bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrodeposited ZnO-Based, Organic-Dye Sensitized Solar Cells: Advantages and Limitations
Authors: Canto Aguilar Esdras Josué , Rodríguez Pérez Manuel Jesús , García Rodríguez Rodrigo , De Denko Alexandra T. , Osterloh Frank E. , Oskam Gerko 
Published: February 2020

The dye-sensitized solar cell (DSSC) is one of the most promising third generation photovoltaic technologies, which nowadays shows conversion efficiencies as high as 14 %. The attractive qualities of DSSCs include promising efficiencies, but also the low cost projected for their large-scale production for niche applications, in particular, for semi-transparent windows and indoor lighting conditions. This implies the optimization of all processing steps and components used, and a better understanding of the mechanisms of generation and loss of electrons involved in the solar cell functioning. Based on these observations, we have selected ZnO as the electron transporting material, not only for its much better electrical properties (when comparing with the commonly used TiO2), but also for the simple synthesis methods by which it can be obtained, such as electrodeposition (a low temperature an scalable technique), which offers to move toward the fabrication of more economically profitable devices. Hence, part of this work presents a detailed study on the effect of the bath composition, additives and deposition conditions used on the morphological and structural features of materials electrodeposited from ZnCl2 and Zn(NO3)2 solutions.
The combination of this material with organic dyes with high absorption coefficient in the solar spectrum regime, promise an increase in cell current and voltage. For that reason, we have prepared solar cells with nanostructured, mesoporous ZnO films electrodeposited from an optimized aqueous ZnCl2 solution, an organic fluorenyl-thiophene dye (OD-8) as sensitizer, and an electrolyte solution with either the I-/I3
- or the [Co(2,2'-bipyridyl)3]2+/3+ redox couple. An improvement in efficiency may be expected, related to the more positive redox potential of the [Co(2,2'-bipyridyl)3]2+/3+ couple and faster dye regeneration kinetics, but this can only be achieved if the recombination rate at the semiconductor/electrolyte interface is sufficiently slow. Hence, we have evaluated the effect of CDCA (chenodeoxycholic acid) as coabsorbent in the dye solution, with the purpose to diminish the amount of uncovered area of the electrode surface, in order to minimize recombination. We use I-V curves in combination with intensity-modulated photovoltage spectroscopy, charge extraction measurements, and surface photovoltage spectroscopy to gain insight in the factors involved into the photochemical charge separation in ZnO-based organic-DSSCs.
Additively Manufactured Electrochemical Plating Enclosures
Authors: Thorpe Adam J , Arrington Christian L. , Pillars Jamin R. 
Published: February 2020

Additively manufactured plating enclosures can be used as a cheap alternative to traditional plating tanks and fixturing, which can reduce the volume of chemistry required, allow for complex fluid dynamics across the part surface, and offer the possibility of augmenting and tuning the thermal gradients and electrical fields surrounding the part. Selective tank geometries allow for electrodes that can be integrated or conformally shaped onto the enclosure. By allowing for such diverse electrode geometries, these enclosures create the possibility of near-uniform electric fields for complex parts, unique electrical contact mechanisms that can be integrated into the enclosure itself, as well as accurate and minimally invasive part fittings to maintain part alignment during the plating process.
Several commercially-available thermoplastics and photopolymers were analyzed for compatibility with a variety of chemistries commonly used in the electrodeposition processes. Preliminary testing and analysis of custom polymer plating enclosures was performed to demonstrate process viability. Parylene coatings can further increase the chemical resistance of the enclosure, leading to a wider range of chemistries which the custom polymer enclosures are resistant to. Further, polymer metallization and evaporation techniques offer the possibility of directly incorporating electrodes into the fixture itself, as well as for creating thermal contacts with external heat sources.
Together, these techniques create the possibility of creating more uniform parts and coatings, while reducing chemical waste, material and equipment cost, and development time for laboratory-scale electroplating processes.
Supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.
An Analysis of Transient Impedance-like Diagnostic Signals in Batteries
Authors: Teo Linnette , Pathak Manan , Kolluri Suryanarayana , Dawson-Elli Neal , Schwartz Daniel T. , Subramanian Venkat R. 
Published: February 2020

Electrochemical impedance spectroscopy (EIS) is an established technique for monitoring and testing of electrochemical systems, including batteries. Parameters related to electrochemical phenomena such as charge-transfer kinetics and mass transport can be estimated from the impedance response over a range of frequencies1.
The classical description for impedance of an electrochemical system, subjected to a periodic input perturbation, depends upon achieving a steady periodic output state2. However, there may be value in analyzing the joint time-frequency response of a dynamic impedance-like output signal under conditions that are not steady periodic3. For example, it has been shown that using a dynamic impedance-like response allows parameter estimation to be carried out in shorter times than waiting for a steady periodic state to be reached4. This may be particularly valuable for accessing low frequency (slow) phenomena such as thermodynamic and diffusion effects. As a result, dynamic impedance-like signals may be a valuable tool for real time diagnostics of battery degradation processes.
The objective of this study is to develop time and frequency dependent solutions for existing battery models to further investigate the full dynamic response of the system. Devan et al. has performed transient voltage analysis for a porous electrode model5 and short-time current density response for an intercalation particle model4. A comparison to the steady periodic response for parameter estimation and the choice of optimum frequencies for measurements will be explored. While the analysis will begin with a simple physics-based model, the goal is to develop a fast and efficient tool for porous electrode 2D models. In particular, the focus will be on the gain in estimating parameters with specific confidence intervals, and mechanism validation from using the transient data compared to steady state models.

References

Yu, B. N. Popov, J. A. Ritter, and R. E. White, Journal of The Electrochemical Society,
146, 8 (1999).

Ceder, M. Doyle, P. Arora, and Y. Fuentes, MRS Bulletin, 27, 619–623 (2002).

Doyle and J. Newman, in Tutorials in Electrochemical Engineering—Mathematical Modeling, edited by R.F. Savinell, J.M. Fenton, A.C. West, S.L. Scanlon, and J. Weidner (The Electrochemical Society, Seattle, 1999) p. 144.

Devan and R. E. White, Journal of The Electrochemical Society, 154(2007).

Devan, V. R. Subramanian, and R. E. White, Journal of The Electrochemical Society, 152 (2005).
Development of High Temperature Operation SiC Power Module
Authors: Sato Shinji , Kato Fumiki , Tanisawa Hidekazu , Koui Kenichi , Watanabe Kinuyo , Murakami Yoshinori , Sato Hiroshi , Yamaguchi Hiroshi 
Published: February 2020

We have developed a Silicon Carbide (SiC) power module that can operate at high temperatures up to 250 °C. Figure 1 shows the overview of the developed power module. The withstand voltage of the power module is 1200 V, two SiC - MOSFETs are built in, and it is a circuit composition of one phase of the power inverter. The two-layer SiC-Active Metal Brazed Copper(AMC) not only reduces the area of the power module but also reduces circuit inductance. In addition, this power module has a built-in snubber circuit that reduces the switching surge voltage of the SiC-MOSFET during high-speed switching.
Generally, when the power module is operated at a high temperature, the reliability such as occurrence of lowering of the main bonding strength of the power module is significantly reduced due to thermal deformation. In this power module, the main components of the module are joined using eutectic solder with a solidus line above 350 °C. Copper-tungsten (CuW) was selected as the base plate material. Since the Coefficient of Thermal Expansion (CTE) values of CuW and SiN - AMC are close, it is possible to reduce the stress applied to these joints when the temperature changes. In addition, CuW has excellent thermal conductivity and heat capacity and suppresses heat generation of SiC-MOSFET.
To evaluate the performance of this module, a switching test at 100 A was performed at 250 °C. The switching waveform is shown in Fig.2. The turn-off switching time tf was about 10 ns, and the switching surge voltage at that time was about 150 V. The turn-off switching waveform was almost the same from room temperature to 250 °C. As a result, it was shown that this power module can operate at 250 °C and the built-in snubber circuit works effectively at all temperatures.
Acknowledgement
This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), "Next-generation power electronics / Consistent R&D of next-generation SiC power electronics" (funding agency: NEDO).

Figure 1
In-Operando Observation of Lithium-Silicon Alloy Phase Propagation in Particle-Based Electrodes Using Nanoscale X-Ray Computed Tomography
Authors: Choi Paul , Litster Shawn 
Published: February 2020

Silicon (Si) is considered to be one of the most promising anode materials for next-generation lithium-ion batteries primarily due to its high theoretical specific capacity of up to 4200 mAh g-1 and its abundance in nature. However, the irreversible capacity loss and poor cycle life caused by the dramatic volumetric expansion of Si upon alloying with lithium (Li) (>300%) prevents practical implementation of anodes with high Si loading. A better understanding of the interactions between the electrochemistry and mechanical behavior of Si anodes during cycling is therefore needed to develop novel materials and electrode design that can efficiently accommodate the volumetric expansion. In addition, there are significant questions regarding the interactions of the Si with the surrounding carbon materials.
In this work, we use nano-resolution x-ray computed tomography (nano-CT) and an in-house micro-capillary sample cell to directly observe the cycling (lithiation/delithiation) process of Si particle-based electrodes as a function of time. We will show preliminary results on the effects of the electrode composition (Si particle size distribution, particle proximity, etc.) on the Li-Si alloy phase nucleation and propagation.
This material is based upon work supported by the National Science Foundation under Grant No. CBET-1705321. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
(Invited) The Paradox of High-Energy Density Materials for Li-Ion Batteries
Authors: Doublet Marie-Liesse , Saubanere Matthieu , Vergnet Jean 
Published: February 2020

Increasing the energy density of cathode materials is a central goal of the ongoing research in Li-ion batteries. This implies improving simultaneously the capacity and the potential of the materials used at the positive electrode of the electrochemical device. While the electrochemical potential is well controlled through an appropriate choice of the redox centre involved in the Li-driven electrochemical reactions, the increase of capacity appears more difficult to achieve without penalizing the material structural stability.[1-3] So far, materials showing the highest energy densities are the Li-rich layered transition metal oxides (LLOs) for which a cumulative cationic and anionic redox activity has been demonstrated. Ever since, numerous materials have been synthesized with various combinations of 3d, 4d, 5d or non transition metals [4-6] and different mechanisms have been proposed to rationalize their electrochemical activity vs. Li or Na with no real consensus about the directions to follow to overcome the structural instability that often comes along with the anionic process. In this paper, we review the different interpretations proposed in the literature to address the fundamental questions of increasing both the potential and the capacity of current positive electrodes with the hope that a common language will help in clarifying the relationship between the material electronic structure, the potential, the (extra)-capacity and the consequences of high-energy-density on the material structural stability. This unified picture highlights that a trade-off needs to be found for the development of high-energy-density materials for alkali-ion batteries.
References:
[1] Zhao, C., Wang, Q., Lu, Y., Hu, Y.-S., Li, B. & Chen, L. Review on anionic redox for high-capacity lithium- and sodium-ion batteries. J. Phys. Appl. Phys. 50, 183001 (2017).
[2] Yabuuchi, N. Solid-state Redox Reaction of Oxide Ions for Rechargeable Batteries. Chem. Lett. 46, 412
(2017).
[3] Li, B. & Xia, D. Anionic Redox in Rechargeable Lithium Batteries. Adv. Mater. 1701054 (2017).
[4] Yabuuchi, N., et al.. High-capacity electrode materials for rechargeable lithium batteries: Li3NbO4-based system with cation-disordered rocksalt structure. Proc. Natl. Acad. Sci. 112, 7650 (2015). Takeda N. et al. Journal of Power Sources 367, 122 (2017).
[5] House, R. et al. Lithium manganese oxyfluoride as a new cathode material exhibiting oxygen redox, Energy & Envir. Sci. Accepted (2018).
[6] Maitra, U; Oxygen redox chemistry without excess alkali-metal ions in Na2/3[Mg0.28Mn0.72]O2 Nat. Chem. 10 (2018) online.
[7] a) Saubanère, M., McCalla, E., Tarascon, J.-M. & Doublet, M.-L. The intriguing question of anionic redox in high-energy density cathodes for Li-ion batteries. Energy Env. Sci 9, 984–991 (2016).
[8] Xie, Y., Saubanère, M. & Doublet, M.-L. Requirements for reversible extra-capacity in Li-rich layered oxides for Li-ion batteries. Energy Env. Sci 10, 266–274 (2017).
Energy-Tuned Photoelectron Spectroscopy of Lithium-Ion Battery Cathodes: Revealing Oxygen Redox Activity and Investigating New Materials
Authors: Naylor Andrew , Maibach Julia , Källquist Ida , Makkos Eszter , Roberts Matthew R. , Younesi Reza , Hahlin Maria , Brandell Daniel , Islam M. Saiful , Bruce Peter G. , Edström Kristina 
Published: February 2020

With the quest to find better performing electrode materials for Li-ion batteries becoming hotter by the day, advanced spectroscopic techniques are being employed to better understand the processes at interfaces of the battery components and deeper in the bulk of the active materials. One of those techniques is energy-tuned photoelectron spectroscopy (XPS), typically performed at synchrotron facilities, which offers the possibility to irradiate a sample with soft or hard X-rays and detect electrons with kinetic energies up to 10,000 eV. This builds up a true surface vs. bulk picture including formation of solid electrolyte interphases on anodes, oxidation products on cathodes and redox activity in the bulk of particles, such as that of transition metals or oxygen.
A class of cathode materials which are of particular interest are those exhibiting oxygen redox activity, providing capacity beyond that of the traditional transition metal redox. We have investigated a number of such lithium-excess Ni, Co, or Mn oxide materials, which are known to exhibit oxygen redox, by energy-tuned XPS. The analysis reveals important details of the differences between surface and bulk, which DFT calculations have helped rationalise.
Lithium-rich oxyfluorides (Li2MO2F where M = V, Fe, Mn etc.) are another class of material that have gained increased attention in recent years. These cathode materials have promising potential with high theoretical capacities (420 mA h g-1 for Li2VO2F) at ~2.5 V with minimal volume expansion, but suffer from local structural instabilities. We are using energy-tuned XPS (Figure 1) to study their degradation mechanisms and how they might be mitigated using transition metal doping or coatings.
Figure 1. O 1s and V 2p XPS spectra of a Li2VO2F electrode for the EU H2020 ‘LiRichFCC’ project, at two photon energies: 2005 eV (black, top), 6015 eV (red, bottom).

Figure 1
Surface-Modified Ni-Rich Layered Cathode Materials Via Li-Reactive Inorganic Coatings
Authors: Becker Dina , Schmuch Richard , Winter Martin , Placke Tobias 
Published: February 2020

In recent years, the demand for lithium ion batteries (LIBs) significantly increases due to the wide range of application, from consumer electronics to automotive industry. The improvement of the LIB’s energy density is one of the key factors to the mass market penetration of electric mobility. Currently, LIBs are applied in hybrid (HEV), plug-in hybrid (PHEV) and fully electric (EV) vehicles. Particularly, layered lithium Ni-Co-Mn oxides LiNixCoyMnzO2 (NCM, x + y + z = 1) cathode materials are the most promising candidates for LIBs due to their high capacity, lower cost and enhanced stability compared with LiCoO2.[1]

Although the state-of-the-art NCM cathode material is NCM-523, the trend is going towards a higher energy density. Recently, the focus of research is on the cathode materials with high nickel content. For example NCM-811 with a Ni content of 80% can deliver a discharge capacity of 200 mAh/g at 4.3 V. At the same time, the high Ni content causes some disadvantages, such as an unstable electrode structure and rapid capacity fading.
One of the challenges is the synthesis and stabilization of Ni-rich materials. In order to avoid cation mixing, an excess of lithium must be ensured. Consequently, the unreacted lithium on the surface of the active material can react with water and CO2 from the air. As a result of the contamination, LiOH and L2CO3 are formed on the surface of the active material. These residues can form an insulating layer of LiF in contact with the electrolyte, which leads an increased internal resistance of the electrode. Furthermore, the highly reactive Ni4+ ions in the delithiated state of the electrode of Ni-rich cathode materials can oxidize the electrolyte and result in active material loss.[2]

In this contribution, we investigate the effect of surface modification of NCM-811 via an inorganic coating on the electrochemical performance. The inorganic coating acts as protective layer on the surface of the active material, preventing the direct contact of the cathode material with the electrolyte. Moreover, it suppresses the side reactions on the particle surface. The effect of the coating on the structural and electrochemical properties was investigated in NCM-811/graphite full cells. The cells with coated electrodes were significantly improved with respect to their long-term cycling performance compared to the uncoated electrodes (Figure 1).
[1] S.-K. Jung, H. Gwon, J. Hong, K.-Y. Park, D.-H. Seo, H. Kim, J. Hyun, W. Yang and K. Kang, Advanced Energy Materials, 2014, 4, 1300787.
[2] W. Liu, P. Oh, X. Liu, M.-J. Lee, W. Cho, S. Chae, Y. Kim and J. Cho, Angewandte Chemie International Edition, 2015, 54, 4440-4457.
Figure 1: Cycling performance of uncoated and coated NCM-811/graphite LIB full cells at room temperature using a voltage window of 2.5 – 4.3 V. Three formation cycles at 0.1C and following cycling at 0.5C rate.

Figure 1
Luminescent Properties of Twelve Novel MOFs Based on 2,7-Bis(4-benzoic acid)-N-(4-benzoic acid)Carbazole and Their Application in Ni2+ Ions Concentration Sensing and Vis-NIR Fluorescent Materials
Authors: Chen Dong-Hui , Wu Xin-Tao 
Published: February 2020

I will present twelve novel luminescent metal-organic frameworks, TCZ-001 – TCZ-005 and TCZ-M (M = Nd, Sm, Eu, Gd, Tb, Dy, Ho). All of the twelve MOFs were assembled from a novel luminescent carbazole-based ligand, 2,7-bis(4-benzoic acid)-N-(4-benzoic acid)carbazole. TCZ-001, TCZ-003 and TCZ-004 show a remarkable response to the Ni2+ concentration in DMA, H2O or EtOH. Some of Zn2+ ions were replaced by Ni2+ ions and the rate of the transmetalation depended on the concentration of Ni2+ ions. Also, changing part of the metal node would transform the colour of emitted light. Additionally, the colour of the luminescence displays a linear correlation with the Ni2+ concentration range from 0.005 M to 0.35 M (mol·L−1). Besides selective sensing of Ni2+, TCZ-004 can also be utilized to detect Eu3+ ions in DMA solution. Thus, several potential sensory probe materials for Ni2+ and Eu3+ detection in DMA solution have been obtained. As to TCZ-M (M = Nd, Sm, Eu, Gd, Tb, Dy, Ho), X-ray crystallography showed that all of them are isomorphous and possess a 3,6-connected three-dimensional (3D) framework with a point symbol of {4·62}2·{42·610·83}. The photoluminescence measurement indicates that TCZ-Eu shows reddish-orange emission bands and TCZ-Sm shows both visible and near-infrared (NIR) emission bands. In addition, the isomorphous structure of TCZ-M (M = Nd, Sm, Eu, Gd, Tb, Dy, Ho) provide the potential to fabricate multicolour luminescent materials.
[1] D.-H. Chen, L. Lin, T.-L. Sheng, Y.-H. Wen, S.-M. Hu, R.-B. Fu, C. Zhuo, H.-R. Li and X.-T. Wu, CrystEngComm, 2017, 19, 2632.
[2] D.-H. Chen, L. Lin, T.-L. Sheng, Y.-H. Wen, X.-Q. Zhu, L.-T. Zhang, S.-M. Hu, R.-B. Fu and X.-T. Wu, New J. Chem., 2018, 42, 2830.
Local Conductivity Measurements of Metal-Organic Layers By Conductive AFM on Micropatterned Electrodes Produced By Metal Polymer Blend Lithography
Authors: Walheim Stefan , Redel Engelbert , Wöll Christof , Schimmel Th. 
Published: February 2020

The electronic characterization of thin metal-organic layers like SURMOFs is often difficult, since transport contributions in global measurements may be dominated by pin holes with direct electrical contact of top and bottom electrodes. In addition, these measurements average over a wide surface area and no local information can be derived.
Using an AFM with a metalized tip, local measurements of the conductivity and I-V characteristics can be extracted. But these measurements have three important draw backs: (I.) the small contact area in the 20-nm-range restricts the range of measureable conductivity due to a limited sensitivity of the electronic amplifiers, (II.) the electric field underneath the AFM Tip is rather inhomogeneous and current contributions in-plane and off-plane are mixed and (III.) the contact area varies individually from tip to tip and with the applied force.
With our approach of polymer blend lithography (PBL) we produce billions of small metal islands with diameters in the range of a few hundred nanometers up to a few microns with a simple process (Metal-PBL) [1]. These Islands serve as planar top electrodes, which we can address individually with the AFM-tip in a highly reproducible way. Using a set of AFM scans in the same region, a manifold of data sets concerning conductivity and I-V characteristic can be extracted, since many individual islands are measured simultaneously.
1.: Polymer blend lithography for metal films: large-area patterning with over 1 billion holes/inch2: C. Huang, A Förste, S. Walheim, and Th. Schimmel: Beilstein Journal of Nanotechnology 2015, 6, 1205–1211