Fabrication and Performance of Cu_6Sn_5 Alloy Anode Using Porous Cu as Current Collector

以氢气泡为动力学模板电沉积获得多孔铜,并通过热处理增强其结构稳定性.进一步将多孔铜作为基底通过电沉积制备Cu-Sn合金负极.Xrd结果给出其组成为Cu6Sn5合金,扫描电子显微镜(SEM)观察到Cu6Sn5合金电极为三维(3d)多孔结构.充放电结果指出,Cu6Sn5合金电极具有较好的充放电性能,其首次放电(嵌锂)和充电(脱锂)容量分别为735和571MAH·g-1,并且具有较好的容量保持率.运用电化学阻抗谱研究了Cu6Sn5合金电极在商业电解液中的界面特性.Porous Cu was fabricated by electrodeposition through a kinetic template of hydrogen bubbles.The product was subsequently annealed to increase its structural stability.The Cu-Sn alloy was then electrodeposited onto porous Cu which served as a current collector.X-ray diffraction (XRD) studies ascertained that the composition of the Cu-Sn alloy was Cu6Sn5 and scanning electron microscopy (SEM) investigations showed a three-dimensional (3D) porous structure of the electrode.The first charge/discharge capacities of the Cu6Sn5 alloy electrode were measured respectively at 735 and 571 mAh·g-1,and a good retention of the capacities has been determined.Interfacial properties of the Cu6Sn5 alloy electrode in a commercial electrolyte were also studied by electrochemical impedance spectroscopy (EIS).国家重点基础研究发展规划(973)项目(2009CB220102)资

Electrochemical Impedance Spectroscopy Study on Phase Transformation of Cu_6Sn_5 Alloy Anode

以粗糙铜箔为基底,采用一步电沉积法获得Cu-Sn合金,X射线衍射(Xrd)测试结果显示其主要为Cu6Sn5合金相.扫描电子显微镜(SEM)测试结果表明该合金表面由大量“小岛“组成,且每个“小岛“上存在大量纳米合金粒子.充放电测试结果表明,以该合金为锂离子电池负极,其初始放电(嵌锂)和充电(脱锂)容量分别为461和405MAH·g-1.电化学阻抗谱测试结果显示,Cu6Sn5合金电极在阴极极化过程中分别出现了代表固体电解质界面膜(SEI膜)阻抗、电荷传递阻抗和相变阻抗的圆弧,并详细分析了它们的变化规律.The Cu-Sn alloy electrode was prepared by a one-step electrodepositing method using rough Cu foil as the substrate,and was determined as the intermetallic composite of Cu6Sn5 using an X-ray diffraction(XRD) method.The electrode surface morphology was analyzed by scanning electron microscopy(SEM) which displayed "small islands" structure with many nano-particles on it.The first discharge and charge capacities were determined as 461 and 405 mAh·g-1,respectively.Electrochemical impedance spectra(EIS) indicated that there appeared three arcs in the Nyquist plots respectively representing the impedance of solid electrolyte interphase film,charge transfer and phase transformation in the first lithiation,and their evolutive principles were also investigated.国家重点基础研究和发展规划(973)(No.2009CB220102);国家自然科学基金(No.20773102)资助项

Effects of Temperature on the Intercalation-Deintercalation Process of Lithium Ion in LiCoO_2

运用电化学阻抗谱(EIS)研究了LiCoO2正极在1mol/LLiPF6-EC(碳酸乙烯酯):DEC(碳酸二乙酯):DMC(碳酸二甲酯)和1mol/LLiPF6-PC(碳酸丙稀酯):DMC+5%VC(碳酸亚乙烯酯)电解液中0～30℃范围内的阻抗谱特征、固体电解质相界面(SEI)膜阻抗、电子电阻和电荷传递电阻等随温度的变化.结果表明,LiCoO2正极的阻抗谱特征随温度变化,当温度升高其低频区域在上述两种电解液中分别于10和20℃出现反映锂离子固态扩散的斜线.测得LiCoO2正极在上述两种电解液中,锂离子迁移通过SEI膜的离子跳跃能垒平均值分别为37.74和26.55kJ/mol;电子电导率的热激活化能平均值分别为39.08和53.81kJ/mol;嵌入反应活化能平均值分别为68.97和73.73J/mol.The temperature dependent properties of the impedance spectral characters,the electronic resis-tance,the resistances of the SEI(solid electrolyte interphase)film as well as the charge transfer reaction of the LiCoO2 electrode in 1 mol/L LiPF6-EC(ethylene carbonate):DEC(diethyl carbonate):DMC(dimethyl carbonate)and 1 mol/L LiPF6-PC(propylene carbonate):DMC+5% VC(vinylene carbonate) electrolyte solutions were studied and reported.The temperature was varied from 0 to 30℃ .The studies of electrochemical impedance spectroscopy(EIS) revealed that,the common EIS features of the LiCoO2 electrode in the 1 mol/L LiPF6-EC:DEC:DMC and 1 mol/L LiPF6-PC:DMC+5% VC electrolyte solutions were related to the temperature,and a straight line reflecting solid state Li ion diffusion in the bulk of active mass appeared at 10 and 20 ℃ ,respectively.In 1 mol/L LiPF6-EC:DEC:DMC and 1 mol/L LiPF6-PC:DMC +5% VC electrolyte solutions,the energy barriers for the ion jump relating to migration of lithium ions through the SEI film of the LiCoO2 electrode were determined to be 37.74 and 26.55 kJ/mol,the thermal active energy of the electronic conductivities to be 39.08 and 53.81 kJ/mol,and the intercalation-deintercalation reaction active energies to be 68.97 and 73.73 kJ/mol,respectively.国家重点基础研究和发展规划“973”项目(No.2002CB211804)资助项

Preparation and Electrochemical Performance of Three-Dimensional Porous SnCo Alloy Electrode

采用化学镀方法制备三维多孔铜.以其作为集流体,借助电沉积制备三维多孔Sn-Co合金电极.X-射线衍射(XRD),扫描电镜(SEM)分析表明,以多孔铜为集流体制备的SnCo合金电极主要存在CoSn2相和纯Sn相,为三维多孔结构.充放电结果显示,三维结构SnCo合金电极比平面铜集流体上镀得的SnCo合金电极表现出更优越的充放电性能.前者的首次放电(嵌锂)容量为636.3mAh/g,充电(脱锂)容量为528.7mAh/g,首次库仑效率为83.1%,70周后容量为529.5mAh·g-1,保持率为82.6%.此外,还应用电化学阻抗初步研究了三维Sn-Co合金电极在充放电过程发生的嵌脱锂过程.Three-dimensional porous Cu film was prepared by electroless plating,and used as a current collector for preparation of three-dimensional structured SnCo alloy electrode,which was mainly prepared by an electrodeposition method,and composed of pure Sn and CoSn2 phases. Electrochemical experimental results show that three-dimensional structured SnCo alloy electrode exhibits much better cycleability than planar SnCo alloy electrode,with first discharge capacity and charge capacity of 636. 3 and 528. 7 mAh·g-1,respectively. After 70th cycling,capacity retention is 83. 1% with 529. 5 mAh·g-1. The lithiation process during first discharge was investigated by electrochemical impedance spectroscopy作者联系地址：厦门大学化学化工学院化学系;厦门大学固体表面物理化学国家重点实验室;Author's Address: 1. Department of Chemistry,College of Chemistry and Chemical Engneering, 2. State Key Lab for Physical Chemistry of Solid Surface,Xiamen University,Xiamen 361005,Fujian,Chin