全自动电位滴定法测定镍钴锰酸锂中残余的碳酸锂含量

采用自动电位滴定法测定镍钴锰酸锂中残余的碳酸锂含量。试样经搅拌水浸出其中的残余碳酸锂,用盐酸进行滴定。对试样进行11次平行测定,相对标准偏差(RSD)小于3.2%。在镍钴锰酸锂试样中加入基准物质无水碳酸钠进行碳酸根的加标回收实验,碳酸根的加标回收率在97.7%~103%。方法测定结果准确、可靠。     

Enabling High‐Voltage Lithium Metal Batteries by Manipulating Solvation Structure in Ester Electrolyte

Lithium metal is an ideal electrode material for future rechargeable lithium metal batteries. However, the widespread deployment of metallic lithium anode is significantly hindered by its dendritic growth and low Coulombic efficiency, especially in ester solvents. Herein, by rationally manipulating the electrolyte solvation structure with a high donor number solvent, enhancement of the solubility of lithium nitrate in an ester‐based electrolyte is successfully demonstrated, which enables high‐voltage lithium metal batteries. Remarkably, the electrolyte with a high concentration of LiNO₃ additive presents an excellent Coulombic efficiency up to 98.8 % during stable galvanostatic lithium plating/stripping cycles. A full‐cell lithium metal battery with a lithium nickel manganese cobalt oxide cathode exhibits a stable cycling performance showing limited capacity decay. This approach provides an effective electrolyte manipulation strategy to develop high‐voltage lithium metal batteries.     

Theoretical Study of the Interplay between Lithium Bond and Hydrogen Bond in Complexes Involved with HLi and HCN

The lithium‐ and hydrogen‐bonded complex of HLi? NCH? NCH is studied with ab initio calculations. The optimized structure, vibrational frequencies, and binding energy are calculated at the MP2 level with 6‐311++G(2d,2p) basis set. The interplay between lithium bonding and hydrogen bonding in the complex is investigated with these properties. The effect of lithium bonding on the properties of hydrogen bonding is larger than that of hydrogen bonding on the properties of lithium bonding. In the trimer, the binding energies are increased by about 19 % and 61 % for the lithium and hydrogen bonds, respectively. A big cooperative energy (?5.50 kcal mol^?1) is observed in the complex. Both the charge transfer and induction effect due to the electrostatic interaction are responsible for the cooperativity in the trimer. The effect of HCN chain length on the lithium bonding has been considered. The natural bond orbital and atoms in molecules analyses indicate that the electrostatic force plays a main role in the lithium bonding. A many‐body interaction analysis has also been performed for HLi? (NCH)_N (N=2–5) systems.     

Material Design Concept of Lithium‐Excess Electrode Materials with Rocksalt‐Related Structures for Rechargeable Non‐Aqueous Batteries

Dependence on lithium‐ion batteries for automobile applications is rapidly increasing, and further improvement, especially for positive electrode materials, is indispensable to increase energy density of lithium‐ion batteries. In the past several years, many new lithium‐excess high‐capacity electrode materials with rocksalt‐related structures have been reported. These materials deliver high reversible capacity with cationic/anionic redox and percolative lithium migration in the oxide/oxyfluoride framework structures, and recent research progresses on these electrode materials are reviewed. Material design strategies for these lithium‐excess electrode materials are also described. Future possibility of high‐energy non‐aqueous batteries with advanced positive electrode materials is discussed for more details.     

Carbonation of polymeric organolithium compounds: Effects of chain end structure

The carbonation of the adduct of poly(styryl)lithium with 1,1-diphenylethylene with gaseous carbon dioxide in benzene proceeds in high yield (>99%) compared to the inefficient functionalizations for poly(styryl)lithium (66%), poly(isoprenyl)lithium (59%), and polybutadienyl)lithium (27%). The quantitative carboxylation of poly(isoprenyl)lithium and poly(butadienyl)lithium requires the presence of larger amounts of Lewis bases such as THF ([THF]/[Li] = 300) or TMEDA ([TMEDA]/[Li] = 46) compared to poly(styryl)lithium in which a ratio of [TMEDA]/[Li] = 12 is effective. © 1992 John Wiley & Sons, Inc.     

富锂锂锰氧化物的制备及其在溶液中的抽Li+/吸Li+性能

采用柠檬酸配合法合成了系列尖晶石富锂锂锰氧化物Li2O.nMnO2(n=1.75,2.0,2.25,2.5,3.0)。通过X射线衍射(XRD)和酸浸实验发现,350℃合成的Li2O.2.25MnO2具有纯相尖晶石锂锰氧化物结构,且在弱酸性介质中具有较高的锂溶出率和较低的锰溶损率。Li2O.2.25MnO2在酸浸之后转型为锂离子筛。XRD和扫描电子显微镜(SEM)分析发现锂离子筛能够保持尖晶石锂锰氧化物的结构和形貌。吸附实验表明,该锂离子筛在碱性含锂溶液中对Li+具有吸附性能,且吸附容量随着溶液温度和pH值的升高而增大,最高能达到40.14 mg.g-1。通过傅立叶红外光谱(FTIR)研究了锂离子筛的吸附机理,并用Langmuir模型描述了其在LiCl+LiOH溶液中的吸附行为。     

Investigation of Kinetics of Solid-Phase Synthesis of Lithium Orthosilicate

The kinetics of the interaction between lithium carbonate and silica with various degrees of dispersion was investigated by TG and DTA methods. It was found that the utilization of pyrogenic silica with a specific surface area of about 300 m²g^-1 instead of aerosil with one of 175 m²g^-1 leads to an increase of the reaction rate between lithium carbonate and silica, which depends on the formation and growth of lithium orthosilicate crystals in the first stage, and is conditioned by the diffusion of lithium and oxygen ions through the lithium orthosilicate layer formed at temperatures above 800 K. This supposition is supported by the kinetic analysis results obtained with the use of the different models. The optimal regime of heating is recommended. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cycling a Sulfur Electrode: Effect of Physicochemical Properties of Electrolyte Systems

A sulfur electrode is cycled in mixtures of 3-methoxysulfolane and sulfolane with linear ethers (glyme, diglyme, tetraglyme) and lithium trifluoromethane sulfonate (lithium triphlate) as the supporting electrolyte. The decrease in the electrode capacity, observed with an increase in the number ethylene oxide links in glyme molecules and in the number of donor centers in sulfone molecules, is attributed to changes in the form taken by lithium polysulfides in solutions and the increase in the electrolyte viscosity.     

Electrochemistry of a lithium electrode in lithium polysulfide solutions

The effect of lithium polysulfides on the cycling of a lithium electrode and the corrosion rate of lithium cathodic deposits in sulfolane electrolytes is studied. Lithium polysulfides are found to affect the shape of polarization curves, the overpotential of electrode processes, and the cycling time. The presence of lithium polysulfides in electrolyte systems increases the cycling time of a lithium electrode and positively affects the quality of lithium cathodic deposits. A suggested reason for the positive effect of lithium polysulfides is the appearance of a surface film on metallic lithium: this film has quite high protective properties but does not inhibit electrochemical processes.     

柱状金属锂沉积物:电解液添加剂的影响

二次电池的能量密度已成为推动电动汽车和便携式电子产品技术向前发展的重要指标。使用石墨负极的锂离子电池正接近其理论能量密度的天花板,但仍难以满足高端储能设备的需求。金属锂负极因其极高的理论比容量和极低的电极电位,受到了广泛关注。然而,锂沉积过程中枝晶的生长会导致电池安全性差等问题。电解液对金属锂的沉积有着至关重要的影响。本文设计了一种独特的电解槽体系来进行柱状锂的沉积,研究了不同电解液体系(1mol·L^-1LiPF6-碳酸乙烯酯/碳酸二乙酯(EC/DEC,体积比为1:1)、1 mol·L^-1 LiPF6-氟代碳酸乙烯酯(FEC,体积分数5%)-EC/DEC (体积比为1:1))对金属锂沉积的影响。对两种电解液中金属锂沉积物长径比的研究表明,电解液的组分可以显著地影响金属锂的沉积形貌,在加入氟代碳酸乙烯酯(FEC)添加剂之后,柱状锂的直径从0.3–0.6μm增加到0.7–1.3μm,长径比从12.5下降到5.6。长径比的降低有助于减小金属锂和电解液的反应面积,提高金属锂负极的利用率和循环寿命。通过考察循环后锂片的表面化学性质,发现FEC的分解增加了锂表面固态电解质界面层中氟化锂(LiF)组分的比例,提高了界面层中锂离子的扩散速率,减少了锂的成核位点,从而给予锂核更大的生长空间,降低了沉积出的柱状锂的长径比。     

Formation and Thermal Decomposition of Indium Oxynitride Compounds

During the reactions of lithium oxide with indium nitride, lithium nitride with indium oxide, and lithium nitride with lithium indate LiInO2, the formation of a previously unknown crystalline phase, of composition Li4InNO2, was observed. The course of thermal decomposition of the new compound was determined. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ionic‐Liquid–Nanoparticle Hybrid Electrolytes: Applications in Lithium Metal Batteries

Development of rechargeable lithium metal battery (LMB) remains a challenge because of uneven lithium deposition during repeated cycles of charge and discharge. Ionic liquids have received intensive scientific interest as electrolytes because of their exceptional thermal and electrochemical stabilities. Ionic liquid and ionic‐liquid–nanoparticle hybrid electrolytes based on 1‐methy‐3‐propylimidazolium (IM) and 1‐methy‐3‐propylpiperidinium (PP) have been synthesized and their ionic conductivity, electrochemical stability, mechanical properties, and ability to promote stable Li electrodeposition investigated. PP‐based electrolytes were found to be more conductive and substantially more efficient in suppressing dendrite formation on cycled lithium anodes; as little as 11 wt % PP‐IL in a PC‐LiTFSI host produces more than a ten‐fold increase in cell lifetime. Both PP‐ and IM‐based nanoparticle hybrid electrolytes provide up to 10 000‐fold improvements in cell lifetime than anticipated based on their mechanical modulus alone. Galvanostatic cycling measurements in Li/Li₄Ti₅O₁₂ half cells using IL–nanoparticle hybrid electrolytes reveal more than 500 cycles of trouble‐free operation and enhanced rate capability.     

Highly Stable Lithium Metal Batteries Enabled by Regulating the Solvation of Lithium Ions in Nonaqueous Electrolytes

Safe and rechargeable lithium metal batteries have been difficult to achieve because of the formation of lithium dendrites. Herein an emerging electrolyte based on a simple solvation strategy is proposed for highly stable lithium metal anodes in both coin and pouch cells. Fluoroethylene carbonate (FEC) and lithium nitrate (LiNO₃) were concurrently introduced into an electrolyte, thus altering the solvation sheath of lithium ions, and forming a uniform solid electrolyte interphase (SEI), with an abundance of LiF and LiN_xO_y on a working lithium metal anode with dendrite‐free lithium deposition. Ultrahigh Coulombic efficiency (99.96 %) and long lifespans (1000 cycles) were achieved when the FEC/LiNO₃ electrolyte was applied in working batteries. The solvation chemistry of electrolyte was further explored by molecular dynamics simulations and first‐principles calculations. This work provides insight into understanding the critical role of the solvation of lithium ions in forming the SEI and delivering an effective route to optimize electrolytes for safe lithium metal batteries.     

Correlation between the 6Li,15N coupling constant and the coordination number at lithium

The 6Li,15N coupling constants of lithium amide dimers and their mixed complexes with n-butyllithium, formed from five different chiral amines derived from (S)-[15N]phenylalanine, were determined in diethyl ether (Et2O), tetrahydrofuran (THF) and toluene. Results of NMR spectroscopy studies of these complexes show a clear difference in 6Li,15N coupling constants between di-, tri- and tetracoordinated lithium atoms. The lithium amide dimers with a chelating ether group exhibit 6Li,15N coupling constants of approximately 3.8 and approximately 5.5 Hz for the tetracoordinated and tricoordinated lithium atoms, respectively. The lithium amide dimers with a chelating thioether group show distinctly larger 6Li,15N coupling constants of approximately 4.4 Hz for the tetracoordinated lithium atoms, and the tricoordinated lithium atoms have smaller 6Li,15N coupling constants, approximately 4.9 Hz, than their ether analogues. In diethyl ether and tetrahydrofuran, mixed dimeric complexes between the lithium amides and n-butyllithium are formed. The tetracoordinated lithium atoms of these complexes have 6Li,15N coupling constants of approximately 4.0 Hz, and the 6Li,15N coupling constants of the tricoordinated lithium atoms differ somewhat, depending on whether the chelating group is an ether or a thioether; approximately 5.1 and approximately 4.6 Hz, respectively. In toluene, mixed trimeric complexes are formed from two lithium amide moieties and one n-butyllithium. In these trimers, two lithium atoms are tricoordinated with 6Li,15N coupling constants of approximately 4.6 Hz and one lithium is dicoordinated with 6Li,15N coupling constants of approximately 6.5 Hz.     

合成气制乙醇的铑基催化剂中助剂铁,锂的作用本质研究

催化活性测试表明,助剂Fe具有显著提高乙醇生成选择性及铑催化活性的双重作用;助剂Li具有显著提高乙醇选择性的作用,对铑催化活性影响不大。基于H_2/D_2同位素效应结果及CO化学吸附、IR、XRD、XPS等的表征结果,认为助剂Fe经活化处理后大部分与Rh形成RhFe合金,使Rh分散度显著提高,从而提高了乙醇的选择性;Rh分散度的提高以及小部分以Fe~(2+)(Fe~(3+))形式存在的助剂Fe促进甲酰基的生成及随后的氢解断C-O键反应是助剂Fe促使铑催化活性提高的两个因素。Li的主要作用在于通过与C_2含氧中间体乙烯酮氧端的弱亲合作用,促进了乙醇前驱体的生成,从而使乙醇生成选择性提高。     

全自动电位滴定法测定锂电池原料碳酸锂中主成分的含量

采用全自动电位滴定法测定锂电池原料碳酸锂中主成分的含量,用盐酸标准溶液进行滴定,考虑自动电位滴定仪的灵敏性和准确度,通过多次对比实验,确定了仪器的最佳工作参数、滴定剂浓度和样品称样量等滴定条件;对两个不同品位试样分别进行了11次平行测定,相对标准偏差(RSD)均小于1％.在碳酸锂试样中加入基准物质无水碳酸钠进行碳酸根的...     

Facile Protection of Lithium Metal for All-Solid-State Batteries

A nanolayer of reactive propyl acrylate silane groups was deposited on a lithium surface by using a simple dipping method. The polymerization of cross-linkable silane groups with a layer of ally-ether-ramified polyethylene oxide was induced by UV light. SEM analysis revealed a good dispersion of silane groups grafted on the lithium surface and a layer of polymer of about 4 μm was obtained after casting and reticulation. The electrochemical performance for the unmodified and modified lithium electrodes were compared in symmetrical Li/LLZO/Li cells. Stable plating/stripping and low interfacial resistance were obtained when the modified lithium was utilized, indicating that the combination of silane and polymer deposition is promising to increase Li-metal/garnet contact.     

金属锂在含(亚)硫酰基添加剂电解液中电化学可逆性研究

分别以亚硫酰氯(SOCl2)、硫酰氯(SO2Cl2)、二甲亚砜(DMSO)、苯磺酰氯(BSC)和苯基乙烯基亚砜(PVSO)作为添加剂, 加入至1 mol•L－1 LiPF6/碳酸乙烯酯(EC)＋碳酸二甲酯(DMC)(体积比为1∶1)电解液中, 采用恒电流沉积-溶出法、循环伏安法(CV)、电化学阻抗谱(EIS)、X射线光电子能谱(XPS)测试技术, 研究了添加剂对电化学金属锂沉积-溶出可逆性以及金属锂负极/电解液界面性质的影响. 电化学测试结果表明, 添加SO2Cl2和BSC能显著改善金属锂电极的循环性能, 100% DOD(锂全溶出)条件下, 循环效率稳定在90%左右. 电化学测试、添加剂分子电子亲和能计算并结合XPS测试结果表明, 较早反应成膜的SO2Cl2和BSC添加剂可以在一定程度上抑制电解液溶剂的分解, 使锂电极循环效率和寿命得以提高. 洞察和比较添加剂的结构揭示, 含磺酰基的化合物明显优于含亚磺酰基的化合物.     

Metallic Li in carbonaceous nanotubes grown by metalorganic chemical vapor deposition from a metalorganic precursor

Metallic Li in carbonaceous nanostructures was obtained in high concentration (as much as 33.4%) through metalorganic chemical vapor deposition involving certain lithium–aminoalkyl moieties, which are formed in situ , by decomposition of a precursor containing both cobalt and lithium. The bimetallic complex containing both lithium and cobalt was characterized by IR spectroscopy, mass spectroscopy, nuclear magnetic resonance spectroscopy, elemental analysis and thermogravimetric analysis. X‐ray photoelectron spectroscopy measurements performed on the as‐grown films demonstrate that lithium can be stable in metallic form in such a film. Results of X‐ray photoelectron spectroscopic analysis of the as‐grown films are presented as direct evidence of the formation and stabilization of metallic lithium in carbon nanotubes. Carbon nanotubes, encapsulating metallic lithium, can potentially act as a miniaturized nanobattery. Such a battery would be potentially useful in the next generation of communication and remote sensing devices, where a pulse of current is required for their operation. In addition, with metallic lithium, having an effective nuclear magnetic moment, such materials can be envisioned to show potential applications in devices based on nuclear magnetic resonances. Copyright © 2008 John Wiley & Sons, Ltd.     

锂金属电池用三维半互穿网络聚合物电解质的制备

锂金属电池作为下一代高比能量电池技术受到人们越来越广泛的关注。然而由锂枝晶生长引发的安全问题是锂金属电池商业化面临的最大挑战之一。具有高锂离子迁移数和离子电导率的聚合物电解质是抑制锂枝晶生长的重要策略之一。本文将季戊四醇四丙烯酸酯和自由基引发剂AIBN添加至商业化电解液中,采用具有单离子传导功能的多孔聚合物电解质为锂金属电池的电解质隔膜,通过在电池内部发生热诱导原位聚合制备三维半互穿网络单离子传导聚合物电解质,达到提高电解质隔膜离子电导率和机械拉伸性能,以及有效抑制锂枝晶生长的目的。通过该策略的实施,成功获得了室温离子电导率0.53 mS·cm^-1和锂离子迁移数0.65的良好结果。应用于锂金属电池,证明该电解质能够有效抑制锂枝晶的生长和倍率性能的提高,为锂金属电池的开发提供了良好的解决路径。