bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure Design and Doping Modification of Li4Ti5O12 for Lithium Lion Batteries
Authors: Fan Li-Zhen , Ni Haifang 
Published: February 2020

Because of its extreme safety and outstanding cycle life, spinel Li4Ti5O12
has been regarded as one of the most promising anode materials for lithium-ion batteries [1]. However, Li4Ti5O12 suffers from poor electronic conductivity, making it a challenge to achieve high capacity at high rates. Due to the superior electron mobility, high surface area and structural stability, carbon materials are expected to be a potential alternative for the conductive phase in lithium ion batteries.
Here, we describe a new strategy to the synthesis of three-dimensional (3D) hybrid-structure Li4Ti5O12/carbon for high-performance lithium-ion batteries by liquid deposition technique using carbon nanotubes (CNTs) [2], graphite oxide (GO) [3], porous carbon (PC) [4], carbon black (CB) as matrix, respectively. The intimate contact between the carbon framework and Li4Ti5O12 nanoparticles suppresses the agglomeration and growth of Li4Ti5O12 nanoparticles, and affords a highly conductive matrix for the rapid ionic and electronic conductions.Thereby, the as-prepared Li4Ti5O12/carbon composites exhibit greatly improved electrochemical performance compared with bulk Li4Ti5O12, showing excellent rate capability (120~150 mAh g-1 at 20 C) and cycling performance. The good performance is due to the short diffusion lengths of the Li4Ti5O12 nanoparticles uniformly dispersed on the highly conductive 3D carbon matrix.
In addition, Br-doped Li4Ti5O12 in the form of Li4Ti5Br
x
O12-x
(x= 0, 0.1, 0.2, 0.3, 0.4) was synthesized, the effects of Br doping on the structures and electrochemical properties of Li4Ti5O12 were extensively studied. Although Br doping did not change the phase composition, obvious effects on the particles morphology and size were observed. The as-synthesized Li4Ti5O11.8Br0.2 electrode presents much higher discharge capacity (161 mAh g-1 at 5C) and better cycle stability than that of other electrodes.

References

1. T. Ohzuku, A. Ueda, and N. Yamamoto, J. Electrochem. Soc.,
142, 143 (1995).
2. H.F. Ni, and L.-Z Fan, J. Power Sources, 214, 195 (2012).
3. L.F. Shen, C.Z. Yuan, H.J. Luo, X.G. Zhang, S.D. Yang, and X.G. Lu, Nanoscale, 3, 572 (2011).
4. L.F. Shen, X.G. Zhang, E. Uchaker, C.Z. Yuan, and G. Z. Cao, Adv. Ener. Mater.,
2, 691 (2012).
Elucidation of Electrode-Electrolyte Interfaces Using Neutrons
Authors: Veith Gabriel M , Browning James F , Baggetto Loic 
Published: February 2020

This presentation will describe experimental characterization of the thickness and composition of the reaction products on silicon anode materials and aluminum current collectors measured using neutron reflectometry. NR is a neutron scattering technique highly sensitive to morphological and compositional changes occurring across surfaces and interfaces, including buried interfaces. It can be used to study such changes over lengths scales extending 1 nm to hundreds-of-nanometers. Neutrons, by virtue of their nature, are deeply penetrating and therefore ideally suited as a probe to study materials in complicated environments, such as electrochemical cells. Unlike x-rays, neutrons interact with the nuclear potential of constituent element and are sensitive to light elements like Li and H.
We will show that the SiOx surface of silicon materials react irreversibly with the electrolyte 1.2M LiPF6-3:7 wt% ethylene carbonate:dimethyl carbonate. The reaction product is a complex mixture of Si-O-F-C species. It is dense and homogenous and has a thickness of about 3.5 nm. Similar reaction chemistry is observed for Al current collectors. Insights from these measurements will provide a framework to understand capacity losses with cycling of high energy density materials.
Acknowledgement:
This research was supported by the Materials Sciences and Engineering Division, Office of Basic Energy Sciences, U.S. Department of Energy under contract with UT-Battelle, LLC (LB, GMV). This Research at Oak Ridge National Laboratory's Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U. S. Department of Energy.
Structure Evolution and Kinetics Study of Layered LiNixMnyCozO2 (x+y+z=1) Cathode Materials during Charge Using Synchrotron X-Ray Techniques
Authors: Zhou Yongning , Cho Sung-Jin , Bak Seong-Min , Yu Xiqian , Nam Kyung-Wan , Yang Xiao-Qing 
Published: February 2020

Layer structured mixed transition metal oxides LiNixMnyCoyO2 (x+y+z=1, NMC) have been widely studied as promising cathode materials for Li-ion batteries due to their superior properties, better thermal stability, lower cost and higher capacity comparing to LiCoO2, which is the widely used cathode material for Li-ion cells. A typical NMC cathode with a composition of 1:1:1 (LiNi1/3Mn1/3Co1/3O2) is already being used in commercial lithium-ion battery cells. However, more systematic studies on the structure-performance relationship of the NCM materials are needed. It is critical to understand the role of each element in electrochemical performance in terms of the capacity, rate capability, cycling and calendar lifes as well as safety characteristics. In this regard, we present here a systematic study on the structural changes that occur in the NMC cathode materials with several different compositions such as NMC = 333, 433, 532, 622 and 811 during charge using combined in-situ synchrotron based X-ray techniques.
While in situ X-ray diffraction (XRD) was used to track the average bulk crystal structural changes, in situ X-ray absorption spectroscopy (XAS) was applied to monitor the electronic structure and local structure changes around each transition metal element (Ni, Mn and Co) in the NMC cathode during charge. In addition, time-resolved XRD and Quick-EXAFS were also used for monitoring its structural changes and kinetic property of each transition metal upon charge at different C rates (C/10 to 30C). Detailed results including in situ XRD and XAS on the NMC materials with various NMC compositions during charge will be present.

Acknowledgement

The work done at Brookhaven National Lab. was supported by the U.S. Department of Energy, the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies under Contract Number DEAC02-98CH10886.
Investigation of Rare-Earth Electrochemistry in Molten Oxides
Authors: Lambotte Guillaume , DeLucas Rachel , Allanore Antoine 
Published: February 2020

Molten oxides have successfully been used as electrolyte for the extraction of relatively noble metals in their liquid phase [1], offering a new paradigm in metal extraction that can mitigate GHG emissions thanks to the use of C-free electricity as well as the development of new inert anode materials [2,3].
Such developments have been possible thanks to the commensurable knowledge gained on well-established molten oxide systems that have a key role in pyrometallurgy, glassmaking or magma chemistry. Unfortunately, the perspective of extending such concept to more reactive metals extraction like the rare-earths is rapidly challenged by a surprising reality: there are only a limited amount of thermodynamic data available to describe rare-earth oxide chemistry in molten oxides.
The present paper therefore offers to discuss the recent thermodynamic and electrochemical developments achieved in our laboratory on rare-earth oxides chemistry in such electrolytes. In particular, the methodology behind electrolyte design, and the results obtained in the prediction of the corresponding phase diagrams will be discussed. Recent electrochemical results obtained with the identified systems will be presented.
[1] D. Wang, A.J. Gmitter, and D.R. Sadoway, J. Electrochem. Soc., 158 (6), E51-E54 (2011)
[2] A. Allanore, L. Yin and D.R. Sadoway, Nature, 497 (7449), 353–356, (2013)
[3] A. Allanore, Electrochimica Acta, 110, 587-592, (2013)
Voltammetric Analysis of Antispasmodic Drug Drotaverine Hydrochloride in Pharmaceutical Preparations Andbiological Medium
Authors: Jadon Nimsha , Jain Rajeev 
Published: February 2020

Drotaverine hydrochloride is an antispasmodic drug widely used to relieve cramps or spasms of the stomach, intestines, and bladder.The electro reductive behavior of drotaverine has been investigated and one irreversible well-defined cathodic peak was observed at -1.04 V vs. Ag/AgCl (3M KCl). The electrochemical reduction and adsorption of drotaverine hydrochloride was studied in phosphate buffer medium by cyclic voltammetric (CV), differential pulse cathodic adsorptive stripping voltammetric (DPCAdSV) and square-wave cathodic adsorptive stripping voltammetric (SWCAdSV) techniques at hanging mercury drop electrode (HMDE). A fully validated, sensitive and reproducible cathodic adsorptive stripping voltammetric procedure for the trace determination of the bulk drug in pharmaceutical formulation and in biological medium has been developed.
The peak current showed a linear dependence with the drug concentration over the range 50 ng/mL to 25.6 µg/mL for SWCAdSV and 0.2 µg/mL to 51.8 µg/mL for DPCAdSV. The achieved LOD and LOQ were 7.1 ng/mL and 23.7 ng/mL by SWCAdSV and 33.84 ng/mL and 112.8 ng/mL by DPCAdSV respectively. The procedure was applied to the assay of the drug in tablets form with mean percentage recoveries of 100.4% with SWCAdSV and 100.2% with DPCAdSV. Applicability to assay the drug in spiked urine and serum samples were illustrated and minimum detectability were found to be 32.66 ng/mL and 49.83 ng/mL respectively.
Rapid Voltammetric Determination of Traces of Zn2+ in 105 Excess of Ni2
Authors: Zlatev Roumen , Stoytcheva Margarita , Medina Pablo Alberto Romero , Reyes Ana Luisa , Valdes Benjamin 
Published: February 2020

The impurities determination in Ni electrolysis baths is of a great importance for the quality of the Ni electroplating protective and decorative coatings. Inclusions having more negative potential than Ni form corrosion anodic zones in the presence of humidity, corrupting the Ni layer protective properties. One of the most dangerous inclusions is Zn.
Zn often appears in the Ni coatings deposited on brass, as a result of the brass detail dissolution in the low pH Ni baths before the beginning of the electrolysis: the deposition of the first Ni layer.
As known, the maintenance of the Zn2+ concentration in the Ni bath bellow 3 ppm can prevent Zn inclusions formation in the Ni coatings, which requires on-line Zn2+ determination. Nevertheless, spectral analytical methods such as AAS and ICP cannot be applied after Zn2+ extraction from the high concentrated matrix, because the huge Ni2+ concentration will provoke crystallization in the nebulizer area corrupting the analysis. The direct application of some voltammetric techniques also cannot yield any results, because of the very small difference of the E½ of the two species, which will cause peak overlapping. Some specific properties of the Ni2+ and Zn2+ ions however can be used to avoid the interferences. It is known that Zn2+ forms soluble hydroxyl complex in the presence of excess of OH-, while Ni2+ forms the very stable Ni(OH)2 precipitation product. Thus, KOH or NaOH can be applied as a supporting electrolyte, in which a well defined peak of Zn2+ is registered as shown in Fig. 1, while no peak of Ni2+will appear because of its precipitation.
The effect of the NaOH concentration applied as a supporting electrolyte, of the Zn2+ adsorption by the formed Ni(OH)2 precipitation product, and of the Ni2+/Zn2+ concentration ratio on the analytical characteristics of the Zn2+ determination are the subject of this study. The results are presented and discussed. It is demonstrated that the developed method consisting in adding of a small volume of Ni electroplating bath solution to the NaOH supporting electrolyte, followed by DPV determination can be applied for the on-line Zn2+ determination.
In-Situ X-ray Absorption Spectroscopy Elucidating Mechanisms in HT-PEM Fuel Cells
Authors: Roth Christina , Kaserer Sebastian , Caldwell Keegan M. , Ramaker David E. 
Published: February 2020

The development of phosphoric acid (H3PO4) imbibed polybenzimidazole (PBI) membranes used in so-called high temperature polymer electrolyte membrane fuel cells (HT-PEMFC) has attracted increasing interest lately. Working temperatures of up to 180 °C can be utilized in this approach, which offers several advantages. For instance, it allows the use of less pure and therefore less expensive anode feeds due to a higher tolerance towards impurities, such as CO and H2S, easier water management, simpler cooling systems and enhanced electrode kinetics. However, at these elevated temperatures degradation phenomena may play an important role and phosphate adsorption may poison electrode surfaces. These need to be understood in detail in order to develop both more active as well as more durable materials.
X-ray absorption spectroscopy (XAS) is a technique optimally suited to in-situ studies, as neither UHV conditions, nor long-range order in the sample are required. It can be applied to monitor the geometric structure of the catalytically active nanoparticles directly following particle oxidation and growth during operation. With the delta µ XANES method and complementary theoretical FEFF8 calculations [1] it is possible to identify different adsorbates on small Pt nanoparticles and follow their change in coverage. Phosphoric acid [2], which is used as electrolyte, or impurities in the fuel gases may strongly adsorb and alter the reaction mechanisms.
In this work the coverage of different adsorbates and possible poisons on the anode and cathode side in H3PO4 imbibed PBI HT PEM fuel cells was investigated. At the cathode side, the adsorption of phosphoric acid and OH on the Pt surface was followed at different temperatures and potentials. At the fuel cell anode, the effect of CO and water was analysed.

1 Teliska M., O’Grady W. E., Ramaker D. E., J. Phys. Chem. B,
108, 2333 (2004); 109, 8076 (2005).

2 Zelenay P., Scharifker B. R., Bockris J.O´M., J. Electrochem. Soc.,
133, 2262 (1986).
Universal Activity Volcano for 2e- and 4e- Reduction of Oxygen on Metal Surfaces
Authors: Viswanathan Venkatasubramanian , Hansen Heine , Nørskov Jens 
Published: February 2020

Oxygen reduction reaction (ORR) has been a subject of major interest in electrochemistry owing to its technological and scientific importance. The fundamental understanding of this reaction has been largely based on the surface science approach to electrocatalysis.[1] The surface science approach has allowed the bridging of theory and experiment by enabling direct theoretical investigations of the reaction mechanism of oxygen reduction reaction on model systems.
In this talk, we will address the issue of 2e− versus 4e− reduction of oxygen on metal surfaces. Using a detailed thermodynamic analysis based on density functional theory calculations, we show that to a first approximation an activity descriptor, ΔGOH*, the free energy of adsorbed OH*, can be used to describe trends for the 2e− and 4e− reduction of oxygen. We demonstrate the existence of a universal activity volcano shown in the Figure and find quite a remarkable agreement between the predictions of the model and experimental results spanning nearly 30 years.[2-4]
References
[1] Fuel Cell Catalysis: A Surface Science Approach, Marc Koper and Andrzej Wieckowski, (2009)
[2] V. Viswanathan, H. A. Hansen, J. Rossmeisl, and J. K. Nørskov, ACS Cat., (2012) 2, 1654-1660.
[3] V. Viswanathan, H. A. Hansen, J. Rossmeisl, and J. K. Nørskov, J. Phys. Chem. Lett., (2012) 3, 2948-2951.
[4] H. A. Hansen, V. Viswanathan and J. K. Nørskov, (submitted).
Fig 1: Activity volcanoes for the 2e− and 4e− reduction of oxygen are shown in red and blue respectively. The source of the experimental data for the 2e− and 4e− reduction of oxygen are listed in ref. [3]. The experimental value of the limiting potential, UL, is determined by the half-wave potentials for the 4e− reduction and by the onset of ring current for the 2e− reduction. The activity of (111) and (100) surfaces has been plotted in circles and squares, respectively.
Understanding the Oxygen Reduction Reaction on a Y/Pt(111) Single Crystal
Authors: Ulrikkeholm Elisabeth Therese , Johansson Tobias Peter , Malacrida Paolo , Vej-Hansen Ulrik Grønbjerg , Hernandez-Fernandez Patricia , Friebel Daniel , Nilsson Anders , Rossmeisl Jan , Stephens Ifan Erfyl Lester , Chorkendorff Ib 
Published: February 2020

Polymer electrolyte membrane fuel cells (PEMFC) hold promise as a zero-emission source of power, particularly suitable for automotive vehicles. However, the high loading of Pt required to catalyse the oxygen reduction reaction (ORR) at the PEMFC cathode, prevents the commercialisation of this technology. Improving the activity of Pt by alloying it with other metals could decrease the loading of Pt. An earlier theoretical study conducted at our laboratory identified PtxY as an active and stable catalyst for oxygen reduction. Experiments conducted on sputter-cleaned polycrystalline Pt3Y confirmed that it showed exceptional activity for the ORR [1]. Later studies also revealed that Pt5Y, prepared in the same manner also showed similar high activity, as shown in Figure (a) below. However, our X-ray photoelectron spectroscopy measurements revealed that the structure formed under reaction conditions was significantly different from our initial expectations.
In order to understand this phenomenon, we investigated a Y/Pt(111) single crystal, formed by depositing large amounts of Y om Pt(111) under ultra-high vacuum (UHV) conditions and annealing to high temperatures. We subsequently characterised the surface using electrochemical measurements, low energy electron diffraction, ion scattering spectroscopy, angle resolved X-ray photoelectron spectroscopy, temperature programmed desorption of CO, and synchrotron based X-ray absorption spectroscopy and surface sensitive X-ray diffraction. These measurements were supported by DFT calculations. From the experimental investigations of the crystal structure, it could be concluded that we have obtained a Pt5Y structure with a 5.5 % compressive strain compared to Pt. Electrochemical measurements show that the activity approximates that of sputter-cleaned Pt3Y, as shown in Figure A. Since there is no Y in the first few atomic layers, we attribute the high activity to the compressive strain exerted onto the surface by the alloy bulk.
[1] J. Greeley, I.E.L. Stephens, A.S. Bondarenko, T.P. Johansson, H.A. Hansen, T.F. Jaramillo, J. Rossmeisl, I. Chorkendorff, J.K. Nørskov, Nature Chemistry, 1 (2009) 552-556.
Electron Transfer in One- and Zero-Dimensional Nanooptofluidic Devices
Authors: Bohn Paul W. , Ma Chaoxiong , Zaino Lawrence P. , Wichert William , Contento Nicholas M. 
Published: February 2020

Working in the same hallway as Prof. Wieckowski and his students for 22 years taught us to appreciate the beauty of heterogeneous electron transfer. We are now pursuing that appreciation through coupled electron transfer and spectroscopic probing of processes in zero- and one-dimensional nanostructures.
One-dimensional architectures are explored in two formats: (1) a horizontal geometry in which a small number of nanochannels are arrayed at the top surface of a fluidic device so that optical spectroscopy can be employed to augment studies of electrochemistry at embedded planar electrodes; and (2) vertically-oriented nanopores supporting embedded annular nanoband electrodes (EANEs) in massively parallel high-density arrays. Because transport and electron transfer are intimately coupled, high efficiency (unit efficiency in many cases) electrochemical conversions can be achieved in many structures, and the horizontal geometry allows detailed measurements of the spatiotemporal distributions of electrochemical products for comparison with finite-element modeling.
Zero-dimensional architectures are also being studied in two formats: (1) arrays of nanoconfined recessed ring-disk electrodes (RRDEs), in which redox cycling can be carried out at very high efficiency; and (2) electrochemically-active zero-mode waveguides (ZMWs), in which strongly confined optical fields can be coupled to single molecule electron transfer events in order to study the dynamics of single enzyme molecules and single redox-active organic chromophores. Nanoscale separation in RRDE arrays allows ultra-efficient coupling of counterpoised electron transfer processes at the bottom disk and upper ring electrodes in an attoliter-volume nanopore, processes that can be exploited for improving both sensitivity and selectivity in electroanalysis. In the other geometry, the Au optical cladding layer of a ZMW is used as the working electrode in order to couple the local potential to the fluorescence dynamics of molecules exhibiting large changes in emission quantum efficiency with redox state. These experiments allow the distributions of single molecule E
eq values and other details of electron transfer reactions to be measured on a single molecule basis.
Sonoelectrochemistry: Modeling Acoustic Energy in a Thin Layer System
Authors: Landgren Jeffrey K , Null Emily M , Duda Chester G , Strohmer Gerhard , Leddy Johna 
Published: February 2020

Recent experiments in thin layer sonoelectrochemistry demonstrate that sonication increases the rates of electrocatalysis. Heterogeneous electron transfer rates increase substantially upon ultrasound irradiation1. A model is developed to understand catalytic effects observed when sound waves are applied in a thin layer electrochemical cell.
The cell consists of a hollow Teflon cylinder with a transducer as the base seen in Figure 1. A three electrode system is used with the electrodes spaced equally apart and parallel to the cylinder base. The cylinder is filled with a redox probe and electrolyte solution such that a meniscus forms at the top. The transducer propagates sound waves through the solution (i.e., sonication). A comparison of cyclic voltammograms before, during, and after sonication reveals enhancement effects from the sound waves. For redox probes with slow kinetics, sonication simultaneously increases currents and appears to shift the reaction to more reversible. Data indicate that a combination of the height and shape of the meniscus play a vital role in this enhancement effect.
Numerical analysis is used in conjunction with partial differential equations to develop the model. It takes into account the shape and height of the meniscus as well as the pressure, density, elasticity, mass, and surface tension of the fluid near the meniscus. The model then reveals the standing waves of the system. Standing waves occur in a stationary medium when waves are traveling in opposite directions and cause interference with one another. In general, if this scenario occurs with waves of approximately the same amplitude there is no net change in energy, another indication that the height of the meniscus is relevant.
This model is important for prediction of behavior of the sound waves before and after they contact the top boundary and the role of the meniscus convexity. This will lead to advances in understanding the experimental system for applications in electrocatalysis.

Duda, C. G. Thin Layer Sonoelectrochemistry. Ph.D. thesis, University of Iowa. 2012.

2. Leddy, J.; Duda, C.G.; and Leddy, W.J. provisional patent application, 2013.