Chemistry Commons^™

Magnetic Resonance Studies On Lithium Intercalation Into Carbons, Xiao-Rong Zhou, Zhen-Ming Du, Lin Zhuang, Jun-Tao Lu

Journal of Electrochemistry

The electron spin resonance(ESR) and 7Li-NMR magnetic resonance (7Li-NMR) studies on lithium intercalation into carbons were reviewed based on recently published papers, including those by the authors of this review. Two kinds of electronic spins were found in ESR studies. One corresponds to the charge carrier electrons and is called the Pauli spin. From the ESR intensity of Pauli spins, the curve of the density of electronic states can be deduced for the carbon material studied and, in turn, the contribution of the band model mechanism to the lithium intercalation can be calculated for the given carbon sample. The other …

The Electrochemical Performance Studies On Novel Lifepo4 Cathode Materials For Li-Ion Batteries, Zhi-Cong Shi, Chen Li, Yong Yang

Journal of Electrochemistry

The cathode materials of LiFePO₄ and  LiFePO₄ coated with carbon were synthesized by means of solid state reaction and ballmilling. The samples were characterized by X-ray diffraction, scanning electron microscopy, gas-phase element analysis and titration analysis methods. Electrochemical tests of two kinds of materials showed that both of them exhibit a 3.4V discharge voltage plateau, however, the coated samples demonstrated the improved performance in terms of discharge capacity and cyclic stability.

The Study On The Synthesis And Electrochemical Property Of K2Feo4, Yong-Long Wang, Ning Zhou, Shi-Hai Ye, Xue-Ping Gao, Feng Wu, Zuo-Xiang Zhou, De-Ying Song

Journal of Electrochemistry

The synthesis,characterization and electrochemical property of K₂FeO₄ for positive materal of lithium ion battery were studied. K₂FeO₄ with low purity was gained through the reaction of KCIO and Fe(NO₃)₃ in KOH solution and after recrystalization the purity of K₂FeO₄ reached 97%～98%. The methods of XRD and FTIR were used to measure the structure of K₂FeO₄ and its initial discharge performance was tested.

Study Of Electrochemical Lithium Intercalation Performance Of Ni0.67Mg0.33O, Zhen-Cai Huang, Mao-Hui Chen, Guo-Tao Wu, Jin-Kua You, Zu-Geng Lin

Journal of Electrochemistry

In the present work, Ni_0.67Mg_0.33O and NiO were produced by sol-gel method, and characterized by XRD, a rietveld refinement and the discharge/charge test.It was found that the magnesium-doping restrained the reduction of Ni and decreased the reversible capacity for the sample of Ni_0.67Mg_0.33O. But the formation of the solid solution after the magnesium-doping facilitated the high dispersion of NiO, and accordingly improved the electrochemical performance.

Application Of Biphenyl Electroploymerization For Overcharge Protection In Li-Ion Batteries, Li-Fen Xiao, Xin-Ping Ai, Yu-Liang Cao, Han-Xi Yang

Journal of Electrochemistry

The electropolymerization of biphenyl at overcharged positive electrode was investigated for overcharge protection of Li-ion batteries. Biphenyl in electrolyte as an additive can electrochemically polymerize at 4.5～4.75 V(vs. Li/Li⁺) to form a layer of conductive film on cathode surface. The surface film increases the internal resistance and the gases released during the electropolymerization also increases the internal pressure of the batteries, which therefore enhance the sensitivities of the electrical disconnecting devices. During prolonged overcharge, the growth of the conductive polymer film can create short circuit between the positive and negative electrodes and cause self-discharge of the batteries to …

The Preparation And Characterization Of Zno-Pani Composite Film, Yan-Yan Xi, Huai-Guo Huang, Zhi-Xin Zheng, Ping Dong, Jian-Zhang Zhou, Ling-Ling Wu, Zhong-Hua Lin

Journal of Electrochemistry

ZnO nanoparticle films were prepared on the Au film, PANI film and ITO by sol-gel method, and their morphological optical and photoelectrochemical properties were also studied. The results showed that the porous structure of PANI can suppress the aggregation of ZnO particles, resulting in the blue shift of on-set in the UV-Vis spectra and fluorescence spectra of ZnO-PANI composite film compared with that of ZnO-Au film. It was suggested that the ZnO-PANI composite film can be used in photoelectric coversion.

The Electrochemical Behavior Of Amorphous Ni-P And Ni-B Alloys In 0.5 Mol/L H2So4, Xu-Cheng Wang, Wei-Jiang Wang, Hou-Tian Liu, Zu-Zhan Yu

Journal of Electrochemistry

Polarization curves and impedance spectra were used to investigate the electrochemical behavior of amorphous Ni-P and Ni-B alloys in 0.5 mol/L H₂SO₄ solutions. The possible reason about the remarkable difference in the electrochemical behavior between amorphous Ni-P and Ni-B alloys was discussed.

An Eqcm Study Of Water Adsorption And Oxidation On Pt Electrodes In Sulfate Acid Sulotions, Heng Lin, Sheng-Pei Chen, Jin-Mei Lin, Ai-Lan Lin, Guo-Liang Chen

Journal of Electrochemistry

Simultaneous frequency and current responses during potential cycling of Pt electrode were measured in 0.1 mol·L^-1 H₂SO₄ solution by using EQCM. Quantitative analysis of the mass change revealed that the increase of mass in the hydrogen and double-layer regions in a positive-going potential scan was due to water adsorption on the Pt electrode, further calculation indicated that water molecules adsorbed on Pt electrode in the double-layer regions through a low discharge quomodo .The EQCM studies provided quantitative results of surface mass variation during water adsorption and oxidation,and have thrown new light in elucidating the structure of …

Behaviors Of Fe-Cr Alloys During Cavitation Damage, Xia Bai, Dong-Bai Sun, Hong-Ying Yu, Hui-Ming Meng, Hui-Qin Li, Zi-Shuang Fan

Journal of Electrochemistry

The influence of the surface galvanic effect on the behaviors of three Fe-Cr alloys during cavitation damage in NaCl solutions have been investigated. The results showed that the galvanic effect caused by the inhomogeneity between the undamaged surface of the alloy and the damaged one will be enhanced by the area ratio of the undamaged and the damaged. The behaviors of alloys during cavitation are closely related to both their mechanical performance and anti-corrosion capabilities.

Study On The Corrosion & Electrochemical Properties Of Alloy Aa5083 And The Effect Of Active Chlorine In Seawater, Hong-Ren Wang, Jian-Hua Wu, Jun-Tao Wang, Hong-Bin Wang, Zhi-Gang Fang

Journal of Electrochemistry

In this paper potentiodynamic technique, cyclic polarization technique and immersion corrosion method were used to study the corrosion and electrochemical properties of AA5083 alloy in quiescent seawater, the effect of active chlorine on its properties was also studied. The results obtained indicate that the active chlorine has no remarkable impact on the corrosion and electrochemical properties of AA5083 alloy in area of design concentration which range from 0.2 to 0.5 mg/L, and it has favorable influence on the improvement of pitting corrosion resistance. While the pH value of seawater has evident influence on the corrosion resistance of AA5083 alloy.

Study For The Cathodic Behavior Of Active Chlorine On 316l Ss Electrode Surface, Hui Yu, Ming-Xian Sun, Yan Ma, Xiao-Bin Wang

Journal of Electrochemistry

The cathodic reducing reactions of active chlorine on 316 L SS electrode surface have been investigated by electrochemical techniques. The open circuit potential shifted positively and the limited diffusion current density increased significantly with the increasing content of active chlorine in the 3.5% sodium chloride solution. The two cathodic reduction processes of HClO and ClO^- exhibited on the surface of electrode with the active chlorine added to the 3.5%sodium chloride solution and the corresponding potentials of the two reducing reactions were confirmed. The linear relationship of the mass transport-limited Faradaic current, Id vs. the square root of the angular …

Development And Study Of The (Ag)-Ni/Cr Composite Plating With Antibacterial Properties And Corrosion Resistance, Ya-Ping Zhao, Jin-Hua Wang, Ren-He Yin, Jin Zheng, Le-Shu Yu

Journal of Electrochemistry

The 3-factor and 3-level orthogonal experiment was designed and through the comparison of the different films' antibacterial properties measured by bacterial colony counting and the corrosion resistance studied with the AC impedance method. The optimal plating conditions of the (Ag)-Ni/Cr composite plating, a novel functional plating, were determined. The results have indicated that the (Ag)-Ni/Cr composite plating is characterized by both antibacterial and corrosion resisting properties and has its wide applied prospect.

Synthesis By Complexation Processes And Characterization Of Lini0.8Co0.2O2 Cathode Materials, Jing Liu, Zhao-Yin Wen, Zhong-Hua Gu, Xiu-Jian Zhu, Zu-Xiang Lin

Journal of Electrochemistry

The layered LiNi_0.8Co_0.2O₂ compound, which has been of great interest for lithium ion batteries, was prepared at low temperatures by calcining a complex precursor at different temperatures. The physical properties of the synthesized cathode materials were discussed in the light of structural (XRD). The charge and discharge cycling of the cells containing the synthesized oxide as the positive electrode in conjunction with lithium metals and employing a non-aqueous electrolyte showed that LiNi_0.8Co_0.2O₂ treated at 900 ℃ exhibited excellent performances. The first discharge capacity of LLiNi_0.8Co_0.2O_{2 …}

Investigations Of Smooth Function Of Polyethylene Glycol Surfactants On The Electrolessly Deposited Silver Film, Hao Tong, Zhi-Qing Qiao, Fen-Ning Jing, Meng-Ke Li, Chun-Ming Wang

Journal of Electrochemistry

Some non-ionic surfactants of Polyethylene Glycol 2000, 6000 and 20000 were used to estimate the smooth affection on the electrolessly deposited silver film. The adsorption state of the surfactants about Si/solution interface was investigated by using open circuit potential-time technology (Opt). As comparative experiments, the atomic force microscopy (AFM) was also performed to study the surface smooth effection of the surfactants. It was found that with the increasing of the carbon chain in the surfactants, the smooth effection is getting great. PEG 20000 showed the best smooth function.

Fabrication Of SncuX/Cms Composite Materials For Lithium-Ion Batteries, Yu Liu, Jing-Ying Xie, Jun Yang, Ke Wang, Bao-Feng Wang

Journal of Electrochemistry

The composite material were prepared by sub-ctrochemical cycling tests showed that coulombic efficiency of the electrodes prepared by the composite materials was near 100 % after second cycle and the capacity dropped less than 5% after the 30th cycle, versus 390 mAh⋅g^-1 special capacity, improving 26% special capacity of pure CMS electrode. The electrochemical performance of the composite materials is depended strongly on the alloy content in the composite, the addhesive strength between alloy particles and CMS matrix, the distribution of particles on the surface of CMS and the particle size of alloy. The composite material can be applied …

Pure Iron Electrolyzed From Scrap Iron Chips And Its Corrosion Characteristics, Wei-Min Cao, Ren-He Yin, Hui-Ceng Yan, Zhi-Qiang Ye

Journal of Electrochemistry

The high purity electrolytic iron was made from scrap iron chips. Electrolytic conditions of pure iron were determined in chloride baths and the highest purity was 99.983% by chemical analysis. Pure iron had very compact texture and high mechanical strength by SEM figures of cross section. In deaerated 0.5 kmol·m^-3 H₂SO₄ and 0.5 kmol·m^-3 NaCl solutions, the corrosion rate of iron decreased with increasing purity.

Electroreduction Of Cd(Ⅱ) In Dmso And Complexation Of Cd(Ⅱ) With Coumarin Derivates, Ji-Guo Song, Hua-Can Song, Qi-Qin Yang, Yi-Wen Chen, Zun-Le Xu

Journal of Electrochemistry

Cadmium p-toluenesulfonate was synthesized and tested electrochemically for the first time. This salt can lose all the hydrated water easily and the dehydrated salt do not deliquesce in the air.Hence,the cadmium p-toluenesulfonate is suitable for the electrochemical studies in organic solvents.When the Cd(Ⅱ) reduced on Pt electrode in Cd(p-CH₃C₆H₄SO₃)₂+TBAP+DMSO, underpotential deposition of cadmium occurred at first, and then cadmium deposited. 4-Methyl-7-hydroxylcoumarin and 3-aminocoumarin coordinate with Cd(Ⅱ) respectively, as a result the reductive potentials of Cd(Ⅱ) moved to the negative direction.

Experimental Investigation Of Steel Corrosion In Lead Bismuth Eutectic (Lbe): Characterization, Species Identification, And Chemical Reactions, John Farley, Dale L. Perry, Allen L. Johnson

Transmutation Sciences Materials (TRP)

The goal of the present research is to achieve a basic understanding of corrosion of steels by Lead Bismuth Eutectic (LBE). Liquid LBE is under consideration in the transmuter as both a spallation target and as a blanket coolant. There have been previous studies of LBE, especially by the Russians, who have over 80 reactor-years experience with LBE coolant in their Alpha-class submarine reactors. The Russians found that the presence of small amounts (ppm) of oxygen in the LBE significantly reduced corrosion. However, a fundamental understanding and verification of its role in the corrosion of steels is still very incomplete. …

Corrosion Of Steel By Lead Bismuth Eutectic: Quarterly Report November- December 2002 January 2003, John Farley

Transmutation Sciences Materials (TRP)

We continue to get valuable data from sputter depth profiling of steel samples. We meet weekly to discuss progress. We took depth-profiling data on D9 steel that had been exposed to LBE. This the first time we have examined this type of steel. This is important because it will enable us to separate out two effects and determine their effect on corrosion: composition of the steel vs surface preparation.

We started to plan a small experiments using a crucible of heated LBE, with the research program to be conducted at UNLV, on basic aspects of corrosion in this system. The …

Deuterium Nmr Studies Of Bulk And Silica-Absorbed Polystyrene, Macduff O. Okuom, Jinhua Yang, Frank D. Blum

Chemistry Faculty Research & Creative Works

Thin polymer films are used in applications such as electronics, biomedical devices and coatings. As the trend to make the devices smaller continues, a film's influence on a material's overall properties becomes more prominent. Previous studies have shown that thin polymer films have characteristics slightly different from those of bulk polymers. Film behavior has been characterized by examining thermal expansion, diffusion, conformation, density and glass transitions. The dynamics of glassy polystyrene has been investigated using a wide variety of theoretical and experimental methods. Schaefer et al., using 13C NMR, reported that ~7% of phenyl rings in polystyrene undergo -flips. Using …

Ft-Ir Studies Of Stereo Regular Pmma On Silica: Drying Effects, Bing Zhang, Suntree Kulkeratiyut, Suriyaphongse Kulkeratiyut, Frank D. Blum

Chemistry Faculty Research & Creative Works

A great amount of work has been done on the configuration of surface adsorbed poly(methyl methacrylate) (PMMA), especially on surfaces to which they have a strong attraction. Some studies have been make on the relationships between configuration and tacticity, molecular weight, adsorbed amount, and density of surface hydroxyl groups. The effect of tacticity on the conformation of alumina-adsorbed PMMA in solution and dry spin-coated films were studied by Grohen et al. Their results showed that surface-adsorbed PMMA chains adopted a relatively flat configuration, but iso-PMMA (isotactic) adsorbed on aluminum, with a much larger fraction of the bound carbonyl groups, had …

Molecular Mass And Dynamics In Pma-D₃ In The Glass Transition Region, Burak Metin, Frank D. Blum

Chemistry Faculty Research & Creative Works

The segmental dynamics through the glass transition region, by which the glassy polymer becomes rubbery, are not well understood. Free volume, thermodynamic and kinetic theories have been used to describe the phenomenon behind the glass transition and some of those theories were tested with computer simulations. Different experimental techniques, such as NMR, thermo-mechanical analysis (TMA), differential scanning calorimetry (DSC), dilatometry and dynamic mechanical analysis (DMA) have all been also used to probe this important phenomena. Deuterium (2H) NMR has been a valuable tool for the investigation of the dynamics of macromolecules. Deuteration of macromolecules at specific locations on the chains …

Dynamics Of Bulk And Adsorbed Poly(Vinyl Acetate), Frank D. Blum, Robert D. O'Connor

Materials Science and Engineering Faculty Research & Creative Works

We have recently completed a series of experiments on methyl-labeled poly(vinyl acetate)-d3, (PVAc-d3)1 and poly(methyl acrylate)-d3 (PMA-d3).234 the systems have been studied as a function of the adsorbed amount, molecular weight, and presence of a protonated overlayer. Using deuterium line shape analysis, we have found that around the glass transition temperature, the adsorbed polymers show the presence of a motional gradient. Polymer segments near the silica-polymer interface have less mobility than the bulk polymer and those near the polymer-air interface are more mobile than those of the bulk polymer. A schematic representation of the motional gradient is shown in Figure …

Corrosion Of Steel By Lead Bismuth Eutectic, John Farley, Allen L. Johnson, Dale L. Perry

Transmutation Sciences Materials (TRP)

Materials for transmuter systems must be able to tolerate high neutron fluxes, great temperatures, and chemical corrosion. For lead bismuth eutectic (LBE) systems, there is an additional challenge in that the corrosive behaviors of materials in LBE are not well understood. Most of the available information on LBE systems has come from the Russians, who have over 80 reactor-years experience with LBE coolant in their Alpha-class submarine reactors. The Russians found that the presence of small amounts of oxygen (on the order of parts per million) in the LBE significantly reduced corrosion. However, a fundamental understanding and verification of its …

Surface Studies Of Corrosion Of Stainless Steel By Lead Bismuth Eutectic, Daniel Koury, Brian D. Hosterman, John Farley, Dale L. Perry, D. Parsons, J. Manzerova, Allen L. Johnson

Transmutation Sciences Materials (TRP)

Why is Lead Bismuth Eutectic Important?

• Changing national security stances have led to reexamination of nuclear waste reprocessing

• Dangerous actinides can be separated and

• Transmuted into safer products, creating a waste form dangerous for only hundreds of years, in addition to the production (up to 1/3 of the original fission energy) of useful energy

• Non-moderating coolants or spallation targets for production of fast neutrons is required for transmutation

• Russian experience with LBE coolants in their nuclear submarine fleet makes LBE an attractive possible transmutation coolant technology

• Corrosion of steel by LBE is an important …

Environment-Induced Degradation And Crack-Growth Studies Of Candidate Target Materials, Ajit K. Roy, Brendan O'Toole, Zhiyong Wang, David W. Hatchett

Transmutation Sciences Materials (TRP)

The primary objective of this task is to evaluate the potential for the environmentally-assisted cracking of candidate target materials for applications in spallation-neutron-target systems, such as accelerator-driven system for the transmutation of waste. The materials selected for evaluation and characterization are martensitic stainless steels (SS) including Alloys HT- 9, EP 823 and Type 422 stainless steel.

More recently, this experimental program has been expanded to evaluate the effect of molten lead-bismuth eutectic (LBE) on the corrosion behavior of target materials in the presence of oxygen. Since the materials performance laboratory (MPL) at UNLV currently cannot accommodate this type of testing, …

Modeling Corrosion In Oxygen Controlled Lbe Systems With Coupling Of Chemical Kinetics And Hydrodynamics, Samir Moujaes, Yitung Chen

Transmutation Sciences Materials (TRP)

The corrosion of structural materials is a major concern for the use of lead-bismuth eutectic (LBE) systems for nuclear applications such as in transmuter targets or fast reactors. Corrosion in liquid metal systems can occur through various processes, including, for example, dissolution, formation of inter-metallic compounds at the interface, and penetration of liquid metal along grain boundaries. Predicting the rate of these processes depends on numerous system operational factors: temperature, system geometry, thermal gradients, solid and liquid compositions, and velocity of the liquid metal, to name a few. Corrosion, along with mechanical and/or hydraulic factors, often contributes to component failure. …

Modeling Of Corrosion In Oxygen Controlled Lead Bismuth Eutectic Systems With The Coupling Of Chemical Kinetics And Hydrodynamics, Samir Moujaes, Yitung Chen, Kanthi Kiran Dasika, Chao Wu

Transmutation Sciences Materials (TRP)

Objectives:

• To simulate a 2-D model of the Materials Test Loop by approximating it to be a toroid with a pie cross section for the purpose of comparing the simulated results with the analytical results.
• The temperature and concentration profiles on the wall boundaries imposed are similar to the actual test model.
• Geometry effects have great influence on local corrosion rate.
• A 2-D benchmark problem and a sudden expansion case are studied which show good consistency to analytical solution.
• Results from 2-D sudden expansion problem are similar to experimental data obtained by other researchers.

Investigation Of The Corrosion Of Steel By Lead-Bismuth Eutectic (Lbe) Using Scanning Electron Microscopy And X-Ray Photoelectron Spectroscopy, Daniel Koury

UNLV Theses, Dissertations, Professional Papers, and Capstones

Lead Bismuth Eutectic (LBE) has been proposed for use in programs for accelerator transmutation of waste. LBE is the leading candidate material as a spallation target and an option for the sub-critical blanket coolant. The corrosion of 316 and 316L stainless steels by LBE has been studied using UNLV's facilities for Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). We have compared exposed and unexposed samples and studied the differences. Some amount of surface contamination is present on the samples and has been removed by ionbeam etching. The unexposed samples reveal typical stainless steel characteristics: a chromium oxide passivation …

Lithium Intercalation Performance Of P-Doped Phenolic Resin Pyrolysis Carbon, Bao-Hua Li, Kai-Xi Li, Yonggen Lv, Chun-Xiang Lv, Dong Wu, Li-Cheng Ling

Journal of Electrochemistry

Phosphorus-doped phenolic resin carbon was prepared by low temperature (700 ℃) pyrolysis of thermoplastic phenolic resin containing different amounts of phosphorus pentoxide after curing. X-ray diffraction pattern and the constang-current charge-discharge properties of phenolic resin carbon were studied. The results showed that the phenolic resin carbon microstructure became out of order with increasing of content phosphorus pentoxide, otherwise, the first discharge reversible capacities increased firstly and then decreased. The first discharge reversible capacity of phenolic resin carbon containing 9wt% phosphorus pentoxide was 528 mA·h·g^-1 which was higher than that of non-phosphorus doped phenolic resin carbon(230 mA·h·g^-1) did.