四氟硼锂和六氟砷锂的合成与拉曼光谱分析

介绍了合成高纯无水的ＬｉＢＦ４和ＬｉＡｓＦ６的新方法，并讨论了其合成条件，指出制备多孔状ＬｉＦ和控制反应温度是合成的关键。     

Improved electrochemical redox performance of 2,5-dimercapto-1,3,4-thiadiazole by poly(3-methoxythiophene)

High electrocatalytic activity of an electropolymerized film of poly(3-methoxythiophene) (PMOT) is reported toward the redox reaction of 2,5-dimercapto-1,3,4-thiadiazole (DMcT) as a promising cathode material for the lithium ion battery. Cyclic voltammetry showed improved electrochemical performance of DMcT on PMOT-coated Pt electrode, indicating accelerated redox kinetics. Moreover, charge-discharge tests exhibited higher discharge capacity and slower capacity fading of the PMOT-doped DMcT composite cathode compared with pure DMcT.     

Zwitterion effect in polyelectrolyte gels based on lithium methacrylate-N,N-dimethyl acrylamide copolymer

Zwitterionic compounds such as those based on 1-butylimidazolium-3-(n-butanesulfonate) have previously been shown to have positive effects on the transport properties of polyelectrolytes. The addition of the zwitterion has been found to, in some cases, increase the dissociation of the lithium ion and enhance the conductivity by almost an order of magnitude. In this work, we report the effects of adding the above-mentioned zwitterion into the polyelectrolyte gel system poly(lithium methacrylate-co-N,N-dimethyl acrylamide); the anionic group being a stronger base leads to different behaviour for this copolymer compared to previous work. Polyelectrolyte gels based on dimethyl sulfoxide and polyether solvents were investigated to determine the breadth of applicability of the zwitterion in improving lithium ion transport. Impedance spectroscopy and pulse field gradient-NMR diffusion indicate an increase in the number of available charge carriers with zwitterion addition in some gel systems, however, the effect is not universal.     

Mg~(2+)、Zr~(4+)离子掺杂对Li_4Ti_5O_(12)电化学性能的影响

以固相反应法合成了尖晶石型Li4Ti5O12电极材料,进行了金属离子掺杂以提高其导电性及综合性能,以适应用于大电流充放电的目的。采用XRD、室温恒流充放电循环、交流阻抗和循环伏安等测试手段,考察了A位掺杂Mg(Li4-xMgxTi5O12,x=0.15),B位掺杂Zr(Li4ZrxTi5-xO12,x=0.15)对Li4Ti5O12结构和电化学性能的影响。结果表明:掺杂少量的Mg2+、Zr4+未引起材料结构的变化,明显降低了Li4Ti5O12电荷转移阻抗,使导电性得到有效提高。0.1 C放电倍率下放电,未掺杂及掺杂Mg2+、Zr4+的Li4Ti5O12首次放电容量分别为159.8、144.9、161.2mAh/g,循环40次后,容量分别保持为113.8、130.6、133.6 mAh/g。与未掺杂的Li4Ti5O12相比,掺杂后的电极材料极化减小、循环容量及稳定性提高。     

Performance of a magnesium–lithium alloy as an anode for magnesium batteries

In this work, we describe an evaluation of an Mg–Li alloy (Li: 13 wt %) for possible use in magnesium primary reserve batteries. Higher OCP for the Mg–Li alloy have been observed in 2 M MgCl₂ and MgBr₂ electrolyte. The corrosion rate of the Mg–Li alloy is found to be in the order: MgCl₂ < Mg(COOCH₃)₂ < MgSO₄ < MgBr₂ < Mg(ClO₄)₂. Mg–Li alloys exhibit higher (81%) anodic efficiencies even when the current density is increased to 8.6 mA cm ^–2. It has been observed that Mg–Li/MgCl₂/CuO cells offer higher operating voltage and capacity than those with the conventionally used Mg–Al alloy.     

Noise characterization of surface processes of the Li/organic electrolyte interface

The processes occurring in aprotic electrolyte on a lithium electrode in the steady state conditions and under polarization are studied using the method of electrochemical noise characterization. The evidence of the electro-chemical noise measurements on polarized lithium electrodes indicates that the discharge of lithium ions under cathodic polarization, as well as lithium anodic dissolution, is localized under the passive film rather than on its surface. An increase in the polarizing current results in local breakdown of the film; in this case, the electrochemical process emerges on the electrode surface affecting the character of potential fluctuations. The intensity of electrochemical noise significantly increases in the course of cathodic polarization with high currents. The reason is that lithium metal crystals, which are formed under the passive film, perforate the film, and dendrites grow on its surface. The method shows the dependence of electrochemical noise intensity on the nature of the electrolyte and establishes the correlation between the stability of the lithium electrode in the course of cycling and the intensity of fluctuations. This offers an opportunity of using the method of electrochemical noise for screening organic electrolytes for lithium batteries.     

Mg:Mn:Fe:LiNbO3晶体的全息存储性能

在同成分铌酸锂晶体中掺入0.03?2O3和0.1%MnO2(质量分数),分别掺入0,1%,3%,4.5%,6%的MgO(摩尔分数),用提拉法生长了一系列Mg:Mn:Fe:LiNbO3晶体.检测了Mg:Mn:Fe:LiNbO3晶体的红外光谱和抗光损伤能力.掺0,1%,3%,4.5%Mg的Mg:Mn:Fe:LiNbO3晶体的OH-红外振动峰位于3484cm-1,而掺6%Mg的Mg:Mn:Fe:LiNbO3晶体红外振动峰移到3 535gm-1.采用波长为632nm的He-Ne激光器作为光源,通过二波耦合方法测试晶体的全息存储性能.结果表明:Mg:Mn:Fe:LiNbO3晶体的写入时间和动态范围随掺镁量的增加而显著减小,而光折变灵敏度略有上升,抗光损伤性能增强,其中掺镁量为3%Mg:Mn:Fe:LiNbO3晶体更适合作为全息存储介质.     

浅析氯化氢合成余热利用

介绍了采用热水型溴化锂机组对氯化氢合成中产生的余热的利用,通过计算,对比分析了节能效果。     

水溶液晶体的空间生长及其地基模拟实验

空间水溶液晶体生长是通过搭载人造卫星、宇宙飞船和空间站等飞行器,在微重力条件下从水溶液中进行晶体生长实验.许多透明单晶体,诸如:KDP(磷酸二氢钾,potassium dihydrogen phosphate)、ADP(磷酸二氢铵,ammonium dihydrogen phosphate)、TGS(硫酸三甘氨酸,triglycine sulfae)、沸石和α-碘酸锂(α-LiIO3)等无机非线性光学晶体,尿素等有机非线性光学晶体以及蛋白质等生物晶体,均可采用水溶液法生长.美国、前苏联、西欧和日本等国在从事空间材料科学研究的高科技发展计划中,均把水溶液晶体生长作为一项重要项目.由于水溶液晶体生长方法的研究在地面上已有丰富的基础,而且具有温度低,能耗小,可实现原位实时观察等优点,所以,它是探索空间晶体生长原理和方法、研究晶体生长微重力效应的重要材料制备技术.由于空间晶体生长受搭载条件限制,空间实验的次数与地面相比是十分稀少的,为了获得空间实验的高成功率,在地面上必须建立相应的实验基地,开展深入的地基研究工作.本文将分别从空间实验和地基研究两个方面作系列介绍,包括蛋白质晶体,沸石晶体,α-LiIO3晶体的空间生长以及TGS,NaClO3(sodium chlorate,氯酸钠),Sr(NO3)2(strontium nitrate,硝酸鍶)和Ba(NO3)2(barium nitrate,硝酸钡)等晶体生长过程的原位实时观察,并展望了空间晶体生长的发展前景.     

一种能够抑制锂枝晶的锂金属电池电解液润湿性添加剂

将氟代有机溶剂2,2,3,3-四氟丙基甲基丙烯酸酯(TFPMA)作为双功能添加剂引入碳酸酯电解液体系,考察了TFPMA质量分数对增大润湿性的影响.采用交流阻抗、恒流充放电等测试了添加TFPMA后的锂金属电池性能.采用SEM和XPS表征了循环后的锂金属电极表面.结果表明,1.0％(质量分数,下同)TFPMA的添加使电解液与隔膜间的接触角从54°降至44°,内阻从6.15Ω降至1.94Ω,Li-LiFePO4电池在5 C电流密度下的比容量从66 mA·h/g提升至80 mA·h/g,1 C电流密度下的恒电流循环在100圈时还保持99％以上的库仑效率.TFPMA还促进了Li+的均匀沉积和优良固体电解质界面膜的形成,抑制了锂枝晶,电解液添加了1.0％TFPMA后,Li-Cu电池可以循环100圈以上,而库仑效率没有发生较大下降.循环后电极的SEM图表明,添加了1.0％TFPMA电解液的锂金属负极表面沉积更加平整,有较少的锂枝晶生成.