bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ageing Induced Changes in a Lithium-Ion Battery Analysed By Correlating EIS Simulations and Experiments
Authors: Wolff Nicolas , Heinrich Marco , Röder Fridolin , Seitz Steffen , Krewer Ulrike 
Published: February 2020

Electrochemical Impedance Spectroscopy (EIS) is a widely-used measurement technique to analyse properties of Lithium-Ion Batteries, since impedance spectra are sensitive to changes of battery parameters like surface layer thicknesses, material conductivities and reaction rate constants. Physico-chemical models of Lithium-ion batteries are a useful tool to correlate changes of measured impedance spectra to changes of Lithium-ion battery parameters. We will present a model based on the work of Doyle and Newman [1] extended with double layers and aging processes to simulate EIS during degradation of a Lithium-ion battery. The model has been used to simulate impedance spectra and to fit them to measured impedance spectra with a linear least square fitting tool.
Within this study, we provide fits of a physico-chemical battery model to cycle aged cell EIS measurements. Achieving reliable results is only possible if measured and simulated impedance spectra meet linearity, causality and stationarity requirements for EIS. Various ageing induced changes in the charge distributions at the anode surface interphases have been assumed and compared under the preconditions mentioned above. These ageing model approaches differ in their passivated specific surface area for reactions and double layers. Each of these ageing models aim to describe the effect of the Solid Electrolyte Interphase (SEI) on the impedance spectrum during cyclical ageing. It is assumed that the aging model providing the best possible agreement between simulation and experiment for all spectra of a cycled Lithium-ion battery is also the best approximation of the real physical behavior. We will show that the SEI influences the reaction and the double layer at the anode/SEI interphase as well as the reaction at the SEI/electrolyte interphase. Figure 1 shows a good agreement between experiment and simulation results for the assumed aging model. Relative deviations between measurements and simulations, e.g. in the second semicircle, can be reduced to 10
-

6.

References:

[1] M. Doyle, T.F. Fuller, J. Newman, J. Electrochem. Soc. 140 (1993) 1526

Figure 1
Morphology Impact By Graphite Variations on Silicon-Alloy Negative Electrodes for Lithium-Ion-Batteries
Authors: Becker Lisa Kathrin , Figgemeier Egbert , Sauer Dirk Uwe 
Published: February 2020

Today, lithium-ion batteries represent the most widely used secondary battery. They play an important role in the further development of electric mobility or mobile applications (smartphones, laptops). They are characterized by their high energy and/or power density. In order to meet the needs of the future, higher energy and power densities, longer cycle life and higher safety standards are required. Due to their wide range of applications, the expectations of their lifetime and performance are increasing. The energy density is a critical factor for future energy storage systems in mobile applications. In order to achieve higher energy densities, an anode material must combine high specific capacities with high columbic efficiencies.
Due to its low average voltage, low voltage hysteresis, good rate capability, low irreversible capacity, low volume expansion during lithiation causing excellent cycle life, graphite has been the material of choice as anode material [1].
However, the low theoretical specific capacity limits the application potential of graphite anodes. With its high theoretical specific capacity, silicon is the most promising anode material. However, the use of pure silicon is severely restricted by its mechanical behavior during charge/discharge cycling. Crystallization effects and massive volume changes during cycling seriously limit the cycle life of battery cells with Silicon as main component [2]. Therefore, Silicon/graphite blends seem to be the preferred route towards high energy anode formulations with relevant life times.
In this context it is essential to understand the interplay between the various components of the blend electrodes for optimized performances, which is addressed in the current publication.
Different industrially available graphites (KS6, KS6L. MCMB, LFP2, ECC Graphit) and a Silicon alloy material were used for anode preparation in order to investigate their structural morphologies and electrochemical performance of the resulting electrodes. The electrodes were tested in coin cell assemblies and charged and discharged at various rates. The morphologies of fresh and aged electrodes were investigated by means of optical and electron microscopy. Furthermore the volume changes of cells were monitored in order to relate it with the morphological appearance, porosity and graphite type.

References

[1] M. N. Obrovac and V. L. Chevrier, “Alloy Negative Electrodes for Li-Ion Batteries,” Chemi. Rev., pp. 11444–11502, 2014.
[2] W. J. Zhang, “A review of the electrochemical performance of alloy anodes for lithium-ion batteries,” J. Power Sources, vol. 196, no. 1, pp. 13–24, 2011.
Engineering Solid State Batteries: A Structural, Mechanical and Interface Engineering Adventure
Authors: Rupp Jennifer L. M. , Pfenninger Reto , Struzik Michal 
Published: February 2020

The next generation of energy storage and sensing devices may largely benefit from fast Li+ ceramic electrolyte conductors to allow for safe and efficient batteries and real-time monitoring anthropogenic CO2. Recently, Li-solid state conductors based on Li-garnet structures received attention due to their fast transfer properties and safe operation over a wide temperature range. Through this presentation basic theory and history of Li-garnets will first be introduced and critically reflected towards new device opportunities. Central to our research is the fundamental investigation of the electro-chemo-mechanic characteristics and design of electrode-Li garnet interfaces to new battery architectures. Here, we firstly present new Li-garnet battery architectures for which we discuss lithium titanate and antimony electrodes in their making, electrochemistry and assembly to full battery architectures1-4. Secondly, new insights on processing of Li-garnet thin films are presented based on first developed field maps for pulsed laser deposition processing. Here, the thermodynamic stability range of maximum Li-conduction, phase and nanostructure is discussed using high resolution TEM studies, near order Raman investigations on the Li-bands and electrochemical transport measurements. The insights provide novel aspects of material structure designs for both the Li-garnet structures (bulk to films) and their interfaces to electrodes, which we either functionalize to store energy for next generation solid state batteries.
1) Interface‐Engineered All‐Solid‐State Li‐Ion Batteries Based on Garnet‐Type Fast Li+ Conductors
J van den Broek, S Afyon, JLM Rupp
Advanced Energy Materials 6 (19), 2016
2) A shortcut to garnet-type fast Li-ion conductors for all-solid state batteries
S Afyon, F Krumeich, JLM Rupp
Journal of Materials Chemistry A 3 (36), 18636-18648, 2015
3) On the chemical stability of post-lithiated garnet Al-stabilized Li 7 La 3 Zr 2 O 12 solid state electrolyte thin films
M Rawlence, I Garbayo, S Buecheler, JLM Rupp
Nanoscale 8 (31), 14746-14753, 2016
4) Investigating the all-solid-state batteries based on lithium garnets and a high potential cathode-LiMn1.5Ni0.5O4.
C Hänsel, S Afyon, JLM Rupp
Nanoscale, in press 2016
All Solid-State Thin Film Microbatteries Using Bismuth or Antimony As Anode Material
Authors: Larfaillou Séverin , Bailly Nicolas , Boissel Jean-Marc , Porthault Hélène 
Published: February 2020

Thin film all-solid-state secondary microbatteries are extensively studied since the 1990’s [1-3]. These systems present specific features such as reduced surface, high thermal resistance, excellent cycle life, absence of liquid electrolyte, etc. that make them the most suitable energy sources for some emerging applications (real time clock, medical implants, secured smart cards, etc.). All-solid-state microbatteries are realized by successive deposition of thin films with a total thickness of less than 20 µm. The corresponding manufacturing steps are mainly carried out using physical vapor deposition processes such as thermal evaporation or sputtering, which are commonly used in the microelectronics industry. Then, microbattery systems need to tolerate microelectronics constraints, namely the solder reflow (T°C > 260°C) and short-circuits during manufacturing. Lithium metal anode is then no longer satisfactory.
In this work, we study two original anode materials: antimony Sb and bismuth Bi. In a first step, the study was focused on half cell composed of Sb or Bi versus lithium metal with LiPON as electrolyte. Thin film materials exhibit two large plateaus around 1V (Fig.1) which were previously reported for bulk materials [4-5]. Bi and Sb thin films also exhibit good electrochemical performance (capacity retention upon cycling and high C-rate, etc.). Materials were then integrated in full cell configuration: LiCoO2/LiPON/Sb or Bi to develop 3V-microbatteries. The main difficulty in Li-ion configuration is to obtain the good cathode/anode capacity balance. At first, a theoretical study was done to determine the influence of under- or over-balance. Afterwards, in the first realized systems, a low initial capacity and a large capacity loss are observed, mainly due to the poor LiPON/anode interface (Fig.2). Good cycling results were then obtained with an improvement of this anode/electrolyte interface (Fig.3). This system exhibits specific capacity close to the LiCoO2 vs Li one and the lower 3V potential needed for microelectronics application. This lithium-ion system can also tolerate short-circuit without any degradation of active materials and be heated beyond the solder reflow temperature (260°C) due to the absence of metallic lithium.

The authors thank EnSO project for financial support. EnSO has been accepted for funding within the Electronic Components and Systems For European Leadership Joint Undertaking in collaboration with the European Union's H2020 Framework Program (H2020/2014-2020) and National Authorities, under grant agreement n° 692482.

[1] Bates et al., J. Power Sources, 54 (1995) 58-62.
[2] Bates et al., Solid State Ionics, 135 (2000) 33-45.
[3] Fleutot et al., J. Power Sources, 196 (2011) 10289-10296.
[4] Aldon et al., J. Power Sources, 119-121 (2003) 585-590.
[5] Xianming et al., J. Power Sources, 104 (2002) 90-96.

Figure 1
Fluoride Phosphors with Mn4+ Ions: Relations between Structure and Emission Spectra
Authors: Brik Mikhail G. , Srivastava Alok M 
Published: February 2020

The search for new phosphor materials that can be excited by blue LED and emit in the red spectral range is a very important for development of white LED with high color rendering index and suitable color correlated temperature for emission either of cold or warm white light.
Fluoride materials like K2SiF6, Na2GeF6 etc are suitable candidates for this role. High degree of iconicity of chemical bonds in fluorides ensures a weak nephelauxetic effect and results in shifting of the Mn4+ emission to shorter wavelengths. In the present work we consider how the structure of the fluorides affects the manganese emission wavelengths. Such factors as geometry of the fluorine octahedra around the Mn4+ ions, chemical bond lengths, angles between the chemical bonds, mutual arrangements of the octahedra (either they are aligned or tilted with respect to each other), the nature of chemical bonds with the ions from the second coordination sphere, polarizability of the chemical bonds etc are all very important for the formation of spectroscopic properties of the Mn4+ ions. Thus, they all should by analyzed carefully before making a final conclusion about suitability of a particular fluoride phosphor for applications.
Investigation on Structure-Energy Relationship for Ce3+ Coordinated with Six or Eight Oxygen Ions Based on First-Principles Calculations
Authors: Ogasawara Kazuyoshi 
Published: February 2020

As a red phosphor to improve the color rendering index of white LEDs, (Sr,Ca)AlSiN3:Eu phosphor is widely used. However, since the production cost of this phosphor is high, cheaper alternative is strongly desired. As an alternative, Mn4+-doped fluoride phosphor has been recently put into practical use [1]. In the case of oxide host, however, the shortest emission wavelength reported for Mn4+ is ca. 650 nm [2] which is still longer than 630 nm required for the red phosphor for white LEDs. Therefore, establishment of a design guideline to decrease the emission wavelength for Mn4+-doped oxide phosphor is an important issue. In order to provide such information, we have recently constructed the energy level diagrams and maps for Mn4+ in oxides based on first-principles calculations [3]. On the other hand, Ce3+ phosphor is also a candidate for the red phosphor for white LEDs. In this case, the emission wavelength is much shorter than 630 nm in the case of oxide host. Therefore, a design guideline to increase the emission wavelength is required. Recently an emission at ca. 600 nm was reported for Ce3+ at a six-coordination site in Sr6Y2Al4O15 [4]. In this crystal, there are several sites which can be occupied by Ce3+. However, only Ce3+ at the six-coordination site shows red emission, while Ce3+ at eight- or nine- coordination sites show blue emission. In this work, in order to clarify the effect of local structures such as coordination number, bond length, and symmetry on the energy levels of Ce3+, first-principles relativistic molecular orbital calculations were performed for model clusters with various local structures, and the energy level diagrams and maps were constructed.
As model clusters, CeO6
9- and CeO8
13- clusters with Oh or D4h symmetries were constructed. The first-principles relativistic molecular orbital calculations were performed using the relativistic SCAT code [5]. The calculations were performed for clusters with gradually changed bond lengths and bond angles. Various energy level diagrams and maps depending on the bond length and the bond angle were constructed by connecting the obtained orbital energies.
The energy level diagram for CeO6
9- cluster with Oh symmetry shows that both the crystal field splitting of 5d level and that of 4f level increase as the bond length decreases. As a result, the 4f level and 5d level begin to overlap at ca. 1.9 Å. The relationship between the 4f-5d transition energy and the local structure was also clarified based on various energy diagrams and maps. Such information would be useful for the theoretical search of the novel Ce3+-doped oxide red phosphor for white LEDs.
References
[1] J. E. Murphy et al., SID 2015 DIGEST, 927 (2015).
[2] M.H. Du, J. Mater. Chem., C2, 2475 (2014).
[3] K. Ogasawara et al., ECS J. Solid State Sci. Technol., 5, R3191 (2016).
[4] Y. Kawano et al., Opt. Mater. Express, 4, 1770 (2014).
[5] A. Rosen et al., J. Chem. Phys., 65, 3629 (1976).
(Invited) Cr3+ and Mn4+: Dopants for Near-Infrared Emitting Persistent Phosphors
Authors: Poelman Dirk , De Clercq Olivier Q , Du Jia Ren , Verfaillie Gwenny Veronique , Korthout Katleen 
Published: February 2020

Since it was realized a few years ago that near-infrared emitting persistent or ‘glow-in-the-dark’ phosphors could be used for medical imaging applications, there is an active research interest in this class of compounds [1]. Persistent phosphors having an emission spectrum in the wavelength range between 650 and 950 nm, in the so-called first tissue transparency window, can be injected and applied as diagnostic and therapeutic agents. To this end, the afterglow should be bright and long enough, and the injected particles should be bio-compatible.
While most of the persistent phosphors for visible light are based on Eu2+ doped compounds, most materials for near-IR are based on emission from Cr3+ ions [2]. Depending on the host material and the corresponding dopant-lattice interactions, Cr3+ shows sharp emission features due to the 2E-4A2 transition (usually accompanied by phonon side-bands), a broad emission band attributed to 4T2-4A2 or a combination of both. In this work, we focus on LiGa5O8as a host lattice for the Cr ions, an inverse spinel compound where the Ga-ions occupy both tetrahedrally and octahedrally coordinated lattice sites. Using a combination of x-ray absorption and magnetic resonance measurements, the incorporation of Cr in the lattice was studied. In addition, the effect of co-dopants – increasing the number of trap levels for energy storage – on the afterglow characteristics was investigated.
Next to Cr3+, Mn4+ is a very promising dopant for near-IR persistent luminescence. The ion’s electronic configuration is identical to that of Cr3+, therefore the absorption and emission characteristics are also very similar. Mn4+ is currently a popular dopant for red-emitting LED phosphors, but has hardly been considered as a near-IR dopant [3]. The challenge here is to incorporate the ion in its 4+ valence state in the host, which requires the necessary precautions or charge-compensating co-dopants. In the present work, we selected the perovskite LaAlO3 as the host for Mn4+. The afterglow of this material is limited by the limited incorporation of Mn in its 4+ state in the host. The latter is however strongly improved by co-doping with ions with a lower valence state for charge compensation.
[1] Q. le Masne de Chermont et al., Nanoprobes with near-infrared persistent luminescence for in vivo imaging. Proc. Natl. Acad. Sci. 104 (2007) 9266–9271.
[2] P.F. Smet, K. Van den Eeckhout, O.Q. De Clercq, D. Poelman. “Persistent Phosphors.” In Handbook on the Physics and Chemistry of Rare Earths, Including Actinides, ed. Jean-Claude Bünzli and Vitalij K Pecharsky, 48 5 (2015) 1–108. Amsterdam, The Netherlands: Elsevier.
[3] R. Cao et al. , Synthesis and photoluminescence properties of LaAlO3:Mn4+, Na+ deep red-emitting phosphor, Appl. Phys. A 122 (2016) 299.

Figure 1
Transparent Ce,Sm:TAG Luminescent Ceramics for High Power Blue Laser Driven Lightning and Display Technologies
Authors: Balci Mustafa H , Chen Fan , Cunbul Ahmet Burak , Svensen Oyvind , Akram Muhammad Nadeem , Chen Xuyuan 
Published: February 2020

Phosphor converted warm white light with high luminous efficacy and color-rendering index is crucial for the future of blue laser driven display technologies. Particularly in projection design where the high power (over 150 W) blue laser source is focused on the phosphor, the ideal phosphor candidate has to provide better conversion efficiency; longer lifetime (20000 hours) and lower thermal overheat. Conventional Ce:YAG suffers from efficient green and particularly red emission. Tb and Sm, known as green and red line emitters, respectively, can improve the color quality drastically. Ce, Sm: TAG ceramic powders were synthesized through spray pyrolysis from nitrate salts. Transparent ceramics has been produced via spark plasma sintering. Their phase compositions and structure parameters were checked by X-ray diffraction. The luminous properties of the transparent ceramics are improved when compared to the commercial phosphor wheels (Ce:YAG). Transparent ceramic exhibited broad emission with improved green and red region of the visible light compared to conventional Ce:YAG phosphor. Balanced Sm3+, Ce 3+admixture into the TAG lattice provided excellent color coordinates and CRI for the phosphor for warm white light illumination. Optical and luminescence characteristics were investigated throughout absorbance, excitation and, emission spectra with temperature dependence. Luminous efficacy over 250 lm/W with correlated color temperature (CCT) ~3800 K, color rendering index (CRI) >80 are achieved. The high-power blue diode laser driven temperature increase versus luminous efficacy and quantum efficiency is discussed. The results indicate that Ce, Sm:TAG transparent ceramics can serve as potential phosphors candidates for high-power blue diode laser driven display technologies.
Investigation of Blue Excitation Dependent Conversion Efficiency in Phosphors for High Luminance Applications: Part 2
Authors: Raukas Madis , Avallon James , Kelso John , Lenef Alan 
Published: February 2020

This study is a continuation of work discussed earlier [1]. The efficiency of high luminance semiconductor pumped phosphor sources depends not only on efficient generation of primary radiation from the semiconductor (LEDs or laser diodes), but also strongly on the conversion material which is often pushed to optical and thermal limits. Such conversion materials are typically operating upon high excitation flux and thermal load and nearly always exhibit sublinear behavior in output at high incident fluxes, due to several reasons. We have separated contributions from thermal and non-thermal quenching mechanisms, and in particular investigated phosphor saturation, or excitation quenching, in the converted light output as a function of blue pump intensity. It is important to distinguish between the true loss mechanisms (for example via Auger-like or excited state absorption processes) and the reduction in converted output due to increased transparency for the pump light (e.g. activator ground state depletion). The behavior of measured conversion efficiency as a function of excitation intensity is discussed in the context of parameters like temperature, activator concentration and excited state lifetime or host lattice. An updated model describing the observed dependencies in different luminescent systems (e.g. Ce3+ and Eu2+ based) is reviewed.
[1] M. Raukas, J. Avallon, J. Kelso, A. Lenef, 230th ECS Fall Meeting (PRiME 2016), Honolulu, HI, Oct 2-7, 2016.
Rare Earth Doped Nanocrystalline Anatase Powders: Structural, Morphological and Optical Properties
Authors: Đorđević Vesna , Milićević Bojana , Dramićanin Miroslav 
Published: February 2020

Titanium dioxide (TiO2) is a wide band gap semiconductor which is used in many applications for decades. Its technical application highly depends on its crystalline structure and morphology. Because of its high photocatalytic activity, anatase is preferred TiO2 form in many applications such as photocatalyst for air and water splitting and purification. TiO2 is also considered as a good host candidate for doping with optically active rare earth ions (RE) for potential application in phosphor materials since it has wide band gap and good thermal and mechanical properties. Sol-gel method is the most used wet chemical method in preparing nano TiO2. When doped with RE(III) crystallinity is highly affected by the RE(III)-Ti(IV) ion mismatch which impact structural, morphological and optical properties.
Our goal was to investigate how doping with various rare earth (RE) ions influence crystallographic, morphological and optical properties of sol-gel synthesized nanocrystalline TiO2. To draw the conclusions, fixed content of RE was kept trough all samples, where RE= Pr, Nd, Sm, Eu, Dy, Tb, Ho, Er and Tm. X-ray diffraction measurements showed decrease of crystallite size from 150 Å for the undoped sample to 70 Å for Nd doped sample, while BET measurements showed an increase of specific area from 10 to 100 m2/g for Nd doped sample. Transmission electron microscopy showed densely aggregated crystalline nanoparticles of irregular shapes, dimensions of about 10-20 nm in size. Diffuse reflectance measurements showed small difference in optical absorption thresholds due to modifications of materials density of states after incorporation of trivalent rare earth ions. Photoluminescence measurements showed efficient emission in the case of doping with the following RE(III) ions: Nd, Sm, Eu, Dy, Ho, and Er, while luminescence of low intensity is detected for: Pr, Tb, and Tm. Basic assessment on photocatalytic activity based on MO degradation was performed and when compared to the undoped sample, photocatalytic performance of nanopowder improves with addition of RE in small concentrations except for Pr and Tb ions.