies and they decreased in the order: primary alcohol > primary bromide ~ tertiary alcohol. In addition to the structures of the linker groups, melting points of porphyrins also affect the reactivity of the porphyrin. Porphyrins with long alkyl chains reacted faster than those without long alkyl chains, because the long alkyl groups would facilitate molecular motion to reach the transition state of the reaction. Hydrolysis of the porphyrin monolayer prepared from primary alcohol in 1 M aq. HCl at 50 oC proceeded in a similar rate to that prepared from tertiary alcohol. Base catalyzed hydrolysis in 1 M aq. NH3 at 30 oC of the porphyrin monolayer prepared from tertiary alcohol proceeded 20 times slower than that prepared from the primary alcohol. In the literature, it is well established that the hydrolysis of the silicate ester bond proceeds via the Si-O bond cleavage, since the silicon atom can form a penta-coodinated structure, and much more reactive than carbon atom toward a substitution reaction. Hydrolysis of the porphyrin monolayer prepared from the tertiary alcohol in H2
18O afforded 18O-labelled tertiary alcohol, indicating that there was a covalent bond between the porphyrin and silicate glass, and the C-O bond was cleaved in the acid catalyzed hydrolysis reaction of the tertiary alkyl silicate ester on the silicate glass.
Iron(III) Protoporphyrin IX Associates with Proteins in a Sequence-Dependent Manner
Authors: Imhof Diana , Kühl Toni , Goradia Nishit , Brewitz Hans Henning , Wißbrock Amelie , Ohlenschläger Oliver
Published: February 2020

The role and action of heme as a regulatory effector of proteins came more and more into the focus of biochemical research aiming at a complete understanding of this molecule’s function in the organism apart from its well-investigated embedment in hemoproteins, which e.g. are involved in gas transport, catalytic reactions or electron transfer [1-3]. Transient binding of regulatory heme to proteins might significantly change a protein's function. Distinct sequence stretches on the protein surface are responsible for interaction with heme. As a consequence of association, conformational changes within the protein may lead to changes in the protein's activity [4]. Interactions between heme and characteristic iron-coordinating amino acids (cysteine, histidine, tyrosine) are well-known. In addition, however, the surrounding amino acids contribute to the association of the protein with the protoporphyrin ring system. This fact was confirmed by results of a combinatorial peptide library screening [1]. Based on these data we predicted motifs for heme binding as well as proteins as possible targets, such as dipeptidyl peptidase 8 which subsequently was proven to be inhibited by heme [5]. Further targets possessing a great potential as heme-regulated proteins are currently under investigation. In-depth structural studies e.g. using UV-vis, resonance Raman, and NMR spectroscopy revealed the existence of different binding modes for heme-peptide/protein complexes [6]. These investigations resulted in the first structures of heme-peptide complexes known so far [5,7]. Binding data and structural characteristics displayed specific sequence requirements that, in turn, present suitable tools to identify potential heme-regulated proteins and, moreover, open new perspectives for diagnosis and treatment of pathophysiological conditions associated with non-balanced concentrations of bound and free regulatory heme in the organism [6].

References

1.  Kühl, T., Sahoo, N., Nikolajski, M., Schlott, B., Heinemann, S.H., Imhof, D., Chembiochem
2011, 12, 2846-2855.

2. Yao, X., Balamurugan, P., Arvey, A., Leslie, C., Zhang, L., Biochem. Biophys. Res. Commun. 2010,403, 30-35.

3. Atamna, H., Boyle, K., Proc. Natl. Acad. Sci. USA
2006, 103, 3381-3386.

4. Shimizu, T., J. Inorg. Biochem.
2012, 108, 171-177.

5. Kühl, T., Wißbrock, A., Goradia, N., Sahoo, N., Galler, K., Neugebauer, U., Popp, J., Heinemann, S.H., Ohlenschläger, O., Imhof, D., ACS Chem.
Biol.
2013, 8, 1785-1793.

6. Kühl, T., Imhof, D., Chembiochem
2014, 15, 2024-2035.

7.  Brewitz, H.H., Kühl, T., Goradia, N., Galler, K., Popp, J., Neugebauer, U., Ohlenschläger, O., Imhof, D., submitted.
Hydrogen-Bonding and Pi-Stacking Induced Self-Assembly of Picolinic Acid-Substituted Phthalocyanine Derivatives
Authors: Bottari Giovanni , Ballesteros Beatriz , Fernandez Collado Javier , Torres Tomas
Published: February 2020

The preparation of organic-based, supramolecular architectures which present a high degree of order spanning from the nanoscopic to the macroscopic level across multiple length scales is highly desirable and represents a key issue within the fast-growing fields of nanoscience and nanotechnology.[1] In this context, self-assembly appears as an attractive and efficient strategy for the construction of such ordered structures as it can allow the preparation of complex, (multi)functional systems in an efficient and controlled way.[2] Among the organic compounds used for this purpose, π-conjugated systems such as phthalocyanines (Pcs),[3] aromatic macrocycles featuring unique structural, optical and redox properties,[4] are ideal candidates due to their excellent self-organization ability.[5]

We present here a new family of picolinic acid-terminated Pcs (1-3, Figure 1) which are able to self-aggregate in different solvents giving rise to the formation of columnar H-aggregates as a result of a combination of π-π supramolecular interactions between the Pc macrocycles and hydrogen bonding interactions between the terminal picolinic acid moieties.[6] Remarkably, the assembly/disassembly of these supramolecular systems can be reversible controlled by the addition of acids or bases to the Pc solutions. In Pc 3, chiral alkoxy units have been introduced at the Pc peripheral positions with the aim of influencing the stacking of the H-aggregates towards the formation of single-handed columnar structures.

References

1.   Special issue on “Supramolecular approaches to organic electronics and nanotechnology”. Adv. Mater.
2006, 18, 1227-1329.

2.   Special issue on “Supramolecular chemistry and self-assembly”. Science
2002, 295, 2395-2421.

3.   G. de la Torre, C.G. Claessens, T. Torres Chem. Commun.
2007, 2000-2015.

4.   G. Bottari, G. de la Torre, D. M. Guldi, T. Torres Chem. Rev.
2010, 110, 6768-6816.

5.   G. Bottari, J. A. Suanzes, O. Trukhina, T. Torres J. Phys. Chem. Lett.
2011, 2, 905-913.

6.   Manuscript in preparation.

Figure 1
Spectroscopic and Nonlinear Optical Properties of 3, (4-tert-butylphenoxy) Phthalocyanine Constitutional Isomers
Authors: Ngubeni Grace Nomthandazo , Britton Jonathan , Mack John , Nyokong Tebello , Khene Samson
Published: February 2020

Introduction

Organic material with second-order nonlinear optical (NLO) material properties are useful in applications such as optical data processing or storage devices and can be easily processed and integrated into optical devices [1, 2]. Organic materials such as phthalocyanines (Pcs) exhibit large and fast nonlinearities, which can be fine-tuned by rational modification of the molecular structure [3, 4, 5]. Pc molecules are known to have large third-order optical nonlinearities which arise from the highly delocalised two dimensional 18-electron system [6, 7, 8, 5]. Pcs have been intensively investigated for their NLO properties. In most studies, NLO properties of tetra substituted Pcs have been studied as a mixture of isomers [9].

Aims

In this work four constitutional isomers of unmetalated tert-butylphenoxy phthalocyanine were separated and their NLO properties measured, in order to identify which isomer contributes the most to the measured NLO response.This work presents spectroscopic and nonlinear optical properties of unmetalated 3, (4-tert-butylphenoxy) phthalocyanine constitutional isomers. Second order nonlinear polarizability, second order hyperpolarizability and third order imaginary susceptibility (Im[χ(3)]) values were determined for monomeric and aggregated constitutional isomers.

Z-scan technique is employed in determining the second order NLO property. Spectroscopic and photophysical properties of the isomers, such as fluorescence lifetime and rotational correlation lifetimes are determined. Magnetic circular dichroism (MCD), time correlated single photon counting spectroscopy (TCSPC), ultra-violet visible (UV/vis) spectroscopy,   Infra-red (IR) spectroscopy and density functional theory (DFT) are some of the techniques used to characterise physical properties of the isomers.

References

G. de la Torre, P. Va´zquez, F. Agullo´-Lo´pez, T. Torres, J. Mater. Chem., 1998, 8, 1671-1683.

T. Verbiest, S. Houbrechts, M. Kauranen, K. Clays, A. Persoons, J. Mater. Chem., 1997, 7, 2175-2189

J. M. Fox, T. J. Katz, S. V. Elshocht, T. Verbiest, M. Kauranen, A. Persoons, T. Thongpanchang, T. Krauss, L. Brus, J. Am. Chem. Soc.,1999, 121, 3453-3459

E. M. Maya, A. W. Snow, J. S. Shirk, R. G. S. Pong, S. R. Flom, G. L. Roberts, J. Mater. Chem., 2003, 13, 1603-1613

G. de la Torre, P. Vazquez, F. Agullo-Lopez and T. Torres, J. Mater. Chem., 1998, 8, 1671-1683.

J. Britton, M. Durmus ̧ S. Khene, V.Chauke, T. Nyokong, J. Porphyrins Phthalocyanine, 2013, 17, 692-702.

C. Mkhize, J. Britton, T. Nyokong, Polyhedron, 2014, 81, 607-613.

J. Britton, M. Durmuş, V. Chauke, T. Nyokong, Journal of Molecular Structure, 2013, 1054-1055, 209-214.

C. Nitschke, S. M. O’Flaherty, M. Kroll, J. J. Doyle, W. J. Blau, Chemical Physics Letters, 2004, 383, 555-560.
Point Defect Equilibria and Diffusion in Siderite (FeCO3) Passive Film Studied Using Density Functional Theory
Authors: Youssef Mostafa , Yildiz Bilge
Published: February 2020

In a CO2-rich anoxic aqueous environment as in some oil fields, a layer of siderite (FeCO3) grows on carbon steel as a byproduct of steel corrosion. This layer acts as a resistive barrier that kinetically slows down further corrosion of steel. Understanding and predicting the rates of  progression of both general and pitting corrosion  requires a fundamental understanding of defect equilibria and diffusion in the passive film [1]. In this work we address this need by modelling point defect equilibria and mobility using a combination of density functional theory (DFT) and thermodynamic analysis. The defects of interest in this study are the native cation and anion vacancies and extrinsic chlorine defects whose concentrations vary depending on temperature and the chemical potential gradient from the steel/siderite interface (iron rich) to the siderite/water interface (carbonate rich). Defect formation energies were calculated using the DFT+U approach and defect mobility’s were computed the nudged elastic band method. Preliminary results indicate that iron vacancies are predominantly fully ionized (2- charge state), whereas oxygen vacancies are mainly neutral and carbon vacancies are never fully ionized (charge state less than 4-) as shown in Figure 1. In addition we identified hole polarons localized on iron cations to be a predominant electronic defect that participate in the equilibria of charged defects in this material.

The predictions of point defects thermodynamics and kinetics in FeCO3 is major step toward an atomistics-informed corrosion model of carbon steel in oil fields.

[1] D. D. Macdonald, Pure Appl. Chem., 71, 951, (1999).

Figure 1
Study of Stable Cathodes and Electrolytes for High Specific Density Lithium-Air Battery
Authors: Hernandez-Lugo Dionne , Zhu Yu
Published: February 2020

Future NASA missions require high specific energy battery technologies, > 400 Wh/kg. Current NASA missions are using “state-of-the-art” (SOA) Li-ion batteries (LIB), which consist of a metal oxide cathode, a graphite anode and an organic electrolyte.   The design and chemistry of these cells have safety issues and relatively low specific energy.  Among all the advanced energy storage systems, metal-air batteries, especially lithium-air batteries comprise a new system that has the potential to significantly enhance the energy density (10,000 Wh/kg). It has been shown theoretically work that their energy density is comparable with that of gasoline. The most challenge is that the lithium-air batteries undergo severe degradation upon cycling which limit the cycle life. An intriguing possible solution can be found in pairing a pure sp2carbon cathode with a non-traditional electrolyte such as ionic liquids.

NASA Glenn Research Center is currently studying the physical and electrochemical properties of the anode-electrolyte interface for ionic liquid based Li-air batteries. The voltage-time profiles for Pyr13FSI and Pyr14TFSI ionic liquids electrolytes studies on symmetric cells show low overpontentials and no dendritic lithium morphology. Cyclic voltammetry measurements indicate that these ionic liquids have a wide electrochemical window. As a continuation of this work, sp2 carbon cathode and these low flamability electrolytes were paired and the physical and electrochemical properties were studied in a Li-air battery system under an oxygen environment.
Electrical Circuit-Based Modeling of a Non-Aqueous Lithium-Oxygen Battery for High Accuracy State-of-Charge Estimation
Authors: Kim Jonghoon
Published: February 2020

With the increased interest in electric-powered transportation such as electric vehicle (EV) and hybrid electric vehicle (HEV) application, lithium-ion cell and large-format lithium-polymer cell were taken it for granted that they have become more preferable selection. Unfortunately, they are still limited to the application that requires much higher specific energy density. As a result, in order to overcome an aforementioned problem, non-aqueous lithium-oxygen (Li-O2) batteries have attracted substantial attention because of their high energy density. Moreover, the need for accurate and reliable state-of-charge (SOC) information which is considered as one of the key factors in battery management system (BMS) is significantly increased for supporting optimal battery performance and safety. So far, no definitive solution has been provided to this question. Therefore, this research gives insight to the design and implementation of the electrical circuit-based modeling of a non-aqueous lithium-oxygen battery for high accuracy SOC estimation. Four experimental tests including discharge capacity/impedance tests with cycling, open-circuit voltage (OCV) test and discharging/charging cycling test were priorly implemented for a detailed analysis of electrochemical characteristic analysis and parameters identification of a non-aqueous lithium-oxygen battery. Through these tasks, it can be completely succeeded in constructing a finalized electrical circuit-based model that consists of the OCV, one series resistance and one RC-ladder with dynamic characteristic. This model enables us to provide appropriate information for high accuracy and reliable SOC estimation based on the extended Kalman filter (EKF). This research has been extensively validated by additional experimental results conducted on a non-aqueous lithium-oxygen battery that had a rated capacity of 1700mAh/g by the ‘Materials and Electro-Chemistry Laboratory in Inha University’. Consequently, it can be well known that all verification results clearly indicate the robustness of the proposed research.
Amorphous Metal Fluorides Coatings By Atomic Layer Deposition for Stable Li-Ion Batteries
Authors: Mane Anil U. , Park Joong Sun , Croy Jason R. , Elam Jeffrey W
Published: February 2020

Metal fluorides pose interesting optical and chemical properties and thin films of these materials can be used in various applications to serve as optical coatings, protective layers, catalysts, solid state electrolytes, and barrier layers for thin film batteries. The properties of metal fluorides show broad trends based on the charge of the metal. Metals in an oxidation state of +3 or lower tend to form ionic, refractory fluorides. Metals of +5 oxidation or higher tend to form covalently bonded fluorides, polymers, and discrete molecules.  Consequently, bi-metallic fluorides comprised of high and low valence metals might possess novel properties. The development of thin film methods for preparing these materials may pave the way for new applications of nanophase materials.

In order to reduce the unfavorable side reactions in Li-ion batteries, ultrathin metal oxides such as Al2O3, LiAlO2, and LiTaO3, deposited by atomic layer deposition, have been demonstrated [1,2] to significantly enhance both stability and safety of electrodes. However, metal oxide coatings are likely to be susceptible to hydrofluoric acid (HF) attack upon electrochemical cycling. Metal fluorides may be suitable alternatives for electrode coating materials due to their stability against HF attack and the strong bonding between metals and fluorine.

Here we report the atomic layer deposition of complex fluorides such as AlxWyFz and MgxWyFz utilizing WF6 as the source of both fluorine and the high valence metal with Al(CH3)3 (TMA) and Mg(Cp)2 [4]. In-situ quartz crystal microbalance studies were performed during the deposition of these chemistries and in both cases the QCM data showed self-limiting, linear growth. Films were prepared at 200oC and the deposited layers of AlxWyFz and MgxWyFz were found to be x-ray amorphous in nature.  SEM EDAX elemental mapping of these layers, deposited in high aspect ratio trenches, showed uniform and conformal distributions of the various elements within the films, Figure 1.   We have used ~1 nm layers of AlxWyFz and MgxWyFz materials in an effort to improve the performance of a model Li-ion battery cathode, LiCoO2 [5].  This presentation will present the results of ALD of these materials, characterization, and Li-ion battery stability tests.

References

(1) Jung, Y. S.; Cavanagh, A. S.; Dillon, A. C.; Groner, M. D.; George, S. M.; Lee, S.-H. Journal of The Electrochemical Society
2010, 157, A75.

(2) Park, J. S.; Meng, X.; Elam, J. W.; Hao, S.; Wolverton, C.; Kim, C.; Cabana, J. Chemistry of Materials
2014.

(3) Li, X.; Liu, J.; Banis, M. N.; Lushington, A.; Li, R.; Cai, M.; Sun, X. Energy & Environmental Science
2014, 7, 768.

(4) Anil U. Mane, and Jeffrey W. Elam, ALD (2014), Kyoto, Japan

(5) Park J. S, Mane A. U, Elam J. W., Croy J. R., Submitted to Chemistry of Materials

Figure 1
Optimized Discrimination Based on the Data Mining Combined with the Discrete Wavelet Transform for LiFePO4 Cells Consistency
Authors: Kim Jonghoon
Published: February 2020

The cell’s discrimination process has been absolutely considered to be a prerequisite for stable configuration of the series/parallel-cell configured battery pack. Specifically, our conventional technique based on the pattern recognition was efficiently implemented to minimize cell-to-cell variation in the LiCoO2 battery pack. However, an identical discharging/charging current profile was only applied to all experimental cells for obtaining each discharging/charging voltage considered as representative patterns in the conventional technique. As a result, the application of the discharging/charging current signal (DCCS) profiles with different time interval, abrupt changes, and current magnitude results in erroneous information for correct discrimination of the cells that have similar electrochemical characteristics when using the conventional technique. Moreover, considered in case of the LiFePO4 cell, because of the flatness and hysteresis effect of the open-circuit voltage (OCV), it has been more difficult to succeed in solving aforementioned problems. Therefore, this research investigates a new approach in order to accomplish an optimized LiFePO4 cell’s discrimination for stable operation of the battery pack, together with the LiCoO2 cell. In this research, two-level basis discrimination based on the data mining combined with the discrete wavelet transform (DWT) for LiFePO4 cells consistency is newly introduced. In the first level, 10 current profiles with different discharging/charging sequence are applied to a LiFePO4 cell for obtaining different DCCS patterns. At this level, low/high frequency components decomposed by DWT-based multi-resolution analysis (MRA) are applied as characteristic parameters in the data mining of an unknown DCCS. In the second level, 15 representative discharging/charging voltage signal (DCVS) patterns considering previously discriminated DCCS in the first level, are applied to other data mining of an arbitrary DCVS. Through proposed work, it can be expected to provide an elaborate identification of the representative DCCS and DCVS that most closely match those of an arbitrary LiFePO4 cell.
Density Functional Theory Study of Li Intercalation Voltage Near Cathode Interfaces
Authors: Xu Shenzhen , Jacobs Ryan , Wolverton Chris , Morgan Dane
Published: February 2020

Interfaces are ubiquitous and important in battery electrode as they occur in regions of material intergrowth, in compositional gradients and also at interfaces with protective coatings. In this work, we study the Li intercalation voltage behavior across the interface of olivine FePO4-MPO4 (M=Co, Ti, Mn). These olivine-structured interfaces provide a representative model to help us further understand the physics of Li intercalation across material interfaces with different intercalation voltages. We find that as one moves across the interface from high to low Li intercalation voltage material the voltage stays constant in the higher voltage material and decays approximately linearly in the lower voltage region.  This effect is shown to be due to electron transfer from the intercalated Li across the interface. The existence of the higher voltage material and the interface can significantly enhance the Li intercalation voltage in the lower voltage region within a 1-2 nm scale. Implications of this result for cathode structures will be discussed.
A High-Throughput Search for Functional Cathode Coatings for Lithium-Ion Batteries By First-Principles Thermodynamics
Authors: Aykol Muratahan , Kim Soo , Kirklin Scott J. , Morgan Dane , Wolverton Chris
Published: February 2020

A widely employed remedy to slow down the degradation of the electrochemical performances of lithium-ion batteries (LIBs) is to apply coating materials on cathode surfaces.[1] Such coatings can serve as physical barriers to inhibit electrode-electrolyte side reactions, and they can possess an additional functionality such as scavenging the detrimental acids (e.g., the hydrofluoric acid, HF) in electrolytes. Recently, we introduced a density functional theory (DFT) based framework to find promising HF-scavenging binary metal oxide coatings by considering their HF-scavenging tendencies and lithiation voltages.[2] Building on that framework, here we present a new high-throughput (HT) coating design strategy to search among thousands of candidate oxide materials and find the most promising candidates.

In the current framework, we consider three main thermodynamic criteria to assess the effectiveness of a compound A
a
B
b
C
c
…O1/2 as a coating. First criterion is the thermodynamic stability of the candidate material. We evaluate this criterion by finding whether the material is stable against decomposition to other phases in its chemical space A-B-C-…-O. The second criterion is the electrochemical stability. This criterion tests whether the material is stable against reduction and oxidation during cycling. The third criterion is the HF-scavenging tendency. We evaluate this criterion for systems where an HF-scavenging functionality is preferred, by identifying the HF-scavenging reactions and free energies. In addition, we take into account the effect of different cathode-electrolyte chemistries on these three criteria, namely, presence of common cathode materials (LiCoO2, LiMn2O4, etc.), as well as presence of HF-free or HF-bearing electrolytes.

Utilizing the HT-coating design framework described above, we screen more than ~100,000 oxide materials available in the Open Quantum Materials Database (OQMD)[3] to find coating materials with different target properties. We suggest promising multi-component oxide cathode coatings that can prolong the cycle-lives of LIBs, and surpass the effectiveness of common coatings used such as Al2O3, MgO and ZrO2.

Acknowledgement

This work has been supported by The Dow Chemical Company.

References

[1] Z. Chen, Y. Qin, K. Amine, Y.-K. Sun, J. Mater. Chem.
2010, 20, 7606.

[2] M. Aykol, S. Kirklin, C. Wolverton, Adv. Energy Mater.
2014, in press.

[3] J. E. Saal, S. Kirklin, M. Aykol, B. Meredig, C. Wolverton, JOM
2013, 65, 1501.

Figure 1
(Invited) Fabrication of High-Quality TiO2 Nanotubes on Conductive Glasses
Authors: Li Shibin , Yang Xiaohui , Wei Xiongbang , Xuan Yaoyu , Chen Zhi David , Jiang Yadong
Published: February 2020

In recent decades, titanium dioxide nanotube arrays has attracted many researcher’s interest due to their excellent physical and chemical properties, such as high order, large specific surface area, stability, and efficient electron transporting for dye-sensitized solar cells. However, it is difficult to prepare high quality TiO2 nanotubes on conductive glasses. Most TiO2 nanotubes on conductive glasses reported in literatures exhibit poor organized structures.

As shown in Fig.1, a highly self-ordered titania nanotube arrays have been prepared on conductive glass (SnO2:F) (FTO) substrates in ethylene glycol organic electrolyte which contains ammonium fluoride through anodic oxidation. The Ti film was deposited first on the FTO via DC magenetron sputtering. The sputtering power and substrate temperature were adjusted to obtain compact films. The incipient nanotubes have been covered by the surface oxide layer. To clean the surface, the sample after anodization was etched in diluted hydrofluoric acid solution via ultrasonic cleaning for a short time. Furthermore, the results indicate high quality TiO2 nanotubes on the conductive glass substrates can be fabricated by using longer oxidation time (2h).

Figure 1
Invited: Colloidal Semiconductor Nanocrystals for Sensing and Optoelectronic Applications
Authors: Schaller Richard D
Published: February 2020

Quantum confined semiconductor nanocrystals offer size-tunable energy gaps, large photoluminescence quantum efficiencies at room temperature, scalable synthesis, and low cost solution processing. Owing to these characteristics, significant interest exists in the development of these materials for use in optoelectronic and sensing applications. Despite high room temperature photoluminescence quantum yields that in some cases can approach unity, many important devices such as displays, lighting, and optical amplifiers experience elevated temperatures during operation, which has generally not received much attention. For three semiconductor compositions (cadmium selenide, indium phosphide, and silicon), we utilize static and time-resolved optical characterizations to improve understanding of carrier dynamics under operational conditions. Specifically, we measure quantum yield vs elevated temperature, reveal reversible as well as irreversible exciton quenching pathways, and investigate the role of surface termination on exciton integrity with temperature. This work points to strategies to improve upon the performance of these materials in high temperature applications. We have also made use of these materials in biological sensing applications where we make use of the large absorption cross-sections and high optical stability of some nanocrystals compositions. Using these materials, we report a selective, stable, fast and sensitive all-optical pathogen detection assay.
(Invited) Applications of Electrochemistry for Novel Wide Bandgap GaN Devices
Authors: Park S. H. , Zhang C. , Yuan G. , Chen D. , Han Jung
Published: February 2020

In the recent two decades we have witnessed phenomenal progress in GaN optoelectronic and power electronic devices, culminating in the recent 2014 Nobel Prize in Physics. In both light emitting devices and power transistors, GaN has transitioned from laboratory curiosity to commercial maturity. Most of the innovative claims nowadays need to be benchmarked with industrial manufacturability and cost effectiveness. We intend to show in this talk new opportunities rendered by applying electrochemistry to GaN.

Recently our group discovered a simple and versatile electrochemical (EC) etching of GaN at room temperature with no need of any ultraviolet irradiation.[i] The EC etching relies on the generation of holes at the GaN/electrolyte surface for oxidation and chemical dissolution. Depending on the layer conductivity and applied bias, the EC etching may cause no effect, nanoscale porosification, or complete etching of GaN.[ii] The EC etching has been applied to different areas of GaN material and device technologies, including layer separation, LED light extraction, the formation of distributed Bragg reflector (DBR) for photonic applications, and the preparation of flexible GaN membrane devices. Highlights from each application will be reviewed in this talk.

The work was supported by the U.S. Department of Energy, National Science Foundation (NSF), and Seoul Optodevices.

[i] Zhang, Y. et al., “A conductivity-based selective etching for next generation GaN devices”, Physica Status Solidi B 2010 247, 1713-1716

[ii] Zhang, Y. et al., “The fabrication of large-area, free-standing GaN by a novel nanoteching process”, Nanotechnology 2011, 22, 045603
H2/O2 Alkaline Membrane Fuel Cell Performances Using Carbon-Supported Metal Phthalocyanine (MPc/C,M = Co, Cu, Zn, Ni) as Cathode Catalysts
Authors: Zhu Taishan , Qing Xin , Xu Pan , Song Yanxi , Qiao Jinli
Published: February 2020

Supercapacitors are one of the most promising electrochemical energy-storage device and have been widely applied due to their advantages of large power density, long cycle stability and environmentally friendly[1]. In the past few decades, many metal oxides were investigated as active electrode material for supercapacitor, among which ruthenium oxide (RuO2) is the best candidate[
2-3]
. However, the high cost and toxic nature of RuO2  has  limited its practical production and commercial applications. 

Aiming at new cost-effective, high performance electrode material for supercapacitors, partial or complete replacement of precious metal has been under great effort by many research groups[4]. Manganes oxide (MnO2) is generally considered to be the most promising transition metal oxide for the next-generation supercapacitors by virtue of its high energy density, low cost, environmental friendliness, and natural abundance. For obtaining the specified morphology with increased surface area and predetermined microstructure, the MnO2 has been proposed to be synthesized by various methods such as hydrothermal method[5] and  microwave method[6] to  realize the improved reaction kinetics. However, these methods are relatively complex, which inevitably adds the cost. In this work, use glucose reducing potassium ermanganate, the mesoporous MnO2 can be easily prepared at ambient conditions with high production rate. Thus a very simple, economic and green synthesis procedure is realized compared to other procedures reported in the literature. In addition, the as-prepared mesoporous MnO2 exhibits high-performance in electrochemical capacitors.
(Invited) Advanced Materials for Electrochemical Systems
Authors: Li Dongguo , Kang Yijin , Strmcnik Dusan , Markovic Nenad M , Stamenkovic Vojislav
Published: February 2020

Fundamental understanding of processes that are relevant for energy conversion and storage have been in the research focus that will be presented.  Atomic scale insight at the electrified solid-liquid interfaces is considered critical in further advancement of materials that could be implemented in electrochemical systems such as electrolyzers, batteries and fuel cells. 

It has been demonstrated that fine tuning of the surface properties can lead towards unprecedented improvements in their functional properties that are relevant for electrochemical technologies.  This presentation will address unique research approach that is capable of revealing structure-function relationships in the design of tailored materials for electrochemical systems.  The following topics will be discussed:  well-defined materials obtained by varying their surface structure, composition profile and electronic properties; atomic/molecular insight into electrified solid-liquid interfaces; modeling of electrochemical systems; identification of the active and the most vulnerable surface sites under reaction conditions; insight into chemical nature between the surface atoms, reactants, and molecular species in the electrolyte; engineering of advanced nanomaterials with desired size, shape and composition profile; ex-situ and in-situ characterization of tailored nanostructured electrochemical interfaces.

This synergistic approach encompasses highly diverse experimental and theoretical methods and has been proven to serve as a foundation in the development of novel materials with advanced properties.
Understanding on Electrochemical Structure of Low Temperature Proton Exchange Membrane Fuel Cells
Authors: Andersen Shuang Ma
Published: February 2020

Membrane electrode assembly (MEA) is the heart of a PEM fuel cell. In the catalyst layer, the electrochemical reactions only happen on the catalyst, which has simultaneous access to proton, electron and gas. Therefore, it is also called three-phase boundary (TPB). The larger and more stable TPB, the better performance of the cell will be.

Different from fundamental material studies, catalyst performance was evaluated based on the electrode structure point of view. Interaction between catalyst or catalyst support with Nafion ionomer was systematically investigated through an adsorption isotherm study[i], [ii]. Various adsorption strengths were observed depending on the surface properties of the absorbent. The structure of the resulting catalyst-ionomer-electrode (CIE) and the corresponding degradation pattern due to accelerated stress test were monitored with X-ray photoelectron spectroscopy[iii]. Based on our earlier studies[iv], the polymer phase can directly influence the other two phases in the electrode. Degradation of the polymer / corruption of the interphase structure in the catalyst layer can be the bottle neck of the overall challenge. Corresponding strategy for the improvement is proposed.

[i] Carbon, 71 (2014) 218-228.

[ii] J. Phy. Chem. C, 118 (2014) 10814–10823.

[iii] J. Power Sources, 274 (2015) 1217-1223.

[iv] ACS Appl. Mater. Interfaces 6 (2014) 16565−16576.
Preparations of Highly Stable RuxCo/CNTs Electrocatalysts for Oxygen Reduction Reaction
Authors: Gao Dong , Li Hengyi , Cheng Xuan
Published: February 2020

The carbon nanotubes (CNTs) supported ruthenium cobalt alloy (Ru
x
Co) nanoparticles (Ru
x
Co/CNTs) were prepared with different Ru/Co ratios (x=Ru/Co=0.5, 1.0, 2.0, 3.0) by impregnated method using less expensive metal chlorides (CoCl2 and RuCl3) as precursors. The heat treatments were carried at the temperatures of 300°C, 400°C, 500°C and 700°C for comparison. It was found that the as prepared Ru
x
Co nanoparticles were uniformly dispersed on the CNTs support and exhibited mainly hexagonal alloyed phase with small amounts of metal oxides being presented at the surface. The mean particle sizes were smaller than 10 nm and the potentials corresponding to oxygen reduction reaction (ORR) were 0.67~0.73 V with the electron transfer numbers (n) of 3.0~4.0 by varying the Ru/Co ratios from 0.5 to 3.0. The amounts of Co presented in the alloy significantly influenced the growth of Ru
x
Co nanoparticles and the defects of CNTs support. The best ORR activity with high stability in an acid solution was achieved with the Ru2Co/CNTs when heat-treated at 400°C under H2 for 2 h.
Surface Segregation and Inter-Diffusion of Cations and Impurities in Microelectrodes for Solid Oxide Fuel Cells and Electrolyzers
Authors: Téllez Helena , Druce John , Shi Yanuo , Kubicek Markus , Simrick Neil J. , Rupp Jennifer L. M. , Ishihara Tatsumi , Kilner John A.
Published: February 2020

The surface segregation and inter-diffusion of cations and impurities in La0.6Sr0.4Co0.8Fe0.2O3-δ (LSCF) micro-patterned electrode structures on a single crystal Zr0.84Y0.16O1.92(YSZ) electrolyte was investigated by high-resolution ion beam analysis (Time-of Flight Secondary Ion Mass Spectrometry and Low-Energy Ion Scattering). The outermost and near surface of these microelectrodes showed significant changes in the distribution of the cations and impurities after micro-patterning, annealing and electrochemical testing of the cells. As occurring for bulk LSCF ceramics, strong segregation of Sr towards the electrode surface is observed during annealing of the microelectrode, as well as due to the thermal treatments required for electrochemical measurements. This segregation might have a drastic effect on the surface oxygen exchange reaction as the electrochemically active transition metals (Fe, Co) are not directly exposed to the gas phase. Impurities, such as Si and Ca, are also observed at the annealed electrolyte surface. Furthermore, the microstructured electrode showed that impurities can also migrate between the different components (i.e. Na and Si impurities migrate from the electrolyte to the LSCF electrode, showing a “cleaner” surface after the thermal treatments).

This study has provided a further understanding of the migration and segregation of cations and impurities taking place in real devices, building upon previous studies performed on ceramics materials.

Figure 1
(Invited) Theoretical Approach for Understanding Oxygen Reduction at the Cathode Surface of Solid Oxide Fuel Cell
Authors: Koyama Michihisa , Ishimoto Takayoshi
Published: February 2020

Doped lanthanum cobaltite and its derivatives are used as cathode materials in solid oxide fuel cell (SOFC), thus the cathodic reaction mechanism has been extensively investigated. As results, it is generally accepted that the dissociative adsorption of oxygen at the cathode surface is one of rate-determining steps. Therefore, it is important to understand factors governing the surface kinetics. Preceding experimental and theoretical studies have pointed out the correlation between electronic structure of doped lanthanum cobaltites and oxygen dissociation properties on surface, formation energy of oxygen vacancy, and oxygen diffusivity [1-6]. In our preceding study [7], we focused on the change of spin states in LaCoO3 to have a basis for analyzing catalytic properties of the material at the operation temperature. Further analyses in collaboration with experimental observation have clarified the electronic properties of LaCoO3 at the operation temperature on the basis of density functional theory calculations taking into account the statistical thermodynamics [8]. 

 As an extension of our preceding studies, we will discuss how the electronic structure affects the surface kinetics in this study. We adopted the La0.5Sr0.5O3-δ as cathode material and prepared the (001) surface model with the LaO termination. The model consists of five layers with the total 48 atoms. For the electronic structure calculations, we used Vienna Ab initio Simulation Package (VASP) based on the density functional theory. U parameter is adopted as correction for electronic correlation calculation. We investigated the oxygen adsorption energy, vacancy formation energy and oxygen dissociation energy by changing the spin states of Co in La0.5Sr0.5O3-δ. We observed dependency of the calculated energies and the spin states. Based on the calculated properties, we will discuss the kinetic process of oxygen reduction at La0.5Sr0.5O3-δ surface together with the perspectives of future analysis. 

References

[1] Z. Chen, C. H. Kim, L. T. Thompson, and W. F. Schneider, Surf. Sci. 619, 71 (2014).

[2] A. M. Ritzmann, M. Pavone, A. B. Muñoz-Garcia, J. A. Keith, and E. A. Carter, J. Mater. Chem. A 2, 8060 (2014).

[3] W. T. Hong, M. Gadre, Y. Lee, M. D. Biegalski, H. M. Christen, D. Morgan, and Y. Shao-Horn, J. Phys. Chem. Lett. 4, 2493 (2013).

[4] S. Mukhopadhyay, M. W. Finnis, and N. M. Harrison, Phys. Rev. B 87, 125132 (2013).

[5] A. Kushima, S. Yip, and B. Yildiz, Phys. Rev. B 82, 115435 (2010).

[6] Y. Lee, J. Kleis, J. Rossmeisl, and D Morgan, Phys. Rev. B 80, 224101 (2009).

[7] T. Ishimoto, Y. Ito, H. Kohno, M. Koyama, ECS Trans., 57(1) (2013) 2655-2660.

[8] T. Ishimoto, Y. Ito, T. Tada, R. Oike, T. Nakamura, K. Amezawa, M. Koyama, submitted

Acknowledgement

The activities of INAMORI Frontier Research Center is supported by KYOCERA Corporation.