Cu单掺杂和Cu/Al复合掺杂纳米氢氧化镍的结构和电化学性能(英文)

采用超声波辅助沉淀法制备Cu单掺杂和Cu/Al复合掺杂的纳米Ni(OH)2样品,测试样品的晶相结构、粒径、形貌、振实密度及电化学性能。结果表明,样品均具有α相结构且其平均粒度的分布范围窄,Cu单掺杂的纳米Ni(OH)2呈现不规则形态,而Cu/Al复合掺杂的纳米Ni(OH)2呈准球状且具有更大的振实密度。将纳米样品以8%的比例掺入到商业用微米级球形镍中制成混合电极。充放电和循环伏安测试结果表明,Cu/Al复合掺杂纳米Ni(OH)2的电化学性能优于Cu单掺杂的纳米Ni(OH)2的,前者的放电比容量最高达到330mA·h/g(0.2C),比Cu单掺杂样品的高12mA·h/g,比纯球镍电极的高91mA·h/g。此外,Cu/Al复合掺杂纳米样品的质子扩散系数比Cu单掺杂样品的高52.3%。     

Synthesis and behavior ofAl-stabilized α-Ni（OH）2

Nano-fibrous Al-stabilized α-Ni(OH)2 was synthesized by the urea thermal decomposition method. The grain morphology, crystal structure, thermal stability, chemical composition and electrochemical performance of the Al-stabilized α-Ni(OH)2 were investigated. It is found that the urea thermal decomposition is an appropriate way to precipitate the Al-stabilized α-Ni(OH)2 with excellent performance. The fiber cluster TEM pattern shows that the synthesized α-Ni(OH)2 powder is composed of agglomerates of much smaller primary particles. The stabilized α-Ni(OH)2 powder with a 7.67 A c-axis distance and low thermal stabilities is obtained. The FTIR spectrum shows that the materials contain absorbed water molecules, and intercalated CO32- and SO42- anions. The experimental α-Ni(OH)2 electrode exhibits excellent electrochemical redox reversibility, high special capacity, good rate discharging performance and perfect cyclic stability. Moreover, the synthesized α-Ni(OH)2 electrode also shows high discharge capacity and cyclic stability at high temperature. The electrode specific capacity remains 290 mA-h/g at 60 ℃, which is only 15 mA-h/g lower than its ambient value, and the capacity loss is 0.9 mA-h/g per charge-discharge cycle.     

非晶态纳米氢氧化镍电极材料物理特性与电化学性能

采用快速冷冻沉淀法制备出了非晶态纳米氢氧化镍。对制得材料样品进行了XRD，SEM，TEM，DSC和比表面积与孔径分析，将其制成MH-Ni电池正极材料进行充放电性能测试。结果表明：材料粉体为非品态，颗粒粒度为纳米级，类似球形。非晶纳米Ni（OH）2的热分解温度286．4℃低于常规球形Ni（OH）2的热分解温度333.8℃，同时具有较大得比表面积和孔径，分别为76．2089m^2·g^-1和37．7nm。与普通β-Ni（OH）2相比较，非晶态纳米氢氧化镍电极充电电压低，放电电压平台时间长，且高达1．258V，放电比容量为349．85mAh／g，具有较好的循环性能，20次循环后其容量衰减仅为1．28％。     

Phase and particle of Y-doped Ni（OH）2 prepared from different nickel sources and Na2CO3 amount

Multiple nano-sized a-Ni(OH)2was synthesized by ultrasonic-assisted precipitation under different conditions. The crystal structure and particle size distribution of the sample were characterized with X-ray diffraction(XRD), infrared spectroscopy, and laser particle size analyzer(PSA). The results show that the samples are anisotropic polycrystalline of a and b Ni(OH)2, and the ratio of a and b changes with the difference of nickel source, resulting in the largest ratio of a-Ni(OH)2using nickel nitrate as reactant. Larger amount of Na2CO3is conducive to the formation of a-Ni(OH)2; while the resultant phases are all b with the same conditions but no doping. The results of PSD indicate that the samples are about 100–120 nm in size, and the sample with nickel sulfate as nickel source has the minimum particle size. The three ions of nickel source appear in the absorption peaks in the Fourier transform infrared spectrum showing that the ions change the crystal structure of Ni(OH)2. EDS testing shows that Y and anion distribute in the lattice of aNi(OH)2uniformly.     

Effect of transformation pH on performance of nano-scale β-Ni（OH）2

The influence of transformation pH value on the performance of nano-scale Ni（OH）2 was analyzed. The measurement results of XRD and TEM indicate that the samples are composed of β-Ni（OH）2 with crystal size of 20-50 nm, and the crystal lattice parameters of nano-scale Ni（OH）2 prepared at different transformation pH values are different. With the increase of transformation pH value, the agglomeration of nano-scale Ni（OH）2 becomes obvious. Cyclic voltammograms（CV） and electrochemical impedance spectroscopy（EIS） measurement results show that transformation pH value affects the proton diffusion coefficient（D） and charge-transfer resistance（Rot） of the material. The specific capacity is up to 327.8 mA·h/g, and the discharge performance of electrodes depends on both D and Rct, so the kinetic characteristics that electrodes reaction is controlled by both mass-transfer step and charge-transfer step was put forward.     

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.     

Synthesis and high-temperature performance of Ti substituted α-Ni (OH) 2

Ti substituted α-Ni(OH)2 (c=2.121 nm, a =0. 307 nm) with perfect high-temperature performance was prepared by the co-precipitation method. The effects of Ti addition on the structure and the electrochemical properties were investigated. The results indicate that the substitution of Ti for Ni leads to the conversion of β-Ni(OH)2 to α-Ni(OH)2 and the increase of the inter layer distance along c-axis from 0. 464 nm to 0. 707 nm. Infrared study reveals that more anions(SO2-4 and CO2-3 ions) and H2O exist in the Ti substituted α-Ni(OH)2. The discharge capaciinhibition of the oxygen evolution at high temperature.     

Nickel-based layered double hydroxide from guest vanadium oxide anions

The layered double hydroxides (LDHs) are well known for ionic exchange properties to intercalate anionic compound in interlayer region. The Ni/V LDH composite was explored by co-precipitation method. The maximum capacitance of Ni/V LDH composite was 2612 F g^?1 at the scan rate 2 mV s^?1. As-synthesized Ni/V LDH composite provides a three-dimensional conducting network frame for manifesting electrochemical capacitance. This is because the insertion of vanadium oxide anions (VO_x ^?) into nickel interlayer space between nickel layers is compensated for hydroxyl vacancies during synthesis of lower-pH condition. The network frame makes it possible to promote fast electron transfer for Ni/V LDH composite electrode material and consequently allows the improvement of the electronic conductivity for Ni/V LDH composite electrode material. Thus, the Ni/V LDH composite exhibits high capacitance than β-Ni(OH)₂ due to its unique properties, with vanadium oxide anions embedded in the turbostratic structure and shorter diffusion pathway.     

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…     

A study on the structure and electrochemical characteristics of a Ni/Al double hydroxide

Aluminium-substituted nickel based layered double hydroxides (LDHs), Ni_0.78Zn_0.04Co_0.04Co_0.02Al_0.16(OH)₂(CO₃)_0.08· 1.0H₂O, were synthesized by a chemical co-precipitating process. It was shown that the structure of the LDHs is similar with that of α-Ni(OH)₂ investigated by X-ray diffraction and transmission electron microscopy. The electrode comprising the LDHs was charged/discharged according to a galvanostatic model, and displayed better discharge capacity than the common β-Ni(OH)₂ electrode. In addition, the effects of losing structure water on structure and electrochemical performance were investigated. This article is based on a presentation in “The 7th Korea-China Workshop on Advanced Materials” organized by the Korea-China Advanced Materials Cooperation Center and the China-Korea Advanced Materials Cooperation Center, held at Ramada Plaza Jeju Hotel, Jeju Island, Korea on August 24≈27, 2003.     

Study on the Performances of Nickel Hydroxide Coated with Ytterbium Hydroxide at High-Temperature

在氢氧化镍表面包覆氢氧化镱和氢氧化钴并用XRD、XPS、SEM和恒电流充放电技术进行表征。结果表明:β-Ni(OH)2为六方晶型,Co的存在形式主要为Co2+及有少量的Co3+。样品表面Co和Ni原子比大于8:1。65℃下0.2、1和3C恒电流充放电时,表面包覆2%Yb(OH)3的样品放电容量和活性物质利用率最大。65℃时经过30次充放电循环后,在不同的充放电倍率下,表面包覆不同量Yb(OH)3的氢氧化镍的放电循环稳定性和放电容量随着Yb(OH)3含量的增加而增大。     

Effect of preparation conditions on properties of Al-substituted α-Ni(OH)2 prepared by homogeneous precipitation

Al-substituted α-Ni(OH)2 was synthesized under different reaction conditions by a homogeneous precipitation method. The effect of reaction temperature, reaction time, Ni and Al ions concentration and reagent ratio on the physico-chemical properties and electrochemical performance of Al-substituted α-Ni(OH)2 was studied. The Alsubstituted α-Ni(OH)2 samples were characterized by X-ray diffractometry(XRD), infrared spectrometry(FT-IR),inductively coupled plasma(ICP), thermogravimetry(TG) and electrochemical test. The results reveal that the physico-chemical properties and electrochemical performance of the sample are influenced strongly by the preparation conditions. Keeping reaction temperature at 100 or 104 ℃ is appropriate and the largest specific discharge capacity of creases slightly. It is appropriate that the Ni and Al ions concentration and the ratio of urea to Ni and Al ions are 0.42 mol/L and 0.75: 1, respectively.     

α-Ni(OH)2 electrodeposition from NiCl2 solution

α-Ni(OH)₂ was synthesized from a NiCl₂ solution by electrodeposition method. In order to conduct a systematic study on the effects of experimental parameters, a series of electrolyte initial pH values, current densities, electrodeposition temperatures, and electrodeposition time were used. Cyclic voltammetry results demonstrated a side reaction of Ni²⁺+2e→Ni. The X-ray diffraction analysis, Fourier-transform infrared spectrum, and the color of the product showed that pure α-Ni(OH)₂ could be obtained in the initial pH value range of 2–5.86, current density range of 10–25 mA/cm² electrodeposition temperature range of 25–35 °C, and electrodeposition time range of 1.0–3.0 h. When electrodeposition temperature increased to 45 °C, a mixture of α-Ni(OH)₂ and metallic Ni was obtained. A current density higher than 30 mA/cm² resulted in the sample with features of β-Ni(OH)₂. A small amount of metallic Ni existed in the as-prepared sample when current density decreased to 5 mA/cm². A slight increase of electrolyte pH was observed with increasing initial solution pH and current density. Electrodeposition mass revealed a slight decrease with initial pH decreasing and showed an almost linear increase with current density increasing. The slope of the curve for electrodeposition mass versus electrodeposition time remained stable in the first 2.0 h and then decreased.     

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。     

β-NiOOH的臭氧氧化法合成、表征及电化学性能

利用臭氧在常温下氧化球形β-Ni(OH)2,制得β-NiOOH。通过X射线衍射、光电子能谱分析、扫描电镜等对样品结构进行表征。采用循环伏安及恒流放电实验研究所制β-NiOOH样品的电化学性能。结果表明:样品主要成分是平均粒径为13μm的球形β-NiOOH颗粒,不含γ-NiOOH。在样品以0.5C的放电倍率放电至0.5 V时,其放电比容量为200.4 mA·h/g,并具有较平坦的放电曲线。采用本方法所制样品的电极可逆性优于采用其他方法制备的β-NiOOH的可逆性,且未额外引入杂质元素,是一种制备纯净NiOOH的方法。     

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…     

Al代α-Ni（OH）2的结构与电化学性能

采用化学共沉积法制备了Al代α-Ni(OH)2并对其结构和电化学性能进行了研究。采用XRD，IR，SEM和TGA等方法研究了其结构特征和热稳定性，采用循环伏安法研究了所制备的α-Ni(OH)2的电化学性能。结果表明：采用25mol％的Al取代的方法得到的晶体结构为α-Ni(OH)2，且试样可以在碱性溶液中稳定存在。与β-Ni(OH)2相比，其具有较大的扩散系数，电极反应受扩散控制。     

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.     

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…