还原剂对Ni(OH)_2/还原氧化石墨烯复合材料结构及电化学性能的影响

为研究还原剂对Ni(OH)_2/还原氧化石墨烯(RGO)复合材料结构及电化学性能的影响,首先以氧化石墨烯(GO)和硝酸镍作前驱体,采用水热法制备了Ni(OH)_2/RGO复合材料;然后,利用XRD、SEM和Raman光谱仪表征了复合材料的结构和形貌,并采用循环伏安法、恒流充放电曲线和电化学阻抗谱研究了复合材料的电化学性能。结果表明:以(NH2)2CSO2作还原剂时,制备的β-Ni(OH)_2/RGO复合材料为RGO纳米片与Ni(OH)_2纳米片相互插层的结构;在电解液(6mol/L KOH溶液)中,0.2C放电倍率时β-Ni(OH)_2/RGO复合材料的比容量高达341.0mAh/g,10.0C放电倍率为时复合材料的比容量为242.2mAh/g,仍能保持β-Ni(OH)_2理论比容量的83.8%。所得结论表明制备的Ni(OH)_2/RGO复合材料显现出良好的电化学性能。     

Ni(OH)_2/RGO复合材料的化学沉淀-回流法制备和放电性能

以氧化石墨(GO)和NiSO_4·6H_2O为前驱体,氨水为沉淀剂,用化学沉淀-回流法制备Ni(OH)_2/还原氧化石墨烯(RGO)复合材料,用XRD、SEM表征材料的结构和表面微观形貌,用循环伏安(CV)、恒电流充放电和电化学阻抗(EIS)测试电极材料的电化学性能,研究了GO:Ni(OH)_2质量比和氨水浓度对复合材料结构、形貌和电化学性能的影响。结果表明:所制备的β-Ni(OH)_2/RGO复合材料为Ni(OH)_2纳米片与RGO片相互插层的结构,当氨水的浓度为3 mol/L,GO:Ni(OH)_2=1:8(质量比)时复合电极材料在0.2C的放电比容量高达334.9 mAh/g,5C的放电比容量为260.2 mAh/g,保持在β-Ni(OH)_2理论比容量的90%,表现出良好的倍率性能和循环性能。     

微波法合成Ni(OH)_2/RGO复合材料及其电化学性能研究

利用改进的Hummers法制备氧化石墨烯(GO),以GO为碳源、Ni(NO_3)_2为镍源、尿素为沉淀剂,采用微波二甲基亚砜溶剂法一步成功合成α-Ni(OH)_2/还原氧化石墨烯(α-Ni(OH)_2/RGO)复合电极材料,研究了不同微波功率、不同GO与Ni(OH)_2质量比对复合材料性能的影响。采用X射线衍射和扫描电镜测试其结构、表面微观形貌;利用恒电流充放电技术对其电化学性能进行研究。结果表明:α-Ni(OH)_2在石墨烯片层上形核长大,当微波功率为600W,GO∶Ni(OH)_2=1∶6(质量比)时,0.2C放电比容量可以达到326.7mAh/g,从0.2C到5C,放电比容量仅下降了15.6%,显示了高的容量保持率和循环稳定性。     

水热温度对Ni(OH)_2/RGO复合材料结构及其电化学性能影响

以氧化石墨(GO)和硝酸镍为原料,采用水热法制备氢氧化镍/还原氧化石墨烯(Ni(OH)_2/RGO)复合材料,通过FT-IR光谱、X射线衍射仪和扫描电镜表征了材料的形貌和结构,并采用循环伏安法、恒流充放电和交流阻抗谱测试了复合材料的电化学性能。结果表明,当水热温度为100℃时,制备了具有α相与β相互嵌型的α/β-Ni(OH)_2/RGO复合材料。在电解液为6 mol/L的KOH溶液中,放电倍率0.2C时复合材料比容量高达388.6mAh/g,放电倍率为10C时,复合材料比容量为266.1mAh/g,比容量保持率为68.5%,显现出良好的电化学性能。     

Ni (OH)2-碳纳米管-还原氧化石墨烯复合材料的制备及电化学性能

利用简单易行的一步水热法制备了Ni（OH）₂-碳纳米管-还原氧化石墨烯（Ni（OH）₂-CNTs-RGO）三元复合材料,研究了不同水热反应温度对三元复合材料性能的影响。采用XRD、FTIR、Raman、X射线光电子能谱（XPS）、SEM及TEM对Ni（OH）₂-CNTs-RGO复合材料的结构和表面微观形貌进行表征。利用循环伏安（CV）、电化学交流阻抗（EIS）和恒电流充放电测试了复合电极材料的电化学性能。研究结果表明,当反应温度为120℃时,所制备的Ni（OH）₂-CNTs-RGO复合材料具有大的比表面积和三维网状结构,复合材料中六角形的β-Ni（OH）₂纳米片和CNTs均匀分散在RGO片层表面,有效阻止了RGO的团聚。Ni（OH）₂-CNTs-RGO复合电极材料在充电倍率为0.2 C时,放电比容量达到362.8 mAh/g,5 C时放电比容量为286.2 mAh/g,仍大于Ni（OH）₂在0.2 C时的放电比容量,表明CNTs与RGO的协同作用有效提高了电极材料的导电性和活性物质的利用率,最终提升了Ni（OH）₂-CNTs-RGO复合材料的倍率性能。     

水热法制备还原氧化石墨烯担载Ni(OH)_2纳米带复合材料及其电容特性

以氧化石墨烯溶液和硝酸镍为原料,采用一步水热法制备了Ni(OH)_2/还原氧化石墨烯(Ni(OH)_2@RGO)复合材料。在Ni(OH)_2/还原氧化石墨烯的研究中,两组分间的配比对复合物的形貌和电化学活性具有显著的影响。在最佳配比下(RGO含量26.7%),Ni(OH)2以纳米带形式担载于石墨烯片相互搭接成的三维网络结构中,从而可暴露更多的活性位点和有效比表面积,利于展现更好的电化学性能。该复合材料用作超级电容器电极材料时,展现了高的比电容(在1 A·g~(-1)下的比电容高达1 804 F·g~(-1)),良好的倍率性能(在25 A·g~(-1)下比电容保持率仍在46%以上),以及优异的循环稳定性(在2 A·g~(-1)下循环2 000次的电容保持率为90.3%)。     

滴加速率对TiO2/RGO复合材料结构和储钠性能的影响

以钛酸丁酯为前驱物,无水乙醇为溶剂,采用溶胶-凝胶法和热处理法制备了钠离子电池TiO_2/还原氧化石墨烯复合负极材料(TiO_2/RGO),研究了溶胶-凝胶法过程中反应物钛酸丁酯滴加速率对TiO_2/RGO复合材料形貌结构及储钠性能的影响。结果表明,TiO_2/RGO复合材料由锐钛矿相TiO_2和还原氧化石墨烯组成,TiO_2富集在RGO片层边缘。电化学测试结果表明,随着滴加速率的增大,首次放电比容量和库伦效率呈现先增大后减小的趋势;当滴加速率为1.0mL/min时,TiO_2/RGO复合材料具有良好的储钠性能,在1C(1C=20mA·g~(-1))倍率下首次放电比容量和库伦效率分别为140.14mAh·g~(-1)和27.92%,具有良好的循环和倍率性能。     

β-Ni(OH)_2/石墨烯复合纳米材料的制备及其电化学性能研究

以NaBH4为还原剂,采用成核晶化隔离法和氧化还原法相结合低温下制备了Ni(OH)_2/石墨烯纳米复合材料,并以此为电极研究了其电化学性能。实验发现:六方形片状结构的β-Ni(OH)_2成功地分散在石墨烯载体表面,石墨烯片层结构没有发生团聚及严重的堆垛现象,提高了电极的稳定性。当石墨烯与Ni(OH)_2的质量比为5∶5时,显示了最佳的电化学性能:在0~0.47V的电位窗口,1A/g的电流密度下,比电容高达922F/g。     

还原氧化石墨烯(RGO)/硅复合材料的制备及用作锂离子电池负极的电化学性能

利用天然鳞片石墨通过改进的Hummers法制备氧化石墨烯(GO),在碱性条件下通过超声波剥离、静电自组装、磁力搅拌和高温还原的方法合成了还原氧化石墨烯/硅(RGO/Si)复合材料。借助XRD、SEM、TEM、EDX能谱分析和比表面积分析等发现,Si颗粒均匀分布在RGO片层内。在室温下,以该复合材料作为锂离子电池负极,在不同电流密度下研究了其电化学性能。结果表明,RGO/Si复合材料(2∶1)首次循环的放电比容量为1 231 mAh/g,首次库仑效率高达90.9%,在20次循环后,可逆容量保持在452 mAh/g,库仑效率为99.2%。RGO/Si复合材料(1∶1)的RGO片层包覆Si颗粒最紧密,其复合结构最稳定,在高电流密度下容量保持率较高。     

钴掺杂纳米花瓣状氢氧化镍的制备及其电化学性能研究

采用水热法制备了钴掺杂的纳米花瓣状Ni(OH)2,讨论了钴掺杂量对产物形貌、结构和电化学性能的影响。结果表明,不同钴摩尔分数掺杂的样品都呈现α/β混合相花瓣微球,其比表面积均在280m2/g以上,远高于普通球形氢氧化镍(5~10m2/g)。电化学性能测试表明,钴添加剂显著提高了氢氧化镍高倍率放电容量和循环稳定性能,1.0C倍率时钴摩尔分数10%的样品放电容量可达430.1mAh/g(以纯氢氧化镍计),接近-αNi(OH)2的理论容量(480mAh/g),3.0C倍率时其放电容量(367.1mAh/g)仅比0.2C时的放电容量(406.9mAh/g)衰减9.8%。     

温度及搅拌速度对纳米氢氧化镍性能的影响

采用化学沉淀法制备出片状和棒状混合的纳米β-Ni（OH）_2,将纳米粉体以 8%比例掺入到球镍中制成复合电极,研究了反应温度和搅拌速度对纳米粉体结构、形貌及其复合电极电化学性能的影响,结果表明,反应温度升高,纳米颗粒粒径增大;搅拌速度提高,粒径减小;复合电极的放电比容量随反应温度和搅拌速度提高先增大后减小,当反应温度为 50℃、搅拌速度为 600 r/min时,相应的复合电极放电比容量最大,达到了 263.3 mAh/g,比纯球镍电极放电比容量（239.4 mAh/g）提高了约 10%。研究还显示,复合电极的放电比容量与其粉体的压实密度有直接对应关系,其放电比容量和放电平台均高于纯球镍电极。     

A study on the effect of nanosized tin oxide on the electrochemical performance of nanosized nickel hydroxide in alkali solution

The nickel hydroxide nanopowders mixed with SnO₂ nanoparticles as an additive in different proportions were prepared and characterised by X-ray diffraction (XRD), transmission electron microscope (TEM) and electrochemical measurement by cyclic voltammetry. XRD examination suggests that the composite Ni(OH)₂/SnO₂ has both the phases of α-Ni(OH)₂ and β-Ni(OH)₂ with SnO₂ nanoparticles. TEM images show the nanostructures of nickel hydroxide, SnO₂ and dispersion of SnO₂ nanoparticles on nickel hydroxide particles in the composite. The electrochemical studies revealed that the composite electrode has better redox reversibility and specific capacitance values compared to the pure Ni(OH)₂, α-Ni(OH)₂ and usual β-Ni(OH)₂ electrodes and it can be applied as a promising positive active material for alkaline rechargeable batteries.     

Preparation and electrochemical performance of nano-scale nickel hydroxide with different shapes

Platelet-like, flake-like, and needle-like nano-scale β-Ni(OH)₂ particles were prepared by coordination homogeneous precipitation method in this paper. X-ray diffraction (XRD), transmission electron microscopy (TEM) and infrared absorption spectra (IR) were used to characterize the microstructure and morphology of the products. The nano-scale Ni(OH)₂ composite electrodes were prepared by mixing 10 wt.% samples with spherical Ni(OH)₂ to carry out charge-discharge test. The results show that the nano-scale Ni(OH)₂ composite electrodes have higher discharge specific capacity, and the nickel hydroxide nanoneedles show a better adulteration performance than the others.     

A facile preparation of graphene/reduced graphene oxide/Ni(OH)2 two dimension nanocomposites for high performance supercapacitors

A Ni(OH)₂ composite with good electrochemical performances was prepared by a facile method. Ni(OH)₂ was homogeneously grown on the hydrophilic graphene/graphene oxide (G/GO) nanosheets, which can be prepared in large scale in my lab. Then G/GO/Ni(OH)₂ was reduced by L-Ascorbic acid to obtain G/RGO/Ni(OH)₂. Caused by the synergy effects among the components, the G/RGO/Ni(OH)₂ electrode showed good electrochemical properties. The G/RGO/Ni(OH)₂ electrode possessed a specific capacitance as high as 1510 F g⁻¹ at 2 A g⁻¹ and even 890 F g⁻¹ at 40 A g⁻¹. An asymmetric supercapacitor device consisting of G/RGO/Ni(OH)₂ and reduced graphene oxide (RGO) was installed and displayed a high energy density of 44.9 W h kg⁻¹ at the power energy density of 400.1 W kg⁻¹. It was verified that the G/GO nanosheets are ideal supporting material in supercapacitor.     

SiFe@C负极复合材料的结构及性能

以SiFe合金和沥青为原料,采用机械球磨和高温热解法制备了SiFe@C负极复合材料,并对SiFe及一系列不同热解温度下制备的SiFe@C复合材料进行对比研究。利用XRD、SEM、TEM、EDS和恒流充放电测试仪对SiFe@C复合材料的物相、颗粒形貌及电化学性能进行表征。结果表明,在850℃热解温度下制得的SiFe@C负极复合材料首次放电比容量达到1 376.25 mAh/g,首次库仑效率为86.35%,经过70次循环后放电比容量为940.33 mAh/g,库仑效率达到98.78%,容量保持率为76.32%,循环性能远高于SiFe和其他热解温度下的SiFe@C复合材料,而且具有良好的倍率性能。      

Electrochemical properties and controlled-synthesis of hierarchical β-Ni(OH)2 micro-flowers and hollow microspheres

β-Ni(OH)₂ hierarchical micro-flowers, hierarchical hollow microspheres and nanosheets were synthesized via a facile, single-step and selected-control hydrothermal method. Both hierarchical micro-flowers and hierarchical hollow microspheres were built from two-dimensional nanosheets with thickness of 50–100 nm. The as-obtained products were characterized by Brunauer–Emmett–Teller (BET) surface area analysis, X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FESEM). It was observed that marked morphological changes in β-Ni(OH)₂ depended on the initial concentrations of Ni²⁺ ions and glycine. A possible growth mechanism was proposed based on experimental results. In addition, the effect of morphology on the electrochemical properties was also investigated. Both hierarchical micro-flowers and hierarchical hollow microspheres exhibited enhanced specific capacity and high-rate discharge ability as compared with pure Ni(OH)₂ nanosheets. Investigations confirmed that hierarchical structures had a pronounced influence upon the electrochemical performance of nickel hydroxide.     

化学沉淀法制备电极用纳米β-Ni(OH)_2粉体材料

通过化学沉淀法成功制备了电极用纳米B-氢氧化镍粉体。用TEM及XRD时样品进行分析,结果表明,所得产物为球形或椭球形,粒径在2～20nm之间,平均粒径为10nm左右,晶型为β型的纳米晶粒。实验得出了制备纳米氢氧化镍粉体的温度、氨水浓度与pH值的最佳参数。     

Recovery and reuse of Ni(II) from rinsewater of electroplating industries

Discharge of nickel compounds, which may occur in both liquid and solid phases, can cause severe environmental problems. In this work, 'point of source' treatment strategy is followed and reduced the nickel content of rinsewater to about less than 1 mg L(-1) by ion-exchange method using a packed column involving batch recirculation mode of operation and to recovered Ni(II) content by desorption. The treated water could be recycled for rinsing operation. The nickel from resin is first precipitated as nickel hydroxide to synthesize positive active material and that was used in Nickel/Metal hydride cell. The performances in terms of electrochemical utilization of nickel hydroxide, specific capacity as a function of discharge current density and cycle life were examined and the nickel hydroxide electrode with 5% CaCO(3) addition, having 200 mAh g(-1) specific capacity, could be subjected to charge/discharge cycles at C/5 rate for more than 200 cycles without the capacity fading.