Fabrication of highly ordered porous nickel phosphide film and its electrochemical performances toward lithium storage

Highly ordered porous Ni₃P film was successfully electrodeposited through a self-assembled monodisperse polystyrene sphere template on copper substrate after heat treatment. The spherical pores left in the film after the removal of polystyrene spheres are well-ordered and close-packed. The diameter of the pores arranged in the film is about 800 nm and the thickness of the wall connecting adjacent pores is 60 nm. As anode for lithium ion batteries, the nanostructured porous Ni₃P film exhibits improved capability and reversibility over the dense one. After 50 cycles, the reversible capacity of the porous Ni₃P film is 403 mAh g⁻¹ and 239 mAh g⁻¹ at 0.2 C and 2 C, maintaining 78.1% and 67.9% of the capacity in the 2nd cycle, respectively. The enhanced electrochemical performance of the porous film is attributed to the better contact between Ni₃P and electrolyte, which provides more sites for Li⁺ accommodation, shortens the diffusion length of Li⁺ and enhances the kinetics of electrode process. Moreover, the porous structure is stable and can sustain well even after 50 cycles.     

Surface behavior of pasted nickel electrodes with electrodeposited Co-Ce on substrate

1 Introduction MH/Ni batteries have supper specific energy density, better performance of charging and discharging, and are friendly to the surroundings. So, MH/Ni batteries have been applied widely in power tools[1]. The design of MH/Ni batteries is limi…     

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.     

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…     

Mn-substituted nickel hydroxide prepared by ball milling and its electrochemical properties

In order to reduce the price of nickel hydroxide and extend the application of nickel based alkaline secondary batteries, Mn substituted nickel hydroxide (Ni_1−xMn_x(OH)₂, x = 0-0.4) was prepared by using a simple ball milling method in this paper. The optimal ball milling conditions were obtained for the preparation of Ni_0.8Mn_0.2(OH)₂. The results of X-ray diffraction, electrochemical impedance spectroscopy and charge-discharge tests indicated that (i) a structure of β-Ni(OH)₂ was maintained for Ni_1−xMn_x(OH)₂; (ii) the surface electrochemical activity of nickel hydroxide could be effectively improved by Mn substitution; (iii) capacity of Ni_0.8Mn_0.2(OH)₂ reached 282 mA h/g and it showed an excellent cycling durability; (iv) compared to no-substituted nickel hydroxide, Ni_0.8Mn_0.2(OH)₂ showed a decrease both in charge-discharge plateau and capacity; but with the increase of discharge rate, the difference in discharge plateau between them was smaller, and capacity of the latter exceeded the former.     

The passivation of nickel in aqueous solutions—I. The identification of insoluble corrosion products on nickel electrodes using optical and ESCA techniques

In situ differential reflectometry in conjunction with ESCA techniques are used to identify various surface films which form electrochemically on nickel. The film observed on pure Ni in a 0.15 N Na₂SO₄ electrolyte has been identified to be primarily Ni(OH)₂. At different values of pH and potential, NiO has been found to form simultaneously with Ni(OH)₂. At solutions with pH > 8, the Ni(OH)₂ film partially transforms into a third oxide, presumably NiOOH, which can only be observed in situ.     

Supercapacitor characteristic of La-doped Ni(OH)<Subscript>2</Subscript> prepared by electrode-position

Samples of lanthanum-doped nickel hydroxide were prepared by electrodeposition method. The structure and electrochemical properties of the samples were studied by X-ray diffraction and a home-made open three-electrode cell system, respectively. The results show that the deposition process of Ni(OH)₂ and La(OH)₃ is mainly controlled by electrochemical polarization, which makes it easy to form uniform fine crystals. In addition, La(OH)₃ is not a separate phase and lanthanum ions are doped into Ni(OH)₂ crystal lattices. When V(0.5 mol/L Ni(NO₃)₂)/V(0.25 mol/L La(NO₃)₃) was 9:1, the lanthanum-doped nickel hydroxide reached the highest discharge capability of 840 F/g with a good cyclic reversibility. The capability still retains 670 F/g when the discharge current reaches 1000 mA/g.     

Nanostructured MgFe2O4 as anode materials for lithium-ion batteries

Transition metal oxides in the nano size region are enormous attention as a new generation of anode materials for high energy density Li-ion batteries. MgFe₂O₄ is used for the first time as active electrode vs. lithium metal in test cells. The research has been focused on the effect of grain size of MgFe₂O₄ and their electrochemical performance studied. In this studies, nanostructured milled MgFe₂O₄ (grain size 19 nm) sample have been compared with relatively large-sized as-prepared sample (grain size 72 nm). From the result, the 19 nm grain size sample delivered an improved discharge capacity of around 850 mAh/g, whereas it is only 630 mAh/g for as-prepared sample (72 nm). These values are two times higher than that of a carbon anode (372 mAh/g). The anomalous capacity may be associated with the formation of oxygen rich MgFe₂O₄ samples.     

EFFECT OF ELECTROLESS PLATING COBALT UPON CHARACTERISTICS OF NICKEL HYDROXIDE ELECTRODE FOR RECHARGEABLE ALKALINE BATTERIES

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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。     

In-situ hydrothermal synthesis of Ni–MoO2 heterostructure on porous bulk NiMo alloy for efficient hydrogen evolution reaction

The Ni–MoO₂ heterostructure was synthesized in suit on porous bulk NiMo alloy by a facile powder metallurgy and hydrothermal method. The results of field emission scanning electron microscopy (SEM), field emission transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) reveal that the as-prepared electrode possesses the heterostructure and a layer of Ni(OH)₂ nanosheets is formed on the surface of Ni–MoO₂ electrode simultaneously after hydrothermal treatment, which provides abundant interface and much active sites, as well as much active specific surface area. The results of hydrogen evolution reaction indicate that the Ni–MoO₂ heterostructure electrode exhibits excellent catalytic performance, requiring only 41 mV overpotential to reach the current density of 10 mA/cm². It also possesses a small Tafel slope of 52.7 mV/dec and long-term stability of electrolysis in alkaline medium.     

Effect of underpotential deposition of lead on polarization behavior of nickel in acidic perchlorate solutions at room temperature

The effect of Pb²⁺ on polarization behavior of nickel has been investigated in 0.1 M NaClO₄ + 10⁻² M HClO₄ + x M PbO solutions (x = 0, 10⁻⁵, 10⁻⁴, 10⁻³) at room temperature. The cyclic voltammogram has suggested that Pb²⁺ degrades the stability of the passive film on Ni. The corrosion potential of Ni shifted to the more noble direction and the anodic current peak of Ni dissolution decreased with increasing Pb²⁺ concentration in solution, indicating that Pb²⁺ suppresses significantly the anodic dissolution. The underpotential deposition (UPD) of lead on Ni in the potential range more noble than −0.215 V (SHE) corresponding to the equilibrium potential of the Pb²⁺ (10⁻³ M)/Pb electrode was confirmed by XPS and GDOES analyses. The anodic Tafel slope, b⁺, of Ni dissolution changed from b⁺ = 40 mV decade⁻¹ in the absence of Pb²⁺ to b⁺ = 17 mV decade⁻¹ in the presence of 10⁻⁴ or 10⁻³ M Pb²⁺, which was ascribed to the increase in active sites of Ni surface emerged as a result of electrodesorption of Pb adatoms. The roles of Pb adatoms in active dissolution and active/passive transition of Ni were discussed from the above results.     

Oxidative dissolution of nickel metal in hydrogenated hydrothermal solutions

A platinum-lined, flowing autoclave facility is used to investigate the solubility behavior of metallic nickel in hydrogenated ammonia and sodium hydroxide solutions between 175 and 315 °C. The solubility measurements were interpreted by means of an oxidative dissolution reaction followed by a sequence of Ni(II) ion hydrolysis reactions:

Ni(s)+2H⁺(aq)=Ni²⁺(aq)+H₂(g)     

Ni（OH）2 particles synthesized by high energy ball milling

1 Introduction Ni(OH)2/NiOOH has been used as positive materials in alkaline secondary batteries for more than 100 years[1- 3]. The performance improvement of Ni(OH)2/NiOOH electrode is crucial for the application of these batteries as they are all positi…     

Preparation and electrochemical performance of copper foam-supported amorphous silicon thin films for rechargeable lithium-ion batteries

Amorphous Si thin films, which have been deposited on copper foam by radio-frequency (rf) magnetron sputtering, are employed as anode materials of rechargeable lithium-ion batteries. The morphologies and structures of the as-prepared Si thin films are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). Electrochemical performance of lithium-ion batteries with the as-prepared Si films as the anode materials is investigated by cyclic voltammetry and charge-discharge measurements. The results show that the electrode properties of the prepared amorphous Si films are greatly affected by the deposition temperature. The film electrode deposited at an optimum temperature of 300 °C can deliver a specific capacity of ∼2900 mAh/g and a coulombic efficiency above 95% at charge/discharge current density of 0.2C after 30 cycles. The Li⁺ diffusion coefficiency in copper foam-supported Si thin films is determined to be 2.36 × 10⁻⁹ cm²/s.     

Effect of Aspergillus niger Tiegh. L-10 on the physical and chemical properties of a polyaniline coating in the growth substrate

The influence of the growth of Aspergillus niger Tiegh. fungi on the morphological, chemical and electrochemical properties of the polyaniline (PANI) modified Ni surface has been investigated. The strain of Aspergillus niger Tiegh. L-10 was cultivated on the malt extract agar (DIFCO OXOID). A PANI film was synthesized by potentiodynamic polymerization in an aqueous 0.3 M H₂C₂O₄ solution containing 0.1 M aniline on the Ni electrode. The electrochemical behaviour of polymer films was determined in a 0.05 M H₂SO₄ solution by the cyclic voltammetry method. The composition of PANI and Aspergillus niger Tiegh. treated PANI surfaces have been characterized using X-ray photoelectron spectroscopy (XPS). The morphology has been studied using scanning electron microscopy (SEM). The attachment of a polymer film via the metabolic product resulted in oxidation of the surface. It was estimated that at the PANI/microorganism interface, a Ca-complexed carboxylate interfacial reaction product was formed.     

Properties and fast low-temperature consolidation of nanocrystalline Ni-ZrO2 composites by high-frequency induction heated sintering

Nanopowders of Ni and ZrO₂ (11 nm and 90 nm, respectively) were synthesized from NiO and Zr by high energy ball milling. A highly dense nanostructured 2Ni-ZrO₂ composite was consolidated at low temperature by high-frequency induction heat sintering within 2 min of the mechanical synthesis of the powders (Ni-ZrO₂) with horizontal milled NiO + Zr powders under 500 MPa pressure. This process allows very quick densification to near theoretical density and prohibits grain growth in nano-structured materials. The grain sizes of Ni and ZrO₂ in the composite were calculated. Finally, the average hardness and fracture toughness values of nanostructured 2Ni-ZrO₂ composites were investigated.     

Ellipsometry of passive oxide films on nickel in acidic sulfate solution

Nickel passive film has been studied in acidic sulfate solutions at pH 2.3 and 3.3 by ellipsometry. During anodic passivation followed by cathodic reduction, the roughness increases with dissolution of nickel, being indicated by gradual decrease of reflectance. However, the ellipsometric parameters, Ψ (arctan of relative amplitude ratio) and Δ (relative retardation of phase), are relatively insensitive to the roughness increase. From the change of Ψ and Δ, δΨ and δΔ, during the anodic passivation and reduction, thickness of the passive oxide film was estimated with assumption of refractive index of n_f = 2.3 of the film. The thickness estimated is a range between 1.4 and 1.7 nm in the passive potential region from 0.8 to 1.4 V vs. RHE, having a tendency of thickening with increase of potential. Cathodic reduction at constant potential induces a change of the oxide film to an oxide film with lower refractive index of n_f = 1.7, accompanied by thickening of the film about 30% more in the initial stage of reduction for 30 s. The gradual decrease of thickness takes place for the oxide with the lower refractive index in the latter stage. The potential change from the passive region to cathodic hydrogen evolution region may initially cause hydration of the passive oxide of NiO, i.e., NiO + H₂O = Ni(OH)₂, and during the latter stage of reduction, the hydrated nickel oxide gradually dissolves.     

Morphology control and electrochemical properties of nanosize LiFePO4 cathode material synthesized by co-precipitation combined with in situ polymerization

Nanosize carbon coated LiFePO₄ cathode material was synthesized by in situ polymerization. The as-prepared LiFePO₄ cathode material was systematically characterized by X-ray diffraction, thermogravimetric-differential scanning calorimetry, X-ray photo-electron spectroscopy, field-emission scanning electron microscopy, and transmission electron microscopy techniques. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images revealed that the morphology of the LiFePO₄ consists of primary particles (40-50 nm) and agglomerated secondary particles (100-110 nm). Each particle is evenly coated with an amorphous carbon layer, which has a thickness around 3-5 nm. The electrochemical properties were examined by cyclic voltammetry and charge-discharge testing. The as-prepared LiFePO₄ can deliver an initial discharge capacity of 145 mAh/g, 150 mAh/g, and 134 mAh/g at 0.2 C, 1 C, and 2 C rates, respectively, and exhibits excellent cycling stability. At a higher C-rate (5 C) a slight capacity loss could be found. However after being charge-discharge at lower C-rates, LiFePO₄ can be regenerated and deliver the discharge capacity of 145 mAh/g at 0.2 C.     

Preparation and characterization of Y3Al5O12:Ce and Y2O3:Eu phosphors powders by combustion process

A nickel hydroxide, Ni(OH)₂, was prepared by microwave-assisted heating technique from nickel nitrate aqueous solution and sodium hydroxide (assigned as PM). Then, the as-prepared PM was oxidized by liquid oxidation with sodium hypochlorite (assigned as PMO). Further, pure nanocrystalline nickel oxide (NiO) particles were obtained from the as-prepared PMO by calcination at 300, 400, 500, 600, 650 and 700 °C (labeled as C300, C400, C500, C600, C650 and C700, respectively). The as-prepared powders (PM and PMO) and the NiO nanoparticles were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), temperature-programmed reduction (TPR) and scanning electron microscope (SEM). The results indicated that the particle size of nickel oxide was controlled by the calcined temperature. The average crystal size of the NiO nanoparticles ranges from about 5 to 35 nm at 300–700 °C. Mechanism of nickel oxide nanocrystallite growth during thermal treatment was investigated.