花状Ni(OH)2的制备及其电化学性能研究

以NiCl₂·6H₂O和NH₃·H₂O为原料,采用简单的水热法,借助表面活性剂CTAB成功合成了β-Ni(OH)₂。研究表明,该材料具有以纳米片相互穿插构成的花状分层微米球结构,比表面积高达45 m²?g^-1。电化学测试表明材料具有良好的电化学性能,在3 A?g^-1的充放电电流密度下,Ni(OH)₂的比容量达到505 C?g^-1,在超级电容器领域具有良好的应用前景。     

Ni(OH)2基复合材料的制备及其在超级电容器方面的进展

超级电容器是一种很有前途的电化学储能系统,合理设计和构建高比电容材料,对于超级电容器技术的发展至关重要。具有高化学稳定性、高理论容量、高速率性能等优点的Ni(OH)₂材料在近年引起了广泛关注。然而,其实际测试性能(尤其是速率能力)通常远低于理论值,这可能归因于活性位点的可接近性受限、反应动力学缓慢或电子转移能力不足,严重阻碍了其的实际应用。研究人员试图打破Ni(OH)₂固有结构的限制,探索提升其性能的方法。本文综述了Ni(OH)₂及其复合材料的制备方法：溶剂热法、电沉积法、化学沉积法、微波水热合成法等,并将其应用于超级电容器方面的进展进行了总结。此外,本文指出了Ni(OH)₂及其复合材料应用于超级电容器所面临的挑战和前景,以满足现代社会的应用需求。     

脲酶诱发合成纳米Ni(OH)2及其电化学性能

采用脲酶催化尿素水解,诱发均匀沉淀制备了纳米Ni(OH)2,经XRD测试为-βNi(OH)2。TEM测试显示,向反应体系中加入表面活性剂可将Ni(OH)2的粒径由50 nm降为10 nm。恒流充放电和循环伏安实验表明,纳米Ni(OH)2比微米级Ni(OH)2具有更优的电化学性能,放电容量提高11%左右。其原因在于脲酶的高效催化性使均匀沉淀在很短时间内即被诱发,生成的纳米Ni(OH)2晶体内部缺陷多,有更大的扩散系数(约是微米级Ni(OH)2的3倍),降低了电极的反应内阻,从而有效地改善了质子的传递和扩散。     

Ni(OH)2/ACMS复合电极材料的合成及其超电容性能研究

以可溶性淀粉为原料,通过水热法和高温碳化得到活性炭微球(ACMS),然后与Ni(Ac)_2·4H_2O、LiOH溶液反应,得到Ni(OH)_2/ACMS复合电极材料。测试结果表明,最终产物具有球状规则外观,Ni(OH)_2均匀分布在其表面,XRD测试表明Ni(OH)_2晶型结构未发生改变。Ni(OH)_2/ACMS复合电极材料具有良好的电化学性能,首次放电比容量为223.0 F·g~(-1),在0.5A·g~(-1)测试电流密度条件下,充放电循环200次后的比容量保持率为90.0%,说明复合材料具有较优异的循环稳定性。     

Ni(OH)2催化剂催化氧化醇的研究

采用共沉淀法制备了Ni(OH)2催化剂,该催化剂对温和条件下以分子氧为氧化剂的苯甲醇及烯丙醇类的氧化反应有十分理想的催化效果,并且完全可以通过简单的处理回收利用.     

搅拌型式对球形Ni(OH)2物理性质的影响

在不同搅拌方式下用控制结晶方法制备了球形Ni(OH)2,用扫描电镜、BET比表面分析及激光粒度分析方法对制得的Ni(OH)2进行了表征.研究表明:下叶轮为透平桨的搅拌系统使产品的振实密度随搅拌强度呈稳定的近线性的正相关,得到粒度呈正态分布和堆积密度大的产品,比表面积及平均粒度随输入能量的改变而稳定地变化;而推进式桨则使振实密度、比表面积及平均粒度对搅拌强度的变化敏感而不规律,制备的产品粒度呈非正态分布,堆积密度小.可见下叶轮应用透平桨使流体对流方式更加平稳可控,在同样的能耗条件下得到的产品性能比推进式桨更好.     

Ni(OH)_2/C作为锂离子电池负极材料的研究

采用控制沉淀法制备Ni(OH)2/C复合材料,用XRD和SEM表征材料的结构和形貌。首次将材料用于锂离子电池,通过充放电测试、循环伏安法和交流阻抗实验研究其嵌/脱锂行为和电化学性能。结果表明,Ni(OH)2/C复合材料具有嵌/脱锂性能,首次可逆比容量达到992mAh/g,20次循环后的可逆比容量为211mAh/g,循环效率为95.6%,高于Ni(OH)2材料(128mAh/g和94.4%),循环性能的改善可归因于掺杂石墨后,使电极电导率明显提高,同时减缓体积效应。     

高比容量镍氢电池的制备及电化学性能

Cylindrical nickel metal hydride （Ni-MH） battery with high specific volume capacity was prepared by using the oxyhydroxide Ni（OH）2 and AB5 type hydrogen storage alloy and adjusting the designing parameters of positive and negative electrodes. The oxyhydroxide Ni（OH）2 was synthesized by oxidizing spherical β-Ni（OH）2 with chemical method. The X-ray diffraction （XRD） patterns and the Fourier transform infrared （PT-IR） spectra indicated that 7-NiOOH was formed on the oxyhydroxide Ni（OH）2 powders, and some H2O molecules were inserted into their crystal lattice spacing. The battery capacity could not be improved when the oxyhydroxide Ni（OH）2 sample was directly used as the positive active materials. However, based on the conductance and residual capacity of the oxyhydroxide Ni（OH）2 powders, AA size Ni-MH battery with 2560 mA.h capacity and 407 W·h·L^-1 specific volume energy at 0.2C was obtained by using the commercial spherical β-Ni（OH）2 and AB5-type hydrogen-storage alloy powders as the active materials when 10% mass amount of the oxyhydroxide Ni（OH）2 with 2.50 valence was added to the positive active materials and subsequently the battery designing parameters were adjusted as well. The as-prepared battery showed 70% initial capacity after 80 cycles at 0.5C. The possibility for adjusting the capacity ratio of positive and negative electrodes from 1 ： 1.35 to 1 ： 1.22 was demonstrated preliminarily. It is considered the as-prepared battery can meet the requirement of some special portable electrical instruments.     

PVA/PEG/Mg(OH)2复合材料的热塑加工性能

采用熔融共混法,制备了聚乙烯醇（PVA）／聚乙二醇（PEG）／氢氧化镁[Mg（OH）2]复合材料,利用转矩流变仪考察了复合材料的熔融加工性能;利用差示扫描量热仪（DSC）、热重分析仪（TG）考察了复合材料的热性能;采用注塑成型工艺制备了复合材料标准样条,利用万能电子拉力机、扫描电子显微镜（SEM）等对复合材料力学性能及微观形貌进行了测试分析。结果表明：当复合材料体系配比为PVA／PEG／Mg（OH）2为100／20／8（质量比）时,复合材料能形成良好的复合体系,具有良好的热塑加工性能及力学性能（拉伸强度为33．42MPa,断裂伸长率为224．3％）。     

高电化性能球型氢氧化亚镍的研制

叙述了球型氢氧化亚氧化亚镍的制备及电化性能测定的情况。结果表明：球型与普通型氢氧化亚镍相比,改善了粉末的流动性,提高了充填密度和活性利用率,是制备高能镍电极的理想材料。     

非晶态氢氧化镍复合碳纳米管电极材料的电化学性能

采用快速冷冻化学共沉淀法制备非晶态Ni(OH)2粉体,将其作为电化学活性物质复合碳纳米管合成镍电极材料,研究了其电化学性能. 结果表明,加入碳纳米管有效减少了镍电极的电荷转移电阻,增大了电极反应过程的质子扩散系数. 复合0.5%(w)碳纳米管合成的非晶态氢氧化镍电极材料在1 C充放电制度下,放电终止电压为1.0 V时,其放电比容量高达336.5 mA×h/g,放电中值电压为1.251 V,充放电循环30次,放电比容量保持率为96.74%,表现出较好的高倍率充放电性能.     

冷冻-解冻循环及气体吹扫对质子交换膜燃料电池的影响

1 INTRODUCTION Polymer electrolyte membrane fuel cell (PEMFC) is promising for its advantages of simple structure, relatively low operating temperature, high efficiency, convenient maintenance and rapid startup. PEMFCs can be used in many potential fields, especially as power sources for vehicles to replace normal combus- tion engine[1,2]. However, the availability of fuel cell vehicles is not quite close to us so far, although both concept design and demonstration have proved its feas…     

Polymer membranes for high temperature proton exchange membrane fuel cell: Recent advances and challenges

Proton-exchange membrane fuel cells (PEMFCs) are considered to be a promising technology for efficient power generation in the 21st century. Currently, high temperature proton exchange membrane fuel cells (HT-PEMFC) offer several advantages, such as high proton conductivity, low permeability to fuel, low electro-osmotic drag coefficient, good chemical/thermal stability, good mechanical properties and low cost. Owing to the aforementioned features, high temperature proton exchange membrane fuel cells have been utilized more widely compared to low temperature proton exchange membrane fuel cells, which contain certain limitations, such as carbon monoxide poisoning, heat management, water leaching, etc. This review examines the inspiration for HT-PEMFC development, the technological constraints, and recent advances. Various classes of polymers, such as sulfonated hydrocarbon polymers, acid-base polymers and blend polymers, have been analyzed to fulfill the key requirements of high temperature operation of proton exchange membrane fuel cells (PEMFC). The effect of inorganic additives on the performance of HT-PEMFC has been scrutinized. A detailed discussion of the synthesis of polymer, membrane fabrication and physicochemical characterizations is provided. The proton conductivity and cell performance of the polymeric membranes can be improved by high temperature treatment. The mechanical and water retention properties have shown significant improvement., However, there is scope for further research from the perspective of achieving improvements in certain areas, such as optimizing the thermal and chemical stability of the polymer, acid management, and the integral interface between the electrode and membrane.