纳米阵列和纳米晶薄膜锡电极性质的电化学研究

采用氧化铝为模板的电化学沉积方法制备锡纳米阵列电极,用扫描电镜和X射线衍射仪表征电极微观形貌结构,并采用循环伏安和交流阻抗研究电极嵌锂过程,同时研究纳米晶锡薄膜电极和轧制锡箔电极.结果表明:纳米阵列电极与锡薄膜、锡箔电极具有不同交流阻抗谱特征,锡纳米阵列电极在中频区出现双电层阻抗,与其电解液/电极接触面积较大有关;不同微观结构形态下锡电极的电化学反应表面阻抗相差大于一个数量级,锡纳米阵列的表面膜电阻为19.8～14.6 Ω·cm2;锡纳米阵列电极上的锂离子扩散速率最大,0.2V嵌锂电位下扩散系数为10-10 cm2·s-1;采用纳米阵列结构使电极具有很高电的化学活性.     

采用PITT与EIS技术测定锂离子电池正极材料LiFePO4中锂离子扩散系数

采用恒电位间歇滴定法（PITT）和电化学阻抗谱技术（EIS）测定锂离子电池正极材料LiFePO4中Li^＋扩散系数。结果表明：随着嵌锂量的变化,锂离子的扩散系数（D Li＋）先出现一个极大值,然后出现一个极小值,随后随嵌锂量的增加而增大;扩散系数在10^-13 cm^2/s-10^-16 cm^2/s数量级范围内变化;2种方法计算得到的扩散系数在数量级上相符合。     

双电极碳钢体系在薄液膜初期干燥过程中的阻抗谱演化规律

采用电子天平和交流阻抗法在湿干变化环境中原位监测了碳钢双电极体系电化学阻抗谱,并研究了其大气腐蚀初期阻抗谱的演化规律.结果表明,薄液膜较厚时,可以利用简单的传输线模型对电化学阻抗谱进行最小二乘法拟合.薄液膜减薄至128 μm以下时,阻抗谱出现Warburg阻抗。当电极表面的薄液膜减薄至不连续时,在腐蚀初期表面没有腐蚀产物的条件下,两电极间的溶液电阻急剧增大,干燥后变为两电极间填充的绝缘材料的电阻.     

添加剂四氟硼酸四乙基铵对石墨负极界面性能的影响

采用恒流充放电、循环伏安(CV)和交流阻抗(EIS)测试方法研究四氟硼酸四乙基铵(Et4NBF4)作为锂离子电池电解液添加剂对石墨负极材料界面性质的影响,通过傅里叶变换红外光谱(FTIR)对固体电解质界面膜(SEI)的成分变化进行分析。结果表明:添加剂Et4NBF4参与了SEI膜的形成,提高了人造石墨(AG)/Li半电池充电容量和后续的循环效率,但是降低了首次充放电效率;首次放电过程中1.0～0.5 V是SEI膜形成和生长的电位区间,而0.5 V以下SEI膜进行不断的修复;添加少量Et4NBF4降低了SEI膜阻抗,提高了电解液与石墨负极的相容性。     

Influence of Helium on Microstructure and Electrochemical Properties of LiFePO4 Thin Films Electrodes

提出利用氦渗透法优化LiFePO4材料的结晶生长过程,达到提高材料电化学性能的目的。采用磁控溅射法制备含氦LiFePO4薄膜电极,利用扫描电镜观察样品的微观形貌,发现样品表面与截面皆呈现多孔结构。用X射线衍射仪分析含氦LiFePO4薄膜电极的晶体结构。结果表明,氦渗入薄膜后显著增强了材料在29.81o的衍射峰强度,而此处正对应了锂离子在LiFePO4材料中的扩散路径（[010] 方向）。这表明含氦LiFePO4薄膜中存在有利于材料脱锂/嵌锂的结晶择优生长取向,会导致薄膜电极电化学性能的提高。     

He对LiFePO_4薄膜电极的微观结构及电化学性能的影响（英文）

提出利用氦渗透法优化LiFePO_4材料的结晶生长过程,达到提高材料电化学性能的目的。采用磁控溅射法制备含氦LiFePO_4薄膜电极,利用扫描电镜观察样品的微观形貌,发现样品表面与截面皆呈现多孔结构。用X射线衍射仪分析含氦LiFePO_4薄膜电极的晶体结构。结果表明,氦渗入薄膜后显著增强了材料在29.81°的衍射峰强度,而此处正对应了锂离子在LiFePO_4材料中的扩散路径([010]方向)。这表明含氦LiFePO_4薄膜中存在有利于材料脱锂/嵌锂的结晶择优生长取向,会导致薄膜电极电化学性能的提高。     

二氧化钛纳米管阵列电极的光电化学性能研究

采用阳极氧化法在钛片上制备了垂直排列的TiO2纳米管阵列，利用SEMXRD对纳米管阵列的形貌和结构进行了表征，并通过电化学交流阻抗谱、光照开路电位谱和瞬态光电流谱技术对纳米管阵列电极的光电化学特性进行了研究。实验结果表明，TiO2纳米管的内径约为90nm，管壁约为10nm，纳米管阵列厚度约为500nm，经600℃退火处理后，转变为锐钛矿型与金红石型的混晶结构。光电测试结果表明，随着退火温度升高，TiO2纳米管阵列电极的界面电荷转移电阻减小，光电流逐渐增大，光照开路电压增大，至600℃达到最大，当退火温度继续升高，电极的光电性能急剧下降。与TiO2纳米多孔膜电极相比，光电性能显著提高，这主要归因于TiO2纳米管阵列更大的孔隙率和比表面积。     

TiAlN/CrN多层膜的组织结构及耐蚀性机理

目的研究Ti AlN/CrN多层膜及Ti AlN、Cr N单一膜层的微观组织和电化学性能区别,分析不同结构薄膜材料的耐腐蚀性影响因素。基于电化学参数、组织结构和腐蚀形貌特征,为开发新型腐蚀性薄膜提供理论依据。方法采用多弧离子镀方法,在316不锈钢基底上先沉积150 nm Cr薄膜作为过渡层,然后交替沉积Cr N薄膜和Ti AlN薄膜,制备单层厚度为10 nm的Ti AlN/CrN多层膜。作为对比,制备单一Ti AlN、CrN薄膜。通过SEM、XRD表征薄膜断面形貌、组织结构,并分析耐蚀机理,结合极化曲线和阻抗谱对三种涂层进行电化学性能分析,最后对涂层进行浸泡腐蚀试验。结果 Ti Al N/Cr N纳米多层膜为面心立方结构,呈现共格外延生长,且呈(200)择优取向。纳米多层膜的动电位极化曲线测量结果与不锈钢基体和单层薄膜相比,其腐蚀电位正移为-0.36 V,腐蚀电流密度降低为0.501μA/cm~2,极化电阻为120 kΩ·cm~2。阻抗谱试验结果表明,相比较于单层膜和基体,Ti Al N/Cr N多层膜的CPE值最低,为29.83×10~(-6)Ω~(-1)·cm~(-2)·sn,n值为0.922,电阻为1.50×1~06Ω·cm~2。腐蚀形貌分析可得出,多层薄膜腐蚀后表面形貌与沉积态涂层形貌最为接近,认为其具有较高的耐腐蚀性。结论纳米层状结构改变了单一薄膜的原始生长模式,抑制了粗大柱状晶的生长,减小了薄膜的固有缺陷、晶粒尺寸,对薄膜的耐蚀性有正面积极的作用。     

连续变化电导池常数法测定电导率的等效电路分析及应用

通过分析所得的交流阻抗谱,探讨了采用交流阻抗技术使用连续变化电导池常数法测定溶液和熔盐电导率的合理实验条件。通过对交流阻抗等效电路进行分析,认为实验电路的交流阻抗过程是电化学极化与浓差极化共同控制的过程,对于溶液来说,扩散体现出Warburg扩散特性,而熔盐的扩散体现出Gerischer特性。采用边连续变化电导池常数公式进行电导率计算时,对应的电路电阻最好选择对所得的Nyquist图拟合分析所得的溶液／熔盐与电极及导线电阻之和。如果考虑拟合误差,也可以采用读取高频率时电路电阻的方法来进行计算。     

Monel(400)合金在NaCl溶液中的电化学腐蚀行为

采用动电位极化扫描法、交流阻抗法对Monel(400)合金在不同浓度NaCl溶液中的腐蚀行为进行研究,结合SEM图对合金表面形貌进行分析。结果表明,合金在低浓度时腐蚀电流小,腐蚀速度慢;在高浓度时,电极电位负移,腐蚀电流增大,腐蚀速度加快。在交流阻抗谱中,高频区为电荷传递控制,低频区为扩散控制,出现了明显的Warburg阻抗效应。当NaCl溶液浓度增大时,极化电阻减小,故腐蚀行为增强。     

Electrochemical impedance studies on oxidative degradation,overoxidative degradation,deactivation and reactivation of conducting polymers

Electrochemical impedance spectroscopy (EIS) measurements in a wide frequency range were used to study the oxidative degradation, overoxidative degradation, deactivation and reactivation phenomena in polythiophene (PT) films on Pt electrode doped from aqueous solution of lithium trifluoromethanesulphonate (LiTFMS). The different parameters as electrolyte resistance, double layer capacitance, pore resistance, fractal dimensions, internal capacitance and charge resistance were derived. In addition, they furnish information about the different phenomena that can occur in the polymer film during the doping process. SEM observation of PT films provided strong evidence of the close relationship between the polarization potential, deactivation, reactivation and their morphology, also in good agreement with ac impedance results interpretation. The results are interpreted on the basis of models developed for intercalation electrodes in relation to the geometry and morphology of the polymer electrode. The deactivated PT films could reactivate by polarizing at a highly positive potential. The mechanisms of degradation, deactivation and reactivation are also discussed.     

商品化石墨作为聚合物锂离子电池负极材料的性能表征

采用商品化中间相碳微球(MCMB)及人造石墨与中间相碳微球的混合体作为聚合物锂离子电池的负极材料,通过SEM、XRD对比研究了两种负极材料电化学循环前后的微观形貌和相结构,测试了两种聚合物锂离子电池的倍率放电性能和循环寿命,并通过交流阻抗谱分析了两种负极材料的电化学性能差异.结果表明:掺入人造石墨后,中间相碳微球的平均粒径和比表面积增大,电化学循环200次后的晶面间距减小、石墨化度增大,倍率放电性能降低,电荷转移电阻及锂离子扩散阻抗均增大,循环性能得到较大提高.     

Determination of H^＋ diffusion coefficient in the course of H^＋ response of a W/WO3 pH electrode

A WAVO3 pH electrode was prepared by a method of sol-gel. In order to study the H^＋ response dynamic mechanism, the electrochemical impedance spectroscopy （EIS） experiment was conducted. It was found that the H^＋ response course is controlled by the H^＋ diffusion from the solution to the WO3 film, based on the analysis of EIS spectra. The EIS and potential step method were used to determinate the H＋ diffusion coefficient （D） in the course of H^＋ response of this WAVO3 electrode, and the values of D calculated by these two method correspond very well, which all are about 10^-19cm^2/s The imposed different potential steps make little effect on the calculation of H^＋ diffusion coefficient, and it was found that the limiting Cottrell equation of short elapsed time fits well to the current transient caused by a potential step, based on the analysis of the time constant.     

电沉积制备的两种形貌Sn薄膜锂离子嵌入电极性能的比较

用电沉积方法在Cu集流体上分别制备出用于锂离子电池负极材料的密集细粒状(＜0.5 μm)和分散粗粒状(≈3 μm)两种Sn薄膜电极.用X射线衍射、扫描电镜、循环伏安及充、放电实验研究比较了两电极的组织与性能.结果表明,在氟硼酸盐溶液中使用以醛类为主的复合添加剂,在静止条件下可制得细粒Sn薄膜电极,在搅拌条件下可制得粗粒Sn薄膜电极;细粒Sn薄膜电极比粗粒Sn薄膜电极具有较优的初始嵌锂容量和循环稳定性:细粒Sn薄膜电极首次放电比容量达到787 mA·h/g,40次循环时放电比容量仍保持在630 mA·h/g;而粗粒Sn薄膜电极首次放电比容量只有576 mA·h/g,至20次循环放电比容量降至150 mA·h/g.     

Heat treatment effect on electrochemical properties of spinel Li4Ti5O12

Anode material Li4Ti5O12 was prepared at 800℃ by a solid-state reaction, followed by heat-treatment at 600℃ for different times （0, 2, 8, and 12 h）. The effects of heat-treatment time on the particle morphology, rate-capability, and electrode kinetic process of the Li4Ti5O12 electrode, and on the lithium ion diffusion coefficient inside the Li4Ti5O12 electrode were investigated. Proper heat treatment could smoothen the particle surface of Li4Ti5O12 particles and increase the rate-capability of the electrode. Overlong heat treatment might cause particle aggregation and hence result in a poor electrode kinetic process. A sample with 8 h of heat treatment showed the best rate-capability and the lowest electrode reaction resistance. Heat treatment for 2-8 h does not significantly change the lithium ion diffusion coefficient inside the Li4Ti5O12 electrode, whereas, 12-h treatment results in a lower lithium ion diffusion coefficient.     

阳极氧化制备TiO2纳米管阵列电极反应及阻抗研究

为使TiO2纳米管阵列电极更好地应用于太阳能电池中,采取恒压阳极氧化法在质量分数0.5%NH4F/甘油电解液中在钛基体上制备出TiO2纳米管阵列.采用XRD、SEM、电子顺磁波普仪(EPR)、交流阻抗法(EIS)和循环伏安法(CV)研究TiO2纳米管阵列电极的电子传输性能及界面性质,确定各电极反应过程对应的阻抗曲线,计算得出电极的电子传输动力学参数.研究表明,TiO2纳米管阵列电极表面发生三价钛化合物转化成四价钛氧化物的氧化反应,电极电阻明显降低,加速了电极-电解液界面电子扩散速度,有利于TiO2电极表面自由羟基的产生.     

Degradation mechanism of Ti---Zr---V---Mn---Ni metal hydride electrodes

The degradation mechanism of Ti---Zr---V---Mn---Ni metal hydride electrodes was investigated because they rapidly degraded within 10 cycles despite having a high discharge capacity of 360464 mAh g⁻¹ at the first cycle. It was observed that Ti-oxide formed and grew on the surface of the alloy powder in the early and later stages of degradation using the scanning electron microscopy (SEM) and the auger electron spectroscopy (AES) analyses. Also, it was found that the contact and the reaction resistances for the electrochemical hydrogenation reaction increased as the number of cycles increased using the EIS (Electrochemical Impedance Spectroscopy) analysis. It was suggested that the reason for the degradation of Ti-based hydride electrodes was because it was extremely difficult for hydrogenation to occur through the Ti-oxide film into the inner part of the alloy. This was due to a high polarization resistance during the electrochemical hydrogenation reaction, which included the resistance of the hydrogen diffusion through the Ti-oxide film and the resistance of the electron conduction between Ti-oxide on the surface of the alloy powder and external circuits, as well as between the Ti-oxide layers on the surface of the alloy powders.     

工艺条件对 BAg50 CuZn 钎料表面电镀锡溶液电阻的影响

采用硫酸盐系电解液在BAg50CuZn钎料表面电镀Sn,考察了电流密度、镀液温度、阴阳极间距、超声波功率及超声波频率对AgCuZn钎料电镀锡溶液电阻的影响,得出了较佳的工艺条件,并对该条件下制备的锡电镀层的微观表面形貌进行了观察。结果表明,施镀时间一定时,随着电流密度或超声波频率的增大,溶液电阻逐渐增大;阴阳极间距增大时,溶液电阻呈现先减小、后增大的趋势。在较佳工艺条件下施镀,可获得表面平整、致密的Sn电镀层。     

Ti-Zr-V-Mn-Ni固溶体贮氢合金电极衰变机理的探讨

采用FESEM-EDS、EIS及ICP-MS技术对Ti0.26Zr0.07V0.24Mn0.1Ni0.33合金电极的容量衰减机制进行研究。该合金的容量衰减涉及到以下三方面:随循环次数的增加,合金电极表面的裂纹明显加宽、加深,存在氧化现象,这既增加电极的内阻,又阻碍氢在合金内的扩散;电荷转移电阻增加,交换电流密度减小,这些动力学因素的变化使得氢化物电极的放电容量逐渐减小;合金组分元素V、Ti和Zr的腐蚀溶解明显,这是合金电极容量衰减的主要原因之一。     

LiTFSi/KTf熔盐电解质中锂在铝电极上的电化学行为(英文)

采用循环伏安、计时电位和计时电流等电化学测试技术考察LiTFSI/KTf熔盐电解质中锂在铝电极上的电化学行为。结果表明:在该熔盐中,锂在铝电极上的电化学还原过程伴随着锂铝合金的成核过程,锂在铝电极上的嵌入过程平缓、稳定。恒电流充放电循环实验发现,首次循环的库仑效率很低,这主要归结于Li-Al合金对锂元素的持留能力。通过XRD和SEM表征了充放电前后铝电极的物相组成和表面形貌。计时电流实验发现,锂原子嵌入铝电极中形成α-Li-Al合金的过程受锂在铝基体内的扩散步骤控制,且该扩散系数为1.8×10-10cm2/s。