Potential instabilities of lead silver alloy anodes in acidic sulfate electrolytes

The kinetic behaviour of lead and lead–silver anodes, polarized under galvanostatic conditions in a H2SO4ZnSO4MnSO4 electrolyte, has been studied. Whereas the potential of the lead anode stabilizes during electrolysis, the potential of the lead–silver alloy anode oscillates between two limits after an induction time. Both silver on the anode surface and manganese in the electrolyte are required for the potential oscillations to appear. With increasing time the potential oscillations change in shape and period. From impedance data obtained earlier, at the beginning of, and during the potential oscillations, it is shown that the potential instabilities originate from electrode coverage by a silver salt adsorbate.     

Electrodeposition of Zn–Co alloy coatingsfrom sulfate–chloride electrolytes

The composition, surface morphology and appearance of Zn–Co alloy deposits as a function of current density, electrode potential and Co2+ concentration in the electrolyte was studied. It was found that coatings of good quality with low (1%) Co content are formed at a current density of 0.2Adm–2 and with high (6.5%) Co content at 2Adm–2 from electrolytes containing 1.0M Co2+ under galvanostatic conditions. The potentiodynamic dissolution of coatings with Co content of 6.5% indicates successive deposition of Co enriched phases and a pure Zn phase. The Zn–Co alloys are more corrosion resistant than zinc but are less resistant than cobalt.     

Electrodeposition of Zn−Ni−Fe alloy in acidic chloride bath with separated anodes

The electrodeposition of ternary Zn–Ni–Fe alloy films was investigated in acidic chloride electrolyte. Electrodeposition was performed onto mild steel plates at pH 3 and 43°C. The influence of the chloride concentration (ZnCl₂, NiCl₂ and FeCl₂) on the surface appearance and deposit composition, as well as cathodic current efficiency, were investigated. Bright Zn–Ni–Fe alloy deposits were obtained in the electrolyte containing 0.4m of each of ZnCl₂ and NiCl₂ with 0.02 to 0.08m FeCl₂. The influence of current density, pH and temperature were also examined.     

EDLC performance of carbide-derived carbons in aprotic and acidic electrolytes

This study shows that carbide-derived carbons (CDCs) with average pore size distributions around 0.9-1 nm and effective surface areas of 1300-1400 m² g⁻¹ provide electrochemical double-layer capacitors with high performances in both aqueous (2M H₂SO₄) and aprotic (1M (C₂H₅)₄NBF₄ in acetonitrile) electrolytes.In the acidic electrolytic solution, the gravimetric capacitance at low current density (1 mA cm⁻²) can exceed 200 F g⁻¹, whereas the volumetric capacitance reaches 90 F cm⁻³. In the aprotic electrolyte they reach 150 F g⁻¹ and 60 F cm⁻³.A detailed comparison of the capacitive behaviour of CDCs at high current density (up to 100 mA cm⁻²) with other microporous and mesoporous carbons indicates better rate capabilities for the present materials in both electrolytes. This is due to the high surface area, the accessible porosity and the relatively low oxygen content.It also appears that the surface-related capacitances of the present CDCs in the aprotic electrolyte are in line with other carbons and show no anomalous behaviour.     

Electrodeposition of Sn-Cu alloy anodes for lithium batteries

Electrodeposition and heat-treatment was attempted to directly obtain a Sn-Cu alloy anode with fine grain of crystals for lithium ion batteries. The preparation of Sn-Cu alloy anode started with pulsed electrochemically depositing tin on the substrate of copper foil collector, and a protection coating layer of copper was plated on the surface of deposited Sn. An alloy of tin and copper was formed when heated. The energy dispersive spectroscope (EDS) and X-ray diffraction (XRD) analysis showed the copper and tin were partially alloyed to form Cu₆Sn₅ and Cu₃Sn after annealing. The SEM analysis showed the uncoated electrode is cracked after a cycle and the copper coated electrode was not cracked after 50 cycles. The Cu-coated electrode presented the first cycle coulomb efficiency reaching 95% and good cycleability.     

Mechanism of nickel-molybdenum alloy electrodeposition in citrate electrolytes

The kinetics of the induced codischarge of Mo with Ni in citrate-ammonia electrolytes was investigated by means of polarization and a.c. impedance measurements. Three potential ranges were considered. At low polarization, hydrogen evolution resulting from citrate reduction is the main reaction. The impedance plots exhibit a large capacitive loop with a small high frequency inflection characteristic of the development of a porous layer and a low frequency inductive feature. At intermediate polarization, the partial currents for Ni and Mo discharge increase in the same proportion; the hydrogen evolution is first constant and then rapidly decreases. Then a large low-frequency capacitive feature is observed on the impedance plots, whose size decreases with increasing polarization. At still higher polarization, the Mo discharge becomes increasingly controlled by diffusion which generates an additional capacitive loop. A reaction scheme is proposed which accounts for the polarization data and the major impedance features.     

Hygroscopic growth of nucleation-mode acidic sulfate particles

The hygroscopic growth factors of acidic sulfate nanoparticles relevant to atmospheric new-particle formation and growth were measured using a tandem nano-differential mobility analyzer (TnDMA). The dry diameters of the particles ranged from 5.5 to 53.2 nm. The growth factors progressively decreased for smaller dry particle diameters. For the largest particles, a model including the Kelvin effect and assuming fully acidic particles agreed well with the observed hygroscopic growth factors. For particles having dry diameters smaller than 36.1 nm, an expanded model based on a progressively increasing extent of neutralization for smaller particles and for higher relative humidity values explained the observations. Partial neutralization occurred because of adventitious ${\mathrm{NH}}_3$ in the experimental setup and was most significant for the lowest ${\mathrm{H}}_2{\mathrm{SO}}_4$ mass loadings, corresponding to the smallest nanoparticles. The extent of neutralization reached as high as 0.50 for the smallest particles at 80% relative humidity. Alternative explanations such as inaccuracies or nanosize effects in the density or the surface tension of the particles could not explain the observations. These results show that the hygroscopic behavior of acidic sulfate nanoparticles is more sensitive to the extent of neutralization than to the other considered possible nanosize effects, at least for dry particle diameters as small as 5.5 nm.     

Coprecipitates of dibasic lead phthalate and tribasic lead sulfate

Coprecipitates of dibasic lead phthalate and tribasic lead sulfate tend to crystallize with the latter forming the core of a core/shell structure. The reactivity of this structure towards hydrolysis of ester plasticizers is considerably lower than that of physical blends of the basic lead salts.     

以脱硫铅膏为原料制备四碱式硫酸铅

铅酸电池在人们的生活中已经广泛使用,其每年的巨大报废量使得环境面临较大威胁。有研究表明,已有较为成熟的技术对废铅膏进行脱硫回收处理。研究了以脱硫铅膏为原料,通过控制硫酸、十二烷基苯磺酸（DBSA）添加量和煅烧温度来合成四碱式硫酸铅。通过对各条件下得到的四碱式硫酸铅产品进行分析,得到制备四碱式硫酸铅适宜的工艺条件。研究结果表明：按n（铅）∶n（硫酸）=5∶1加入硫酸、按照n（铅）∶n（DBSA）=18∶1加入DBSA、煅烧温度为600 ℃条件下制得的四碱式硫酸铅纯度最高（92.7%）,产物为斜方晶体,满足铅酸电池对其作为添加剂的要求。本研究可以提供一种废铅膏回收利用的途径,实现铅资源的循环再利用。     

湿法回收废铅蓄电池制备三碱式硫酸铅

研究了湿法回收废铅蓄电池，并利用其中的有效铅成分制备三碱式硫酸铅。采用正交实验考察了硝酸浓度、物料比、反应时间等因素对回收率的影响。结果表明，湿法回收废铅蓄电池中铅的最佳工艺条件为：硝酸质量分数15％，Pb^2＋与NO3^-物质的量比1：4，反应时间3h。合成的产品三碱式硫酸铅质量符合原化工部行业标准（HG2340-1992）。     

不锈钢基二氧化铅涂层阳极的制备及电化学性能

采用阳极恒流电沉积法在不锈钢上制备了PbO<,2>涂层阳极和分别由Fe、Ni掺杂的PbO<,2>涂层阳极.利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、X射线荧光光谱仪(XRF)研究了涂层的微观结构、表面形貌及元素组成.采用电化学工作站测定了涂层的开路电位,并通过循环伏安法研究了涂层分别在0.1 mol/L N...     

Electrical double layer in solid electrolytes—silver ion conductors

Published data and the results of authors' investigations of the electrical double layer properties in silver ion conducting solid electrolytes are discussed. These are classical systems with point defects AgBr,AgCl (pure and doped), β-AgI and superionic conductors α-AgI and RbAg₄I₅. The comparative analysis of the results for the different systems is made. The double layer structure on graphite electrodes in crystals with Frenkel defects corresponds to the Helmholtz layer. In the case of metallic electrodes (Pt,Au) it was found that double layer properties are strongly influenced by the electrode nature; it means that the specific absorption of electrolyte ions plays the essential part. Some results may be satisfactorily explained in terms of the intrinsic surface disorder model.     

酸性氯化铜蚀刻废液电解再生用阳极的筛选

采用热分解法制备了8种DSA涂层阳极,通过循环伏安曲线、极化曲线、强化寿命等测试研究了不同涂层的电催化性能。结果表明,RuIrTiSnMn/Ti涂层阳极在酸性蚀刻废液电解再生工艺的阳极电流密度范围内具有最高的析氯电位,且强化寿命高(为538h),涂层成本最低,可作为酸性蚀刻废液电解再生工艺用的阳极。     

Structure of silver electrodeposits plated from different complex electrolytes

The structure of silver deposits plated from different complex electrolytes is investigated. It is shown that from all electrolytes based on cyano-argentate complexes, electrodeposits with a basic orientation along the <111> axis are plated. If other complex-forming agents are used, textures along different crystallographic axes can be obtained. At high current densities the deposits display a random orientation. No evidence for a direct relationship between the type of texture and the deposition overvoltage of silver in the electrolytes studied has been established. Silver deposits with structural characteristics and properties similar to those of coatings deposited from cyanide baths can be obtained from ferrocyanide-thiocyanate electrolytes.     

Mechanical stability of Sn-Co alloy anodes for lithium secondary batteries

An electro-co-deposited Sn-Co alloy electrode on a copper foil was prepared to study the structure and electrochemical properties. A micro-island structure of the active material was confirmed to be self-organized during the initial cycle, and such a structural change of the active material was compared with that of other Sn-based electrodes. A key to improve the cyclability in terms of the mechanical stability of the active material is discussed.     

Conductometric titration of chitosan sulfate polyanions in the presence of extraneous electrolytes

The possibility of determining the concentration of basic substance and H ₂SO₄ and Na₂SO₄ impurities in technical-grade chitosan sulfate (CS) was demonstrated. Water-ethanol solution containing 80±10% ethanol of the volume of the titratable mixture is the optimum medium for titration of technical-grade CS. Translated from Khimicheskie Volokna, No. 2, pp. 21–23, March–April, 1997.     

Substitution of silver by various metal ions in modified AgI solid electrolytes

The substitution process of silver by various metals in RbAg₄I₅ and other solid electrolytes of the AgI-modified type has been investigated. This process is of technological interest since it permits the use of copper, zinc or cadmium instead of silver as anode materials in solid state batteries which utilize these electrolytes.