Ionic processes in solid-electrolyte passivating films on lithium

The electrochemical behaviour of a Li electrode in solutions of LiAlCl₄ in thionyl chloride, LiBF₄ in γ-butyrolactone and LiClO₄ in the mixed solvent propylene carbonate (PC) + dimethoxyethane (DME) in the process of cell storage has been investigated by the methods of electrode impedance spectroscopy and pulse voltammetry. Analogous studies have been carried out in PC + DME solution with the Li electrode coated with a specially formed protecting film of Li₂CO₃. The results have been compared with those obtained earlier for other lithium electrochemical systems. The general regularities of the Li electrode electrochemical kinetics attributed to the process of Li⁺ ion transport through a passivating film coating a lithium surface have been discussed. Received: 22 February 1999 / Accepted: 20 June 1999     

Irreversible capacity elimination via immediate contact of carbon with lithium metal

A new method for elimination of irreversible capacity during lithium intercalation into graphite is described. The method consists of bringing the graphite electrode into tight contact with lithium metal in an electrolyte. As a result of such shorting, a passive film is formed at the graphite surface. The dynamics of the film formation and its properties depend on the correlation between the masses of lithium and graphite. The method does not result in a decrease of the reversible capacity.Presented at the 3rd International Conference on Advanced Batteries and Accumulators, 16–20 June 2002, Brno, Czech Republic     

Recent advances in the study of layered lithium transition metal oxides and their application as intercalation electrodes

A review is presented on the extensive work carried out during the last 30 years on layered oxides structurally related to LiCoO₂ and LiNiO₂. The studies considered here range from the structural and chemical characterization of the layered solids to the detailed evaluation of their aptitude towards lithium deintercalation-intercalation reactions, which form the basis of their successful application in rechargeable battery technology. The different challenges remaining in this area, such as the development of advanced preparation procedures and the optimization of the electrochemical performance by controlled changes in composition, structure, and particle morphology, are discussed. Received: 15 May 1998 / Accepted: 24 July 1998     

Association of bromate ion in nonaqueous solutions of alkali metal salts

Manifestations of ion association of lithium cation with BrO₃ ^- ion in the vibrational spectrum have been studied by IR spectroscopy. The microstructure of the bromate ion with lithium cation in a contact ion pair in an aprotic solvent has been determined by the density functional theory method in the B3LYP/cc-pVTZ approximation, and the vibrational spectrum of coordinated bromate ion has been calculated.     

铅电极在硫酸溶液中的光电化学行为

研究了铅电极在阳极氧化过程中光响应的产生机制。结果表明，Ｐｂ电极在光照氧化时存光活化过程，且光经过程须在电位高于０Ｖ时才能发生。采用现场测量光电压技术研究了Ｐｂ电极在硫酸溶液中的恒电流极化过程。     

CdS超微粒子薄膜电极的光电化学特性

采用电化学方法制备了含不同粒度的ＣｄＳ超微粒子薄膜电极，应用表面光电压谱和光电化学技术对电极的光电化学特性进行了研究。结果表明，这些电极具有明显的量子限域效应，同体相材料相经，ＣｄＳ超微粒子萍奄极显示出较高的光电响应，说明该薄膜电极具有独特的光电压和电荷传输机理。     

Electrolyte additive maintains high performance for dendrite-free lithium metal anode

Because of their high capacity and low potential, lithium metal anodes are considered to be promising candidates for next generation electrode materials. However, the safety concerns and limited cycling life associated with uncontrollable dendrite growth hamper practical applications. In this work, the acidified cellulose ester, which is a mixed fiber microporous membrane film, was used as a novel electrolyte additive that effectively improves the cycle stability of the lithium metal anode and inhibits dendrite growth. The focus of this paper is on inhibiting the formation and growth of lithium dendrites. The coulombic efficiency of a Li|Cu battery with this acidified cellulose ester additive remains stable at 99% after 500 cycles under a current density of 1 mA/cm². Symmetric batteries also remain stable after 500 cycles (1000 h) under a current density of 1 mA/cm². These superior properties can be ascribed to the induced nucleation and the uniform distribution of lithium ion flux. This study uncovers an approach for effectively enabling stable cycling of dendrite-free lithium metal anodes.     

The recent advances in constructing designed electrode in lithium metal batteries

In this review, we focus on the design of lithium electrode and its recent advancements, which suppress the growth of lithium dendrites and improve the performance of the rechargeable batteries. To suppress the growth of lithium dendrites, the general design rules of the system require a uniform lithium ion flux, a low current density, a homogeneous nucleation process and a stable SEI layer. Improvements of the battery performance have been achieved through the delicate design of lithium electrode and here they are summarized into three groups:i) optimizing the 3D porous nanostructure of the current collector, ii) constructing rational host for lithium metal and prelithiating the 3D host matrix with molten lithium, iii) protecting the surface of lithium metal by functional layers. An outlook of the challenges and the potentials of lithium metal battery is also provided, which will facilitate the future development of lithium metal battery.     

Solubilization of SEI lithium salts in alkylcarbonate solvents

The SEI (Solid Electrolyte Interphase) at the surface of electrodes in lithium-ion batteries is composed of various lithium compounds, organic or mineral, which have a direct impact on cycling performance. The main lithium species constituting the SEI and selected in this study are lithium fluoride LiF, lithium carbonate Li₂CO₃, lithium hydroxide LiOH, lithium oxide Li₂O, lithium methoxide LiOCH₃ and lithium ethoxide LiOC₂H₅. Their solubilities were determined in ethylene, propylene, dimethyl, diethyl and vinylene carbonates (EC, PC, DMC, DEC and VC) and in one of their mixtures commonly used in lithium-ion batteries (EC/PC/3DMC) by mean of atomic absorption spectroscopy (AAS). These solutions were also investigated by EIS (Electrochemical Impedance Spectroscopy) and conductimetry measurements. Results show that while solubilization properties differ between LiF and other lithium compounds considered, their association pattern in solution is identical and solutions are mainly constituted of quadrupolar aggregates.     

汞溴红敏化TiO2纳米多孔膜电极的光电化学性质研究

用汞溴红(Mercurochrome)作敏化剂敏化TiO2纳米多孔膜电极,UV-Vis,光电流作用谱和SPS谱表明,该敏化剂能有效地敏化TiO2电极,并且染料聚集体能扩大染料的敏化区间,增加了太阳光的利用效率,对电极施加不同的偏压,测试电极产生的瞬态光电流,研究了偏压对光生电荷转移及复合速率的影响,从不同方向照射电极,对阳极光电流影响显著,结合电化学、光电化学原理对这些现象进行了讨论.     

Mineral salts removal and lithium traces determination in highly concentrated solutions and natural brines

The usual methods, of lithium traces determination, refer in particular to the aqueous solutions whose dry residues do not exceed 7 g L⁻¹. Flame spectrometry or atomic absorption is used for the determination of the considered element.In the case of natural brines, the total dissolved salt ranges from 250 to 350 g L⁻¹. Consequently the determination of lithium traces in this kind of solutions, by the above mentioned spectroscopic methods, may be disturbed due to interferences phenomena. So, a preparatory processing step of the samples is needed.In order to prevent the mentioned phenomena, the total or partial removal of mineral salts, by adding appropriate organic solvent, is carried out. Accordingly, it is significant to make sure that the total quantity of lithium remains in the solution.Therefore, the experimental conditions (sulfate ion removal, solvent ratio and solid-liquid contact time) are optimized. After that the different experimental steps are arranged to make sure the lithium determination, by flame spectrometry, practicable.Finally, the established method is applied firstly to determine Li⁺ in some natural brines and secondly to estimate the lithium reserves in the Tunisian natural brines deposits.     

纳米结构ZnO/染料/聚吡咯光阳极的光电化学性质

用光电化学方法研究了染料RuL2 (NCS) 2 (L =2 ,2′ bipydine 4,4′ dicarboxylicacid) (简写为Dye)、聚吡咯 (PPy)敏化氧化锌 (ZnO)纳米晶电极以及用RuL2 (NCS) 2 和PPy复合敏化ZnO纳米晶膜电极的光电化学行为 .实验表明 ,ZnO/PPy纳米多孔膜电极为双层n 型半导体结构 .PPy和RuL2(NCS) 2 都可对ZnO纳米晶膜产生敏化作用 ,ZnO/RuL2 (NCS) 2 /PPy复合多孔膜电极产生的光电流远大于ZnO/PPy纳米多孔膜电极和ZnO/Dye多孔膜电极产生的光电流 .讨论了该电极的光生电子的机理 ,初步测定了ZnO/RuL2 (NCS) 2 /PPy电极作为光阳极的光电化学电池的工作特性曲线 ,测得该电池的光电转换效率为 1 .3% ,填充因子为 0 .75 .     

纳米尺度TiO2／聚吡咯多孔膜电极光电化学研究

用光电流作用谱，光电流－电势图和ＵＶ－Ｖｉｓ光说研究了ＴｉＯ２／聚吡咯多孔膜电极在不含氧化还原对和含不同氧化还原体系电解质溶液中的光电转换过程。ＴｉＯ２／聚吡咯多孔膜电极双层ｎ型半导体结构，内层ＴｉＯ２多孔膜的禁带宽度为３．２６ｅＶ，外层聚吡咯膜的禁带宽度为２．２ｅＶ。     

纳米尺度TiO2聚苯胺多孔膜电极光电化学研究

用光电流作用谱，光电流－电势图等光电化学方法研究了ＴｉＯ２／聚本胺复合多孔膜电极在不含氧化还原和含有没氧化还原对体系中的光电转换过程。结果说明，ＴｉＯ２／聚苯胺复合多孔膜电极为双层ｍ－型半导体结构，ＴｉＯ２多孔膜的禁带宽度为３．２ｅＶ，外层聚苯胺膜的禁带宽度为２．８８ｅＶ。     

Recent advances in metal-organic frameworks for lithium metal anode protection

The lithium metal battery has been considered as a promising candidate for next generation batteries.However,safety concerns caused by uncontrollable lithium dendrite growth on lithium anode are severely hampering the commercial application.Metal-organic frameworks(MOFs)become one of the most attractive materials due to the high porosity,structural designability and tunability.With unique open channels and pores as well as functional components in MOFs,the transportation and deposition of lithium ions can be regulated,which leads to enhanced electrochemical prope rties.Various strategies for lithium metal protection are proposed in recent wo rks on applications of MOFs in lithium metal batteries.In this review,we highlight latest key approaches in this field and discuss the prospects for MOFs in advanced Li anodes.     

TiO2与ZnO复合纳米结构电极的光电化学研究

利用尿素加压共沉淀法以Ti(SO4)2与Zn(NO3)2为原料制备了TiO2-ZnO复合纳米粒子, 其纳米结构电极的光电化学研究结果表明, 反应物摩尔比为3∶1, 于530 ℃煅烧制备的复合纳米结构电极的光电转换效率最高. 对吸附染料RuL2(SCN)2∶2TBA的纳米结构TiO2和各种复合纳米粒子的纳米结构电极进行光电研究的结果表明, 染料对各纳米结构电极都起到了敏化作用, 其中也是由反应物摩尔比为3∶1, 于530 ℃煅烧制备的纳米结构电极的光电转换效率最高. 对聚3-甲基噻吩修饰的纳米结构TiO2和摩尔比为3∶1, 于530 ℃煅烧的复合纳米粒子构成的纳米结构电极进行光电性能研究, 结果表明, 聚3-甲基噻吩与半导体纳米粒子之间存在p-n结, 在一定条件下p-n结的存在有利于光生电子/空穴的分离, 从而提高了光电转化效率.     

Plasmonic photoelectrochemical reactions on noble metal electrodes of nanostructures

Plasmonic noble metal nanostructures have been targeted due to their strong surface plasmon resonance at photoelectrochemical interfaces. Recently, it has been concluded that, the plasmonic noble metal nanostructures on photoexcitation permit the transfer of effective hot carriers (hot electron/hole pair) to nearby adsorbed molecules where, the transformed hot carriers can efficiently decrease the activation barrier of a reaction. In this review, our recent achievements in the plasmon-mediated chemical reactions of organic molecules such as para-aminothiophenol, substituted para-aminothiophenol and para-nitrothiophenol at nanostructures modified noble metal electrodes using surface enhanced Raman spectroscopy, electrochemical methods, and theoretical calculations will be discussed.     

炔醇类缓蚀剂对铁在硫酸溶液中保护作用的光电化学研究

在含不同缓蚀剂的0．5mol/L H2SO4的电解质溶液中,用光电化学方法研究了氧化铁钝化膜的电子传递过程;缓蚀剂的加入在金属表面形成的沉积膜是非光电化学活性的,基本上对光电流的瞬态性质不造成影响;在硫酸溶液中测得两个明显的光电流峰,其禁带宽度值Eg^dir=3.7eV(对应300nm处的弱峰）,Eg^ind=1.95eV(380到500nm范围的强峰）,加入不同缓蚀剂后测得Eg^ind值略有减小;测定电位阶跃下发生的电流瞬态引起电荷量的改变,表明在恒定电位下延长钝化时间会减少膜中羟量和水的含量,而缓蚀剂的加入减少了膜中OH^-和H2O的含量,说明缓蚀剂沉积膜与钝化膜之间存在着化学作用,造成了钝化膜表面附近的化学组成发生变化。     

模拟混凝土孔溶液中钢筋钝化膜的光电化学方法研究

利用光电化学方法研究了钢筋在模拟混凝土孔溶液中钝化膜的电子性质，结果表明，钢筋在该溶液中形成的钝化膜是一种无定形的ｎ－型半导体成相膜，膜由多种铁氧化物组成，其组成受溶液中的离子、ＰＨ值、成膜电位影响，腐蚀抑制ＮａＮＯ２影响钝化膜的组成和生长过程，从而提高钢筋的抗氯离子点蚀能力。     

纳米结构TiO2/3-甲基噻吩和2-噻吩甲酸共聚物复合膜电极光电化学性能

用光电流作用谱、光电流-电势图等光电化学方法研究了ITO/3-甲基噻吩和2-噻吩甲酸共聚物(CTCMT)膜电极和ITO/TiO₂/CTCMT复合膜电极的光电转换性质.结果表明,CTCMT膜为p型半导体,禁带宽度为2.36eV,价带位置为-5.52eV.在ITO/TiO₂/CTCMT复合膜电极中存在p-n异质结,在一定条件下异质结的存在有利于光生电子-空穴对的分离.CTCMT膜修饰ITO/TiO₂电极可使光电流增强,光电流起始波长红移至600nm以上,使宽禁带半导体电极的光电转换效率得到改善.