Mg-Li电极在NaCl溶液中的电化学行为

应用熔炼法制备含Li量为8.5%和14%的两种Mg-Li合金,分别由电势线性扫描、计时电流、交流阻抗和失重法等检测Mg-Li电极在NaCl溶液中的电化学特性,SEM观察其放电表面形貌.结果表明:Mg-14Li电极比Mg-8.5Li电极有较负的开路电位、更大的放电电流和较高的放电效率,但附着电极表面的疏松产物易于脱落.Mg-8.5Li电极的放电效率高于Mg-14Li电极的放电效率.两种电极在低恒电位放电电流效率均高于较高恒电位的放电电流效率.     

饱和NaCl溶液浸泡下混凝土试块中有机阻锈剂对钢筋腐蚀行为的影响

利用电化学阻抗谱(EIS)、半电池腐蚀电位(Ecorr)和宏观电池腐蚀电流密度(Icorr)测量技术,在饱和NaCl溶液浸泡的硬化混凝土试块中,研究了4种醇胺基阻锈剂对钢筋电极腐蚀电化学行为的影响和长期阻锈性能.在浸泡初始的100d内,与空白样相比,添加阻锈剂后钢筋电极腐蚀电位升高,阻抗膜值增大,腐蚀电流密度值降低,表明电极表面处于钝态,阻锈剂表现出良好的阻锈性能.随浸泡时间延长,电极腐蚀电位和阻抗膜值下降,腐蚀电流密度增大.浸泡后期,除添加醇胺基CI-4样外,电极电位和腐蚀电流密度与空白样相比无明显差别,表明电极由钝态转变为活性腐蚀状态.但添加CI-4样品,钢筋电极始终保持在钝化状态,阻锈性能最好.基于阻锈剂与Cl-间的竞争吸附,分析探讨了可能的阻锈机理.     

1,3-二氧戊环基LiCF3SO3电解液对锂硫电池正极材料单质硫的电化学性能影响

测试了二元和多元溶剂组分的1,3-二氧戊环基LiCF3SO3电解液的粘度、离子电导率和单质硫的溶解度. 研究结果表明, 由较强的给电子能力溶剂组成的低粘度电解液较容易提高单质硫的氧化还原反应活性和可逆性能, 有利于提高单质硫在2.10 V附近的低放电平台电位和放电比容量. DOL-DME LiCF3SO3电解液能够较好地改善单质硫电极的表面钝化层结构, 促进电活性物质离子扩散和降低界面电荷传递阻抗, 从而表现出很好的放电倍率特性. 在室温下充放电流密度分别为0.1和0.2 mA/cm2时, 单质硫的首次放电比容量为792 mA·h/g, 第29次放电比容量达到412 mA·h/g.     

银-氯化银柔性脑电电极的制备及其评价

本文采用丝网印刷技术制备了一种基于聚酰亚胺(PI)柔性塑料基片的Ag/AgCl脑电电极,并建立了一套系统评价柔性脑电电极性能的方法。评价方法主要包括扫描电镜(SEM)表征、电极电位/时间响应和稳定性测试、电化学阻抗测试、附着性测试。结果表明,该柔性电极表面为多孔结构,且与基底粘附性好;该电极呈现Ag/AgCl的电化学界面性质,其平衡电位为0.97±0.20mV,与Ag/AgCl粉末电极接近;且电极电位一致性和稳定性良好,最大极差电位不超过0.7mV,4h后电位漂移值在10μV/4min以内;经磨砂导电膏GT5处理后,电极-皮肤阻抗在5kΩ以内,满足脑电记录要求;相对于人体皮肤的高阻抗值,柔性电极-导电膏(GT20)的界面阻抗仅为166Ω·cm2。该评价方法系统、实用,可为制定相应国家标准提供技术参考。     

负极材料Li_4Ti_5O_(12)的蔗糖改性研究

以蔗糖为碳源,采用固相法合成了C改性的Li4Ti5O12材料.XRD衍射分析表明,C的引入没有改变Li4Ti5O12的尖晶石结构,且缓解了颗粒间的团聚,并以初始蔗糖含量为10%(by mass)样品的电化学性能最佳.0.2C放电倍率下首次放电比容量达179.1 mAh/g,在2C和3C倍率下首次放电比容量仍达143.8 mAh/g和129.4 mAh/g.循环伏安和电化学阻抗测试显示改性后的Li4Ti5O12材料电极极化程度较小,并且具有较小的电极反应阻抗.     

检测肠毒素用酶免疫电极动力学参数的测定

应用恒电位极化法探讨了酶免疫电极的响应机理 ,通过旋转圆盘电极确定了生物电极的速度控制步骤 ,根据交流阻抗谱的分析 ,计算了各种生物电极在不同电极电位下的动力学参数 ,并进行了比较分析 .     

粘结剂PTFE对泡沫型氢氧化镍电极电化学性能的影响

用恒电流放电，循环伏安法和电化学阻抗谱（ＥＩＳ）研究了ＰＴＦＥ对泡沫型氢氧化镍电极电化学性能的影响，发现ＰＴＦＥ的存在的增加电极的电化学反应电阻，降低电极反应的可逆性，从而使得电极的放电电位及容量有所降低，所以在制作粘结式电极的过程中应尽量减少粘结剂的用量。     

离子液体在多孔碳电极上的电化学性能

制备了数种离子液体及离子液体有机溶液电解质,用线性电位扫描法测试了它们的电化学窗口;并通过循环伏安、交流阻抗、电势阶跃等电化学方法,对它们在多孔碳电极中的电化学性能进行了研究.实验结果表明:溶剂对1-乙基-3-甲基咪唑类离子液体有机溶液电解质的电化学窗口有较大的影响.离子液体及离子液体有机溶液电解质在多孔碳电极上的电化学性能与其电导率密切相关,电导率越大,充电时间常数越小,比容量越大;但比容量降低的倍率远小于电导率降低的倍率.     

室温离子液体电解液中尖晶石LiMn_2O_4的电化学性质

应用循环伏安、恒电流充放电和电化学阻抗技术研究了尖晶石L iMn2O4于室温离子液体电解液中的电化学性质.实验表明,以室温离子液体作电解液,L iMn2O4的首次放电容量可达108.2 mAh/g、循环效率高于90%,温度和电流密度显著影响电极的电化学性能.交流阻抗测定了L i+在电极/电解液相界面迁移的活化能,为55 kJ/mol.根据界面反应的高活化能解释了L iMn2O4在该离子液体电解液中低温性能和倍率充放电性能不佳的原因.     

磁场凝固处理对稀土铝合金电化学性能的影响

在Al-In-Zn-Sn合金的基础上,掺入Ce形成合金样品,将样品进行重熔与磁场凝固处理制成研究电极,通过SEM对其表面形态进行了分析,并在4 mo.lL-1的KOH溶液中进行阳极极化曲线、交流阻抗、恒流放电等电化学性能测试。结果表明:磁场凝固处理能够提高Al-In-Zn-Sn-Ce合金的腐蚀电位,减小阳极材料的阻抗,改善阳极的放电性能。     

MH-Ni电池记忆效应的研究

放电深度 (DOD)、放电速率、循环次数对MH Ni电池的记忆效应影响很大 .经过几次全充放循环可以消除记忆效应 .记忆效应的存在与Zn无关 .电池在低DOD循环过程中 ,其放电电位、放电容量一开始下降很快 ,然后逐渐趋于某一值 ,并且放电电流越小 ,相应的最高充电电压越低 .若放电电流增加 ,在随后的第一周充放电过程中最高充电电压迅速增加、放电容量显著小于稳定值 .最后探讨了导致记忆效应的原因 ,并给出了若干消除或减弱记忆效应的设想     

Methane Conversion Using Dielectric Barrier Discharge：Comparison with Thermal Process and Catalyst Effects

The direct conversion of methane using a dielectric barrier discharge has been experimentally studied. Experiments with different values of flow rates and discharge voltages have been performed to investigate the effects on the conversion and reaction products both qualitatively and quantitatively. Experimental results indicate that the maximum conversion of methane has been 80% at an input flow rate of 5 ml/min and a discharge voltage of 4 kV. Experimental results also show that the optimum condition has occurred at a high discharge voltage and higher input flow rate. In terms of product distribution, a higher flow rate or shorter residence time can increase the selectivity for higher hydrocarbons. No hydrocarbon product was detected using the thermal method, except hydrogen and carbon. Increasing selectivity for ethane was found when Pt and Ru catalysts presented in the plasma reaction. Hydrogenation of acetylene in the catalyst surface could have been the reason for this phenomenon as the selectivity for acetylene in the products was decreasing.     

Electrode kinetics of Eu3+/Eu2+ reaction by cyclic voltammetry

The cyclic voltammetric behaviour of Eu³⁺/Eu²⁺ couple at hanging mercury drop electrode (HMDE) has been studied in chloride, bromide, iodide, thiocyanate and EDTA supporting electrolytes. The apparent rate constant and transfer coefficient for these systems have been calculated at various voltage scan rates, without using the data for standard or formal potential. The values have been compared with those obtained by earlier workers through other electrochemical methods.     

Parametric evaluation of sputtering in a planar, diode glow discharge—I. Sputtering of oxygen-free hard copper (OFHC)

A parametric evaluation of the principal factors which affect cathodic sputtering rates in glow discharge sources is performed. Employing a planar, disk cathode in the simple diode geometry, the roles of discharge voltage, current, and pressure are evaluated for the sputtering of oxygen-free hard copper (OFHC). Samples were sputtered at discharge currents of 5–70 mA over an argon pressure range of 1.5–8 torr (200–1064 Pa). In addition, the relationship between applied power and sputter weight loss is investigated. Studies indicate that the current density at the cathode surface and the discharge voltage are directly related and are keys in the determination of sputtering rates. Through factor analysis, an empirical formula is developed which is useful in quantifying sputter rates for a given set of discharge conditions.     

全钒液流单电池充放电行为及特性研究

建立具有外置双饱和甘汞参比电极及双液流电池的实验装置系统.使用该装置可在同一时刻同时测定小型液流单电池充放电时的电池电压、电池正负极电位及正负极开路电位,进而计算充放电过程电池的欧姆内阻降(iR)及其正负极过电位.以石墨毡为电极、Nafion 117作隔膜的全钒液流单电池,在60 mA.cm-2电流密度下,每一充放电循环的平均iR降约占总电压损耗的74%,表明该电池的电压效率受制于电池的欧姆内阻.充放电曲线显示,电池放电终点之所以出现主要是由于电池负极电位在放电末期的快速上升而引起的.本文设计的全钒单电池于60 mA.cm-2下工作时,其电压及能量效率分别达89%和85%,表明该电池结构合理,且石墨毡是钒电池合适的电极材料.     

温度对空间用氢镍电池电化学性能的影响

以60 Ah氢镍电池为研究对象,研究了温度对电池电性能的影响. 结果表明,电池的放电容量、过充电率随着温度均呈先升后降趋势,最高放电容量可达63.68 Ah（-5 ^oC）,电池的适合涓流值及3天自放电率随着温度的升高呈增加趋势,电池的放电容量、过充电率、适合涓流值和自放电率与环境温度之间有近似的代数公式变化关系. -10 ^oC、80%放电深度（DOD）条件下循环3000次后,电池电性能无明显衰降;25 ^oC下循环550次,放电电压跌至0.8 V,电池失效. 结合相关参考文献结果及EIS试验分析可知,25 ^oC下电池循环性能迅速失效主要是由于高温下镍电极更易析氧和发生极板腐蚀,以及高温下镍极板更易粉化所致.     

低温等离子体原子化器-原子荧光光谱法测定碲

基于介质阻挡放电(DBD)原理和结构,建立了适用于原子荧光光谱仪(AFS)的低温等离子体小型原子化器(Atomizer),并研究了氢化物发生-低温等离子体原子化器-原子荧光光谱(HG-DBDAtomizer-AFS)测定环境样品中痕量碲(Te)的分析方法。DBD等离子体原子化器具有小型、低温等优点。对DBD放电结构和放电功率、载气气体流速,氢化物发生过程中的酸度、KBH4浓度,以及观测高度等实验条件进行了详细的考察并优化。本系统测定Te的检出限(3σ)为0.08μg/L;线性范围为0.5～80μg/L;测定精密度为2.1%(n=7);加标回收率为90%～103%。对国家级标准样品(GBW07404,GBW07405,GBW07406)进行测定,测定结果与标准值一致,证明本方法准确可行。     

Quartz crystal microbalance simulation of the directionality of Si etching in CF4 glow discharges

Two quartz crystal microbalances have been mounted in a planar rf discharge system in such a way that the potential of the microbalances with respect to the glow discharge can be varied. This apparatus allows a rapid simulation of the etching directionality that can be expected in real pattern transfer situations in that operating one microbalance at ground and one at a negative potential gives a measure of the sidewall and vertical etch rates, respectively. The voltage threshold for ion-assisted etching has been determined to be 20 V which is the approximate value of the plasma potential in this asymmetric system.     

H2/Ar direct current glow discharge mass spectrometry at constant voltage and pressure

The addition of hydrogen to a direct current (dc) - argon glow discharge (GD) coupled to a time of flight mass spectrometer has been studied using a fixed voltage between the electrodes and a fixed discharge pressure. Hydrogen contents investigated were 0.5%, 1% and 10% v/v in the argon discharge and the samples under study consisted of a copper-base, a nickel-base and an iron-base homogeneous materials. Also, the in-depth profile analysis of a tin plate was investigated. Results have shown that hydrogen addition gives rise to significant changes in the slope of the linear relationship between the electrical current and the discharge voltage. Clearly, the electrical resistance of the discharge at the typical operation voltages in the interval 600–1000 V increases with hydrogen added to pure argon.A decrease of the sputtering rates was observed the higher the hydrogen concentrations. Besides, the “reduced sputtering rates”, i.e. the sputtering rates divided by the corresponding electrical current, were also lower for the H₂/Ar discharges than for pure argon. However, the analytical ion signals observed using discharge voltages higher than 900 V turned out to be higher in a 0.5% H₂/Ar discharge than in pure argon for the copper and nickel materials. Besides, for the three samples investigated the ion yields were from 1.5 up to 3 times higher in 0.5% H₂/Ar discharges as compared to the pure argon.Finally, the effect of 0.5% H₂ addition to the Ar discharge on the in-depth profile of a tin plate has also been investigated. As compared to the use of a pure Ar GD, higher sensitivity for major and minor components of the coating were observed without loss of the relative depth resolution achieved.     

Comparison of modeling calculations with experimental results for rf glow discharge optical emission spectrometry

A model developed recently for a radio-frequency glow discharge, is applied to experimental Grimm-type discharge conditions, to check the validity of the model calculations. The calculated electrical characteristics (rf voltage, d.c. bias voltage, electrical power, peak-to-peak current, as well as the time-profiles of voltage and current), and the calculated erosion rates are compared with the measured values for an rf frequency of 3.5 MHz. The electrical characteristics are found to be in fairly good agreement. The calculated and measured erosion rates show larger discrepancies. Compared to the d.c. Grimm-type glow discharge, where similar quantities were compared and were found in excellent agreement, the agreement is less satisfactory in the rf discharge. This illustrates that the rf discharge is much more complicated than a d.c. discharge, and that more fundamental studies are required.