bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Using Fluorinated Ether and Sulfone As Electrolyte Solvents for Lithium Ion Batteries with Lithium Rich Layered Cathode and Silicon Oxide Anode
Authors: Noguchi Takehiro , Hasegawa Takuya , Yamauchi Hideki , Yamazaki Ikiko , Utsugi Koji 
Published: February 2020

Introduction

Li rich layered cathode is one of the candidates for next generation cathode active material of Lithium ion batteries, because of large capacity more than 250 mAh/g. On the other hand, because of the higher potential than conventional cathode active materials, Li rich layered cathode has the problem of the capacity fading and gas emission. We have studied fluorinated electrolyte solvents for high voltage operation batteries with LiNi0.5Mn1.5O4 cathode1) 2), and we have reported that fluorinated ether and fluorinated phosphate were effective to reduce gas emission in high voltage operation cells at elevated temperature. In this report, we examined fluorinated ether and sulfone as electrolyte solvents for Lithium ion batteries with Li rich layered cathode and SiO anode.

Experimental

Li(LixNiyMn1-x-y)O2 was used as a cathode active material, and SiO was used as an active anode material. The discharge capacity as a function of cycle number was tested using stack type laminated cells with these active materials. Ethylene carbonate (EC), diethyl carbonate (DEC), DES (Diethyl sulfone) and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (FE) were used as electrolyte solvents. EC/DEC (30/70 v/v) and EC/DES/FE (x/(30-x)/70 v/v/v (x=0,5,10)) were used as electrolyte solutions. The volume of the cells was measured by the Archimedes method before and after initial 3 charge discharge cycles between 4.5 V and 1.5 V. After that, cycle tests were performed between 4.5 V and 1.5 V at 45 ºC.

Results

Figure 1 shows discharge capacity retention as a function of cycle number for Li(LixNiyMn1-x-y)O2/SiO cells with electrolyte solutions of EC/DEC (30/70 v/v) and EC/DES/FE (5/25/70 v/v/v). Capacity retention of EC/DES/FE after 200 cycles was larger than that of EC/DEC. DES and FE seem to have higher oxidation resistance than DEC and to have the effect of cycle life improvement. Figure 2 shows the volumes increase of cells after initial 3 charge-discharge cycles at 45 °C. The cause of volume increase is gas emission. The volume increase of the cell with EC/DEC (30/70 v/v) was larger than that with EC/DES/FE (x/(30-x)/50 v/v/v). Gas volume increased with amount of EC in electrolyte of EC/DES/FE. This result shows that the cause of gas emission at initial charge-discharge process seems to be due to the reaction between electrolyte solvents and cathode. EC is considered to be the cause of gas emission in initial charge discharge cycles.

References

T.Noguchi, M.Uehara, Y.Katoh, K.Utsugi, PRiMe 2012 Abstract, No.824 (2012)

T.Noguchi, Y.Katoh, K.Utsugi, 228th ECS Meeting Abstract, No.358(2015)

Figure 1
A Detailed-Electrochemistry Model of an LiFePO4/Graphite Lithium-Ion Cell Capturing Abuse and Aging Phenomena
Authors: Kupper Christian , Rißmann Sascha , Bessler Wolfgang G. 
Published: February 2020

Numerical simulations are an important corner stone for the development of lithium-ion batteries as they can save expenses in time and cost for a large number of series of experiments. Empirical models have the advantage of a fast development and a low computational effort, but their predictions are only valid within the range of experimental data used for fitting. In contrast, physically-based models allow a deeper understanding and increase the applicability to different scenarios and the credibility of the model predictions.
We present a multi-scale modelling approach coupling a 1D thermal cell-level (macro-scale) model, a 1D electrode-pair level (micro-scale) model, and a 1D particle-level (nano-scale) model (Figure 1) 1. A particular feature of the model is detailed electrochemistry, capturing multi-step main and side reactions occurring during ageing or thermal runaway. The model is parametrized to commercial lithium iron phosphate cells. We assume solid electrolyte interphase (SEI) formation at the anode as dominant aging mechanism, which is known to be the main contributor to calendaric aging 2. By capturing the nonlinear feedback between electrochemistry and transport, the model is able to simulate cell behavior not only within recommended operating conditions, but also during cell abuse, for example, due to external short circuit, and during long-time operation.
Simulations of short time (external short circuit) and long time (lifetime estimation) scenarios are presented (Figure 2,3). These different events are compared and interpreted, for example in terms of reaction limitation or transport limitation. The sensitivity and reassessment of the model parameter is discussed, and the model as a comprehensive copy of the real battery is verified. Thereby insights into the battery which are experimentally hard to obtain, like concentration and temperature gradients or the distribution of lithium in the active material (Figure 4), are more justified than before.
References
1. C. Kupper and W. G. Bessler, J. Electrochem. Soc.,
164(2), A304-A320 (2017).
2. H. Zheng, L. Tan, L. Zhang, Q. Qu, Z. Wan, Y. Wang, M. Shen and H. Zheng, Electrochim. Acta,
173, 323–330 (2015).

Figure 1
Flexible, Solid-State, Ion-Conducting Membrane with 3D Garnet Nanofiber Networks for Lithium Batteries
Authors: Fu Kun , Gong Yunhui , Wachsman Eric D. , Hu Liangbing 
Published: February 2020

Beyond state-of-the-art lithium-ion battery (LIB) technology with metallic lithium anodes to replace conventional ion intercalation anode materials is highly desirable because of lithium’s highest specific capacity (3,860 mA/g) and lowest negative electrochemical potential (∼3.040 V vs. the standard hydrogen electrode). In this work, we report for the first time, to our knowledge, a 3D lithium-ion–conducting ceramic network based on garnet-type Li6.4La3Zr2Al0.2O12 (LLZO) lithium-ion conductor to provide continuous Li+ transfer channels in a polyethylene oxide (PEO)-based composite. This composite structure further provides structural reinforcement to enhance the mechanical properties of the polymer matrix. The flexible solid-state electrolyte composite membrane exhibited an ionic conductivity of 2.5 × 10−4 S/cm at room temperature. The membrane can effectively block dendrites in a symmetric Li | electrolyte | Li cell during repeated lithium stripping/plating at room temperature, with a current density of 0.2 mA/cm2 for around 500 h and a current density of 0.5 mA/cm2 for over 300 h. The presentation will focus on our recent development of 3D garnet nano structured solid-state electrolyte membrane for Li metal batteries.

Figure 1
Electronic Structures and Optical Properties of Al, Cu and Ag in Bulk, Thin Film and Nanoparticle Forms
Authors: Mishra Kailash C. , Piquette Alan , Schmidt Peter C. , Johnson Keith H 
Published: February 2020

The electronic structures of aluminum, copper, and silver were investigated in bulk, thin-film and nanoparticle forms using first-principles band structure methods. The density of states (DOS) and partial density of states (PDOS) were also calculated. The calculations show the progression from continuous bands to subbands to discrete states as spatial confinement is imposed by going from bulk to thin film to particle forms. The choice of metals in this study allows for the comparison of the degree of localization of the d-electrons on inter-band transitions, which, in part, governs the optical properties of the metals.
The associated optical properties described by the imaginary component of the dielectric function, ε2(ω), were also investigated. The interband contributions to ε2(ω) were calculated from the band structure, while the intraband contributions were calculated using the Drude theory for free electrons. Both contributions to ε2(ω)are needed to understand the optical properties of metals and to interpret their reflectance spectra. The interband transitions need to be considered to explain reflectivity at energies lower than the plasma frequencies, but not all interband transitions result in reflectance peaks since they are significantly weaker compared to the intraband contributions at lower energies.
We have studied the dependence of the DOS, PDOS and ε2(ω) on the choice of exchange potentials by comparing results obtained using the generalized gradient approximation (GGA) and the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. In copper, where ultraviolet photoelectron spectroscopy data are available, the HSE potential leads to better agreement with the experiment than when using the GGA potential, and HSE reproduces correctly the variation of binding energy of the d electrons as spatial confinement is imposed. The corresponding dependence of exchange potential for silver exists, but is less severe.
(Invited) Upconversion: Photoswitching, Photocleavable
Authors: Capobianco J. A. 
Published: February 2020

Research on light controlled drug delivery release systems has shown great potential in biomedical applications. However, in general the photo response of molecules is based on UV excitation. In biomedical applications longer wavelength NIR light is preferable since it shows deeper tissue penetration and is less detrimental to tissue. We report on the synthesis of LiYF4:Tm3+/Yb3+ functionalized(UCNP) with a lipid bilayer and azobenzene. The nanoconstruct synthesised is hydrophilic shows excellent colloidal stability and biocompatibility. The nanocomposite can be used as a drug delivery system making use of NIR light excitation (980 nm) to induce the multiphoton process known as upconversion. The LiYF4 Tm3+/Yb3+ nanoparticles emit in the UV, visible and/or near-infrared. Fluorescence energy transfer (FRET) from the upconverting nanoparticles (UV emission) to the azobenzene triggers the photoswitching of the azobenzene from the trans to the cis. The photoswitching of the azobenzene molecules disrupts conformation of the supported lipid bilayer thus releasing the drug.
Recently, photosensitive drug delivery systems, which make use of a nitrobenzyl-type ‘photocaged’ anticancer drug conjugated to another small or macromolecule. In each of these cases drug release from the conjugate was mediated by UV light. A major limitation of this approach for in vivo drug release is the low tissue penetration ability of UV light and inevitable DNA damage. A potential solution is afforded by UCNPs loaded with photocaged doxorubicin (DOX) onto the surface of the UCNPs via a photocleavable linkage.
Tb3+-Eu3+ Energy Transfer in Tb-Based Phosphates: A Comparison of Two Extreme Cases
Authors: Carrasco Irene , Piccinelli Fabio , Bettinelli Marco 
Published: February 2020

Energy transfer processes involving trivalent lanthanide ions (Ln3+) are crucial for the development of innovative luminescent materials and devices such as phosphors, scintillators, materials for solar cells, nanothermometers or materials for optical bioimaging, among others.
In the case of the Tb3+→Eu3+ energy transfer in Tb-based materials containing Eu3+ as a dopant, different types of behaviour can be observed in different systems due to structural peculiarities of the host. These differences determine the emission colour of the material, since this is strongly related to the presence or absence of energy transfer (both Tb3+→Tb3+ and Tb3+→Eu3+).
In this contribution we present and discuss the luminescence properties of Ca9Tb(PO4)7 powders (whitlockite family, rhombohedral structure) and TbPO4 powders (tetragonal structure) doped with Eu3+. In the case of the Eu-doped TbPO4 powders, a very fast and efficient Tb3+→Eu3+ energy transfer is present upon near UV excitation in the Tb3+ ion. This changes the emission colour of the material from green to red even by addition of small amounts of europium ions. On the contrary, in the Eu-doped Ca9Tb(PO4)7 samples the Tb3+→Eu3+ energy transfer process is not efficient and the resulting emission colour of the Eu3+-doped materials appears to be yellow, even for high europium doping levels.
(Invited) Shedding Light in Nanothermometry
Authors: Carlos Luís D 
Published: February 2020

Luminescent ratiometric thermometers combining high spatial and temporal resolution at the micro and nanoscale, where the conventional methods are ineffective, have emerged over the last decade as an effervescent field of research, essentially motivated by their potential applications in nanotechnology, photonics and biomedicine [1]. Among the distinct luminescent thermal probes, Ln3+-based materials play a central role in the field due to their unique thermometric response and intriguing emission features (e.g., high quantum yield, narrow bandwidth, long-lived emission, large Stokes shifts, and ligand-dependent luminescence sensitization).
One of the main challenge that is currently facing scientists in the field is to use luminescent thermometry for unveiling thermometers’ local surrounding properties, as, for instance, heat transfer in heater-thermometer nanoplatforms [2], the absorption coefficient and thermal diffusivity of tissues in small animals [3] and the measurement of the instantaneous ballistic velocity of Brownian nanocrystals suspended in both aqueous and organic solvents based on upconversion nanothermometry [4].
This lecture presents a general revision of the work done in the last couple of years on ratiometric luminescent nanothermometers with foucus on recent examples in which the technique was used for unveiling thermometers’ local surrounding properties.
[1] C. D. S. Brites, A. Millán, L. D. Carlos, in Handbook on the Physics and Chemistry of Rare Earths, J.-C. Bünzli, V. K. Pecharsky, Eds., Amsterdam: Elsevier Science B.V., Vol. 49 (2016), 339.
[2] R. Piñol, C. D. S. Brites, R. Bustamante, A. Martínez, N. J. O. Silva, J. L. Murillo, R. Cases, J. Carrey, C. Estepa, C. Sosa, F. Palacio, L. D. Carlos, A. Millán, ACS Nano 9 (2015)3134
[3] E. C. Ximendes, W. Q. Santos, U. Rocha, U. K. Kagola, F. Sanz-Rodríguez, N. Fernández, A. da Silva Gouveia-Neto, D. Bravo, A. Martín Domingo, B. del Rosal, C. D. S. Brites, L. D. Carlos, D. Jaque, C. Jacinto, Nano Lett.
16 (2016) 1695.
[4] C. D. S. Brites, X. Xie, M. L. Debasu, X. Qin, R. Chen, W. Huang, J. Rocha, X. Liu, L. D. Carlos, Nature Nanotech.
11 (2016) 851.
Simulating a Potential Step Using Shareware
Authors: Haque Inam ul 
Published: February 2020

Simulation of a potential step experiment of an electrochemical system in an infinite solution using explicit method [1] was done. Listing of program in Fortran was compiled using shareware program FORCE 2.0 FORTRAN compiler and editor [2]. Plot of potential step experiment for Z/Zc vs. X for L/n from above mentioned listing is shown.
Simulations done by transliterating Fortran [3] into Turbo Pascal will also be discussed. Symbols are as per [3].
[1] W. Breen and J. Cassidy, Simulation of dynamic electrochemical processes, Curr. Top. Electrochem., 9 (2003) p. 47
[2]www.igpp.ucla.edu/public/rwalker/ess261_2007_spring/Force/Force%20Fortran%20Compiler%20and%20Editor.htm
[3]A. J. Bard and L. R. Faulkner, Electrochemical Methods: Fundamentals and Applications, 2nd Edition, Wiley (2001) p. 793

Figure 1
Nitrogen-Doped Ordered Mesoporous Carbon/Graphene Framework As Dual Electrocatalyst for Oxygen Reduction and Evolution Reactions
Authors: Zhang Changlin , Wang Biwei , Dong Angang , Peng Zhenmeng 
Published: February 2020

One important research topic in electrocatalysis is electrochemical redox between H2O and O2 for the design of regenerative electrochemical energy storage and conversion system, which involves oxygen reduction reaction (ORR) during discharging process and oxygen evolution reaction (OER) upon charging process. Thus, it is of great importance to develop a dual functional electrocatalyst which is active in both ORR and OER and can reduce the usage of noble metals.
We report the synthesis of highly ordered N-doped mesoporous carbon/graphene frameworks (N-MCF/N-MGF), which possessed large surface area, high porosity, excellent internal diffusion property, and superior intrinsic conductivity and exhibited promising catalytic properties in both ORR and OER. As a dual catalyst, the N-MGF exhibited overpotential as low as 324 mV for harvesting 10 mA cm-2 OER current density, which was lower than most of previously reported carbon-based materials and were comparable with the benchmarking noble metal oxide catalysts. The catalyst was also durable under both OER and ORR conditions. These results presented a low-cost dual ORR/OER electrocatalyst with high activity and good durability as well as their negligible internal diffusion resistance, which could be potentially utilized and implemented in renewable energy techniques such as metal-air batteries, fuel cells, and water splitting devices.
Binary Molybdenum Borides Nanostructures As Novel Electrocatalysts for Hydrogen Evolution Reaction
Authors: Jothi Palani Raja , Fokwa Boniface P.T. 
Published: February 2020

Molybdenum based materials have recently emerged as highly active non-noble metal electrocatalysts for hydrogen evolution reaction (HER) [1, 2]. Molybdenum borides in contrary have not been studied for their HER activity at the nanoscale, however, they were recently shown to be already efficient HER catalysts in the bulk [3]. In this study, we have successfully synthesized nanocrystalline molybdenum boride nanowires (MoB) and nanospheres (MoB2) using a simple, one-step, solid state reaction. The structural and morphological characterizations were studied using XRD, XPS and electron microscopy. The obtained molybdenum borides nanostructures were tested for their electrocatalytic activity for HER in acidic conditions. We found that, nanoscale MoB2 exhibits a low onset overpotential and low Tafel slope value compared to nanoscale MoB indicating a boron- and structural dependency of these nanoborides for the HER. Also, the onset overpotential and Tafel slope values obtained represent a significant improvement from those observed for the already highly active bulk borides [3], thus opening a new avenue for inexpensive nanoscale metal boride nanomaterials as highly efficient non-noble metal HER catalysts.

References:

H. Vrubel and X. L. Hu, Angew. Chem. Int. Ed.,
55 (2012) 12703-12706.

P. Xiao, M. A. Sk, L. Thia, X. M. Ge, R. J. Lim, J. Y. Wang, K. H. Lim and X. Wang, Energy Environ. Sci.,
7 (2014) 2624-2629.

H. Park, A. Encinas, J. P. Scheifers, Y. Zhang and B. P. T. Fokwa, Angew. Chem. Int. Ed.,
56 (2017) https://doi.org/10.1002/anie.201611756.
Observation of First-Order, Marcus Normal, Interfacial Electron Transfer at Dye-Sensitized TiO2 Interfaces
Authors: DiMarco Brian N , Troian-Gautier Ludovic , Sampaio Renato N , Meyer Gerald J 
Published: February 2020

Dye-sensitized solar cells combine the robustness of nanocrystalline TiO2 with molecular dyes or “sensitizers” that absorb broadly across the visible. The surface anchored sensitizer undergoes a photo-induced electron transfer to the TiO2 acceptor states and is subsequently regenerated by a redox mediator present in the external electrolyte. Efficient light-to-energy conversion requires that the injected electron be transported to the external circuit prior to recombination with the oxidized redox mediator. Despite the importance of this unwanted recombination reaction the mechanism remains elusive. This is due in part to complex kinetics that usually cannot be described with first- or second order kinetic models, but satisfactory fitting instead require sums of exponentials or stretched exponential functions. The non-exponential kinetics are likely due to transport of the injected electron and/or the electron acceptor prior to recombination. Here we report charge recombination studies of charge recombination to a family of oxidized amines that provide compelling evidence for first-order kinetics with abstracted rate constants that show a driving force dependence.
The recombination reaction between nanocrystalline anatase TiO2 and a series of symmetrically substituted triphenylamine (TPA) redox mediators that possessed electron donating or withdrawing groups at the para-position of the phenyl rings was quantified on nanosecond and longer time scales. The groups utilized afforded an ~0.5 V change in TPA+/0 reduction potential. The nanocrystalline TiO2 thin films were sensitized by a ruthenium polypyridyl complex bearing either a carboxylic or a phosphonic acid functional group for surface anchoring. Pulsed light excitation of the film resulted in excited-state injection to yield TiO2(e-)|S+. Sensitizer regeneration and the subsequent charge recombination reaction TiO2(e-) + TPA+ → TiO2 + TPA were then monitored spectroscopically. Concentration dependent data revealed that recombination could be described by a distribution of first-order rate constants that became strictly first-order when the driving force was larger. The reaction rate increased with more positive TPA+/0 reduction potentials, consistent with electron transfer in the Marcus normal region. The recombination reaction was monitored as a function of temperature, and an Arrhenius analysis provided activation energies. Interestingly, the same activation barrier was abstracted for all the TPA derivatives, suggesting that a common rate limiting step exists for all these reactions. A model for recombination consistent with both the thermodynamics and activational parameters will be presented.
(Invited) Energy Transfer and Catalysis in Metal Organic Framework Arrays
Authors: Morris Amanda J 
Published: February 2020

Metal Organic Frameworks (MOFs) provide a promising platform for the control of energy transfer within light-harvesting arrays. The efficiency of energy transfer is related to three major factors - the degree of spectral overlap between the donor (emission) and acceptor (absorption), the distance between donor and acceptor, and the orientation of the donor and acceptor in 3D space. Our group has pioneered work in the investigation in effects of separation distance and orientation on energy transfer in chromophore-modified MOFs. Given our results, design parameters for MOF energy transfer candidates will be provided. Additionally, we will explore the capability of MOF arrays to promote electron transfer catalysis. Our results indicate that MOFs promote various energy-related catalytic reactions including oxygen reduction, carbon dioxide reduction, and water oxidation. The mechanism of electron transport through these catalysts-modified MOFs is one of ambi-polar redox hopping. Through MOF incorporation, the current resultant under electrochemical conditions is increased by two orders of magnitude.