硫酸钴对镍电极电化学性能的影响

研究了CoSO4添加剂对镍电极和镍氢电池电化学性能的影响，镍电极反应活性和可逆性随CoSO4添加量增加而增大，CoSO4经过3-5次充放电循环后逐渐转变为CoOOH，与CoO添加剂的变化趋势一致。采用含CoSO4的镍电极与金属氢化物电极组装成MH／Ni电池，在第150次循环之前，电池放电容量一直随着循环次数的增加而增加，经过250次循环后，容量保持率仍高达95％：CoSO4添加量分别为11.2％、18.7％和30.0％时，相应的镍电极最高放电比容量分别为270、280和287mAh／g。由于CoSO4具有制备工艺简单、不容易氧化、成本低等特点，因此可替代CoO降低MH／Ni电池的制造成本。     

碳纸负载钴氧化物的制备及电催化析氧性能研究

高效且廉价的电催化析氧反应（OER）电极材料的制备对其在电化学能源转化和储存系统中的应用具有重要的研究意义。通过溶剂热法和不同气氛焙烧,分别制得碳纤维纸（碳纸）负载的两种钴氧化物（一氧化钴和四氧化三钴）,并将其用作OER电极的催化剂。运用X射线衍射仪（XRD）、场发射扫描电镜（FESEM）和X射线光电子能谱（XPS）技术分别对两种材料的物相、形貌和表面价态进行了表征及分析。结果表明：在氮气气氛下焙烧得到一氧化钴纳米片,而在空气下焙烧得到四氧化三钴纳米片。通过线性扫描伏安法（LSV）、循环伏安曲线（CV）、电化学交流阻抗测试（EIS）和计时电位法对两种材料的电催化析氧性能进行了研究。结果表明：一氧化钴电极比四氧化三钴电极具有更优异的析氧反应催化活性和稳定性。在1 mol/L 氢氧化钾电解液中,一氧化钴和四氧化三钴电极在10 mA/cm ²电流密度下对应的电位分别为1.568 V和1.617 V。     

Structure and electrochemical properties of nickel hydroxide electrodes with cobalt additives

In this article,cobalt additives are introduced into nickel hydroxide electrodes by two incorporation methods—co-precipitated cobalt hydroxide during the nickel hydroxide synthesis or post-added CoO with nickel hydroxide. The results of X-ray diffraction, cyclic voltammetry, electrochemical impedance spectroscopy, and charge–discharge tests indicate that (i) the diffraction peaks show a decrease in intensity and increase in the half peak breadths for Ni(OH)₂ with co-precipitated cobalt hydroxide; (ii) the electrochemical activity of nickel hydroxide can be improved by both incorporated cobalt and the effects of post-added CoO are more notable; (iii) CoOOH derived from post-added CoO is not stable in the KOH electrolyte when the potential of the Ni(OH)₂ electrode is lowered and its reduction product may be inactive, thus results in an irreversible capacity loss of nickel-metal-hydride battery after over-discharge-state storage.     

A study of the electrochemical behaviour of electrodes in operating solid-state supercapacitors

The electrochemical behaviour of electrodes and of complete solid-state supercapacitors has been studied by cyclic voltammetry (CV) and galvanostatic charge/discharge (CD) measurements using two independent electrochemical equipments. The first one controlled the execution of the test and recorded the voltage and current values of the complete supercapacitor while the other one recorded the potential changes of the single electrodes. In this work, two different types of capacitors were studied: (a) a symmetric supercapacitor using carbon electrodes, and (b) a hybrid (asymmetric) supercapacitor with ruthenium oxide/carbon in the positive electrode and carbon in the negative electrode. The studies evidenced that in the symmetric capacitors the positive electrode controlled the capacitive performance and an optimal mass ratio from 1.2:1 to 1.3:1 between the positive and the negative electrodes was found in the investigated conditions. For the hybrid supercapacitor it was observed that the ruthenium-based positive electrode influenced the capacitive performance of carbon-based negative electrode and that an accurate balance of carbon loading in the negative electrode was necessary.     

Pitch-based carbon foam electrodeposited with lead as positive current collectors for lead acid batteries

Lead electrodeposited carbon foam (LCF), whose substrate was made from pitch by a template method, was investigated as possible positive current collectors for lead acid batteries. Scanning electron microscopy, cyclic voltammetry, and galvanostatic charge–discharge tests were employed to characterize the effect of the proposed collector on the structure and electrochemical properties of the positive active material (PAM). The LCF with uniform and dense lead coating shows the similar electrochemical characteristics to metallic lead in the voltage range where the positive electrodes of lead acid batteries operate. The LCF and lead slices were used as the positive current collectors to equip lead acid batteries, respectively. Comparative charge–discharge tests show that a battery equipped with a LCF collector exhibits higher PAM utilization efficiency and longer cycle life, for LCF can provide large specific surface area which is beneficial to electrochemical reactions and PAM adhesion. In addition, a light lead acid battery with a LCF positive current collector and a carbon foam negative current collector was made and tested for the first time. It deserves systematic industrial study in the future.     

聚苯胺／PbO2混合电容器的电化学性能研究

通过原位化学沉积合法,以MnO2为氧化剂将聚苯胺（PANI）均匀地沉积在多孔活性碳（AC）表面,将得到的AC—PANI纳米复合材料作为负极与PbO2电极为正极组成混合电容,进行电化学的循环伏安和恒流充放电测试．结果显示,在1M的硫酸溶液中混合电容器的可以将电容器的最大比功率以及最高比能量提高将近10倍,这种提高主要来自电容器平均电压的提高以及负极利用效率的提高。     

Cobalt Oxide Electrodes-Problem and a Solution Through a Novel Approach using Cetyltrimethylammonium Bromide (CTAB)

In this article, we present a critical review of the literature on cobalt oxide modified electrodes, focusing on their cyclic voltammetric behavior. This article provides a broad survey of the field of electrochemical preparation of cobalt oxide films and their application in elecrocatalysis and electroanalysis. We discuss and analyze the complexity associated with the electrochemical behavior of cobalt oxide films, formed either through electrochemical methods or other methods. A solution is offered to the problem of complex redox couples of CoO film by introducing a novel cobalt oxide film. This is the first review paper on cobalt oxide modified electrodes. Focusing on this topic, all articles from 1922 to April 2014 are verified and the relevant articles are cited.     

Effect of unequal load of carbon xerogel in electrodes on the electrochemical performance of asymmetric supercapacitors

This paper investigates the electrochemical performance of asymmetric supercapacitors in an environmentally friendly aqueous electrolyte (1.0 mol L^?1 sodium sulfate solution). The asymmetric configuration is based on the use of a highly porous carbon xerogel as active material in both the positive and negative electrodes, but the carbon xerogel loading in each electrode has been substantially modified. This configuration leads to an increase in the operational voltage window up to values of 1.8 V and consequently to a higher specific capacitance (200 F g^?1) and energy density (~25 Wh kg^?1). Four different mass ratios were employed (1, 1.5, 2 and 3), and the electrochemical response of the cells was evaluated by means of cyclic voltammetry, galvanostatic charge–discharge and impedance spectroscopy. The results demonstrate that the optimal carbon mass ratio in the electrodes is about 2.0 because in these conditions the devices are able to operate with a maximum cell voltage of 1.8 V and with a high electrical efficiency.     

Polyaniline electrochromic devices with transparent graphene electrodes

Transparent, conductive and uniform graphene films have been prepared and used as electrodes of the electrochromic devices of polyaniline. Polyaniline films on both graphene and the widely used indium tin oxide (ITO) electrodes showed similar electrochemical and spectroelectrochemical properties. However, graphene electrodes exhibited much higher electrochemical stability than ITO in aqueous acidic electrolytes. The performances of the electrochromic devices with graphene electrodes exhibited slight decrease upon voltage switching while those of the devices with ITO electrodes decreased dramatically. After 300 cycles, the electrochromic devices with graphene electrodes showed much larger optical contrast and shorter switching time than those of the devices with ITO electrodes.     

Aging of electrochemical double layer capacitors with acetonitrile-based electrolyte at elevated voltages

Laboratory-scale electrochemical capacitor cells with bound activated carbon electrodes and acetonitrile-based electrolyte were aged at various elevated constant cell voltages between 2.75 V and 4.0 V. During the constant voltage tests, the cell capacitance as well as the capacitance and resistance of each electrode was determined. Following each aging experiment, the cells were analyzed by means of electrochemical impedance spectroscopy, and the individual electrodes were characterized by gas adsorption and X-ray photoelectron spectroscopy. At cell voltages above 3.0 V, the positive electrode ages much faster than the negative. Both the capacitance loss and resistance increase of the cell could be totally attributed to the positive electrode. At cell voltages above 3.5 V also the negative electrode aged significantly. X-ray photoelectron spectroscopy indicated the presence of degradation products on the electrode surface with a much thicker layer on the positive electrode. Simultaneously, a significant decrease in electrode porosity could be detected by gas adsorption.     

Effects of ball milling on the physical and electrochemical characteristics of nickel hydroxide powder

Nickel hydroxide powder was modified by the method of ball milling, and the physical properties of both the ball-milled and un-milled nickel hydroxide were characterized by scanning electron microscopy, specific surface area, particle size distribution and X-ray diffraction. It was found that the ball milling processing could obviously increase the surface area, decrease the particle and crystallite size, and reduce the crystallinity of β-Ni(OH)₂, which was advantageous to the improvement of the electrochemical activity of nickel hydroxide powder. Electrochemical performances of pasted nickel electrodes using the ball-milled nickel hydroxide as an active material were investigated, and were compared with those of the electrodes prepared with the un-milled nickel hydroxide. Charge/discharge tests showed that the ball-milled nickel hydroxide electrodes exhibited better performances in the charging efficiency, specific discharge capacity, active material utilization and discharge voltage. The improvement of the performances of β-Ni(OH)₂ through ball milling could be attributed to the better reaction reversibility, higher coulombic efficiency, higher oxygen evolution potential and lower electrochemical impedance, as indicated by the cyclic voltammetry and electrochemical impedance spectroscopy studies. Thus, ball milling was an effective method to modify the physical properties and enhance the electrochemical performances of nickel hydroxide powder for the active material of rechargeable alkaline nickel batteries.     

A comparison of the aging of electrochemical double layer capacitors with acetonitrile and propylene carbonate-based electrolytes at elevated voltages

The aging behavior of electrochemical double layer capacitors (EDLCs) based on activated carbon electrodes bound with poly(tetrafluoroethylene) (PTFE) was tested in electrolyte solutions based on acetonitrile (AN) and propylene carbonate (PC) at a constant elevated cell voltage of 3.5 V. The aging was quantified in terms of capacitance loss and resistance increase for the full cell and the individual electrodes. It is shown that the enhanced aging rate of symmetric EDLCs in either solvent at elevated voltages is dominated by the aging of a single electrode, and that the polarity of this limiting electrode depends directly on the solvent. In AN, the positive electrode ages much more rapidly than the negative, while in PC the negative electrode exhibits faster aging than the positive. After aging, the electrodes were investigated by nitrogen adsorption and X-ray photoelectron spectroscopy, revealing significant modifications of the electrode surface and providing clear evidence for the deposition of electrolyte degradation products on the electrodes.     

Ball milled cobalt oxyhydroxide coat on the surface of nickel hydroxide

Cobalt oxyhydroxide coat on the surface of nickel hydroxide particles is finished employing a simple ball milling process. The structure, morphology, and surface composition of the coated Ni(OH)₂ particles is characterized by using X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy tests. The results show that numerous strip-like particles of a mixture of Ni(OH)₂ and CoOOH aggregate on the surface of the Ni(OH)₂ particles, and a structure of β-Ni(OH)₂ is preserved. Compared to the Ni(OH)₂ electrodes with a mixed CoO additive, the electrochemical activity of the electrodes with ball milled CoOOH coat can be improved as shown by using electrochemical impedance spectroscopy test, thus resulting in charge–discharge and cycle life performance improvement of the electrodes.     

Characteristics and Vanadium Adsorption Performance of Resin/Carbon Composite Electrodes in Capacitive Deionization

Activated carbon (AC) and carbon nanotubes (CNTs) were used to fabricate resin/carbon composite electrodes (D314/AC and D314/CNTs). The adsorption characteristics of vanadium (V) on the two electrodes under different pH and voltage conditions were compared in capacitive deionization. Physical and electrochemical studies on the electrodes indicated that micropores and mesopores are well balanced in D314/AC, but mesopores are dominant in D314/CNTs. D314/CNTs showed higher specific capacitance and higher ion adsorption capacity than D314/AC. This study indicated that the adsorption performance of composite electrodes for V is affected by the electrode material, especially the pore properties.     

Development of a 100 W rechargeable bipolar zinc/oxygen battery

A bipolar filter press-type electrically rechargeable Zn/O2 battery has been developed. Reticulated copper foam served as substrate for the zinc deposit on the anodic side, and La0.6Ca0.4CoO3-catalysed bifunctional oxygen electrodes were used on the cathodic side of the cells. The 100cm2 unit cell had an open circuit voltage of 1.4V (O2) in moderately alkaline electrolyte. The open circuit voltage and the peak power measured for a stack containing seven cells were sim 10V and sim 90W, respectively. The current-potential behaviour was determined as a function of the number of bipolar cells, and the maximum discharge capacity was determined at different discharge rates.     

Mesoporous cobalt oxide film prepared by electrodeposition as anode material for Li ion batteries

A mesoporous cobalt oxide (CoO) film has been successfully prepared by electrodeposition using surfactant Brij 56 as the structure-directing agent. The scanning electron microscopy and transmission electron microscopy results indicate that the as-prepared CoO film has a highly porous structure constructed by many interconnected nanoflakes with a thickness of about 20 nm. The CoO flakes with continuous mesopores ranging from 5 to 10 nm arrange vertically to the substrate, forming a net-like structure and leaving pores of 30–250 nm. As anodes for Li ion batteries, the porous CoO film exhibits higher coulombic efficiency, weaker polarization and better cycling performance, compared to dense CoO film. The specific capacity after 50 cycles for the porous CoO film electrode is 509 mAh g⁻¹ at 1C rate, much higher than that of dense film (283 mAh g⁻¹). The better electrochemical performances of the porous film are attributed to its highly porous morphology, which shortens the Li ion diffusion paths within the bulk of CoO and relaxes the volume change caused by the reaction between CoO and Li ion.     

Rapid regeneration of chelated iron desulfurization solution using electrochemical reactor with rotating cylindrical electrodes简

A new electrochemical reactor with rotating cylindrical electrodes was designed and used to increase the regeneration efficiency of chelated iron desulfurization solution. The influence of operating parameters, such as the rotation speed of electrode, voltage, and inlet air and liquid flow rates, on the regeneration rate was investigated. Compared with the traditional tank-type reactor, the regeneration rate with the new electrochemical reactor was in- creased significantly. Under the optimum conditions, the regeneration rate was increased from 45.3% to 84.8%. Experimental results of continuous operation indicated that the new electrochemical regeneration method had some merits including higher regeneration efficiency, smaller equipment size and good stability in operation.     

Electrochemical analysis of a photoelectrochemical chloralkali reactor

In the present study, the electrochemical model for a newly designed photo electrochemical hydrogen production reactor is discussed. The reactor integrates the photochemical hydrogen production with an electrochemical chloralkali process. To neutralize the hydroxyl ions into the chloralkali process, the ideal minimum required potential is 2.18 V. However, there are losses in the solution, membranes and electrodes. These losses should be calculated to find the exact voltage requirement of the photoelectrochemical hydrogen production reactor. An electrochemical model is developed to calculate these losses in the reactor. Effect of brine concentration, electrolyte concentration, distance between the electrodes, current density and temperature are evaluated. The results show that a minimum voltage is required when the distance between the electrodes becomes a minimum at the highest possible temperature, lowest current density and at highest concentrations of brine and electrolyte. Furthermore, they indicate that brine and electrolyte concentrations do not have significant effect on required voltage.     

AC impedance investigation of conductivity of automotive lubricants using two- and four-electrode electrochemical cells

Two- and four-electrode electrochemical cells were designed for characterization studies of highly resistive non-aqueous automotive lubricant using electrochemical impedance spectroscopy (EIS). The influence of internal configuration of the impedance analyzer, the media’s temperature and properties, shielding of the cables, and the electrochemical cell geometry and arrangement on the impedance results were investigated. The most accurate EIS measurements can be made in the two-electrode configuration with active shields where a single arc at high frequencies and a complicated low frequency impedance feature were observed in complex impedance plots. When four-electrode cells were employed, the impedance load, geometry and positioning of voltage electrodes; finite resistance of the impedance analyzer; and capacitive coupling between the signal lines introduced two types of impedance measurement artifacts. A capacitive-resistive low frequency load was interpreted as a measurement artifact originating from geometry and positioning of voltage electrodes. The appearance of additional medium frequency load combining resistive, capacitive and inductive features is intrinsic to the measurement setup and is due to a combination of several instrumental and experimental factors resulting in a voltage divider effect.     

Electrodissolution of cobalt in carbonate/bicarbonate media

The electrodissolution of cobalt in carbonate/bicarbonate solutions was studied at room temperature by steady state polarisation, interfacial pH measurements and Raman spectroscopy. The active dissolution of cobalt leads to an initial CoO film formation. The metal passivation occurs by a slow transformation of the CoO into a Co₃O₄ oxide. The influence of HCO₃⁻ and CO₃²⁻ anions was investigated. Two different parallel electrochemical processes were proposed to account for the anion role on the electrochemical steady state behaviour of cobalt in the studied solutions.