浸渍增重率和反渗率研究

对浸溃过程中浸渍剂沥青的浸入率和反渗率进行了分析与探讨。提出了理想增重率、理论增重率与实际增重率的概念和计算方法。并比较了实际增重率与操作增重率的差别。同时分析了抽真空的绝对压力与施压的绝对压力对各项增重率和反渗率的影响。     

Effect of impregnation of La0.85Sr0.15MnO3/yttria stabilized zirconia solid oxide fuel cell cathodes with La0.85Sr0.15MnO3 or Al2O3 nano-particles

Strontium substituted lanthanum manganite and yttria stabilized zirconia solid oxide fuel cell composite electrodes were impregnated with nano-particles of strontium substituted lanthanum manganite or alumina. A clear positive effect was observed on low performing electrodes and on good performing electrodes if the temperature was kept low after the impregnation with strontium substituted lanthanum manganite. On good performing electrodes the effect disappeared on heating. Alumina nano-particles had a detrimental effect on the activity of the strontium substituted lanthanum manganite based electrodes.     

Corrosion as a process determining the efficiency of porous nickel plates impregnated with nickel hydroxide

The methods used for the impregnation of porous nickel plates in alkaline batteries are compared. The effect of the corrosion process on these plates in terms of the efficiency, capacity and life of nickel-cadmium batteries with sintered electrodes is examined.     

二次焙烧温度制度对电极焙烧结焦率的影响

为提高炭──石墨制品的质量，炭素生产采用一次浸渍和二次焙烧（或多次浸渍多次焙烧）生产工艺，隧道窑作为先进的二次焙烧技术具有焙烧温度低、周期短、能耗少等特点，是生产高质量电极重要的工艺技术装备，其焙烧温度制度是影响浸渍电极焙烧质量的关键因素．概述了浸渍坯料二次焙烧温度制度和沥青结焦率的关系。     

Consumption of graphite anodes in chlorine manufacture by brine electrolysis

The anodic behaviour of carbon and graphite electrodes in aqueous electrolytes is described and the important reactions leading to the consumption of graphite during chlorine manufacture by brine electrolysis are discussed in detail. The present state of knowledge concerning the effects of chlorine cell electrolysis conditions on graphite consumption is also reviewed. A new investigation of the influence of graphite manufacturing variables and properties on consumption is also described. The variables studied were coke particle size, degree of pitch impregnation and the final heat treatment at the graphitization stage. Properties considered included electrical resistivity, apparent density, average crystallite size and unpaired electron spin density. The resistance of the graphite to anodic oxidation was found to increase with increasing coke particle size, increasing pitch impregnation and increasing final heat treatment temperature (up to 3000°C). Unpaired electron spin density was the property found best to correlate with this resistance.     

Gas Recombination in Sealed Ni–MHx Cells

This paper focuses on investigation of gas recombination in a positive-limited-sealed Ni–MH_x cell. The positive electrodes were prepared by electrochemical impregnation of fibrous nickel plaques. The metal hydride negative electrodes were made by pasting the mixture of rare-earth hydrogen storage alloy powders, conducting and binding agents on foamed nickel substrates. The measurement of the positive capacity at different charge times was used to estimate the partial current for oxygen evolution at the same time. The effects of charge rate, electrolyte saturation level and initial state of charge of the positive electrodes on the recombination were investigated in sealed Ni–MH_x cells. By determining the differential capacity of nickel hydroxide electrodes, an improved mathematical model was used to evaluate the gas recombination parameters during charge, overcharge, rest and discharge of the positive-limited-sealed Ni–MH_x cell. The gas recombination during rest, discharge and overdischarge was also examined. The oxygen recombination on the nickel hydroxide electrodes can be neglected due to the consumption of water when the nickel hydroxide electrodes were discharged. The longer overdischarge produced an increase in cell pressure for the sealed Ni–MH_x cell at an electrolyte unsaturated level and the evolving gas can be recombined by a following recharge operation. © 1997 SCI.     

Composite electrodes for electrochemical supercapacitors

Manganese dioxide and Ag-doped manganese dioxide powders were prepared by a chemical precipitation method using KBH₄ as a reducing agent. The powders were studied by X-ray analysis, thermogravimetry, and electron microscopy. Composite electrodes for electrochemical supercapacitors (ES) were fabricated by impregnation of slurries of the precipitated powders and carbon black into porous nickel foam current collectors. In the composite electrodes, carbon black nanoparticles formed a secondary conductivity network within the nickel foam cells. Obtained composite electrodes, containing manganese dioxide and 20 wt% carbon black with total mass loading of 50 mg cm⁻², showed a capacitive behavior in the 0.5 M Na₂SO₄ solutions. The capacitive behavior of the composite electrodes can be improved by mixing of manganese dioxide and carbon black in solutions or using Ag-doped manganese dioxide powders. The highest specific capacitance (SC) of 150 F g⁻¹ was obtained at a scan rate of 2 mV s⁻¹. The electrodes showed good cycling behavior with no loss in SC during 1,000 cycles.     

Processing of strong and highly conductive carbon foams as electrode

Porous carbons were processed by the foaming of two-part polymer precursors with pre-loaded carbon powder (graphitic or amorphous), and then resin impregnation and carbonization to control both porosity and mechanical strength of the resulting foam. Electrical conductivity of the foams was improved by nickel-catalyzed graphitization. Different levels of graphitization were obtained for varied concentrations of nickel to the amorphous carbon foams. The presence of graphitic carbon improves the electrical conductivity by a factor of 50, compared to the amorphous counterparts. Electrochemical studies showed that graphitization of the amorphous structures increased the specific electrochemical surface area and electron transfer rate of the carbon electrodes.     

Template-assisted electrodeposited cupric oxide nanotubes and hierarchical nanospikes for tailoring electrode-electrolyte interfacial charge transfer

Morphological modification in materials aids multi-channel electron access sites for easier electrolyte ion access for many electrochemical devices including energy storage devices. Controlled synthesis of such multichannel morphologies of metal oxides offers significant challenges. Herein, we report a template-assisted electrodeposition technique for the synthesis of Cu nanowires, which are transformed into either CuO nanotubes by controlled annealing or CuO hierarchical nanospikes using a simple hydroxyl ion impregnation technique and subsequent annealing. These materials are tested as electrodes in charge storage systems in 6 M KOH electrolyte in a three-electrode system; both electrodes have shown battery-type charge storage behaviour. Despite the chemical similarity between the two materials, the CuO nanospikes electrodes showed improved charge transport between electrode-electrolyte interface compared to the CuO nanotubes. With the cost-effectiveness, easy availability, and multi-channel morphology of CuO nanospikes along with the promising performance of the electrode in a three-electrode system, the present research offers future potential in developing low cost and high performing energy storage devices.     

A simple and novel method for preparing Ni(OH)2 Part I: Structural studies and voltammetric response

Ni/Ni(OH)₂ electrodes were prepared by in situ precipitation of nickel hydroxide into porous nickel substrates. The thermal decomposition of urea in solutions containing Ni²⁺ was used for the synthesis of the active material. The compound prepared by this method was a poorly crystallized (II)-type phase. The electrochemical behaviour of Ni/Ni(OH)₂ electrodes thus prepared was studied by cyclic voltamperommetry and the efficiency of the in situ precipitation was followed by the measurement of the cathodic charge obtained from the j-E response. The amount of incorporated material depends on the urea concentration and the electrochemical response of the electrodes was improved by increasing the number of impregnation cycles.     

PEMFC electrode preparation by electrospray: Optimization of catalyst load and ionomer content

Electrodes for proton exchange membrane fuel cell (PEMFC) have been prepared by means of electrospray deposition, using different ionomer contents and catalyst loads. The electrodes have been mounted in single PEMFC, and tested as cathode. The electroactive platinum area of electrosprayed electrodes has been measured by the hydrogen underpotential deposition method. Polarization curves have been measured to determine the optimal concentration for the platinum catalyst (Pt/C, 20 wt.%) and the ionomer (Nafion^®). Best performance is observed with 15% ionomer content in the electrosprayed cathode due to minimal cell internal resistance. This optimal concentration is lower than that found for electrodes prepared by other standard methods, like airbrushing or impregnation, which is attributed to the improved ionomer distribution within the electrospray deposited catalyst layer. On the other hand, the optimum value for catalyst load is similar to that encountered for electrodes prepared by the other methods, which reflects that electrospray has little or no effect neither on the catalyst nor on the electronic resistance of the catalyst layer.     

Ceramic nanocomposites based on oxides of transition metals for ionistors

Low-temperature synthesis methods are used to produce nanoceramic materials for electrodes of the following ionistors: (ZrO₂)_0.6(In₂O₃)_0.4, praseodymium cobaltite, as well as neodymium, lanthanum, and nickel chromites; they operate in the presence of an ion-conducting phosphorosilicate separator membrane and phosphate impregnation. Film electrodes of ionistors are fabricated that consist of nanocrystalline oxide materials deposited as a thin film on a porous electroconductive metal substrate, i.e., foamed nickel. The MnO₂-foamed nickel electrode has a specific capacity of 45.0 F g^?1, which is compared with that of industrial supercapacitors.     

Carbon nanotubes modified with electrodeposited metal porphyrins and phenanthrolines for electrocatalytic applications

Composites consisting of multi-walled carbon nanotubes (MWCNTs) and iron-nitrogen containing compounds as catalysts for the electroreduction of oxygen in acidic media were directly prepared on a glassy carbon (GC) electrode in a bottom-up synthesis. In a first step, MWCNTs were drop-coated in form of an ink onto the electrode. Afterwards the nanotubes were modified with catalytically active films of iron porphyrin (FeTMPP-Cl) or iron phenanthroline (Fe(phen)₃) through a pulsed potential deposition technique. Finally the prepared electrodes were heat-treated in an inert gas atmosphere.By employing cyclic voltammetry and rotating disc electrode measurements it is shown that the activity for the oxygen reduction reaction (ORR) at such composites increases progressively with every applied synthesis step showing the possibility for direct synthesis of a catalyst on an electrode. The activities of FeTMPP-Cl/MWCNT and Fe(phen)₃/MWCNT composites prepared by this technique are higher than that of similar electrocatalysts prepared by wet impregnation and heat treatment. The presented approach opens possibilities for systematic tuning of electrode structures, for example by stepwise build-up of gas diffusion electrodes.     

多孔堇青石蜂窝陶瓷负载La_(0.8)Sr_(0.2)CoO_3性能的研究

采用真空浸渍法,对多孔蜂窝陶瓷负载稀土复合金属氧化物La0.8Sr0.2CoO3的性能进行研究。利用XRD和SEM对负载后载体的晶体结构和形貌进行表征分析。考察了浸渍时间、浸渍温度和浸渍次数对负载量的影响。实验结果表明:最佳的浸渍时间为60min;最佳浸渍温度为室温;浸渍次数越多负载量越大。     

Electrochemical Oxidation of Phenol on Metal‐Impregnated Zeolite Electrodes

Nanodispersed metallic clusters of platinum, silver and cobalt were incorporated into NaX zeolite cavities by impregnation with acetone solution of corresponding acetylacetonates and solvent evaporation followed by acetylacetonate thermal decomposition. The mixture of modified zeolites and 10 wt % of carbon black, in the form of a thin layer, was pasted onto a glassy carbon surface by Nafion. With such electrode materials, the phenol oxidation in neutral, alkaline and acid solution was studied by cyclovoltammetry. Deactivation of all electrodes in both neutral and alkaline medium was observed, indicating that polymerization reaction might be the main reaction pathway of phenol at higher pH values. Formation of quinine‐type structures was obtained during electro‐oxidation at lower pH values, being more significant in acidic solutions.     

Modification of carbon electrodes by a nitrate-based treatment

The modification of raw carbon electrodes by a nitrate-based treatment improves the fluorine evolution process on carbon anodes. In the case of Al(NO₃)₃-impregnated electrodes, these improvements are attributed to the formation, at the electrode/KF-2HF interface, of a ternary conducting compound C _x (AIF₃) _y F, i.e. a GIC, instead of insulating graphite fluorides, CF _x . In addition, the effect of the NO₃ anions of the impregnation solution is demonstrated by impedance spectroscopy, scanning electron microscopy and mercury porosimetry. Impregnation of crude carbon electrodes by nitrate salts, followed by heat treatment, induces smoothing of the electrode surfaces and an increase in the diameter of the pores. This treatment also improves the electronic transfer at the interface and enhances the wet-ability of the electrode by the melt.     

Nano-structured composite cathodes for intermediate-temperature solid oxide fuel cells via an infiltration/impregnation technique

Solid oxide fuel cells (SOFCs) are high temperature energy conversion devices working efficiently and environmental friendly. SOFC requires a functional cathode with high electrocatalytic activity for the electrochemical reduction of oxygen. The electrode is often fabricated at high temperature to achieve good bonding between the electrode and electrolyte. The high temperature not only limits material choice but also results in coarse particles with low electrocatalytic activity. Nano-structured electrodes fabricated at low temperature by an infiltration/impregnation technique have shown many advantages including superior activity and wider range of material choices. The impregnation technique involves depositing nanoparticle catalysts into a pre-sintered electrode backbone. Two basic types of nano-structures are developed since the electrode is usually a composite consists of an electrolyte and an electrocatalyst. One is infiltrating electronically conducting nano-catalyst into a single phase ionic conducting backbone, while the other is infiltrating ionically conducting nanoparticles into a single phase electronically conducting backbone. In addition, nanoparticles of the electrocatalyst, electrolyte and other oxides have also been infiltrated into mixed conducting backbones. These nano-structured cathodes are reviewed here regarding the preparation methods, their electrochemical performance, and stability upon thermal cycling.     

Activated nickel anodes for average power fuel cells

The activation of nickel gas anodes has been studied using a wide range of transition metal compounds added to the nickel powder before sintering or added by impregnation to the sintered electrodes. Using a hydrogen-oxygen fuel cell for the tests, the efficiency of the impregnant for increasing the performance of the nickel/hydrogen electrode was in the range ammonium wolframate > cobalt acetate > copper basic carbonate > ammonium vanadate. The optimum performance was obtained by using a mixture of the first two compounds. The optimum conditions for the use of these electrodes are shown to be 79–82°C with a KOH electrolyte of 6.5–6.7 N and a hydrogen pressure at the electrode of 400 mm Hg. Under these conditions the cell gave 300mAcm^–2 and a maximum power density of 110mWcm^–2.     

硅胶负载氧化锆除氟吸附剂的制备

应用浸渍法制备了硅胶负载氧化锆除氟吸附剂,用正交实验设计安排实验,获得了最佳制备条件。讨论了制备条件如浸渍固液比、浸渍液浓度和温度、浸渍时间和浸渍次数的影响。浸渍液固液比对吸附剂吸附量有较大影响。浸渍液浓度大于0.10 mol/L后吸附剂的吸附量增加缓慢。浸渍2 h后可达到浸渍平衡。浸渍温度高则吸附量变大,多次浸渍可较大幅度地提高吸附量。     

炭/炭复合材料浸渍-炭化工艺的研究

用高、中、低软化点沥青为浸渍剂,对不同孔率的炭 /炭复合材料编织体进行浸渍。考察了浸渍温度、浸渍压力、浸渍时间等因素对浸渍效果的影响 ;并且对用高产炭沥青浸渍炭 /炭复合材料的工艺进行了初步探索。结果表明,在合适的工艺条件下对不同的基体均可达到很好的浸渍效果。