B参杂对NiO/Ni(OH)2电极材料电容性能的影响

通过化学镀再电化学氧化的方法在铜片表面制备出带有微米微坑和微米微球的均一NiO/Ni(OH)₂和B参杂的NiO/Ni(OH)₂(B)两种电极材料,采用扫描电镜(SEM/EDX)、X射线衍射(XRD)、X射线光电子能谱(XPS)和电化学技术对所制备的两种电极材料进行表征和电化学性能测试。SEM、XRD和XPS的测试结果表明, 所制备的两种电极材料由Ni、NiO和Ni(OH)₂组成,并且NiO/Ni(OH)₂(B)中B的参杂量可达14.6wt%。循环伏安测量和恒电流充放电试验表明,两种电极材料均具有较高的电化学活性和可逆性;在1 A/g的充放电电流密度下, 两种NiO/Ni(OH)₂和NiO/Ni(OH)₂(B)电极材料经历10000次充放电循环后分别给出了1380 和1930F/g的比电容, 显示出较高的比电容特性和良好的电化学稳定性;电化学阻抗谱表明NiO/Ni(OH)₂(B)电极材料较NiO/Ni(OH)₂电化学反应电阻降低了约2个数量级;Ragone曲线揭示了所制备的两种电极材料具有较高的功率密度和较低的能量密度。B的参杂使得NiO/Ni(OH)₂(B)电极材料表面氧化物含量增大并且形成微米微球形貌,增大了电极表面积以及与电解液的接触和润湿作用,降低了电极材料表面能带带隙能,从而导致较小的电化学反应电阻和电导率的提高是其显示优异赝电容性能的主要原因。     

水热电沉积法生长Co9S8薄膜电极

采用水热电沉积法在泡沫镍基体上原位沉积Co_9S_8薄膜,并对其形貌、组成、结构和电化学性能进行表征和测试。结果表明,镍基Co_9S_8薄膜呈花瓣片状,并具有优异的电化学性能,其在电流密度为10mA/cm~2时,比电容可高达2538.7 F/g。即使电流密度扩大至50 mA/cm~2时,比电容依然可达1930.7 F/g。经过1000次循环(电流密度为20 mA/cm2),比电容仍可达为1825.2 F/g,电容保有率72.8%,经过1500次循环后,电容保有率61.4%。     

Controllable preparation of hierarchical NiO hollow microspheres with high pseudo-capacitance

Nickel oxide (NiO) hollow microspheres with hierarchical structure were fabricated through a process consisting of a self-assembling, hydrothermal reaction and calcination. The prepared NiO hollow microspheres composed of many nanoflakes, are about 2-3 μm in diameter. The length of the NiO flakes, having clear edges, is about 500-700 nm, while the thickness is only about 40-50 nm. This indicates that the NiO microspheres possess a hierarchical structure that can provide porous channels to facilitate the transmission of both electrons and electrolyte ions. NiO microspheres exhibit a high specific capacitance of about 1340 F/g at a current density of 1 A/g and high capacitance retention about 96.5% after 1000 cycles. What's more, the conductive mechanism of nickel oxide for electrochemical capacitor electrodes was also studied.     

Electrochemical fabrication of a porous nanostructured nickel hydroxide film electrode with superior pseudocapacitive performance

A porous nickel film is prepared by selectively anodic dissolution of copper from an electrodeposited Ni-Cu alloy film. A porous nanostructured nickel hydroxide film electrode is further fabricated by the cathodic electrodeposition of Ni(OH)₂ film on the obtained porous nickel film. The specific capacitances of the as-prepared porous nanostructured Ni(OH)₂ film electrode at current densities of 2, 5 and 10 A/g are 1634, 1563 and 1512 F/g, respectively. The nanoporous Ni substrate significantly improves the electrochemically cyclic stability of the electrodeposited nickel hydroxide film in 1.0 M KOH solution. The superior pseudocapacitive properties such as large specific capacitance, excellent rate capability and improved electrochemically cyclic stability of the as-prepared nickel hydroxide electrode suggest its potential application in electrochemical capacitors.     

Der Einfluβ Der Spezifischen Adsorption Von Halogenidionen Auf das Elektrochemische Verhalten der Nickel-Elektrode

Small additions of the halide ions (F^?, Cl^?, Br^?, I^?) to 1N H₂SO₄ result in marked deviations of the current density/potential curves as well as the capacitance/potential curves from nickel, compared with those obtained in pure H₂SO₄. The different actions are explained by the varying tendency of the halide ions to specific adsorption at the nickel surface.The time-dependence of the capacitance demonstrates the existence of a two-stage process for the adsorption of iodide ions.In the presence of iodide ions the influence of their concentration was measured with respect to current density and capacitance.     

Flexible free-standing graphene-like film electrode for supercapacitors by electrophoretic deposition and electrochemical reduction

Electrophoretic deposition in conjunction with electrochemical reduction was used to make flexible free-standing graphene-like films. Firstly, graphene oxide (GO) film was deposited on graphite substrate by electrophoretic deposition method, and then reduced by subsequent electrochemical reduction of GO to obtain reduced GO (ERGO) film with high electrochemical performance. The morphology, structure and electrochemical performance of the prepared graphene-like film were confirmed by SEM, XRD and FT-IR. These unique materials were found to provide high specific capacitance and good cycling stability. The high specific capacitance of 254 F/g was obtained from cyclic voltammetry measurement at a scan rate of 10 mV/s. When the current density increased to 83.3 A/g, the specific capacitance values still remained 132 F/g. Meanwhile, the high powder density of 39.1 kW/kg was measured at energy density of 11.8 W·h/kg in 1 mol/L H₂SO₄ solution. Furthermore, at a constant scan rate of 50 mV/s, 97.02% of its capacitance was retained for 1000 cycles. These promising results were attributed to the unique assembly structure of graphene film and low contact resistance, which indicated their potential application to electrochemical capacitors.     

Application of spherical Ni（OH）2/CNTs composite electrode in asymmetric supercapacitor

1 Introduction Electrochemical capacitors (hereafter ECs) have greater power density than usual batteries and can be deeply discharged without any deleterious effect on life time[1]. Activated carbon(AC) with various modifications is the electrode materia…     

Capacitance performance enhancement of TiO<Subscript>2</Subscript> doped with Ni and graphite

Nano-amorphous TiO₂ was prepared by a sol-gel method. The results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that the composite electrode material (TiO₂-NiO-C) is made of powder with a grain size of 36.2 nm. Doping of nickel and graphite can increase the electrical conductivity and the specific surface area of nano-amorphous TiO₂. The electrochemical properties of TiO₂-NiO-C, such as self-discharge, leakage current, and cycle life, were studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge-discharge test. With a charge-discharge current density of 500 mA/g, the specific capacity of the TiO₂-NiO-C composite material reaches 12.88 mAh/g. Also, the expense of capacity is only 3.88% after 500 cycles. The electrochemical capacitor with the electrode material of TiO₂-NiO-C shows excellent capacity and cycling performance.     

Thin-layer electrolytic nickel hydroxide Ni(OH)2 in an electrochemical capacitor

Thin-layer electrolytic nickel hydroxide Ni(OH)₂ has been obtained from an aqueous solution of nickel sulfate and nickel nitrate. The capacitor characteristics of Ni(OH)₂ depending on the synthesis and technology parameters, the thermal treatment and storage conditions of the deposits, the KOH concentration, the potential sweep rates, and the relation with the adverse process of oxygen isolation in an electrochemical capacitor were investigated by cyclic voltammetry. It was established that the optimal KOH concentration in the solution of an electrochemical capacitor is 0.1 M, and it allows one to attain an active material discharge capacitance of 427?C457 F/g. The additional anode polarization of cathode deposited Ni(OH)₂ stabilizes the discharge characteristics of the obtained Ni(OH)₂ + NiO mixture in storage processes. It was established that the mass transport process in the solid state phase is the limiting stage of the Ni(OH)₂/NiOOH system??s electrode process in a KOH medium.     

制备温度对含氮碳材料电化学性能的影响(英文)

以聚苯胺包覆活性碳微球复合电极材料作为前驱体并进行高温碳化得到新型含氮碳材料(NENCs)。通过扫描电镜、透射电镜、傅里叶变换红外光谱、X射线衍射、X射线光电子能谱以及77 K温度下氮气吸脱附测试,研究碳化温度对NENCs形貌和结构的影响。将其组装成超级电容器在6 mol/L KOH电解液中进行了循环伏安、充放电、交流阻抗、循环寿命、漏电流以及自放电测试。结果表明:高温碳化得到的NENCs材料都具有很好的超级电容性能,尤其是碳化温度为600°C时得到的材料,当电流密度为1 A/g时的放电比电容高达385 F/g且显示最低的等效串联电阻值;且2500次循环后容量保持率高达92.8%。     

Effects of the Mixing and Aging Process on the Morphologies and Electrochemical Properties of Co/Fe Co-doped MnO<Subscript>2</Subscript>

Fe/Co co-doped γ-MnO₂ was synthesized by a facile chemical method without using any surfactant at room temperature in this study. The effects of the mixing and aging process on the electrochemical properties of Fe/Co co-doped MnO₂ materials were investigated by cyclic voltammograms (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The Fe/Co co-doped MnO₂ material had a specific capacitance (SC) of 214 F g^?1 at a scan rate of 2 mV s^?1 and good cycling stability, which was better than that produced via the drop-adding method in a stirred mixer and further confirmed the intensifying effect of the T-mixer on the mixing process. Therefore, the electrochemical properties of the co-doped MnO₂ could be significantly improved by the T-mixer and the stirring aging method.     

Nanocrystalline Nickel Deposition on the Titanium Alloys Using High Solution Flow Velocity

An innovative process has been developed for electroplating of nickel on titanium surface using fast solution flow technique. Nickel was directly deposited on a titanium alloy without using any pre-treatment process. Level of adhesion was determined using quantitative peel test and characterization of the deposition was performed by scanning electron microscopy. Results showed that the rate of nickel deposition at 60 °C was higher than that of the rate of nickel deposition at 40 °C. Moreover, Watts solution provided higher rate of nickel deposition compared to the sulfate-based nickel solution. The rate of deposition increased with increasing the solution flow velocity from 1.5 to 3 m/s and raising current density from 0.4 × 10⁴ to 1.6 × 10⁴ A/m² for both solution baths. Adhesion test indicated good level of adhesion between the deposited nickel and titanium surface. The bonding toughness increased to 4 J/m² for 1.2 × 10⁴ A/m² as a result of higher deposition rate. However, the mechanism responsible for the coating process was discussed in detail.     

The Effect of Plating Variables on Zinc-Nickel Alloy Electrodeposition

Acid chloride based solutions, pH approximately 5.5, were used for the deposition of zinc-nickel alloy coatings. The initial objective of this research project was to study the effects of variations in the nickel content of the plating solution and current density on the deposit composition. Subsequently the effects of variations in solution temperature, pH and agitation on deposit composition and cathode current density were evaluated for the solution containing 15 g/l nickel. The influence of plating conditions on appearance, microhardness and macro throwing power were also studied. When corrosion behaviour, which has been reported earlier, was also taken into account, the following plating solution formulation and operating conditions were considered to give the optimum results: ZnCl₂ (62.5 g/l), NH₄Cl (200.0 g/l), NiCl₂.6H₂0 (60.7 g/l), which is equivalent to 15 g/l nickel metal, Ammonia (25%, 50.0 ml/l), Temperature: 25.0 ± 0.5°C, pH: 5.5 ± 0.2, Current Density: 3.0 A/dm², Anode: Pure Zinc, Agitation: Air.     

An Investigation into the Corrosion Behavior of MgO/ZrO<Subscript>2</Subscript> Nanocomposite Coatings Prepared by Plasma Electrolytic Oxidation on the AZ91 Magnesium Alloy

Plasma electrolytic oxidation (PEO) of AZ91 Mg alloys was performed in ZrO₂ nanoparticles containing Na₂SiO₃-based electrolytes. The phase composition and the microstructure of PEO coatings were analyzed by x-ray diffraction and scanning electron microscopy followed by energy dispersive spectroscopy. Pitting corrosion properties of the coatings were investigated using cyclic polarization and electrochemical impedance spectroscopy tests in a Ringer solution. The results showed the better pitting corrosion resistance of the composite coating, as compared to the oxide one, due to the thickened inner layer and the decrease in the surface defects of the composite coating. Also, the PEO process decreased the corrosion current density from 25.06 µA/cm² in the Mg alloy to 2.7 µA/cm² in the oxide coating and 0.47 µA/cm² in the composite coating.     

Preparation of Al-Si Master Alloy by Electrochemical Reduction of Fly Ash in Molten Salt

An electrochemical method on preparation of Al-Si master alloy was investigated in fluoride-based molten salts of 47.7wt.%NaF-43.3wt.%AlF₃-4wt.%CaF₂ containing 5 wt.% fly ash at 1233 K. The cathodic products obtained by galvanostatic electrolysis were analyzed by means of x-ray diffraction, x-ray fluorescence, scanning electron microscopy, and energy-dispersive spectrometry. The result showed that the compositions of the products are Al, Si, and Al_3.21Si_0.47. Meanwhile, the cathodic electrochemical process was studied by cyclic voltammetry, and the results showed the reduction peak of aluminum deposition is at ?1.3 V versus the platinum quasi-reference electrode in 50.3wt.%NaF-45.7wt.%AlF₃-4wt.%CaF₂ molten salts, while the reduction peak at ?1.3 V was the co-deposition of aluminum and silicon when the fly ash was added. The silicon and iron were formed via both co-deposition and aluminothermic reduction. In the electrolysis experiments, current efficiency first increased to a maximum value of 40.7% at a current density of 0.29 A/cm², and then it decreased with the increase of current density. With the electrolysis time lasting, the content of aluminum in the alloys decreased from 76.05 wt.% to 48.29 wt.% during 5 h, while the content of silicon increased from 15.94 wt.% to 37.89 wt.%.     

The Dyeing of Anodised Aluminium

A solution from which satisfactory deposits can be obtained at considerably higher current densities than are possible with conventional solutions has been developed. Using standardized plating conditions and with fixed concentrations of nickel chloride and boric acid, the concentration of nickel sulphamate has been varied and shown to permit the highest current density at 600 g/1. At 60°C, the maximum current density (400 A/ft²) is nearly twice that of conventional sulphamate solutions under the same conditions. When the temperature is raised to 70°C satisfactory deposits can be obtained at 800 A/ft². The internal stress, hardness and lustre of deposits obtained from the 600 g/1 sulphamate solution operated at pH 4·0, 60°C without addition agents, can be varied as desired by appropriate choice of current density. At the conventional current density of 50 A/ft², hard but ductile deposits are obtained having compressive stress. At the highest current densities, the deposits are softer and the internal stress moderately tensile. Stress-free deposits are obtained at current densities in excess of 200 A/ft². The deposits are lustrous at 50 A/ft² but this lustre diminishes at higher current densities. With the aid of organic addition agents, satisfactory mirror-bright deposits can be obtained at current densities as high as 350 A/ft². The throwing-power of the solution is excellent.     

磁致涡流效应对阳极铝箔形貌及比电容的影响

针对盐酸-硫酸体系,通过耦合外加磁场对铝箔进行直流电化学腐蚀,系统研究磁致涡流效应(MagnetoHydrodynamics,MHD效应)对铝箔电化学行为、界面行为以及质量传递的影响。采用X射线衍射(XRD)、低温氮气吸附、扫描电镜(SEM)等手段对腐蚀箔样品进行表征。同时,通过计时电位法、极化曲线、循环伏安法、电化学阻抗法研究MHD效应对铝箔电化学性能的影响。结果表明,MHD效应能够抑制氧化膜的生长,增加铝箔表面Cl-的吸附量,减小扩散层厚度,强化Cl-/Al3+向孔内/孔外的传质,减小电解液中离子传递阻力。通过引入磁场,明显提高了腐蚀箔的蚀孔密度、平均孔径以及平均蚀孔深度的均一性,继而增大了阳极电子铝箔的比电容。     

Tobacco Stem-Based Activated Carbons for High Performance Supercapacitors

Tobacco stem-based activated carbons (TS-ACs) were prepared by simple KOH activation and their application as electrodes in the electrical double layer capacitor (EDLC) performed successfully. The BET surface area, pore volume, and pore size distribution of the TS-ACs were evaluated based on N₂ adsorption isotherms at 77?K. The surface area of the obtained activated carbons varies over a wide range (1472.8-3326.7?m²/g) and the mesoporosity was enhanced significantly as the ratio of KOH to tobacco stem (TS) increased. The electrochemical behaviors of series TS-ACs were characterized by means of galvanostatic charging/discharging, cyclic voltammetry, and impedance spectroscopy. The correlation between electrochemical properties and pore structure was investigated. A high specific capacitance value as 190?F/g at 1?mA/cm² was obtained in 1?M LiPF₆-EC/DMC/DEC electrolyte solution. Furthermore, good performance is also achieved even at high current densities. A development of new use for TS into a valuable energy storage material is explored.     

Fabrication and characterization of flexible and high capacitance supercapacitors based on MnO2/CNT/papers

Flexible paper-based supercapacitors were fabricated using carbon nanotubes (CNTs) and manganese oxides (MnO₂), and their electrochemical properties were characterized in a three-electrode system. CNTs were synthesized via water-assisted chemical vapor deposition (CVD) and dispersed in water using the surfactant sodium dodecylbenzenesulfonate (SDBS). The solution containing dispersed CNTs was simply coated on papers by drop-dry method. MnO₂ was then electrochemically deposited on the CNT-coated papers. The MnO₂/CNT/paper supercapacitors showed high specific capacitance of 540 F/g. Specific energy and specific power were 20 Wh/kg and 1.5 kW/kg, respectively, at current density of 5 A/g in 0.1 M sodium sulfate (Na₂SO₄) aqueous solution. Demonstrated high capacitance of the paper-based electrochemical capacitor makes it a promising candidate for flexible and low-cost energy storage device applications.     

An application of electrochemical method for studying nano-composite plating

Nickel plating is investigated using an electrochemical method in this study. Cathodic polarization indicated that electrode polarization at a current density of 10⁻¹ A/cm² increased by approximately 100 mV in a pH range 3–5, and by nearly 150 mV with 1 g/L of carbon powder in a Watts solution, as compared to bare nickel. The influence of inert particles such as carbon powder, silicon carbide and rice husk ash included in the nickel deposit was studied further using a potentiodynamic technique. Results showed that a co-deposit of nano-particles increased cathodic polarization. With a three-fold increase of the carbon powder in the plating solution, the polarization potential of the nickel deposit was doubled at a current density of 10⁻² A/cm². Passivation of the nickel deposit in the presence of all of the inert particles studied was improved in the area of hundreds of times higher compared to a bare nickel deposit. By increasing the amount of inert particles to twenty times the original amount, the passive current density was decreased by 85–95%. A co-deposit of rice husk ash in the nickel deposit decreased the passive current density by 98%, compared to a carbon and silicon carbide powder. Thus, rice husk ash has the potential to improve the pitting corrosion resistance of nickel composite plating.