Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

高氯酸锂-乙酰胺/乙烯脲体系的二元熔盐电解质

制备了高氯酸锂与乙酰胺和乙烯脲形成的二元低温熔盐电解质，采用差示扫描量热法、交流阻抗法和循环伏安法分别对其热学、电化学性质进行了研究.测试结果表明,高氯酸锂-乙酰胺体系具有较好的热稳定性和高的电导性，配比n（LiClO4）:n（Acetamide）=1.0:5.5的样品室温（25 ℃）电导率为1.25×10－3 S•cm－1，80 ℃电导率为1.15×10－2 S•cm－1;其电化学稳定电位窗近3 V左右.     

改性石墨用于锂离子电池负极

石墨可用于锂离子电池负极材料，其改性方面的研究主要有：石墨的还原、氧化、表面包膜以及物理法处理。这些方法可以改变石墨的电子状态及表面结构，能够提高石墨的性能。本文介绍了改性石墨用于锂离子电池负极的研究概况。     

锂硫电池用石墨烯基材料的研究进展

锂硫电池因其理论能量密度高、资源丰富和环境友好等优势,被认为是最有发展前景的下一代电化学储能系统之一。然而,硫的绝缘性、充放电中间产物多硫化物的溶解和扩散、硫的体积膨胀以及锂负极安全性等问题,严重制约着锂硫电池的商业应用。石墨烯因其具有高导电、高柔性等诸多优异特性而被广泛研究,将其用于锂硫电池的正极载体、隔膜涂层和集流体中,以期实现高比能、高稳定性的锂硫电池。本文综述了石墨烯基材料,包括石墨烯、功能化石墨烯、掺杂石墨烯和石墨烯复合物,在锂硫电池中应用的研究进展,并展望了锂硫电池用石墨烯基材料的未来发展方向。     

MAS-NMR investigations of the crystallization behaviour of lithium aluminum silicate (LAS) glasses containing P2O5 and TiO2 nucleants

Lithium aluminum silicate (LAS) glass of composition (mol%) 20.4Li₂O-4.0Al₂O₃-68.6SiO₂-3.0K₂O-2.6B₂O₃-0.5P₂O₅-0.9TiO₂ was prepared by melt quenching. The glass was then nucleated and crystallized based on differential thermal analysis (DTA) data and was characterized by ²⁹Si, ³¹P, ¹¹B and ²⁷Al MAS-NMR. XRD and ²⁹Si NMR showed that lithium metasilicate (Li₂SiO₃) is the first phase to c form followed by cristobalite (SiO₂) and lithium disilicate (Li₂Si₂O₅). ²⁹Si MAS-NMR revealed a change in the network structure already for the glasses nucleated at 550 °C. Since crystalline Li₃PO₄, as observed by ³¹P MAS-NMR, forms concurrently with the silicate phases, we conclude that crystalline Li₃PO₄ does not act as a nucleating agent for lithium silicate phases. Moreover, ³¹P NMR indicates the formation of M-PO₄ (M=B, Al or Ti) complexes. The presence of BO₃ and BO₄ structural units in all the glass/glass-ceramic samples is revealed through ¹¹B MAS-NMR. B remains in the residual glass and the crystallization of silicate phases causes a reduction in the number of alkali ions available for charge compensation. As a result, the number of trigonally coordinated B (BO₃) increases at the expense of tetrahedrally coordinated B (BO₄). The ²⁷Al MAS-NMR spectra indicate the presence of tetrahedrally coordinated Al species, which are only slightly perturbed by the crystallization.     

Synthesis and Crystal Structure of a new O,N Lithium Coordination Polymer

The reaction of 4‐Amino‐6‐methyl‐1, 2, 4‐triazine‐3(2H)‐thione‐5‐one (HAMTTO) with n‐butyl lithium in dimethoxyethane (DME) gives the complex [Li(DME)(AMTTO)] ( 1 ). 1 was characterized by elemental analysis, IR‐ and mass‐spectrometry and an X‐ray structure analysis [space group P2₁/n, Z = 4, lattice dimensions at —80 °C: a = 867.6(1), b = 1721.5(2), c = 931.8(1) pm, β = 112.81(1)°, R₁ = 0.0315. The complex is a coordination polymer along [001] with a zig‐zag arrangement.     

Synthesis of iron oxide cubes/reduced graphene oxide composite and its enhanced lithium storage performance

Fe₃O₄ is considered as a promising electrode material for lithium-ion batteries(LIBs) due to its low cost and high theoretical capacity(928 mAh/g).Nevertheless,the huge volume expansion and poor conductivity seriously hamper its practical applications.In this study,we use a facile hydrothermal reaction together with a post heat treatment to construct the three-dimensional heterostructured composite(Fe₃O₄/rGO) inwhich reduced graphene oxide sheets wraped the Fe₃O₄ submicron cubes as the conductive network.The electric conduction and electrode kinetics of lithium ion insertion/extraction reaction of the composite is enhanced due to the assist of conductive rGO,and thus the Listorage performance is obviously improved.The composite exhibits a reversible charge capacity of772.1 mAh/g at the current density of 0.1 A/g,and the capacity retention reaches 70.3% after400 cycles at0.5 A/g,demonstrating obviously higher specific capacity and rate capability over the Fe₃O₄ submicron cubes without rGO,and much superior cycling stability to the parent Fe_2 O_3 submicron cubes without rGO.On the other hand,as a synergic conductive carbon support,the flexible rGO plays an important role in buffering the large volume change during the repeated discharge/charge cycling.     

正尖晶石LiMn_2O_4电化学性能研究

采用高温固相反应合成了尖晶石LiMn2 O4 锂离子电池正极材料 ,并对其性能进行研究 .综合考察了影响材料电化学性能的主要因素 ,诸如原材料的选择、合成温度、Li/Mn比以及添加金属元素Co等 .研究了材料在高温下的电化学性能和影响因素 ,并分析了LiMn2 O4 在电解质中的溶解和引起容量衰减的原因     

无水苯甲酸锂的合成、结构表征及热化学研究

用分析纯苯甲酸和一水氢氧化锂作为反应物, 采用水热合成法制得苯甲酸锂. 利用X射线粉末衍射、FTIR、元素分析及化学分析等方法对样品进行组成和结构表征. 采用精密自动绝热热量计测量了其在80~400 K范围内的摩尔热容, 利用最小二乘法将此温区热容实验值对折合温度进行拟合, 得到热容随温度变化的多项式方程. 通过设计合理的热化学循环, 选用0.1 mol/L HCl溶液作为量热溶剂, 利用等温环境溶解-反应热量计分别测定合成反应的反应物和产物在所选溶剂中的溶解焓, 得到反应焓Δ_rH_m⁰=-(9.75±0.27) kJ/mol. 利用Hess定律计算出苯甲酸锂的标准摩尔生成焓Δ_fH_m⁰(C₆H₅COOLi, s)=-(307.82±0.57) kJ/mol.     

锂改性点缺陷石墨烯储氢性能的第一性原理研究

本研究采用基于密度泛函理论的第一性原理方法计算了两种石墨烯点缺陷处原子的分波态密度(PDOS),能带结构和差分电荷密度等,研究了锂掺杂对两种本征石墨烯缺陷C-Bridge和C7557电子结构的改性,以及对其储氢能力的影响.结果表明Li原子能够稳定的掺杂且不易形成团簇,并且Li原子掺杂石墨烯能够对石墨烯能带中的狄拉克锥和费米面起到调控作用,增强了缺陷石墨烯的电子活性.本征缺陷石墨烯的储氢能力较弱,缺陷石墨烯的储氢能力可以通过Li掺杂来改善.