Influence of Temperature on the Performance of a Graphite Electrode

运用电化学阻抗谱(EIS)并结合循环伏安法(CV)研究了石墨电极25和60℃时在1 MOl.l-1 lIPf6-EC(碳酸乙烯酯)∶dEC(碳酸二乙酯)∶dMC(碳酸二甲酯)电解液中,以及60℃时在1 MOl.l-1 lIPf6-EC∶dEC:dMC+5%VC(碳酸亚乙烯酯)电解液中的首次阴极极化过程.发现高温下(60℃)石墨电极在1 MOl.l-1 lIPf6-EC∶dEC∶dMC电解液中可逆循环容量衰减的主要原因在于其表面无法形成稳定的固体电解质相界面(SEI)膜.实验结果显示,VC添加剂能够增进高温下石墨电极表面SEI膜的稳定性,进而改进石墨电极的循环性能.The first lithiation of a graphite electrode in 1 mol.L-1 LiPF6-EC(ethylene carbonate)∶DEC(diethyl carbonate)∶DMC(dimethyl carbonate) electrolyte at 25 and 60 ℃,and in 1 mol.L-1 LiPF6-EC∶DEC:DMC+5%VC(vinylene carbonate) electrolyte at 60 ℃ were investigated by electrochemical impedance spectroscopy(EIS) combined with cyclic voltammetry(CV).It was found that deterioration of the graphite electrode′s electrochemical performance was mainly caused by the unstable solid electrolyte interphase(SEI) film on the electrode′s surface in 1 mol.L-1 LiPF6-EC:DEC:DMC electrolyte at 60 ℃.However,the use of VC as an additive to the above electrolyte significantly improved the electrochemical performance of the graphite electrode,which was attributed to an improvement in the stability of the SEI film that formed on the graphite electrode′s surface.国家重点基础研究发展规划(973)项目(2009CB220102)资

Influence of binder on the performance of graphite anode

研究了水溶性粘结剂f-103和油性粘结剂P(Vdf-HfP)对锂离子电池石墨负极电化学性能和表面SEI膜成膜机理的影响。循环伏安的结果表明:在1 MOl/l lIPf6/EC+dEC+dMC电解液中,油性粘结剂石墨负极的电化学性能较好。电化学阻抗谱的结果表明:水溶性粘结剂石墨负极和油性粘结剂石墨负极表面SEI膜的成膜电位分别为1.00--0.60 V和0.80--0.55 V。油性粘结剂石墨负极表面SEI膜的稳定性较好。The influences of water-soluble binder F-103 and oiliness binder P(VDF-HFP)on the electrochemical performance and the surface SEI film formation mechanisms of graphite anode for Li-ion battery were researched.The results of cyclic voltammetry showed that the graphite anode with oiliness binder had better electrochemical performance in 1 mol/L LiPF6/EC+DEC+DMC.The results of electrochemical impedance spectroscopy showed that the SEI film formation potential on graphite anode with oiliness binder and with water-soluble binder were between 1.00～0.60 V and 0.80～0.55 V,respectively.The stability of surface SEI film on the graphite anode with oiliness binder was better.国家重点基础研究发展规划(973)项目(2009CB220102);中国矿业大学青年科技基金(ON080282

纳米薄层Pt-Ru及Pt-Pd表面合金电极上CO吸附的原位FTIR研究

以玻碳为基底 ,通过电化学共沉积的方法制备纳米级厚度的表面合金电极 ,运用电化学原位红外反射光谱研究CO的吸附 .结果表明 ,所制备的PT ru和PT Pd纳米级厚度的表面合金电极均具有异常红外效应 ,即吸附在不同表面位上的CO给出的红外谱峰强度增强 ,其方向与相应金属电极表面获得的谱峰方向相反 .研究还显示PT ru和PT Pd表面合金在电催化和表面研究中的重要意义国家自然科学基金!(批准号:29833060)资助项

In situ FTIRS Studies of the Electrochemically Induced Coupling of Osmium Nitrido Species in Acetonitrile

采用原位 红外反射 光谱（ｉｎ＿ｓｉｔｕ Ｆ Ｔ Ｉ Ｒ Ｓ） 结合紫 外可见 光谱（ Ｕ Ｖ／ Ｖｉｓ） 和 电化学循 环伏安技术（ Ｃ Ｖ） ，研究了［ Ｏｓ Ｖ Ｉ（ Ｎ）（ Ｎ Ｈ３） ４］（ Ｃ Ｆ３ Ｓ Ｏ３） ３ 的 电化 学诱 导桥 氮偶 联过 程． 首次 在 Ｐｔ 电 极上检测到桥 氮 混 合 价 锇 物 种［ Ｏｓ＿ Ｎ ≡ Ｎ＿ Ｏｓ］ 及 其 随 电 位 的 变 化 过 程 ． 在 约 ２ ｍ ｍ ｏｌ／ Ｌ 〔 Ｏｓ Ｖ Ｉ（ Ｎ）（ Ｎ Ｈ３） ４〕（ Ｃ Ｆ３ Ｓ Ｏ３） ３ ＋ ０ ．１ ｍ ｏｌ／ Ｌ Ｔ Ｂ Ａ Ｈ 的乙腈溶 液中，选 取０ ．４ ～－ １ ．０ Ｖ 电位 区间 １００ ｍ Ｖ／ｓ 扫描速度 ，对 Ｐｔ 或 Ｇ Ｃ 电 极进行电 化学循环 伏安处 理，处 理 后的 电极 表 面均 可积 累 一层 深绿 色 的沉积物，表 明电化 学诱导 Ｎ＿ Ｎ 偶联效 应已在 电极上 发生， 并形 成了 混合 价 桥氮 络合 物． 同时 ，在 上述过程中 所生成 的混合价 锇氮物种 ，有可能 较强地 吸附在电 极表 面，且 形成 一定 厚度 的表 面层， 从而减缓了 体系中 Ｏｓ Ｖ Ｉ≡ Ｎ 物种在电 极上的 继续还 原．同 时可 以看 到，随 着 Ｃ Ｖ 的 不 断进 行，溶 液 颜色将逐渐 地由黄变 绿．经过 长时间（ 约he search for inorganic systems that can cleave N≡N triple bond under mild conditions is an important subject. It is well known that the metal nitrido (M≡N) complexes are possible intermediates in nitrogen fixation [1] and in the reduction of nitrite to ammonia [2,3] . Recently, these complexes have received considerable attention [4～9] for their intriguing photochemical and electrochemical properties. Among different high valence metal nitrido complexes, some osmium(VI) nitrido species are stable enough to be isolated [4～10] , demonstrating that the study on this class of complexes becomes feasible. Meyer and co_workers [4] have reported the electrochemical interconversion between [Os VI (N)(terpy)Cl 2] + and [Os II (NH 3)(terpy)Cl 2] (terpy=2,2':6', 2"_terpyridine). Recently, Che et al. have reported the isolation of an osmium(VI) nitrido complex [Os VI (N)(NH 3) 4Cl] 2+ through oxidation of [Os III (NH 3) 5Cl] 2+[8] . Photolysis of an acetonitrile solution of [Os VI (N)(NH 3) 4](CF 3SO 3) 3 in the presence of an organic electron donor resulted in the formation of the dinitrogen_bridged osmium(II,III) dimer {[Os(NH 3) 4(CH 3CN)] 2(N 2)} 5+[7,8] . It has been found that the one_electron reduced Os V≡N reacts with the starting Os VI ≡N to yield the μ_dinitrogen Os II _N≡N_Os III complex with a second order rate constant of (3.75±0.30)× 10 5 dm 3 mol -1 s -1 in acetonitrile at room temperature [8] . Recently, Taube and co_workers [11] reported that the electrochemical reduction of [Os VI (N)(NH 3) 4] 3+ in acetonitrile resulted also in similar N_N coupling reaction. To our knowledge there is no report, up to now, concerning the in situ FTIR spectroscopic studies of direct coupling of nitrogen atoms of metal nitrido compounds. In the present study, the potential cycling was used to induce the formation of a μ_dinitrogen complex through electrochemical reduction of [Os VI (N)(NH 3) 4](CF 3SO 3) 3 in acetonitrile (donor). The intermediates and products of the reaction on Pt electrode was investigate by means of in situ FTIRS and UV/Vis spectroscopy.作者联系地址：厦门大学固体表面物理化学国家重点实验室!化学系物化所厦门361005,厦门大学固体表面物理化学国家重点实验室!化学系物化所厦门361005,香港理工大学应用生物化学科技学系!香港Author's Address: State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Chemistry, Institute of Physical Chemistry, Xiamen University, Xiamen 361005 Wong Kwokyin Department of Applied Biology and Chemical Techn

Electrochemical Impedance Spectroscopic Studies of Insertion and Deinsertion of Lithium Ion in Spinel LiMn_2O_4

运用电化学阻抗谱(EIS)研究了尖晶石lIMn2O4电极的首次充放电过程.发现EIS谱高频区域拉长压扁的半圆是由两个半圆相互重叠而成的,分别归属于与锂离子通过固体电解质相界面膜(SEI膜)的迁移和与尖晶石lIMn2O4材料的电子电导率相关的特征.通过选取适当的等效电路,对实验所得的电化学阻抗谱数据进行拟合,获得尖晶石lIMn2O4电极首次充放电过程中SEI膜电阻、电子电阻和电荷传递电阻等随电极极化电位变化的规律.根据研究结果提出了嵌锂物理机制模型.The processes of insertion and deinsertion of lithium ion in a spinel LiMn2O4 electrode during the first charge-discharge cycle were investigated by electrochemical impedance spectroscopy (EIS).The results illustrate that the depressed semicircle in the high frequency region consists of two semicircles that are overlapped each other, and were assigned respectively to lithium-ion migration through solid electrolyte interphase (SEI) film as well as the electronic properties of the material.An appropriate equivalent circuit was proposed to fit the experimental EIS data and variations of the resistance of SEI film, the electronic resistance of the material and the resistance of charge transfer along with the increase and decrease of electrode polarization potential were quantitatively analyzed.Based on the EIS results and analysis, a physical mechanism of lithium insertion and deinsertion was suggested.国家重点基础研究和发展规划“973”项目(No.2009CB220102);中国矿业大学青年科技基金(No.ON080282)资助项

石墨电极首次阴极极化过程的两电极和三电极电化学阻抗谱研究

运用电化学阻抗谱(EIS)并结合扫描电子显微镜(SEM)研究了石墨电极在两电极扣式电池和三电极玻璃电解池中的首次阴极极化过程.研究指出,两电极扣式电池体系中石墨电极首次阴极极化过程的EIS谱特征及其变化不能解释固体电解质相界面膜(SEI膜)的形成过程,但是可以用三电极玻璃电解池中获得的石墨电极首次阴极极化的EIS谱特征及其变化加以说明.结果表明,在石墨负极首次阴极极化过程中SEI膜主要在1.0~0.6V电位区间形成.国家重点基础研究发展计划(编号:2009CB220102)资助项

电化学原位扫描显微红外反射光谱及其对铂表面CO吸附的红外成象

利用fOurIEr变换红外光谱仪 ,红外显微镜和X y扫描平台 ,通过设计和研制原位红外显微池和计算机接口及控制软件 ,建立了电化学原位扫描显微红外反射光谱 .研究工作显示 ,这一新的空间分辨原位红外反射光谱技术不仅可以获得固 /液界面环境中表面微区振动光谱的信息 ,还可以用于电极表面红外成象 .获得的CO在PT多晶电极表面吸附性能的化学图象在 10 -2 CM尺度上给出电极表面微区反应性能的不均一性及其分布 .国家杰出青年科学基金资助项目!(批准号:29525307

Synthesis of Na_2MnPO_4 F/C with Different Carbon Sources and Their Performances as Cathode for Lithium Ion Battery

采用湿法球磨和原位热解碳包覆相结合的方法,分别以硬脂酸、柠檬酸、聚乙二醇-6000(PEg-6000)、β-环糊精为碳源,制备了不同结构的nA_2MnPO_4f/C复合材料,并研究了它们作为锂离子电池正极材料的电化学行为.通过X射线衍射(Xrd)、扫描电镜(SEM)、bET比表面积测试、恒流充放电等表征手段,比较和分析了产物的结构、形貌及电化学性能.研究结果表明,由不同碳源制备的材料在形貌和颗粒尺寸上有明显差异,进而对它们的电化学性能造成很大影响.影响电化学性能的关键因素在于材料一次颗粒的大小.其中,以柠檬酸为碳源制备的样品呈现出典型的微纳结构和最小的一次颗粒(10-40 nM).并给出最佳的电化学性能:在1.5-4.8 V电压范围内,以5MA·g~(-1)充放电电流获得的首次放电比容量约为80MAH·g~(-1),且循环稳定性良好.Na_2MnPO_4 F/C composites were synthesized by wet ball milling and in situ pyrolytic carbon coating.Stearic acid,citric acid,poly(ethylene glycol) 6000,and β-cyclodextrin were used as carbon sources in the synthesis process.The structures,morphologies,and electrochemical performances of the as-synthesized Na_2MnPO_4 F/C composites were further investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),Brunauer-Emmett-Teller surface area analysis,and galvanostatic chargedischarge tests.Distinct differences were observed in the morphologies and sizes of the Na_2MnPO_4 F/C particles obtained from different carbon sources,and this significantly affected their electrochemical performances.It was found that the primary particle size of the Na_2MnPO_4 F/C material is a key factor in the electrochemical performance.The sample synthesized using citric acid as the carbon source had a micro-nano structure,with the smallest primary particle size of 10-40 nm,and displayed the best electrochemical properties.It delivered an initial discharge capacity of 80 mAh·g~(-1) under a current density of 5mA·~(-1) in the voltage range of 1.5-4.8V,and displayed good cycling performance.国家自然科学基金(50574063;21021002;21003102); 四川大学青年科学家基金(2011SCU11081); 高等教育博士点科研基金(20120181120103)资助~

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