溶胶-凝胶法制备NiO薄膜及影响因素

NiO薄膜可作为电致变色材料、电容器材料、气敏材料、电极材料等而受到人们关注。溶胶凝胶法(sol-gel)制备NiO薄膜材料因其无可比拟的优点成为研究的热点。简要介绍了sol-gel法制备NiO薄膜的特点及基本原理,重点论述了成膜方式、溶胶性质以及热处理条件对薄膜形貌、结构和电化学性能的影响,展望了NiO薄膜材料的发展方向,旨在为NiO薄膜材料的研究和开发提供一些借鉴和启发。     

YSZ修饰的花瓣状氧化镍粉体的制备及其电性能表征

采用均匀沉淀法制备了花瓣状NiO粉体,对该花瓣状NiO进行YSZ(Y2O3稳定的ZrO2)修饰,以提高花瓣状NiO粉体的耐高温性,进而构建纳微结构的阳极。采用离子浸渍法制备了YSZ修饰的花瓣状NiO粉体(NiO-YSZ粉体),通过热重--差热分析、X射线衍射、扫描电子显微镜、能谱仪、透射电子显微镜等分析手段对该粉体的热性能、物相、微观形貌、晶粒大小等进行了表征。分别采用商业NiO(颗粒状)粉体和自制花瓣状NiO-YSZ粉体制备了电解质支撑型单电池的阳极,该单电池的组成为NiO+8YSZ‖8YSZ‖LSM+8YSZ,并测试了其电化学性能。结果表明:采用花瓣状NiO-YSZ粉体制备的阳极单电池在操作温度为在750、800和850℃下最大功率密度分别为0.094、0.151和0.376W/cm2,且相对应的电极极化阻抗分别为2.496、1.589和0.814Ω·cm2;而采用商业NiO制备的阳极的单电池在操作温度为在750、800和850℃下的最大功率密度分别为0.024、0.072和0.149W/cm2,且相对应的电极极化阻抗分别为4.265、2.306和1.688Ω·cm2。     

轧膜成型法制备燃料电池NiO/YSZ多孔阳极材料的研究

以水基轧膜工艺制备出了不同粘结剂含量的NiO/氧化钇稳定氧化锆(YSZ)固体氧化物燃料电池多孔阳极材料。研究了粘结剂含量和制备工艺条件等对多孔阳极微结构和性能的影响。实验结果表明:轧膜坯体的烧结温度对NiO/YSZ阳极烧结体的孔隙率有着决定的影响;为获得较高孔隙率和一定孔径分布的阳极烧结体,轧膜生坯的烧结温度应不超过1450℃。此外,粘结剂含量对轧膜生坯的烧结行为及烧结体的性能也有明显的影响,在相同的烧结温度下,高粘结剂含量阳极烧结体的孔隙率和孔径范围明显高于低粘结剂含量的烧结体,其中,粘接剂含量5%的生坯烧结后得到的NiO/YSZ阳极材料具有较好的综合性能;此外,NiO/YSZ材料还原后所得Ni/YSZ金属陶瓷多孔阳极的电导率随试样烧结温度的升高而升高,随测试温度升高而降低,800℃下的其电导率可达150S/cm。     

氧化镍基锂离子电池负极材料研究进展

为了解决NiO体积膨胀(95%)、充放电过程中活性材料严重聚集粉碎以及导电性差等问题,进一步促进锂离子电池的商业化应用进程,对NiO材料的选择和结构改性进行了总结,并论述具有代表性的NiO复合材料的制备方法和电化学性能,最后分析了NiO负极材料存在的问题,并对其发展趋势进行了展望。     

焦粉的高附加值利用

评述了煤基焦粉在生产合成气、制备活性炭、焦炭以及作为燃料和锂离子电池阳极材料等方面的研究现状,介绍了纳米炭材料的合成过程及其电化学性能。指出,煤基焦粉是制备锂离子电池阳极材料的理想碳源之一,从焦粉制备锂电池阳极材料是实现焦粉高附加值利用的有效途经。     

熔盐电解NiO制备Ni的机理探讨

通过固态NiO在CaCl_2-NaCl熔盐中直接电化学还原制备Ni的电解产物随时间变化分析,石墨阳极破损研究以及对NiO低于理论分解电压的槽电压分解现象的解释,探讨了熔盐电解NiO制备Ni的电解反应机理。认为电解反应基本服从氧离子化机理,且NiO阴极片在低于理论分解电压的槽电压下,电化学还原反应和热还原反应同时发生。     

铜电积用惰性阳极材料的研究现状

根据基体材料的不同,综述了国内外铜电积用惰性阳极材料的研究现状,重点阐述了铅及铅合金阳极、铅基涂层阳极、钛基涂层阳极等的制备、电化学性能及优缺点。     

两步法原位制备NiO/N-RGO复合材料及其电化学性能

采用两步法制备了氧化镍/掺氮石墨烯(NiO/N-RGO)复合材料,通过X射线粉末衍射(XRD)、场发射扫描电子显微镜(FESEM)、拉曼光谱(Raman)和X射线光电子能谱(XPS)对样品的形貌和结构进行表征。利用循环伏安、电化学交流阻抗和恒电流充放电测试了复合电极材料的电化学性能。结果表明,线状NiO均匀地负载在N-RGO片层上,呈三维网络结构。NiO/N-RGO复合材料呈现出良好的倍率性能和循环稳定性能。     

NiO薄膜材料的制备及其电化学电容性能

以镍箔为基底,在Ni(NO3)2溶液中,用电沉积法制备Ni(OH)2薄膜,进行热处理后转化为NiO薄膜电极材料。采用X射线衍射(XRD)和场发射扫描电子显微镜(FESEM)表征产物的结构和形貌。用循环伏安法、恒电流充放电等电化学方法系统研究所制样品的电化学性能。研究结果表明,在Ni(NO3)2溶液浓度为0.08 mol.L-1,电压为-0.9 V条件下沉积,并经过250℃热处理制备的NiO薄膜材料属于立方结构,表现出良好的电化学性能,其单电极比电容值达1220 F.g-1。     

直接甲醇燃料电池阳极催化剂的制备

直接甲醇燃料电池（DMFC）阳极催化剂是DMFC的关键材料之一,其电化学活性的大小对燃料电池的输出性能及成本起着关键作用。不同催化剂的制备技术决定了催化剂电化学活性的高低。介绍了DMFC阳极催化剂的几种制备方法,并对这些方法进行了评述,对制备DMFC阳极催化剂具有很好的参考价值。     

Electrochemical Performance of a Ni and YSZ Composite Synthesised by Ultrasonic Spray Pyrolysis as an Anode for SOFCs

The electrochemical performance of an anode material for a solid oxide fuel cell (SOFC) depends highly on microstructure in addition to composition. In this study, a NiO–yttria‐stabilised zirconia (NiO–YSZ) composite with a highly dispersed microstructure and large pore volume/surface area has been synthesised by ultrasonic spray pyrolysis (USP) and its electrochemical characteristics has been investigated. For comparison, the electrochemical performance of a conventional NiO–YSZ is also evaluated. The power density of the zirconia electrolyte‐supported SOFC with the synthesised anode is ∼392 mW cm^–2 at 900 °C and that of the SOFC with the conventional NiO–YSZ anode is ∼315 mW cm^–2. The improvement is ∼24%. This result demonstrates that the synthesised NiO–YSZ is a potential alternative anode material for SOFCs fabricated with a zirconia solid electrolyte.     

Improvement of Ni-Cermet performance of protonic ceramic fuel cells by catalyst

Generally, the NiO composite anode becomes porous after reduction. To infiltrate additional catalysts such as Pd into the NiO-composite anode before reducing NiO to Ni, a porous NiO composite anode for protonic ceramic fuel cells (PCFCs) was fabricated in this study. The porous NiO composite was fabricated by adding graphite as a pore former along with CuO as a sintering agent. The addition of graphite increased the porosity of the NiO composite anode but resulted in poor sinterability, which was addressed by adding CuO as a sintering agent to the NiO composite anode. The Pd catalyst was added to the NiO-composite anode before reducing NiO to Ni. The composite anode for PCFC with three components, namely Ni, protonic ceramics, and a Pd catalyst, was obtained by reducing NiO to Ni during the measurement. The addition of the Pd catalyst improved the anode performance in methane fuel and hydrogen fuel by enhancing the catalytic activity for the electrochemical reaction on the surface.     

Influence of doctor blade gap on the properties of tape cast NiO/YSZ anode supports for solid oxide fuel cells

In this study, various tape cast NiO/YSZ anode support layers with similar geometric properties are fabricated by varying the doctor blade from 100?µm to 200?µm with an increment of 25?µm. The mechanical properties of the anode support layers are investigated by three point bending tests of 30 samples for each doctor blade gap. The reliability curves of the flexural strength data are also obtained via two-parameter Weibull distribution method. The effects of the doctor blade gap on the microstructure and the electrochemical performance of the anode support layers are determined via SEM investigations and single cell performance-impedance tests, respectively. The apparent porosities of the samples are also measured by Archimedes’ principle. The results indicate that the doctor blade gap or the resultant tape thickness influences the microstructure of tape cast NiO/YSZ anode supports significantly, yielding different mechanical and electrochemical characteristics. At a reliability level of 70%, the highest flexural strength of 110.20?MPa is obtained from the anode support layer with a doctor blade gap of 175?µm and the 16?cm² active area cell with this anode support layer also exhibits the highest peak performance of 0.483?W/cm² at an operating temperature of 800?°C. Thus, a doctor blade gap of 175?µm is found to have such a microstructure that provides not only better mechanical strength but also higher electrochemical performance.     

Hollow microspheres of NiO as anode materials for lithium-ion batteries

NiO hollow spheres are prepared by heating the NiCl₂/resorcinol-formaldehyde (RF) gel in argon at 700 °C for 2 h, and subsequently in oxygen at 700 °C for 2 h. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) are employed to characterize the structure and morphology of the as-prepared NiO hollow spheres. These hollow spheres have a diameter of about 2 μm, which are composed of NiO particles of about 200 nm. The electrochemical properties of these NiO hollow spheres are investigated to determine the reversible capacity and cycling performance as anode materials for lithium-ion batteries, and the advantages of their hollow spherical morphology to the electrochemical performance are discussed.     

Effect of the reactive surface area of proton-conducting NiBa0.8Sr0.2Ce0.6Zr0.2Y0.2O3-δ anodes on cell performance

To determine the optimal combination of NiO and Ba_0.8Sr_0.2Ce_0.6Zr_0.2Y_0.2O_3-δ (BSCZY) for fabricating anode materials, Ni-BSCZY samples were prepared using the solid state reaction process. The porous structure of anode substrates not only provides mechanical strength to the fuel cells to enable fuel gases to flow to the electrolyte membrane but also creates an excess surface area on which to form a larger triple-phase boundary when NiO is added to the anode sample. The effect of NiO content on the microstructures, surface area, and electric conductivity of these Ni-BSCZY (NiO55-BSCZY, NiO60-BSCZY, and NiO65-BSCZY) anode materials were systematically investigated using X-ray diffraction, scanning electron microscopy, an analytic technique based on the Brunauer–Emmett–Teller surface area theory, and four-probe conductivity analysis. In addition, three anode-supported cells containing identical electrolytes but various combinations of NiO and BSCZY anode materials were fabricated and used for performance and electrochemical impedance measurement. The results revealed that the reactive surface area of the anode in contact with the electrolyte plays a crucial role in total cell performance. The cell containing the anode material (NiO60-BSCZY) with the highest surface area of 6.91 m² g⁻¹ and the lowest total resistance of 2.19 Ω cm² exhibited the highest power density of 169.2 mW cm⁻² at 800 °C.     

Nanosheets based mesoporous NiO microspherical structures via facile and template-free method for high performance supercapacitors

A novel template-free method to synthesize NiO microstructures is reported and the electrochemical properties of the fabricated microstructures are evaluated. Applying hexamethylenetetramine hydrolysis under a refluxing condition for 2 h, α-Ni(OH)₂ microstructures were synthesized, subsequent calcination at 300 °C yielded NiO microstructures that retained the morphologies of their predecessors. The fabricated NiO microstructures had high specific surface area, large pore volume, and narrow pore size distribution making them ideal candidates for supercapacitor applications. The NiO microstructures have the high specific capacitance and displayed a good retention for more than 1000 cycles in a cycling test. The results suggest that NiO microstructures are a promising supercapacitor electrode material.     

Low Temperature Electrode Materials Synthesized by Citrate Precursor Method for Solid Oxide Fuel Cells

Homogeneous nanocrystalline NiO–Ce_0.9Ln_0.1O_2–δ (Ln = La, Sm, Gd, and Pr) composite anode and nanocrystalline Ce_0.9Gd_0.1O_2–δ electrolyte material have been successfully synthesized by citrate precursor method. LSCF has been synthesized by conventional solid state method and used as cathode material in our studies. The synthesized powders have been characterized by powder X‐ray diffraction, microscopy, and surface area studies. The average crystallite size of the anode materials has been found to be in the range of 5–15 nm by HRTEM. Highly dense electrolyte and porous electrode materials have been observed by FESEM and confirmed by BET surface area studies. Three cells have been fabricated successfully. Based on the performance of the three cells containing three different anode materials we have achieved better electrochemical characteristics in Ni–GDC with maximum power density of 302 mW cm^–2 and open circuit voltage of 1.012 V at 500 °C. The difference in the performance of the cells containing Ni–GDC as compared to Ni–LDC and Ni–SDC anode is due to changes in the microstructure and crystallite size of anode which affects the electrochemical performance of the cells. The performances of all the cells containing nanocomposite powders are suitable anode materials for low temperature SOFCs.     

Synthesis and characterization of graphene–nickel oxide nanostructures for fast charge–discharge application

Graphene–metal oxide composites as anode materials for Li-ion batteries have been investigated extensively, but these attempts are mostly limited to moderate rate charge–discharge applications. Here, graphene–nickel oxide nanostructures have been synthesised using a controlled hydrothermal method, which enabled in situ formation of NiO with a coralloid nanostructure on graphene. Graphene/NiO (20%), graphene/NiO (50%) and pure NiO show stable discharge capacities of 185 mAh/g at 20 C (1 C = 300 mA/g), 450 mAh/g at 1 C, and 400 mAh/g at 1 C, respectively. High rate capability and good stability in prolonged charge–discharge cycling permit the application of the material in fast charging batteries for upcoming electric vehicles. To the best of our knowledge such fast rate performance of graphene/metal oxide composite as anode and such stability for pure NiO as anode have not been reported previously.     

One-step synthesis of Li-doped NiO as high-performance anode material for lithium ion batteries

The poor electronic conductivity and huge volume expansion of NiO are the vital barriers when used as anode for lithium ion batteries. In order to solve above issues, Li-doped NiO are prepared by a facile one-step ultrasonic spray pyrolysis method. The effects of Li doping on the morphology, structure and chemical composition of the Li-doped NiO powders are extensively studied. When used as lithium ion batteries anode, it is demonstrated that the doping of Li has significant positive effect on improving the electrochemical performance. After 100 cycles at 400 mA g⁻¹, The Li-doped NiO samples deliver a discharge capacity of 907 mAh g⁻¹, much more than that of un-doped sample (736 mAh g⁻¹). The improved electrochemical performances can be ascribed to the improved p-type conductivity and lower impedance, which are confirmed by Rietveld refinement, X-ray photoelectron spectroscopy and electron impedance spectroscopy.     

Improvement of cycling performance of Li1.1Mn1.9O4 at 60 °C by NiO addition for Li-ion secondary batteries

We report on electrochemical properties of NiO-blended spinel Li_1.1Mn_1.9O₄ at elevated temperature (60 °C). Thus, we employed two kinds of NiO powders, those are, larger particle size (>10 μm) and submicron-sized NiO powders obtained by a ball-milling. These NiO powders were blended to the spinel Li_1.1Mn_1.9O₄ as an additive for fabrication of cathode. The resulting discharge capacity for the larger NiO particle-blended Li_1.1Mn_1.9O₄ had similar electrochemical properties to the bare Li_1.1Mn_1.9O₄. On the other hand, submicron-sized NiO-blended Li_1.1Mn_1.9O₄ brought about slightly increased capacity and excellent capacity retention, maintaining its initial capacity of 99.2% at 25 °C and 94% at 60 °C when Li metal was employed as the anode. In Li-ion cell using graphite as the anode, the capacity retention was of about 80% during cycling at 60 °C, whereas C/Li_1.1Mn_1.9O₄ cell retained around 68% of its initial capacity. Such improved properties would be ascribed to the HF scavenging into the electrolyte by presence of the submicron-sized NiO particles in Li_1.1Mn_1.9O₄ cathode.