bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water-Splitting for Solar Fuel Devices
Authors: Haro Marta , Guerrero Antonio , Gimenez Sixto , Bisquert Juan 
Published: February 2020

Social environmental concerns about global warming and CO2 emissions provide the stimulus to find the way to replace fossil fuels by solar fuels. In this context, sustainable energetic schemes should be based on the conversion of abundant energy-poor molecules (such as H2O) into energy-rich molecules (as for example H2) using sunlight as the energy source. This solar fuel can be easily stored, transported and used upon demand in fuel cells, where the reverse reaction takes place to convert chemical energy into electricity. This is one of the key challenges of the twenty-first century and multidisciplinary work is needed to succeed in transforming the theory into practice.To achieve a practical technology, low-cost materials and earth-abundant catalysts are required to be used for both reactions (water splitting and H2 oxidation into water). In the present talk, we report the production of solar fuels with low-cost materials based on organic chemistry (3). The synthetic versatility of these materials and understanding of the energetic aspects provides the design rules to extract the generated photocurrent in the organic blend to the electrolyte solution in the scale of mA·cm-2. For technological application, the rational design of the harvesting light material (the organic blend), the interfacial selective layers (hole and electron selective layers) and the catalyst are equally important. Herein, the study of the electron selective layer and catalyst (noble-metal free) are researched towards optimising both H2 production rate and stability in these devices.
References:
[1] H. B. Gray, Nature Chem. 1, 7 (2009)
[2] S. W. Cha, W. Colella, F. B. Prinz, Fuel cell fundamentals New York: John Wiley & Sons (2006)
[3] A. Guerrero, M. Haro, S. Bellani, M. R. Antognazza, L. Meda, S. Gimenez, J. Bisquert, Energ. Environ. Sci. 7, 3666 (2014)
Beyond Li-Ion: Utilization of the High Energy Density of Silver-Zinc in Secondary Button and Coin Cell Miniature Battery Sizes
Authors: Ortega Jeffrey Vincent , Dueber Ross Eugene 
Published: February 2020

The performance data for rechargeable silver-zinc (AgZn) button cells are compared with the published performance data for commercially available rechargeable Li-ion and Li-polymer cells. The results show that silver-zinc cells offer greater capacity and energy densities over the equivalently sized rechargeable Li-ion and Li-polymer batteries. Additionally, for the two smallest sized silver-zinc batteries, there are no equivalently sized Li-ion solutions currently available. In comparison with the smallest Li-ion available, the silver-zinc cell has a 57% greater energy density, while the largest silver-zinc cell is shown to be greater by 20% over the best performing Li-ion option available. How the subcomponents and the construction of the AgZn cell affect this enhanced performance will be discussed.
Non-Stoichiometric Titanium Dioxide Incorporation Onto Reduced Graphene Oxide By Atomic Layer Deposition for Oxygen Reduction Catalysis
Authors: Macedo Andrade Angela , Karimaghaloo Alireza , Grewal Simranjit , Lee Min Hwan 
Published: February 2020

Renewable energy devices such as fuel cells and metal air batteries harness their energy via lethargic oxygen reduction reactions (ORR) whose catalysis is largely relying on expensive and scarce noble metals. To address this issue, in particular, non-precious metal incorporated in carbon nanostructures have been widely explored. In this study, we focus on synthesizing inexpensive and efficient electrode material for ORR catalysis and energy storage using reduced graphene oxide (rGO) incorporated with non-stoichoimetric titanium dioxide by atomic layer deposition (ALD). Although stoichiometric TiO2 has been rarely considered as an effective ORR electrocatalyst, oxygen-deficient TiO2-x recently showed surprisingly competitive ORR activity and excellent durability[1]. The work was performed on a single crystalline TiO2. Motivated by the recent report and the advantages of TiO2 due to its abundance, safety and cost effectiveness, we probed the feasibility of applying this oxygen-deficient TiO2-x to the widely employed oxide nanoparticle-incorporated carbon nanostructures. This is to leverage extremely high surface area and excellent electronic conductivity of carbon-based 3D structures, which is highly advantageous for maximized catalytically active sites per mass.
We used electrophoretically deposited rGO as the matrix structure. Graphene oxides prepared by the modified Hummer’s method are first deposited onto a stainless steel by electrophoresis. The resulting structure was deposited by highly dispersed nanoparticles or ultrathin films of TiO2-x via ALD. The degree of non-stoichiometry is controlled by either changes in ALD temperature or a separate post-thermal process. ALD is a newer variant of chemical vapor deposition in which materials are deposited on a surface by a multiple sequence of ‘self-limiting’ chemical reactions. This unique sequential process enables a highly uniform deposition of dots/films and accurate control over not only the size/thickness at the atomic scale but also chemical composition and location of deposition.
In this presentation, we will present 1) the feasibility of using TiO2-x incorporated rGO as ORR electrode in terms of catalytic activity and cyclability and 2) the correlation among the ALD process parameters, resulting chemical composition/structure and ORR catalytic activity.
This project is funded by the NASA MUREP Institutional Research Opportunity (MIRO) Program (Grant No. NNX15AQ01A). S.G. is supported by NASA Advanced STEM Training and Research (ASTAR) Fellowship.

Figure 1
Studies on Capacity Fading of Lvo Cathode for Li-Metal Batteries
Authors: Kim Byung Hyuk , Yoon Woo Young 
Published: February 2020

Lithium Trivanadate(LVO) cathode has a theoretically high specific capacity of 280 mAh/g, which one of higher energy capacity batteries than commercial LCO battery. However, Li-LVO batteries have problems resulting from the vanadium dissolution into the electrolyte, volumetric extension of LVO. We are planning an experiment to clear relationship between vanadium dissolution and volumetric extension in charge/discharge process. To analyze the main reason of LVO fading, Lithiation amount was different during cell test. Cells were tested at the current densities of 0.2 C-rate and 2 C-rate with 1.8V to 4.0V. And we were a time cut in cell test to control the lithiation amount. The interfacial characteristics and electrolyte after cycles were examined by SEM, EDS, ICP-mass and FT-IR. The results surely confirm that main reason of LVO fading between vanadium dissolution and volumetric extension.
Advances in Metal Fluoride Conversion Materials for High Energy Density Batteries
Authors: O'Neill Cory , Li Bin , Kaye Steven S. 
Published: February 2020

State-of-the-art lithium-ion technology is based upon the shuttling of lithium ions between graphite and layered oxides, a process that limits the amount of Li to <1 per metal site and the volumetric energy density of the cathode to ~3,500 Wh/L. An alternative to intercalation-based electrodes are the so-called "conversion" electrodes, in which lithium reacts with an unstable host that undergoes significant (reversible) atomic rearrangement on charging and discharging. Of the known metal fluoride conversion electrodes, the best balance of operating voltage, energy density, and cost is CuF2, which has a theoretical capacity of 466 mAh/g (based on Cu + 2LiF) and a theoretical voltage plateau around 3.5V.
Recently, Wildcat has addressed several challenges currently prevent use of these materials: 1) poor rate capability due to low electronic/ionic conductivity, 2) low energy efficiency, likely from polarization and non-symmetric charge and discharge mechanisms, and 3) limited cycle life caused by sintering of metal nanoparticles and mechanical stress induced by volume expansion. To overcome these difficulties, Wildcat developed CuF2-based cathodes with conductive and protective coatings to enable high power and stability. Using Wildcat’s proprietary non-graphitic conductive coating, the cathode exhibits 1st cycle capacities of >380 mAh/g at a 1C rate.
Wildcat has also investigated alternative compositions that demonstrate improved conductivity and higher voltage. A second coating is used to prevent copper dissolution and metal agglomeration, leading to a self-discharge rate of 0.2%/day (vs. 2.0%/day for control) and cyclability. To our knowledge, this was the first reported demonstration of rechargeable CuF2. Moreover, the CuF2 material has voltage hysteresis of only 0.1-0.3V, compared with ~0.7-1V for FeF3 or BiF3.
Evaporation Rate Effect on the Sicu Helical Shaped Thin Films™ Morphologies and Their Uses As Anodes for Rechargeable Libs
Authors: Polat Deniz Billur , Keles Ozgul 
Published: February 2020

Structured silicon based anodes are promising for their high cycleability and rate performance. Because, the nanostructures can provide facile relaxation to prevent electrode pulverization. Plus, they maintain effective electrical contacts in cycling and provide short Li diffusion distances improving their electrochemical performances. Among alternative production methods, glancing angle evaporation becomes prominent since it enables to deposit SiCu films with various structures without a need of binder or any conductive additives. By optimizing the evaporation rate of sources materials (Si and Cu in that case), the incident angle and the azimuthal rotation rate of the substrate nanocolumns, chevrons and helices might be deposit directly on the current collector.
In this work, we keep the incident angle and the azimuthal rotation rate as 85o and 0.02 rpm, respectively. We produce two Si based structured thin films with 10% at. Cu, with different evaporation rates. The quartz crystal microbalances of Cu and Si show 0.4-4.4 Ǻ/s and 0.9-10 Ǻ/s for Samples 1 and 2, during evapoaration. The morphological test results show that the interaction between the evaporation and the azimuthal rotation rates change the structure of the film. Following the morphological and structural characterizations, their potential uses as anodes in lithium ion batteries are evaluated by means of electrochemical tests.
Tuning of Lithium Storage Properties of MLi2Ti6O14 (M=2 Na, Sr)
Authors: Yoo Young Geun , Bae Seongjun , Nam Inho , Park Soomin , Park Jongseok , Lee Jong Min , Han Jeong Woo , Yi Jongheop 
Published: February 2020

Supplying precise power is a significant factor in many electric devices to secure optimized performance, energy efficiency and device protection. For example, in OLEDs, the energy efficiency is highly dependent on the applied potential. However, most of electrode materials for batteries have its unique thermodynamic value, which is almost impossible to be adjusted. Therefore, tunability of the electrochemical property of materials is highly desirable for improving the performance of electric devices.
MLi2Ti6O14 (MLTO, M = 2 Na, Sr, Pb, Ca, Ba etc.) have been paid attention for the next-generation anode material for lithium-ion batteries (LIB) because of its lower working voltage than that of Li4Ti5O12 (LTO). Also, they shows flat potential plateau as well as LTO. Their operating potential and equivalent amount of intercalatible lithium ions varies depend on the M species. However, all of their crystal structures are analogous, except minor differences. Based on these observations, we achieved precise tuning of the electrochemical properties of MLTO with two coexisting M species by modulating stoichiometry of M species.
In this research, we used Na, Sr-coexisting MLTO (Na2-2xSrxLi2Ti6O14, NaSrLTO). Na2Li2Ti6O14 (NaLTO) has the lowest working potential (1.25 V) as well as the lowest reversibly intercalatible Li+ (2.0 equiv.-1) among the MLTOs, and SrLi2Ti6O14 (SrLTO) is diametrical of NaLTO (1.4 V and 2.5 equiv.-1). In NaSrLTO, operating potential gradually rises and equivalent inserted Li+ increases as higher ratio of Sr exists. Ab initio calculations revealed that the gradual potential change is originated from the gradual change of electron density of Ti3+/Ti4+ redox center. Also, Because SrLTO has half-vacant 8f Wyckoff position, SrLTO is able to store more Li+ than NaLTO, which all of Na atoms fully occupy the 8f Wyckoff position.
Designing Microstructure with Voids of Si-Based Anode Materials for Li-Ion Batteries
Authors: Kang Inyeong , Jang Juyoung , Kim Moon-Soo , Kim Jae-Hun , Park Jin-Woo , Cho Young Whan 
Published: February 2020

Silicon has been regarded as one of the most promising anode materials for Li-ion batteries because of its higher specific capacity than carbon anodes. However, there is a fatal problem that Si undergoes massive volumetric change (about 400%) during lithiation/delithiation process. This large volume change results in the following sequential processes; pulverization, breakage of solid electrolyte interface (SEI), creation of new surface for SEI formation, continuous exhaustion of electrolyte, and finally sudden capacity fade. Among many attempts to solve these problems, the microstructure control with voids showed notable progress in improving the cycle performance. But the synthetic methods adopted so far were too complicate to apply to large scale commercial processes.
Here, we introduce a microstructure of Si-based anode materials with voids using water-soluble compounds. The role of water-soluble compounds is to create enough spaces within the anode agglomerate particles, so that they can expand without generating excessive crack on the surface during the electrochemical reaction. We synthesized active anode materials using ball-milled ferrosilicon alloy and fine water-soluble compound mixtures as starting materials. After coating with carbon precursor followed by carbonization heat treatment, they were washed with distilled water to remove the water-soluble compounds which create void structure in anode particles. The evidences of the removal of the water-soluble compounds were provided by X-ray diffraction, FIB cross-section/EDS analysis, and BET analysis. From the electrochemical cell test, significant improvement of battery performance including coulombic efficiency, irreversible capacity were observed, especially at the beginning of the cycles, compared to that of anode materials without void structure. The present study shows the simple and practical approach to realize an ideal microstructure of Si-based anode for rechargeable Li-ion batteries.
EU R&D Project "inside" - in-Situ Diagnostics in Water Electrolysers
Authors: Biswas Indro , Schulze Mathias 
Published: February 2020

In this joint R&D project supported by the EU Fuel Cell and Hydrogen Joint Undertaking, an electrochemical in-situ diagnostics tool for the monitoring of locally resolved current densities in polymer electrolyte membrane fuel cells, is adapted to three different water electrolysis technologies. The developed tools allow correlating performance issues and ageing processes with local anomalies. The corresponding mechanisms are investigated with ex-situ analytics.
Partners
– Deutsches Zentrum für Luft- und Raumfahrt e.V., Stuttgart, Germany (Coordination)
– NEL Hydrogen AS, Notodden, Norway (Alkaline water electrolysis)
– Heliocentris Italy S.r.l., Crespina, Italy (Anion exchange membrane based water electrolysis)
– Centre National de la Recherche Scientifique, France (Ex-situ analytics)
– Université de Strasbourg, Strasbourg, France (Ex-situ analytics)
– Hochschule Esslingen, Esslingen, Germany (Ex-situ analytics)
The patented segmented printed circuit board (PCB) for the monitoring of current density distributions in PEM based fuel cells is used and continuously improved at DLR. Applications are e.g. the investigation of specific degradation mechanisms, or systematic optimisation of operation parameters.
The embedding of an in-situ diagnostics tool in water electrolysis system enables:
– monitoring of performance and local anomalies during operation
– revealing systematical deficiencies not detectable with off-line diagnostics
– correlating degradation mechanisms and system parameters
– identifying and preventing critical operation
– systematically improving the efficiency of water electrolysis
Acknowledgements
The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) for Fuel Cell and Hydrogen Joint Technology Initiative under Grant No. 621237 (INSIDE).
Organosilane Coatings for Ni-Rich High-Voltage Lithium Ion Batteries
Authors: Peebles Cameron , Dogan Fulya , Hubaud Aude A. , Vaughey John T. , Liao Chen 
Published: February 2020

One of the more promising cathode materials for high-energy high-voltage lithium ion batteries (LIBs) are Ni-rich layered cathode materials such as LiNixMnyCozO2 (where x + y + z = 1). Although these cathode materials are attractive from a high capacity standpoint, they commonly suffer from poor structural stability at highly delithiated (charged) states leading to poor electrochemical performance.1-3 While incorporation of additives into the electrolyte provides one way to improve cycling performance in LIBs, surface coatings are becoming a widely adopted method to improve the cycling performance of high-voltage cathode materials. More widely investigated coating materials include oxide coatings (Al2O3, TiO2, etc.)4 while comparatively fewer studies have investigated organic monomer or polymer coatings (PEDOT, polyimide, etc.).5 Additionally, the mechanism of the coating interaction with the material is intriguing due to its importance in creating a performance-enhancing coating.
In this work, the surface of LiNi0.5Mn0.3Co0.2O2 cathode materials were coated with organosilane reagents to investigate their effect on cell electrochemical performance. The impact of the cathode pretreatment, the weight percentage of organosilane used and the functionality of the organosilane used will be presented. Characterization of the organosilane coating using SEM shows a slight morphological change in the cathode surface while EDX and FTIR confirm the presence of a Si-containing coating. Half cells (Li/ LiNi0.5Mn0.3Co0.2O2) using the organosilane coated cathodes operating in the voltage window of 3.0 - 4.4 V showed similar cycling behavior to that of non-coated material. In conclusion, a new type of organic coating was utilized on Ni-rich cathode materials and this research explores a new type of coating for high voltage cathodes.
References
1) Son, I. H.; Park, J. H.; Kwon, S.; Mun, J. and Choi, J. W. Chem. Mat.
2015, 27, 7370-7379.
2) Bak, S.-M.; Hu, E.; Zhou, Y.; Yu, X.; Senanayake, S. D.; Cho, S.-J.; Kim, K.-B.; Chung, K. Y.; Yang, X.-Q. and Nam, K.-W. ACS Appl. Mater. Interfaces
2014, 6, 22594-22601.
3) Lin, F.; Markus, I. M.; Doeff, M. M.; Xin, H. L. Sci. Rep., 2014, 4, 5694.
4) Xu, S.; Jacobs, R. M.; Nguyen, H. M.; Hao, S.; Mahanthappa, M.; Wolverton, C.; Morgan, D. J. Mater. Chem. A, 2015, 3, 17248.
5) Zhang, J.; Lu, Q.; Fang, J.; Wang, J.; Yang, J. and NuLi, Y. ACS Appl. Mater. Interfaces
2014, 6, 17965-17973.
Improved Catalysts for Direct Methanol Fuel Cells
Authors: Fang Dan , Yang Bo , Narayanan S. R. 
Published: February 2020

Direct methanol fuel cells (DMFCs) are attractive among advanced energy conversion technologies due to the high energy density of methanol, the overall simplicity of system and easy refueling.[1] Although they made an early market entry but did not achieve large-scale commercialization mainly because of the cost, performance and durability issues. The state-of-art DMFC systems are based on the use of Pt-Ru catalyst at the anode, Pt catalyst at the cathode, and a polymer electrolyte membrane separating the two electrodes.[2] Our present study is focused on the anode catalyst, specifically to improve its performance and durability and reduce its cost. To this end, we have examined the use of titanium oxide-ruthenium oxide solid solutions as co-catalyst supports.
We have prepared Pt/Ti0.7Ru0.3O2 for use as an anode catalyst. Ti0.7Ru0.3O2 as a co-catalyst support was synthesized in a one-step hydrothermal process and then platinum was deposited using polyol method. The structure of the synthesized catalyst was investigated by XRD, SEM and EDX. Results of steady-state voltammetry suggest that the electrocatalytic activity and stability of the newly synthesized catalysts compare well with the commercially available carbon-supported Pt-Ru catalyst. The Tafel slopes suggested that the well-known bifunctional mechanism for methanol oxidation was operative on the new catalyst as well. With further optimization of this type of catalyst we expect to be able to lower the noble metal content further to enable practical use of these materials in fuel cells.
References [1] S. Surampudi, S. R. Narayanan, E. Vamos, H. Frank, G. Halpert, A. LaConti, J. Kosek, G. K. Surya Prakash and GA Olah, "Advances in Direct Oxidation Methanol Fuel Cells," Journal of Power Sources, 47, 377-385 (1994) [2] Handbook of Fuel Cells, “Portable Direct Methanol Fuel Cell Systems”, S. R. Narayanan, T. I.Valdez, in Vol IV Part 1, (Eds. H. Gasteiger, A. Lamm and W. Veilstich), Wiley Interscience ( March 2003)
Effect of Metal Ions Doping on the Structural and Electrochemical Properties of Olivine LiFePO4
Authors: Nieto Ramos Santander M , Mosquera Vargas Edgar E , Morel Mauricio 
Published: February 2020

Li ion rechargeable batteries have better performance over the other competitive rechargeable batteries due to their higher operative voltage (around 3-4 v range), high-energy storage capacity, low self-discharge, and high cycleability. For the application in high power devices (various consumer electronic products such as laptop, camcorder, etc.) the discharge capacity of Li ion batteries at higher current rate required is to be improved. As diffusion of lithium ions inside the active material particles is the rate-limiting step of intercalation process, faster Li+ diffusion in the electrode materials could improve the rate capabilities of Li ion batteries. Olive LiFePO4 is a very promising cathode material used in lithium ion batteries, due to its environmental friendliness, high theoretical capacity (170 mAhg-1), low cost of precursors, high reversibility of Li+ insertion/extraction, good thermal stability, and lack of toxicity. In spite of these attractive features, LiFePO4 requires further modifications to overcome limitations such as poor electronic conductivity and slow lithium ion diffusion. In this work we have synthesized olivine LiFe1-xMxPO4 (M = Nb, Yb, Sb, Mg)(LFMPO) powders by chemical synthesis and co-precipitation method. The synthesized powders were used to prepare cathodes for Li ion coin cells. The structural and electrochemical properties were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared, Raman spectroscopy, cyclic voltammetry and charge-discharge studies, respectively. The phase pure and crystalline quality of the materials was studied from XRD peaks and their line widths respectively. 7Li magic angle spinning nuclear magnetic resonance were used to compare the cation arrangement in the undoped and doped powders. The cyclic voltammetry of both the cathodes revealed the reversible nature of Li-ion intercalation in the cell. The dopant induced structural and stoichiometric modifications were correlated with the voltage cycling and charge discharge characteristics of these cathode materials.