Three-dimensional Porous Cu_6Sn_5 Alloy Anodes for Lithium-ion Batteries

以三维多孔泡沫铜为基底,通过直接电沉积的方法制备锂离子电池Cu6Sn5合金负极材料.发现合金表面大量的微孔和“小岛”不仅增大电极的表面积,而且显著缓解充放电过程中的体积变化.测得三维多孔Cu6Sn5合金的初始放电(嵌锂)容量为620mAh·g-1,充电(脱锂)容量为560mAh·g-1,库仑效率达到90.3%,具有较好的循环性能.扫描电子显微镜(SEM)结果显示,在泡沫铜基底上制备的Cu6Sn5合金电极具有比通常的铜片基底更好的结构稳定性,经过50周充放电循环后无明显的脱落现象.Three-dimensional porous Cu6Sn5 alloy electrodes were prepared by electroplating using copper foam as current collector.The micro-holes and small islands on surface of the Cu6Sn5 alloy increased largely the surface area of the electrode,and improved significantly the ability of the electrode in buffering the volume change in process of charge/discharge when the Cu6Sn5 alloy was employed as anode in a lithium-ion battery.Galvonostatic charging/discharging results demonstrated that the initial discharge(lithiation)and charge(delithiation)specific capacities of the Cu6Sn5 alloy electrode were 620 mAh·g-1 and 560 mAh·g-1,respectively.It demonstrated that the Cu6Sn5 alloy electrode exhibited a large initial coulomb efficiency(90.3%)and good capacity retention.SEM(scanning electron microscope)results illustrated that the Cu6Sn5 alloy deposited on copper foam substrate was more stable than that on a conventional copper substrate,and displayed no obvious exfoliation after 50 charge/discharge cycles.国家重点基础研究发展规划项目(973)(2002CB211804)资

钯纳米粒子及其团聚体特殊红外性能的CO分子探针红外光谱

以聚乙烯吡咯烷酮(PVP)为稳定剂, 用乙醇还原氯钯酸制备分散的钯纳米粒子(Pdn). 从分散于电极表面的Pdn出发, 以50 mV·s-1的扫描速度, 在 0.25～1.25 V间循环扫描30 min可以制备团聚体 Pdnag. 固/气和固/液界面透射和反射CO分子探针红外光谱研究结果指出, 吸附在Pdn上非对称和对称桥位上的桥式吸附态CO(COB)在1964 和 1905 cm-1给出两个红外吸收谱峰, 但CO吸附在Pdnag上仅在1963 cm-1给出一个方向倒反的异常红外谱峰. 此外, CO谱峰的半峰宽由Pdn上的14 cm-1变为Pdnag上的24 cm-1. Pdn形成团聚体Pdnag后, Pd纳米粒子间相互作用增强, Pdn和Pdnag红外光学性质的显著差别初步归因于纳米粒子之间的相互作用

Structure and Properties of Three-dimensional Reticular Sn-Co Alloy Electrodes as Anode Material for Lithium Batteries

应用电沉积技术制备了三维网状结构的Sn-Co合金负极材料,采用XRD、SEM和电化学方法考察了该负极材料的结构和性能.XRD分析表明,该三维网状结构的Sn-Co合金镀层为六方固溶体结构.其电化学性能测试表明:三维网状结构Sn-Co合金微晶电极的性能稳定,其首次放电容量高达493.4mAh·g-1,首次库仑效率达80.03%,而平面结构Sn-Co合金电极的首次库仑效率为63.47%.经50周充放电循环后,三维网状结构Sn-Co合金电极的放电容量为329.6mAh·g-1,放电容量保持率为66.8%;SEM分析表明:三维网状Sn-Co合金电极表面是由大小不一、高低不同的“岛”紧密排列在一起;“岛”和多孔结构的存在,缓冲了锂嵌入时体积的膨胀,部分抑制了材料结构的变化,减缓了电极容量的衰减,改善了电极的循环性能.The three-dimensional reticular Sn-Co alloy deposits were prepared by electroplating.The structure and electrochemical performance of the electroplated three-dimensional reticular Sn-Co alloys have been investigated in detail.Experimental results show that the Sn-Co alloy film is of hexagonal solid solution,with Sn as the solvent,Co as the solute.Electrochemical tests show that the three-dimensional reticular Sn-Co alloy coating electrodes can deliver a discharge capacity of 493.4 mAh·g-1 in the first cycle.At the 50th cycle the charge was 329.6 mAh·g-1.The three-dimensional reticular structure in Sn-Co alloy electrode was beneficial in reducing the irreversible capacity of Sn-Co alloy electrode at initial charge-discharge,and in relaxing the volume expansion during cycling,which improved the cyclability of Sn-Co alloy electrode.They are also beneficial to diffusion of Li into /out of macroporous materials,and improve coulomb efficiency in charge-discharge cycle.国家重点基础研究和发展规划(973项目,2002CB211804)资助项

Preparation and Capacity Fading Mechanism of Tin Thin Film as Anode of Lithium-ion Battery

以电镀的方法在铜基底上沉积薄膜锡作为锂离子电池负极材料.运用X射线衍射、扫描电镜、电化学循环伏安、电化学充放电和交流阻抗等多种方法对其结构和性能进行表征和研究.结果表明所制备的薄膜锡电极主要为四方晶系结构,其初始放电(嵌锂)容量为709mAh?g-1,充电(脱锂)容量为561mAh?g-1.电化学循环伏安研究发现在嵌/脱锂过程中薄膜锡经历了多种相变过程.电化学阻抗谱结果说明,首次嵌锂过程中当电极电位达到1.2V在电极表面形成SEI膜,而当电极电位低于0.4V表面SEI膜出现破裂,归因于体积膨胀所致.SEM研究表明30次充放电循环后薄膜锡负极出现龟裂现象.Tin thin film coated on Cu substrate as anode of lithium-ion battery was prepared by electroplating. Its structure and properties were characterized and studied by X-ray diffration, scanning electron microscopy, cyclic voltammetry, charging/discharging test and AC impedence method. XRD patterns indicate that the tin thin film exhibits a structure of tetragonal crystal. The first discharge and charge capacities of the tin thin film electrode were determined to be 709 and 561 mAh?g-1, respectively. Cyclic voltammetric results illustrated that multi-phase changes occurred during the lithiation and delithiation. Electrochemical impedance spectros- copy (EIS) results indicated that SEI film was begun to form on the surface of tin thin film electrode at 1.2 V, and then break down below 0.4 V because of large volume expansion. SEM investigations revealed that the tin thin film electrode appeared serious cracks after 30 charging and discharging cycles.国家重点基础研究和发展规划(973项目)(No.2002CB211804)资助项目

Preparation and capacity fading mechanism of tin thin film as anode of lithium-ion battery

Tin thin film coated on Cu substrate as anode of lithium-ion battery was prepared by electroplating. Its structure and properties were characterized and studied by X-ray diffration, scanning electron microscopy, cyclic voltammetry, charging/discharging test and AC impedence method. XRD patterns indicate that the tin thin film exhibits a structure of tetragonal crystal. The first discharge and charge capacities of the tin thin film electrode were determined to be 709 and 561 mAh(.)g(-1), respectively. Cyclic voltammetric results illustrated that multi-phase changes occurred during the lithiation and delithiation. Electrochemical impedance spectroscopy (EIS) results indicated that SEI film was begun to form on the surface of tin thin film electrode at 1.2 V, and then break down below 0.4 V because of large volume expansion. SEM investigations revealed that the tin thin film electrode appeared serious cracks after 30 charging and discharging cycles

Structure and properties of three-dimensional reticular Sn-Co alloy electrodes as anode material for lithium batteries

The three-dimensional reticular Sn-Co alloy deposits were prepared by electroplating. The structure and electrochemical performance of the electroplated three-dimensional reticular Sn-Co alloys have been investigated in detail. Experimental results show that the Sn-Co alloy film is of hexagonal solid solution, with Sn as the solvent, Co as the solute. Electrochemical tests show that the three-dimensional reticular Sn-Co alloy coating electrodes can deliver a discharge capacity of 493.4 mAh center dot g(-1) in the first cycle. At the 50th cycle the charge was 329.6 mAh center dot g(-1). The three-dimensional reticular structure in Sn-Co alloy electrode was beneficial in reducing the irreversible capacity of Sn-Co alloy electrode at initial charge-discharge, and in relaxing the volume expansion during cycling, which improved the cyclability of Sn-Co alloy electrode. They are also beneficial to diffusion of Li into/out of macroporous materials, and improve coulomb efficiency in charge-discharge cycle

基于平行四连杆的水下牵引机下限位随动机构设计与仿真分析

波浪滑翔器是一种新型水面无人观测平台，通过水下牵引机中水翼被动摆动获取波浪能来产生前向推力。通过分析常规波浪滑翔器水下牵引机的脐带缆倾斜角造成的波浪能损失现象，设计了一种水翼摆动下限可以随脐带缆倾斜角的变化而改变的水翼摆动机构——下限位随动机构。首先，通过计算流体力学软件Fluent仿真分析了下限位随动机构对于水翼摆动角度的调节能力；其次，通过在常规水下牵引机内部加装一套平行四边形传动机构，设计了下限位随动机构原理样机，并通过搭建大型波浪模拟测试平台进行水池试验，验证了下限位随动机构原理样机的推进性能。研究表明，所提新型水翼摆动机构可以很好地提升水下牵引机的推进性能