Electrocatalytic Processes in Lithium Power Sources

Most important electrocatalytic processes that occur in primary and secondary (rechargeable) lithium power sources are briefly considered.     

Redox Processes in Amidinylcyclopentadiene Compounds and Thallium Complexes

Cyclic voltammetry at platinum and dropping mercury electrodes in acetonitrile suggests that the reduction of amidinylcyclopentadiene ligands involves generation of corresponding radical anions and the oxidation, radical cations, whereas the reduction of thallium complexes occurs through the deposition of the free metal (the process is affected by the complexing agent) and their oxidation leads to the ligand oxidation (the process is affected by the metal ions). Given cyclic voltammetric data on model compounds of rigid structure in solutions, amidinylcyclopentadiene ligands and thallium complexes exist in acetonitrile in a nondissociated covalent form with a bidentate metal (hydrogen) coordination with the complexing agent.     

锂离子在石墨化碳纤维中的扩散系数

锂电子电池;嵌入电极;锂离子在石墨化碳纤维中的扩散系数     

锂和钙在汞中的扩散系数测定

用汞阴极电解法制备锂汞齐和钙汞齐。用毛细管取－小滴汞齐挂洋电极上，以悬汞电极作荼电极，用计时安培法在－０．２Ｖ下测定了锂、钙在汞中的扩散系数。在２５℃下其值为ＤＬｉ＝（８．６５±０．１７）×１０＾－６ｃｍ＾２／ｓ；ＤＣａ＝（７．４３±０．１６）×１０＾－６ｃｍ＾２／ｓ。用Ｓｕｔｈｅｒｌａｎｄ－Ｅｉｎｓｔｅｉｎ扩散方程式计算了汞中扩散粒子半径，其值分别２４７ｐｍ和２８８ｐｍ。这些数值说明锂和钙都是以     

Microscopic Studies of Diffusion and Segregation Processes in Heavily Loaded Tribosystems

Russian Journal of Applied Chemistry - The construction of a wearing-process model is considered. This model should take into account not only the complex multilevel organization of the process,...     

Convective and Diffusion Processes in a Multicomponent Electrochemical Water Purification System

An electrochemical system (ES), which is a multicomponent working environment where bulk chemical reactions occur, is considered. Non-steady-state fields of concentrations, electric potential, velocities, and temperature are modeled mathematically. Dissipative structure of ES as a whole and in local regions is quantitatively estimated in a Prigogine–Glansdorff stability study. The calculation results may come useful in controlling technological parameters of ES intended for water purification.     

Electrolytic Sodium-Vanadium Oxide Compounds in Intercalation Cathodes of Lithium Battery

Electrolytic mixtures of vanadium(V) oxide and -Na_xV₂O₅ bronze were synthesized and studied by X-ray diffraction and thermal analyses, step galvanostatic titration, IR absorption spectroscopy, mass spectroscopy, and electrochemical methods.     

锂在高有序热解石墨(HOPG)电极中的扩散系数

用循环伏安、交流阻抗和电位阶跃法研究了平板高有序热解石墨(HOPG)电极在1mol/LLiPF₆和体积比为1∶1的EC/DMC溶液中的电化学行为.结果表明,石墨的嵌锂反应仅发生在边界面上.随着嵌锂量的增加,表面SEI膜的电阻和嵌入反应的极化电阻减小.用交流阻抗谱和电位阶跃方法测定的锂在高有序热解石墨中的扩散系数一致,并随充电程度的增加而显著减小.在电极电位(vs.Li/Li⁺) 0.2～0.05V区间,扩散系数由10^-11cm²/s下降到10^-12cm²/s.     

Diffusion Kinetics Study of Lithium Ion in the Graphdiyne Based Electrode

Herein,we report a comparative investigation of the electrochemical lithium diffusion within graphidyne(GDY)based electrodes.The transfer kinetic behaviors of lithium ions during the insertion/extraction process are analyzed through different methods including the galvanostatic intermittent titration technique(GITT)and the electrochemical impedance spectroscopy(EIS).GDY with the morphology of nanosheets(GDY NS)shows lithium diffusion coefficients in the orders range of 10-12-10-13 cm2/s through the GITT method.Meanwhile,EIS indicates quite a lower value of lithium diffusion coefficients between 10-13 and 10-15 cm2/s,which indicates that the analysis technique has an influence on the evaluation of GDY-based electrodes.In addition,under the same measurement condition of GITT,GDY nanoparticles(GDY NP)exhibit a lower value of Li+diffusion coefficient(10-14-10-16 cm2/s)during the charge-discharge process compared to those of GDY NS,which can be ascribed to the wide distributing range of particle size in GDY NP based electrodes.The analysis results in this work reveal that the aggregating forms of GDY electrode material have an important effect on the diffusion process of lithium ions,which provides a pathway to optimize the performance of GDY-based energy storage devices.     

锂离子在石墨负极材料中扩散系数的测定

锂离子电池是以各种碳材料为负极而起来的一 种新型电池,成功地解决了以 为负极瓣锂可充电电池的安全性问题,已经应用于锂离子电池的负极材料有石墨和石油焦炭,正在研究的负极材料有热解碳,石墨化碳纤维,硼炭或硼炭氮化合物以及锡基氧化物等[1],石墨的比容量要比石油焦炭的比容量高一倍左右,其理论比容量372mA.h.g^-1,但锂离子在石墨材料中的扩散系数比较低,限制了以其为负极材料的电池的大电流充放电能力,锂离子在电极材料中的扩散系数可以用多种电化学方法测量得到,主要有：电位间歇滴定方法（PITT）（Potentiostatic Intermittent Titratiobn Technique)^[2,3,4,6],恒电流间歇滴定法（GITT）（Galvanostatic Intermittent Titration Technology)^[6],电流脉冲松弛法（CPR）（Current Pulse Relaxation Method)^[3,6]和交流阻抗法（A－C Technology)^[4,5,6],GITT,CPR,A-C等方法测定锂离子扩散系数时,由于相变发生处dE/dy值不容易准确得到（相变时,dE/dy→0）,此时测得的扩散系数误差比较大,PITT方法测定锂离子扩展系统,不存在这个问题,能比较准确地测定整个嵌入组成范围内的锂离子扩散系数。     

Effect of Temperature on Reversible and Irreversible Processes during Lithium Intercalation in Graphite

Effect of temperature on reversible and irreversible processes during lithium intercalation in graphite from 1 M LiClO₄ solution in PC–DME is studied by galvanostatic cycling, cyclic voltammetry, and impedance spectroscopy. Reducing temperature diminishes both reversible and irreversible capacities. Conditions for the passive-film formation on graphite are discussed. If several first cycles are run at a negative temperature, the overall charge spent irreversibly decreases if the temperature is then elevated. The lower the initial-cycling temperature, the smaller the overall irreversible capacity.     

Inorganic-Organic Polymers as Migration Barriers Against Liquid and Volatile Compounds

In addition to the barrier properties against water vapor and oxygen, inorganic-organic polymers can also function as protection layers against unwanted migration of chemical substances in two ways. First, hybrid polymers prevent components from migrating out of polymer substrates. This is of special interest for polymeric materials containing substances like plasticizing agents, unreacted monomers or catalysts. Thus the olfactory nuisance and the toxicological emission are decreased. The plastics are also prevented from becoming prematurely brittle. Second, the coated materials are also protected against the interaction of dyes or dirt staining the material.These functions can be achieved by thermally or UV curable coating materials, synthesized by the sol-gel technique. Since several polymer materials show only a low heat resistance (e.g. PVC, polyolefines), this publication is focussed on the development of new migration barriers based on photochemically curable sols.Another advantage of the UV process in comparison to thermal treatments are the short curing times and low power consumption which make this process even more attractive for industrial applications. The coatings were characterized by IR and solid state NMR spectroscopy. The migration barrier properties were tested according to industrial standards.Due to the choice of specific functional groups, these hybrid polymers can be further modified in order to combine the migration barrier function with additional properties: scratch and abrasion resistance, hydrophobicity, antistatic effects. Examples of feasible combinations of properties are also given.     

Jasmonate Compounds and Their Derivatives in the Regulation of the Neoplastic Processes

Cancer is a serious problem in modern medicine, mainly due to the insufficient effectiveness of currently available therapies. There is a particular interest in compounds of natural origin, which can be used in the prophylaxis, as well as in the treatment and support of cancer treatment. One such compound is jasmonic acid (3-oxo-2-(pent-2’-enyl)cyclopentane acetic acid; isolated active form: trans-(-)-(3R,7R)- and cis-(+)-(3R,7S)-jasmonic acid) and its derivatives, which, due to their wide range of biological activities, are also proposed as potential therapeutic agents. Therefore, a review of literature data on the biological activity of jasmonates was prepared, with particular emphasis on the mechanisms of jasmonate action in neoplastic diseases. The anti-tumor activity of jasmonate compounds is based on altered cellular ATP levels; induction of re-differentiation through the action of Mitogen Activated Protein Kinases (MAPKs); the induction of the apoptosis by reactive oxygen species. Jasmonates can be used in anti-cancer therapy in combination with other known drugs, such as cisplatin, paclitaxel or doxorubicin, showing a synergistic effect. The structure–activity relationship of novel jasmonate derivatives with anti-tumor, anti-inflammatory and anti-aging effects is also shown.     

固态锂电池电极过程的原位研究进展

固态锂电池(SSLBs)由于其安全性和潜在的高能量密度优势,被认为是下一代动力电池的重要发展方向.然而,目前仍存在固态电解质离子电导率低,电极/电解质界面兼容性和稳定性差等瓶颈问题.为了提高SSLBs的性能,阐明循环过程中电极、固态电解质及其界面间的动态演化是至关重要的.在过去的几十年里,各种先进原位表征技术的出现,促进了对高性能锂电池内部工作机制的理解,推动了SSLBs进一步发展.本综述系统地介绍了近几年原子力显微镜、电子显微镜、X射线显微镜等成像表征技术和拉曼光谱、X-ray基技术、中子深度分析等成分分析技术的原位研究进展.重点分析了各类表征技术在SSLBs循环过程中形貌和组分的演化,包括正极材料的相变、形变,金属锂的沉积/溶解、锂枝晶生长,固态电解质结构演化和固体电解质中间相的形成,进一步加深了对固态锂电池的理解.     

磷酸铁锂在饱和硝酸锂溶液中的电极过程动力学

利用循环伏安法(CV)、充放电测试和恒电位间隙滴定技术(PITT)研究了LiFePO4在饱和LiNO3溶液中的电极过程动力学. 研究结果表明, LiFePO4在饱和LiNO3溶液中具有良好的电化学可逆性, 其首次放电比容量达116.2 mAh•g−1, 首次充放电效率达92%. CV法估算出氧化峰和还原峰处锂离子在LiFePO4中的扩散系数分别为4.3×10−11和3.8×10−11 cm2•s−1. 采用PITT测定出锂离子在LiFePO4中的扩散系数随电位的变化规律, 其在充电平台附近达到最小值5.5×10−11 cm2•s−1.     

Investigations of Deintercalation Processes in Graphite Intercalation Compounds With SbCl5 and ICl

Results of the investigations of deintercalation process in intercalation compounds graphite-SbCl₅ and graphite-ICl are presented. It was found that sample mass losses have a step character that testifies to the discrete transition from one stage of graphite intercalation compounds to another. The increase in the rate of heating breaks the step character of mass loss dependence on temperature and intensive mass losses occur without stage transitions. This revised version was published online in August 2006 with corrections to the Cover Date.