碳纳米管(CNT)储氢特性研究

碳纳米管 (CNT)因被认为可能是氢能的主要载体而备受关注 ,但近几年来的文献报道不尽一致。文中主要从碳纳米管的制备、结构、理论计算、气态储氢、电化学储氢方面 ,对碳纳米管在储氢领域的研究工作进行分析和讨论。大量研究工作表明 :碳纳米管具有储氢的理想结构 ,它的储氢特性与制备工艺、测试条件、计算方法等密切相关 ,大比表面积、大直径、表面活化和搀杂后的碳纳米管具有好的储氢性能 ,定向多壁碳纳米管具有较好的电化学性能     

贮氢合金的应用研究进展

本文概括了新型功能材料——贮氢材料的发展状况和应用研究进展,重点综述了稀土储氢合金性能改善方面的最新成果和用于二次电池的贮氢材料的状况。     

Effects of alloying side B on Ti-based AB2 hydrogen storage alloys

Ti-based AB2-type hydrogen storage alloys are a group of promising materials, which will probably replace the prevalent rare earth-based AB5-type alloys and be adopted as the main cathode materials of nickelmetal hydride (Ni-MH) batteries in the near future. Alloying in side B is a major way to improve the performance of Ti-based AB2-type alloys. Based on recent studies, the effects of alloying elements in side B upon the performance of Ti-based AB2-type hydrogen storage alloys are systematically reviewed here. These performance sare divided into two categories, namely PCI characteristics, including hydrogen storage capacity (HSC), plateau pressure (PP), pressure hysteresis (PH) and pressure plateau sloping (PPS), and electrochemical properties, including discharge capacity (DC), activation property ( AP), cycling stability (CS) and high-rate dischargeability (HRD). Furthermore, the existing problems in these investigations and some suggestions for future research are proposed.     

An Investigation on Hydrogen Storage Kinetics of the Nanocrystalline and Amorphous LaMg_(12)-type Alloys Synthesized by Mechanical Milling

Nanocrystalline and amorphous LaMg_(12)-type LaMg_(11)Ni + x wt% Ni(x = 100, 200) alloys were synthesized by mechanical milling. Effects of Ni content and milling time on the gaseous and electrochemical hydrogen storage kinetics of as-milled alloys were investigated systematically. The electrochemical hydrogen storage properties of the as-milled alloys were tested by an automatic galvanostatic system. And the gaseous hydrogen storage properties were investigated by Sievert apparatus and a differential scanning calorimeter(DSC) connected with a H_2 detector. Hydrogen desorption activation energy of alloy hydrides was estimated by using Arrhenius and Kissinger methods. It is found that the increase of Ni content significantly improves the gaseous and electrochemical hydrogen storage kinetic performances of as-milled alloys. Furthermore, as ball milling time changes, the maximum of both high rate discharge ability(HRD) and the gaseous hydriding rate of as-milled alloys can be obtained. But the hydrogen desorption kinetics of alloys always increases with the extending of milling time. Moreover, the improved gaseous hydrogen storage kinetics of alloys are ascribed to a decrease in the hydrogen desorption activation energy caused by increasing Ni content and milling time.     

Application of thermal electrochemical equation to metal-hydride half-cell system

1 INTRODUCTIONNickel-metal hydride ( Ni/ MH) battery be-came the principal power of electronic vehicle be-cause of its excellent characteristics such as highenergy density , high power , no memory effect ,long service life and wide temperature perform-ance . The hydrogen storage alloy is the key mate-rial of Ni/ MH dynamical battery , a mass of re-search work such as the technique of preparation,the performance of thermodynamics , kinetics andelectrochemistry were accomplished in recenty…     

稀土-镁-镍基贮氢合金的研究进展

综述了近几年稀土-镁-镍基贮氢合金电极材料相结构与电化学性能等方面的研究进展。介绍了改善合金电化学性能的方法,包括合金组成的改进、热处理、表面处理、制备复合合金等方法。讨论了稀土-镁-镍基贮氢合金研究中的几个重要问题以及发展方向。     

硼对稀土系AB5型贮氢合金电化学容量及循环寿命的影响

为了提高低钴AB5型贮氢合金的电化学循环稳定性，在MmNi3．8Co0.4Mn0.6Al0．2贮氢合金中加微量的硼．用真空快淬工艺制备了稀土系低钴AB5型MmNi3．8Co0．4Mn0．6Al0．2Bx(x=0，0．1，0．2，0．3，0．4)贮氢合金，分析测试了铸态及快淬态合金的电化学性能及微观结构，研究了硼对铸态及快淬态合金电化学容量及循环寿命的影响．结果表明，硼使铸态及快淬态MmNi3.8Co0.4Mn0．6Al0．2贮氢合金的电化学容量不同程度地降低，但使电化学循环稳定性大幅度提高．硼对电化学性能的影响主要是促进非晶相的形成．     

An Investigation on Hydrogen Storage Kinetics of the Nanocrystalline and Amorphous LaMg<Subscript>12</Subscript>-type Alloys Synthesized by Mechanical Milling

Nanocrystalline and amorphous LaMg₁₂-type LaMg₁₁Ni + x wt% Ni (x = 100, 200) alloys were synthesized by mechanical milling. Effects of Ni content and milling time on the gaseous and electrochemical hydrogen storage kinetics of as-milled alloys were investigated systematically. The electrochemical hydrogen storage properties of the as-milled alloys were tested by an automatic galvanostatic system. And the gaseous hydrogen storage properties were investigated by Sievert apparatus and a differential scanning calorimeter (DSC) connected with a H₂ detector. Hydrogen desorption activation energy of alloy hydrides was estimated by using Arrhenius and Kissinger methods. It is found that the increase of Ni content significantly improves the gaseous and electrochemical hydrogen storage kinetic performances of as-milled alloys. Furthermore, as ball milling time changes, the maximum of both high rate discharge ability (HRD) and the gaseous hydriding rate of as-milled alloys can be obtained. But the hydrogen desorption kinetics of alloys always increases with the extending of milling time. Moreover, the improved gaseous hydrogen storage kinetics of alloys are ascribed to a decrease in the hydrogen desorption activation energy caused by increasing Ni content and milling time.     

石墨烯与碳纳米管氢吸附性能的分子模拟

在293.15 K、101.30 kPa的条件下,测定了氢气在石墨烯、单壁碳纳米管和多壁碳纳米管中的储氢密度,对比了同等条件下采用不同力场计算得到的数据,筛选了3种碳材料的最佳计算力场。在此基础上,进一步计算了3种碳材料在0~1 000.00 kPa、77.00~573.15 K条件下的储氢密度。结果表明,Dreiding力场是计算石墨烯吸附储氢密度的最佳力场,Universal力场是计算碳纳米管吸附储氢密度的最佳力场;在给定条件下,3种材料吸附储氢能力强弱排序为石墨烯>单壁碳纳米管>多壁碳纳米管,储氢能力与材料的比表面积及其与氢气的弱结合力紧密相关。该研究结果可为分子模拟碳材料吸附储氢和储氢材料设计提供数据和理论支撑。     

钕掺杂钛酸钡陶瓷材料的制备及电阻-温度依存性的研究

讨论了稀土元素钕(Nd)对钛酸钡陶瓷材料的微观结构和介电性能的影响,以BaCO3、Nd2O3和TiO2为原材料采用固相法贮备了掺杂钕的BaCO3、TiO2纳米粉体,并经高温烧结后得到(Ba1-xNdx)Ti1-x/4O3基片,并对其进行测试,研究了钕掺杂对钛酸钡陶瓷电阻-温度依存性.     

Electrochemical properties and structure of MlNi_(5-x)Sn_x system

The electrochemical properties and structure of M1Ni5-xSnx(x=0-0.5) hydrogen storage alloys were investigated by pressure-composition isotherms, electrochemical measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and atomic parameters. With a small amount of tin substitution, the cycle life increases by 52% (0.5C) and 42% (1.0C), but maximum discharge capacity decreases only by 3.0% and 3.5%, respectively. The cycle life is obviously improved by the low volume expansion and the formed SnO2 surface layers upon electrochemical cycling. The substitution of Ni by Sn leads to an increase of the unit cell volume and charge-discharge cycle life and decrease of the plateau pressure, hysteresis and the hydrogen storage capacity. The standard enthalpy of hydride formation decreases with increasing tin substitution. The main factor that influences the standard enthalpy of the hydriding reaction is the number of the outer orbit electrons and not the atomic size factor.     

Effects of dispersant on performance of Ni-Zn batteries

A new additive of sodium hexametaphosphate (SHMP) was introduced to the paste of zinc electrode, with the purpose of preventing the zinc active materials from agglomerating and improving the stability of batteries. The properties of the zinc electrodes were characterized by scanning electron microscopy (SEM), constant current charge/discharge measurement, self-discharge test and hydrogen collection experiment. The photographs of zinc electrode show that SHMP can significantly break up the agglomeration, uniformize the particle distribution and increase the surface area, which are advantageous to improve the electrochemical performance of zinc electrode. The experimental battery shows a 97 times cycling life and a 30.2% remaining capacity after 4 d storage. The hydrogen collection experimental results indicate that the SHMP can decrease the ratio of hydrogen evolution. Therefore, the corrosion of zinc electrode is suppressed and the charge/discharge efficiency is enhanced.     

镁基储氢材料的研究进展

镁基储氢材料以吸氢量大、资源丰富、价格低廉、质量轻和无污染而被认为是最有发展前途的固态储氢材料之一.本文从镁基储氢材料的研究历史及现状出发.对其分类及制备、研究进展等进行了综述,并对其广阔的发展前景进行了展望.     

贮氢材料研究进展

氢是一种清洁的绿色能源，其应用研究受到了广泛的关注。氢能的利用可以保护环境、减少污染、充分发挥能源利用率。本文概述了贮氢材料的种类及其最新的研究进展，介绍了贮氢材料的性能特点，并对贮氢合金、轻质金属-铝氢化物、玻璃微球、碳纳米管、高比表面活性炭、有机液体氢化物等贮氢材料做了进一步的综述。     

从废渣中提取的稀土镍钴合金储氢性能的研究

采用水浴—合金置换—电弧渣金熔分三步法从储氢合金冶炼废渣中提取稀土镍钴合金,以此为母合金,依据设计的成分,配入纯金属,电弧熔炼配制成新的储氢合金,测试其储氢性能,结果表明,回收后储氢合金的电化学容量达到315 mAh/g,接近标准储氢合金粉;气固吸氢量为1.403%,PCT曲线平台明显,且平台比较宽,表明吸氢量大;当合金容量衰减到初始容量的80%时,其循环次数为158次.     

锂离子电池正极材料Li0.97Re0.01FePO4的合成及性能

采用固相反应法合成了锂离子电池正极材料Li0.97Re0.01FePO4(Re=Er,Y,Gd,Nd,La),采用X射线衍射、恒电流充放试验对掺杂试样的微观结构和电化学性能进行测试。试验结果表明:掺杂稀土金属离子对LiFePO4的晶体结构没有影响,与LiFePO4相比,掺杂Er3+,Y3+,Gd3+的试样具有优良的循环性能和倍率性能,而掺杂Nd3+,La3+的试样的循环性能和倍率性能较差。掺杂试样中,Li0.97Gd0.01FePO4的电化学性能最佳,在C/10和1C(1C=120 mA.g-1)倍率下放电容量均最大。     

Gaseous and electrochemical hydrogen storage kinetics of as-quenched nanocrystalline and amorphous Mg2Ni-type alloys

The nanocrystalline and amorphous Mg₂Ni-type Mg₂Ni_1?x Co _x (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were synthesized by melt quenching technology. The structures of the as-cast and quenched alloys were characterized by XRD, SEM and HRTEM. The gaseous hydrogen storage kinetics of the alloys was measured using an automatically controlled Sieverts apparatus. The alloy electrodes were charged and discharged with a constant current density in order to investigate the electrochemical hydrogen storage kinetics of the alloys. The results demonstrate that the substitution of Co for Ni results in the formation of secondary phases MgCo₂ and Mg instead of altering the major phase Mg₂Ni. No amorphous phase is detected in the as-quenched Cofree alloy, however, a certain amount of amorphous phase is clearly found in the as-quenched alloys substituted by Co. Furthermore, both the rapid quenching and the Co substitution significantly improve the gaseous and electrochemical hydrogen storage kinetics of the alloys, for which the notable increase of the hydrogen diffusion coefficient (D) along with the limiting current density (I _L ) and the obvious decline of the electrochemical impedance generated by both the Co substitution and the rapid quenching are basically responsible.     

锂离子电池正极材料Li0.97Re0.01FePO4的合成及性能

采用固相反应法合成了锂离子电池正极材料Li0.97Re0.01FePO4（Re=Er,Y,Gd,Nd,La）,采用X射线衍射、恒电流充放试验对掺杂试样的微观结构和电化学性能进行测试。试验结果表明：掺杂稀土金属离子对LiFePO4的晶体结构没有影响,与LiFePO4相比,掺杂Er^3＋,Y^3＋,Gd^3＋的试样具有优良的循环性能和倍率性能,而掺杂Nd^3＋,La^3＋的试样的循环性能和倍率性能较差。掺杂试样中,Li0.97Re0.01FePO4的电化学性能最佳,在C/10和1C（1C=120mA·g^-1）倍率下放电容量均最大。     

碳纳米管/羧甲基纤维素钠杂化材料修饰电极的制备及其电化学性能研究

伴随着纯电动汽车、利用清洁能源的高效储蓄和便携式电子产品的飞速发展,寻找具有高功率密度、低成本、高可靠性、环保且寿命长的新型电化学储能材料与器件迫在眉睫。纤维素是一种自然形成的有机聚合物,其自身良好的生物相容性和可降解性使其在新能源材料应用上备受关注。近年来,天然纤维素微纳化与新型纤维素衍生材料制备的工程化,极大扩大了纤维素基材料在新能源领域的应用范围。通过杂化、物理共混、化学改性、掺杂与互穿等方式,构建与制备纤维素基高性能绿色环保储能材料具有理论研究价值和应用潜力。本工作将羧甲基纤维素钠作为碳纳米管的分散剂构建杂化体系,使碳纳米管的电化学性能得以充分发挥,通过溶剂配比、PH值等影响因素的探索,得到制备电化学性能优异的杂化体系的最佳实验条件,该杂化体系修饰后的电极材料具备构建超级电容器的巨大潜力。     

新法回收废储氢合金性能的研究

针对废储氢合金粉回收提出一种全新的方法,即提炼和冶炼相结合的方法,并研究提炼后的中间合金及再生新合金的性能.经测试,回收后储氢合金的电化学容量达到282 mAh/g,PCT测试固气吸氢量为1.032%(质量分数),X射线测得主体相为CaCu5型六方结构,但其中含有微量杂质相,这有待于对中间合金的提炼工艺做进一步的研究.总之,利用此种方法得到回收后储氢合金的性能与原合金相近,是一种具有广阔发展前景的回收方法.