CoO AS ADDITIVE IN POSITIVE ELECTRODE OF NICKEL-METAL HYDRIDE BATTERY

A series of positive electrodes for Ni/MH battery were fabricated by addition of CoO.The morphology and microstructure of the electrodes were examined by SEM and EDS, and electrochemical behavior was investigated in three-compartment appliances at room temperature.The electrochemical performance of the positive electrodes with CoO was improved. Under the same charge-discharge cycle, the electrodes with CoO showed higher specific capacity, lower charge mean voltage and higher discharge mean voltage. But further increasing the content of CoO in the electrodes contributed negative effect on the overall performance. Addition of 8% (mass) CoO was suggested to be a suitable content for the positive electrode.     

Electrocatalytic Activity of Ti/TiO2 Electrodes in H2SO4 Solution

Ti/TiO2 electrodes were prepared with the polymeric precursor method (PPM). The structure and morphology of Ti/TiO2 electrodes were examined with XRD and ESEM. The voltammetric charge (q*) of Ti/TiO2 electrodes as cathode in 0.5 mol/L H2SO4 solution was investigated with cyclic voltammetry. It was found that the electrocatalytic activity of the Ti/TiO2 electrodes was affected by the structure and morphology of the Ti/TiO2 electrodes, in other words, was affected by the calcination conditions of preparing the electrodes. The value of q*in was considerably larger than that of q*out, which means that the ‘inner’ active surface area was much larger than the ‘outer’ active surface area, and ‘inner’ active surface played a main role in the electrocatalytic activity of the Ti/TiO2 electrodes.     

PVA基碱性聚合物电解质Ni(OH)2/AC超级电容器的电化学性能

Polyvinyl alcohol(PVA)-sodium polyacrylate(PAAS)-KOH-H₂O alkaline polymer electrolyte film with high ionic conductivity was prepared by a solution-casting method.Polymer Ni(OH)₂/activated carbon(AC) hybrid supercapacitors with different electrode active material mass ratios(positive to negative) were fabricated using this alkaline polymer electrolyte,nickel hydroxide positive electrodes,and AC negative electrodes.Galvanostatic charge/discharge and electrochemical impedance spectroscopy(EIS) methods were used to study the electrochemical performance of the capacitors,such as charge/discharge specific capacitance,rate charge/discharge ability,and charge/discharge cyclic stability.Experimental results showed that with the decreasing of active material mass ratio m(Ni(OH)₂)/m(AC),the charge/discharge specific capacitance increases,but the rate charge/discharge ability and the charge/discharge cyclic stability decrease.     

Electrocatalytic Activity of Ti/TiO_2 Electrodes in H_2SO_4 Solution

Ti/TiO_2 electrodes were prepared with the polymeric precursor method (PPM). The structureand morphology of Ti/TiO_2 electrodes were examined with XRD and ESEM. The voltammetric charge(q~*) of Ti/TiO_2 electrodes as cathode in 0.5 mol/L H_2SO_4 solution was investigated with cyclicvoltammetry. It was found that the electrocatalytic activity of the Ti/TiO_2 electrodes was affected by thestructure and morphology of the Ti/TiO_2 electrodes, in other words, was affected by the calcinationconditions of preparing the electrodes. The value of q_in~* was considerably larger than that of q_out~*, whichmeans that the 'inner' active surface area was much larger than the 'outer' active surface area, and'inner' active surface played a main role in the electrocatalytic activity of the Ti/TiO_2 electrodes.     

具有固定硅铝比的Al2O3-2SiO2纳米颗粒制备:过程优化与粉体转化（英文）

Attempts had been made to synthesize Al2O3-2SiO2 nanopowders by sol-gel method with tetraethoxysilane(TEOS) and aluminum nitrate(ANN) as the starting materials.DTS,TEM,SEM and BET were employed to study the effects of process parameters on the size,specific surface area and structure(morphology) of powders.The alkali-activation reactivity of the powders was tested for manufacturing geopolymers and their hydrothermal reactions were performed for fabricating zeolites.The results show that the optimum process parameters and drying method for preparing Al2O3-2SiO2 nanopowders are as follows:the molar ratio of water and ethanol to TEOS are 0:1 and 12:1 respectively at synthetic temperature of 50 ℃ and the drying method is azeotropic distillation with microwave drying.The average particle diameters of the powders were about 70 nm and the largest BET specific surface area was up to 669 m2·g·1.The compressive strength of the geopolymer and the calcium exchange capacity(by CaCO3) of NaA zeolite prepared with the powders reached to 29 MPa and 366 mg·g·1 respectively.     

明胶涂覆于亲水化改性的支撑层上以提高复合膜的结构稳定性和渗透蒸发性能简

The interfacial compatibility of composite membrane is an important factor to its structural stability, andseparation performance. In this study, poly （ether sulfone） （PES） support layer was first hydrophilically modified with poly（vinyl alcohol） （PVA） via surface segregation during the phase inversion process. Gelatin （GE） was then cast on the PVA-modified PES support layer as the active layer followed by crosslinking to fabricate composite membranes for ethanol dehydration. The enrichment of PVA on the surface of support layer improved interfacial compatibility of the as-prepared GE/PVA-PES composite membrane. The water contact angle measurement and X-ray photoelectron spectroscopy （XPS） data confirmed the surface segregation of PVA with a surface coverage density of -80%. T-peel test showed that the maxima/force to separate the support layer and the active layer was enhanced by 3 times compared with the GE/PES membrane. The effects of PVA content in the support layer, crosslinking of GE active layer and operating parameters on the pervaporative dehydration performance were investigated. The operational stability of the composite membrane was tested by immersing the membrane in ethanol aqueous solution for a period of time. Stable pervaporation performance for dehydration of 90% ethanol solution was obtained for GE/PVA-PES membrane with a separation factor of -60 and a permeation flux of -1910 g.m^-2.h1 without peeling over 28 days immersion.     

羟基氧化镍的电解制备，结构表征和电化学性能研究

NiOOH was prepared by one-step electrolysis of spherical Ni（OH）2 and the effects of electrolysis parameters were examined. The highly pure NiOOH was obtained after electrolysis at a current density of 60mA.g^-1 and 30℃ with anodic potential controlled in the range of 1.73-1.85V （vs. Zn/ZnO） for 360min. The NiOOH samriles were characterized bv X-ray oowder diffraction （XRD） and scanning electron microscope （SEM） analysis.Resuits indicate that the electrolysis product is spherical NiOOH doped with graphite. Charge and discharge tests show that the prepared NiOOH offers a discharge capacity of over 270mAh·g^-1 at current density of 30mA·g^-1 and can be directly used as cathode material of alkaline Zn/NiOOH batteries. Galvanostatic charge/discharge and cyclic voltammetry （CV） tests reveal good cycling reversibility, of the NiOOH electrode.     

Influence of Light Calcining Hydration of Magnesite on MgO Sintering

Sintered magnesia clinker(also called sintered MgO) was prepared with Mg(OH)2(prepared by light calcining hydration of magnesite) and magnesite as starting materials,respectively,by the technical process:light calcining(850 ℃ 1 h) → grinding → molding → firing(1 600 ℃ 3 h).The morphology and structure of light calcined MgO powders prepared with magnesite or Mg(OH)2 were analyzed by XRD,SEM and FT-IR.The sinterability and microstructure of sintered magnesia prepared with magnesite or Mg(OH)2 were researched....     

Performance of Ni/Nano-ZrO2catalysts for CO preferential methanation简

Large surface areas nano-scale zirconia was prepared by the self-assembly route and was employed as support in nickel catalysts for the CO selective methanation. The effects of Ni loading and the catalyst calcination temperature on the performance of the catalyst for CO selective methanation reaction were investigated. The cata- lysts were characterized by Brunauer-Emmett-Teller （BET）, transmission electron microscope （TEM）, X-ray dif- fraction （XRD） and temperature-programmed reduction （TPR）. The results showed that the as-synthesized Ni/nano-ZrO2 catalysts presented high activity for CO methanation due to the interaction between Ni active particle and nano zir- conia support. The selectivity for the CO methanation influenced significantly by the particle size of the active Ni species. The exorbitant calcination resulted in the conglomeration of dispersive Ni particles and led to the decrease of CO methanation selectivity. Among the catalysts studied, the 7.5% （by mass） Ni/ZrO2 catalyst calcinated at 500℃ was the most effective for the CO selective methanation. It can preferentially catalyze the CO methanation with a higher 99% conversion in the CO/CO2 competitive methanation system over the temperature range of 260-280℃, while keeping the CO2 conversion relatively low.     

Progress on Preparation of Refractory Powder Using Nonmetallic Minerals and Its Applications

This review summarized the recent advances in the utilization of nonmetallic minerals and their applications for fabrication of unfired refractories.The preparation of refractory powder utilizing cheap nonmetallic minerals of zircon,low-grade bauxite and quartz was discussed,respectively.The preparation of three unfired SiC-based refractories：SiC-SiAlON-ZrN,Al2O3-SiC/β-SiAlON/Ti（C,N）-C,and Al2O3-SiC-Si3N4 using the as-prepared refractory powders was introduced.     

Physical characterization, electrochemical performance and storage stability of spherical Al-substituted γ-NiOOH

Spherical Al-substituted γ-NiOOH as an individual positive electrode material for a new type of alkaline primary/rechargeable Zn-NiOOH battery was prepared by the chemical oxidation of spherical Al-substituted α-Ni(OH)₂. The spherical Al-substituted γ-NiOOH was characterized by XRD, SEM, FT-IR, TGA-DTG, TPD-MS and HT-XRD. The tap density and average nickel oxidation state were measured. Its electrochemical performance and storage stability were also investigated. The results show that the as-prepared spherical Al-substituted γ-NiOOH has remarkably higher specific discharge capacity and superior storage stability in alkaline electrolyte compared to spherical β-NiOOH.     

Preparation of porous spherical α-Ni(OH)2 and enhancement of high-temperature electrochemical performances through yttrium addition

Through homogeneous precipitation method, uniform spherical α-Ni(OH)₂ particles were obtained at appreciate aging time in urea solution without any help of templates or dispersants. From SEM images, aging time exhibited great effects on the morphology of as-synthesized α-Ni(OH)₂. Also, long aging time helped to improve the electrochemical performances of α-Ni(OH)₂. It was found that the proper aging time was 12 h. However, α-Ni(OH)₂ showed low charge/discharge capacities at high temperatures. Therefore, yttrium was added to improve the high-temperature electrochemical performances of α-Ni(OH)₂. The influences of doping ratios of Y on the morphologic and high-temperature electrochemical characteristics were investigated through XRD, SEM, TEM, constant current charge/discharge, and cyclic voltammetric measurements. The α-Ni(OH)₂ samples with the addition of about 5.8 mol% Y showed a discharge capacity of 250 mAh/g at 0.2 C rate and 60 °C, much higher than that of α-Ni(OH)₂ without Y dopants (157 mAh/g).     

Preparation and electrochemical properties of LiMn2O4 by the microwave-assisted rheological phase method

Pure-phase and well-crystallized spinel LiMn₂O₄ powders as cathode materials for lithium-ion batteries were successfully synthesized by a new simple microwave-assisted rheological phase method, which was a timesaving and efficient method. The physical properties of the as-synthesized samples compared with the pristine LiMn₂O₄ obtained from the rheological phase method were investigated by thermogravimetry analysis (TGA), X-ray diffraction (XRD) and scanning electronic microscope (SEM). The as-prepared powders were used as positive materials for lithium-ion battery, whose charge/discharge properties and cycle performance were examined in detail. The powders resulting from the microwave-assisted rheological phase method were pure, spinel structure LiMn₂O₄ particles of regular shapes with distribution uniformly, and exhibited promising electrochemical properties for battery. Furthermore, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize the reactions of Li-ion insertion into and extraction from LiMn₂O₄ electrode.     

Effect of ethyleneglycol addition on the properties of P-doped NiMo/Al2O3 HDS catalysts: Part I. Materials preparation and characterization

Phosphorous-doped NiMo/Al₂O₃ hydrodesulfurization (HDS) catalysts (nominal Mo, Ni and P loadings of 12, 3, and 1.6 wt%, respectively) were prepared using ethyleneglycol (EG) as additive. The organic agent was diluted in aqueous impregnating solutions obtained by MoO₃ digestion in presence of H₃PO₄, followed by 2NiCO₃·3Ni(OH)₂·4H₂O addition. EG/Ni molar ratio was varied (1, 2.5 and 7) to determine the influence of this parameter on the surface and structural properties of synthesized materials. As determined by temperature-programmed reduction, ethyleneglycol addition during impregnation resulted in decreased interaction between deposited phases (Mo and Ni) and the alumina carrier. Dispersion and sulfidability (as observed by X-ray photoelectron microscopy) of molybdenum and nickel showed opposite trends when incremental amounts of the organic were added during catalysts preparation. Meanwhile Mo sulfidation was progressively decreased by augmenting EG concentration in the impregnating solution, more dispersed sulfidic nickel was evidenced in materials synthesized at higher EG/Ni ratios. Also, enhanced formation of the so-called “NiMoS phase” was registered by increasing the amount of added ethyleneglycol during simultaneous Ni–Mo–P–EG deposition over the alumina carrier. That fact was reflected in enhanced activity in liquid-phase dibenzothiophene HDS (batch reactor, T = 320 °C, P = 70 kg/cm²) and straight-run gas oil desulfurization (steady-state flow reactor), the latter test carried out at conditions similar to those used in industrial hydrotreaters for the production of ultra-low sulfur diesel (T = 350 °C, P = 70 kg/cm², LHSV = 1.5 h⁻¹ and H₂/oil = 2500 ft³/bbl).     

Molten salt synthesis of spherical LiNi0.5Mn1.5O4 cathode materials

This paper describes a novel simple redox process for synthesizing monodispersed MnO₂ powders and preparation of spherical LiNi_0.5Mn_1.5O₄ cathode materials by molten salt synthesis (MSS) method. Monodispersed MnO₂ powders have been synthesized by using potassium permanganate and manganese sulfate as the starting materials. By using this redox method, it was found that monodispersed MnO₂ powders with average particle size ∼5 μm can be easily obtained. Resultant MnO₂ and LiOH, Ni(OH)₂ was then used to synthesis LiNi_0.5Mn_1.5O₄ cathode materials with retention of spherical particle shape by MSS method. The discharge capacity was 129 mAh g⁻¹ in the first cycle and 127 mAh g⁻¹ after 50 cycles under an optimal synthesis condition for 12 h at 800 °C.     

Study of the effects of nanometer β-Ni(OH)2 in nickel hydroxide electrodes

Nanometer β-Ni(OH)₂, showed by XRD, was prepared by our supersonic coordination-precipitation method, with an average grain size of about 50 nm by TEM. Proton diffusion coefficient of nanometer Ni(OH)₂ and spherical Ni(OH)₂ were 1.93 × 10⁻¹¹, and 5.50 × 10⁻¹³ cm²/s, respectively, with combination of chronocoulometry and cyclic voltammetry. Charge-discharge test of simulated batteries at 0.2 °C showed that addition of 8 mass% of our prepared nanometer Ni(OH)₂ in nickel hydroxide electrodes led to increases in cathode discharge specific capacity (CDSC) by nearly 10% and the chargeability of the electrode by about 50 mAh/g, and a decrease in polarization. Cycle life test of AA-type MH-Ni batteries discovered that effect of nanometer Ni(OH)₂ in increasing CDSC was more apparent for the first 100 cycles and not much difference was found after 350 cycles. XAS demonstrated a higher oxidation state of Ni in fully charged nanometer Ni(OH)₂ composite electrode (Nano-E) and a lower one in discharged Nano-E, compared with micrometer Ni(OH)₂ spherical electrodes (Micro-E). A larger structure distortion was found in Nano-E, offering more vacancies for proton diffusion. Thus conversion between Ni²⁺ and Ni³⁺ was promoted during the charge-discharge process, which was assumed to be one explanation of increasing CDSC with the addition of nanometer Ni(OH)₂.     

Accelerated formation of barium titanate by solid-state reaction in water vapour atmosphere

Barium titanate (BaTiO₃) powders were synthesized from commercially available raw materials (BaCO₃ and rutile) without particular mechanochemical processing by solid-state reactions in water vapour atmosphere. The formation rate of BaTiO₃ was accelerated by water vapour and single phase of BaTiO₃ was obtained by calcination at 700 °C for 4 h in water vapour atmosphere, though high temperature (850 °C for 2.5 h) was required by calcinations in air to complete the reaction. The formation kinetics followed the Valensi–Carter equation, which suggested that the reaction proceeded by a diffusion controlled process. The apparent activation energy for the formation of BaTiO₃ in air and water vapour atmosphere was estimated to be 361 ± 20 kJ/mol and 142 ± 17 kJ/mol, respectively. Water vapour is considered to enhance thermal decomposition of BaCO₃ and formation of BaTiO₃ by attacking surface Ti–O–Ti bonds in TiO₂, increasing partial pressure of Ba(OH)₂, and producing vacancies in the BaTiO₃ structure.     

Optimization of microwave synthesis of Li[Ni0.4Co0.2Mn0.4]O2 as a positive electrode material for lithium batteries

A positive electrode material for lithium ion battery applications was successfully synthesized using microwave irradiation. This microwave synthesis has several merits such as homogeneity of final product and much shorter reaction time compared to conventional synthetic methods. We synthesized spherical [Ni_0.4Co_0.2Mn_0.4](OH)₂ as a precursor by a co-precipitation method. The pelletized mixture of the precursor and lithium hydroxide was calcined under different reaction times and temperatures by applying 1200 W of microwave irradiation at 2.45 GHz. We determined the optimum conditions of microwave synthesis for positive electrode materials. The powders were characterized by X-ray diffraction, scanning electron microscopy, and electrochemical testing. The capacity, its retention, and thermal stability of Li[Ni_0.4Co_0.2Mn_0.4]O₂ synthesized by the microwave synthesis were comparable to the Li[Ni_0.4Co_0.2Mn_0.4]O₂ prepared by the high temperature calcination method.     

Spherical clusters of β-Ni(OH)2 nanosheets supported on nickel foam for nickel metal hydride battery

Spherical clusters of Ni(OH)₂ nanosheets are directly grown on skeletons of nickel foam via a facile template-free spontaneous growth method. The obtained electrode (β-Ni(OH)₂/Ni-foam) is characterized by X-ray diffractometry, scanning and transmission electron microscopy and thermal analysis. Results show that Ni(OH)₂ has a β-phase structure and presents on the nickel foam skeleton mostly as spherical clusters with a diameter of ∼10 μm. The spheres are composed of nanosheets with thickness of ∼60 nm, width of ∼230 nm and length up to ∼2 μm, and the nanosheets are assembled by nanoparticles with diameter of ∼20 nm. The electrochemical performance of the β-Ni(OH)₂/Ni-foam electrode is evaluated by cyclic voltammetry and galvanostatic charge–discharge tests. The difference between the oxygen evolution reaction onset potential and the anodic peak potential for this electrode (∼100 mV) is larger than that for β-Ni(OH)₂ nanosheets and nanotubes powder electrode (∼65–77 mV) and much larger than that for commercial spherical β-Ni(OH)₂ powder electrode (∼25–47 mV), indicating that the β-Ni(OH)₂/Ni-foam electrode can be fully charged. The specific discharge capacity of β-Ni(OH)₂ in the β-Ni(OH)₂/Ni-foam electrode reaches 275 mAh g⁻¹, which is close to the theoretical value, lower than that of β-Ni(OH)₂ nanotubes (315 mAh g⁻¹), but higher than that of nanosheets (219.5 mAh g⁻¹), commercial micrometer grade spherical powders (265 mAh g⁻¹) and microtubes (232.4 mAh g⁻¹).     

The synthesis of Li(Ni1/3Co1/3Mn1/3)O2 using eutectic mixed lithium salt LiNO3–LiOH

A lithium-ion battery cathode material, Li(Ni_1/3Co_1/3Mn_1/3)O₂, with excellent electrochemical properties was prepared via two-step isothermal sintering, using eutectic lithium salts (0.38LiOH·H₂O–0.62LiNO₃) mixed with Co, Ni, or Mn hydroxides. Based on analysis using X-ray diffraction (XRD), scanning electron microscopy (SEM), a thermogravimetric-differential scanning calorimetric (TG–DSC) analyzer, and Fourier-transform Infrared (FT-IR), this synthetic process consists of procedures including lithium salt melting, permeation, reaction, crystalline transformation, and crystallization. Due to the lower melting point of the eutectic molten salts compared with that of the single lithium salt, a relatively mild synthetic condition (low temperature) is needed, and the product can be highly crystallized with low cation mixing, which facilitates maintenance of the precursor morphology. The electrochemical properties of the product were investigated by constant current discharge–charge and cyclic voltammetry. The results show that the initial discharge capacity is 160 mhA g⁻¹, with excellent cycling stability even after 50 cycles. We conclude that this novel eutectic molten salt method is a promising and practical approach for synthesizing cathode materials for lithium-ion batteries.