金属离子掺杂氢氧化镍的制备、结构与电化学性能

1引言: Ni(OH)2已被广泛用作镍基碱性二次电池的正极材料、电容器的电极材料、催化剂、电解剂和离子交换剂.Ni(OH)2具有α相和β相两种晶格形态,它们在充电时会分别转化为γ-NiOOH和β-NiOOH.α-Ni(OH)2由于其具有较高的平均氧化价态(接近3.67),因而具有较高的理论比容量(482mAh/g),并且能够很好地解决β-Ni(OH)2在过充电时产生的电极体积膨胀问题而受到广泛关注.     

β-NiOOH的制备及充放电性能

电池正负极材料有充放电态之分 ,如 Mn O2 、Zn处于充电态 ,Ni(OH) 2 、MH、Li Co O2 、L i Ni O2等处于放电态 ,将起始荷电态不同的电极组装成电池 ,必然存在充放电态不匹配的问题 ,给电池化成带来困难 [1,2 ] .如 Zn/Ni电池正极改用充电态Ni OOH为原材料 ,则负极就可用充电态 Zn为原材料 ,很显然 Zn作为负极材料优于 Zn O,这就引发了将 Ni(OH) 2 氧化为 Ni OOH的研究 .本文采用改进的化学氧化法由β- Ni(OH ) 2 制备β-Ni OOH粉体 [3,4 ] ,对纯样及其与 Mn O2 混合的掺杂样的充放循环性能和反应机理进行了研究 .所用试剂…     

β—Ni（OH）2电极的原位红外光谱研究

利用原位界面付里叶变换红外反射光谱法研究了β-Ni(OH)_2在3mol/L NaOH溶液中的电化学行为.原位红外反射光谱数据表明,电极电位大于0.5 V时.β-Ni(OH)_2层的表面转变为β-NiOOH.β-Ni(OH)_2层的氧化是从β-Ni(OH)_2/溶液界面开始的.而逆向的β-NiOOH层阴极还原则可能起始于Ni/β-NiOOH界面.用NaOD重水溶液代替NaOH水溶液可减少溶剂对光谱数据的干扰,谱图更清晰.     

金属离子掺杂氢氧化镍的制备、结构与电化学性能

1引言： Ni（OH）2已被广泛用作镍基碱性二次电池的正极材料、电容器的电极材料、催化剂、电解剂和离子交换剂。Ni（OH）2具有仅相和B相两种晶格形态，它们在充电时会分别转化为γ-NiOOH和β-NiOOH。α-Ni（OH）2由于其具有较高的平均氧化价态（接近3．67），因而具有较高的理论比容量（482mAh／g），     

Y掺杂对氢氧化镍电极高温性能的影响

合成了内掺稀土元素Y的β-Ni(OH)2和α-Ni(OH)2材料, 并通过XRD、TEM、CV 和充放电测试等方法研究了Y元素对这两种晶型活性材料的结构、形貌以及高温电化学性能方面的影响, 发现Y元素可显著提高β-Ni(OH)2和α-Ni(OH)2材料的高温性能, 且作用机理相同, 均是通过提高析氧过电位来改善镍电极的高温充电效率. 但是α-Ni(OH)2在高温下的相稳定性仍有待提高.     

Lu2O3对球形Ni(OH)2高温充放电性能的影响

为了改善镍电极的高温充电效率，采用机械混合的方式将球形Ni(OH)2与不同比例的Lu2O3混合后制成粘结式镍正极。充放电测试、循环伏安和XRD等实验结果表明，掺杂Lu2O3后镍电极的析氧过电位明显提高，高温充电效率得到了很大改善，在充电后的电极中β-NiOOH生成；而且Lu2O3的掺杂比例对镍电极的高温性能在不同的充放电倍率下有不同程度的影响，3．5％是最好的掺杂比例，掺杂对高温小电流充电效率的改善作用要大于高温大电流充电。     

Al、Zn掺杂γ-NiOOH的制备、结构与电化学性能

目前镍基碱性二次电池正极活性物质广泛采用的β-Ni(OH)2存在比容量偏低、不能或不适合与单质锌直11接搭配制作一次或二次锌镍电池等缺点[1],因此,合成充电态高比容量的NiOOH具有重要意义.Al、Zn等掺杂改性的α-Ni(OH)2在强碱性电解质中稳定,充放电可逆性好,质量比容量可达400mAh/g以上[2～4],如果直接合成其氧化态物质γ-NiOOH,有望获得较好的电性能,从而为镍基碱性电池提供一种新型的正极活性材料.     

Mn、Mg共掺杂Ni(OH)2的电化学性能

采用缓冲溶液法制备复合掺杂Mn、Mg的正极材料Ni0.82Mn0.18-xMgx(OH)2(x=0.06、0.09、0.12)。采用XRD、XPS和SEM等测试表征材料的晶体结构、锰价态和形貌,采用循环伏安和恒流充放电测试研究Mn、Mg不同掺杂比例对氢氧化镍电化学性能的影响。结果表明,Mn、Mg掺杂样品均为β相,晶粒细化;Ni0.82Mn0.09Mg0.09(OH)2样品具有优异的电极反应可逆性和充放电性能,100 mA·g^-1电流密度下的放电比容量(290.6 mAh·g^-1)优于商用β-Ni(OH)2(281.1 mAh·g^-1);且500 mA·g^-1电流密度下循环30圈后,Ni0.82Mn0.09Mg0.09(OH)2的放电比容量未见衰减,其循环稳定性优于商用β-Ni(OH)2。     

Al、Zn掺杂Y-NiOOH的制备、结构与电化学性能

目前镍基碱性二次电池正极活性物质广泛采用的β-Ni（OH）2存在比容量偏低、不能或不适合与单质锌直^11接搭配制作一次或二次锌镍电池等缺点，因此，合成充电态高比容量的NiOOH具有重要意义。Al、Zn等掺杂改性的α-Ni（OH）2在强碱性电解质中稳定，充放电可逆性好，质量比容量可达400mAh／g以上，如果直接合成其氧化态物质γ-NiOOH，有望获得较好的电性能，从而为镍基碱性电池提供一种新型的正极活性材料。     

混合纳米氢氧化镍的球镍电极材料的电化学活性研究

采用配位沉淀法制备出了Ni(OH)₂样品，经XRD测试为β-Ni(OH)₂，TEM测试结果表明其为平均粒径50nm左右的不规则的颗粒。将所制备的纳米Ni(OH)₂按8wt%的比例在球镍中混合后制成电极，可使正极的比容量提高11%左右。热分析表明，纳米Ni(OH)₂的电化学活性高于球镍的电化学活性。激光拉曼光谱的测试结果说明了8wt%混合后制成的纳米电极确实有较好的放电容量，同时也证实了用拉曼光谱可以表征电极材料的充放电     

Improvement of basic performances of a nickel-metal hydride battery

To develop a sealed-type nickel-metal hydride battery for use in portable equipment or in electric vehicles, investigations were conducted on negative electrodes using AB₅-type hydrogen storage alloy and positive electrodes. For the cycle life performance of the battery, alkaline treatment of the alloy and the substitution of more than 50% to the alloy with Co were effective. For the positive electrode, zinc as a solid solution in the nickel positive electrode obviously prevented γ-NiOOH from being formed in the charging process of β-Ni(OH)₂ and suppressed the migration of the electrolyte solution in the separator to the active material of the positive electrode. Also, hydrophobic treatment of the surface of the alloy was effective to prevent the elevation of the battery internal pressure of the battery in high rate charge.     

镍氢电池的循环性能与活性物质微结构的研究

与循环试验大致同步, 用静态(初态和终态)或准动态(增加若干个中间态)的模式对MH/H电池循环性能、电极(包括负极和正极)材料的微结构进行了X射线衍射(XRD)研究, 发现循环性能衰减与正极材料β-Ni(OH)₂的点阵参数、平均晶粒尺度、微应变和总的层错几率均随循环周期增加而减小以及负极材料中腐蚀产物A(OH)₃和B相出现和增加有一定的对应关系, 发现MH/Ni 电池循环性能的衰减是正极材料和负极材料的结构和微结构随着循环次数的增加发生明显变化, 恶化了正负极材料的电化学性能, 同时消耗和恶化了电解液的综合结果. 为了提高电池的循环性能, 采用不同正极材料的添加剂. 结果表明, CaF₂和Lu₂O₃有明显的效果, 其中CaF₂效果最好, 并有广泛的实用性.     

Transport of alkaline cation and neutral species through the α-Ni(OH)2/γ-NiOOH film electrode

The transport of alkaline cation and neutral species through the α-Ni(OH)₂/γ-NiOOH film electrode has been investigated during the hydrogen extraction from and injection into the film electrode in 0.1 M LiOH, KOH and CsOH solutions by using the electrochemical quartz crystal microbalance technique combined with the potentiostatic current transient technique and cyclic voltammetry. From the ohmic relationship between the initial current density and the applied potential step, it is suggested that the hydrogen transport through the film electrode is exclusively governed by "cell-impedance". On the basis of the "cell-impedance-controlled" hydrogen transport, the mass change measured indicates that during the hydrogen extraction, the alkaline cation is slowly inserted into the film electrode before the finish of the current plateau. After the period of current plateau has finished, it is drastically inserted at an exponential rate. By contrast, during the hydrogen injection, the extraction of alkaline cation is nearly completed before the finish of the current plateau. Most of the neutral species are incorporated into the film electrode during the immersion prior to the hydrogen extraction. The minority is not incorporated until the finish of the current plateau during the hydrogen injection. Electronic Publication     

Hierarchically structured β-Ni(OH)2 clusters: a uniquely efficient aqueous phase pollutant adsorbent for multiple anionic dyes and heavy metal ions

Herein, for the first time mesostructured 3D self-assembled β-Ni(OH)₂ clusters with high surface area, large pore size, and uniform flower-like morphology have been synthesized by implementing a novel microwave heating method, using glycine as the cappant. The β-Ni(OH)₂ clusters are subjected to aqueous phase pollutant adsorption for multiple anionic dyes [congo red (CR), acid fuchsin (AF) and acid red 27 (AR-27)], and heavy metal ions [divalent lead ion, Pb(II) and divalent cadmium ion, Cd(II)]. The comprehensive kinetic analyses show that the adsorption of dyes and metal ions on the β-Ni(OH)₂ cluster surface occurs by chemisorption (pseudo-second order kinetics) and intraparticle diffusion (film and pore diffusion) processes. Further, the β-Ni(OH)₂ clusters show excellent equilibrium adsorption capacity for all the anionic dyes and metal ions. The equilibrium isotherm data show homogenous distribution of CR and AF dyes, and heterogeneous distribution of AR-27 dye on the β-Ni(OH)₂ surface. The excellent adsorption efficiency is attributed to the microwave-induced highly hydroxylated rippled 2D surface, open pore architecture, and suitable pore distribution of the β-Ni(OH)₂ clusters, which collectively cause strong hydrogen bonding between the cluster surface and anionic dyes as well as metal ions.     

Characterisation of redox states of Ni(La)-hydroxide films prepared via the sol-gel route by ex situ IR spectroscopy

Ni(La)-hydroxide films were prepared from aqueous colloidal solutions containing nickel sulfate and lanthanum acetate in the molar ratio 10:1. Two types of film were made by heating for 15 and 60?min at 300?°C. Thermogravimetry (TG) and X-ray diffraction (XRD) reveal that both films consist of NiO (bunsenite 40%) nanoparticles (particle size?～30?Å), the remainder being amorphous. IR spectroscopy showed that the amorphous phase comprised the α(II)-Ni(OH)₂ phase incorporating SO₄ ^2?, carboxylate and water species. Cyclic voltammetry (CV) in a 0.1?M LiOH electrolyte combined with in situ UV-VIS spectroscopy revealed that the colouring/bleaching changes, as a function of applied potential, differed considerably for the two types of film. Ex situ IR spectroelectrochemical measurements at near-grazing incidence angle conditions using P-polarised light (NGIA IR) were performed for films heated for 60?min in 0.1?M LiOH and 0.1?M tetramethylammonium hydroxide (TMAH) electrolytes and cycled 1402 and 1802 times. During the oxidation/reduction cycles the α(II)-Ni(OH)₂ phase transforms to the γ(III)-NiOOH phase, while the β(II)-Ni(OH)₂ did not develop. This explains the high cycling stability of Ni(La)-hydroxide films. The incorporation of TMA⁺ ions was observed from the ν(CH₃) stretching band intensities in the IR spectra of cycled films.     

Nickel oxide hydroxide/platinum double layers modified n-silicon electrode for hydrogen peroxide determination

A novel photo-electrochemical and non-enzymatic hydrogen peroxide (H₂O₂) sensor was fabricated by electrochemically cathodic plating nickel hydroxide (Ni(OH)₂) on platinum films coated n-silicon (Pt/n-n⁺-Si electrode). Nickel oxide hydroxide (Ni(OH)₂-NiOOH) films on the Pt/n-n⁺-Si electrode were formed by cyclic voltammetry in 0.2 M KOH solution. The morphology and composition of Ni(OH)₂-NiOOH film were characterized via scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. A two-electrode cell based on Ni(OH)₂-NiOOH/Pt/n-n⁺-Si electrode and a platinum counter has been used for determination of H₂O₂ in the absence of reference electrode by photocurrent measurement at a zero bias. In these conditions a sensitivity of 96.9 μA mM^?1 cm^?2 and a linear response range from 0.02 up to 0.16 mM with a determination limit (S/N?=?3) of 5.4 μM were achieved in KOH solution at pH 13.3. In addition, the electrode also exhibited superior stability, anti-interference and selectivity.     

Preparation of hierarchical β-Ni(OH)2 nanostructures and adsorption characterization of methyl orange dye

The β-Ni(OH)₂ nanostructures have been prepared by hydrothermal with ammonia as alkali source. The morphology of β-Ni(OH)₂ evolves from hexagon sheets to flower-like hierarchical structure built up from the nanosheets as increasing the amount of ammonia. Hierarchical β-Ni(OH)₂ nanostructures have strong adsorption effect on methyl orange dyes. The adsorption mechanism of β-Ni(OH)₂ has been investigated, which could be expressed by pseudo-second order kinetic model with best match.     

Ni(115)台阶面对氢表面微观动力学行为的影响

用５参数Ｍｏｒｓｅ势模拟氢－镍表面体系相互作用势，考察了氢原子在Ｎｉ（１１５）台面上吸附扩散行为。同时构造了氢分子与Ｎｉ（１００）和Ｎｉ（１１５）台阶面 相互作用推广的ＬＥＰＳ势面面，考察了氢分子解离化学吸附的微观动力学性质。