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。     

贮氢合金热力学测试装置及测试方法的研究

通过对贮氢合金热力学主要研究内容的分析，研究了贮氢合金热力学的ｐ－Ｃ－Ｔ曲线的测定和计算方法，并通过对ＬａＮｉ＿５合金的性能测试，证明了该合金具有良好的活化性能和吸氢性能，在３０℃常温下吸氢平衡压仅为０．２８ＭＰａ，吸氢量（Ｈ／Ｍ）可达１，吸放氢反应热焓达３１．９ＫＪ／ｍｏｌ。     

阴极电弧法制备Ti-Ni合金贮氢薄膜及其性能研究

采用阴极电弧离子镀膜工艺制备 Ti-Ni合金薄膜贮氢材料 ,用电化学方法研究这种材料的电化学贮氢性能 ,采用 XRD方法研究贮氢薄膜在充放氢前后的结构变化 ,分析不同成分、基体对于薄膜试样贮氢性能的影响及其原因 .分析表明 ,贮氢薄膜为纳米晶结构 ,Ti6 1 Ni39晶粒线性尺寸小于 5 nm,电化学容量可达 2 0 0 m A .h/g以上 ,试样在电化学循环后发现贮氢过程形成了稳定的氢化物     

二元系过渡金属贮氢合金材料的形成规律

利用模式识别的偏最小二乘法对过渡金属二元合金氢化物的形成和贮氢性能进行分析，结果表明：利用化学健参数－模式识别方法可以建立过渡金属二元合金贮氢材料形成的数学模型，是贮氢材料设计的一种用方法。     

LaNi5＋TiF0.9Mn0．1合金的贮氢性能

用冶炼法合成LaNi5＋TiFe0.5Mn0.1复合贮氢合金，研究了LaNi5＋TiF0.5，Mn0.1合金的贮氢性能。研究结果表明：由于TiFe.9Mn0.1合金的加入，可有效地降低LaNi5的平台压力；当TiFe0.5Mn0.1的质量分数为15％左右时，放氢曲线中出现两个平台；TiFe0.9Mn0.1的质量分数趋于25％时，它的平台压力又逐渐升高，贮氢量逐渐增大，温度升高则第二个平台消失，贮氢量降低。该合金适用于低温贮氢。     

ZrCr0.6Fe1.2M0.2贮氢性能的研究

ＺｒＣｒ０．６Ｆｅ１．４是一种性能优良的贮氢条件,以其为母合金,通过对不同取代Ｍ制备的ＺｒＣｒ０．６Ｆｅ１．４贮氢合金氢平台压力,平台斜率及其贮氢过程热力学的研究,比较了不同取代元素对母合金贮氢性能的影响。     

贮氢合金还原处理及贮氢电极成型工艺研究

研究贮氢合金表面还原处理对电极性能的影响，以及用泡沫镍作基底制备贮氢电极的成型工艺。经还原处理后，贮氢电极放电容量显著提高。     

Mg-Ni-RE贮氢合金的研究进展

综述了近几年来国内镁基稀土贮氢材料的研究进展，介绍添加不同稀土和采用不同的工艺条件对Mg—Ni合金的贮氢量、吸放氢速度等贮氢性能的影响，总结了当前Mg—Ni—RE(RE＝La，Y，Ce，Pr，Nd)贮氢合金的研究现状和需要解决的主要问题，并提出了今后应用研究的方向．     

粘结剂对V3 TiNi0.56Al0.2贮氢合金电化学性能的影响

自蔓延高温合成法制备了钒基固溶体贮氢合金V3TiNi0.56Al0.2,研究了不同的粘结剂对贮氢合金电化学性能的影响.结果表明:以PTFE为粘结剂的合金电极的最大放电容量比PVA溶液为粘结剂的合金电极的最大放电容量小得多;随着PVA溶液的增大贮氢合金电极的最大放电容量减小,但循环稳定性增强;以6%左右的PVA溶液作为粘结剂,贮氢合金可获得满意的充放电性能.     

贮氢合金中缺陷的研究

用正电子湮没技术（PAT）对贮氢合金MLNi3.8Co0.5Mn0.4Al0.3及其掺Li合金进行了研究。结果表明，掺杂Li合金的空位缺陷增多，并导致贮氢性能改善，这对镍－氢电池有重要意义。     

Recent advances in improving performances of the lightweight complex hydrides Li-Mg-N-H system

A brief review of state-of-the art advances in improving performances of the lightweight complex hydrides Li-Mg-N-H system is reported. Among the hydrogen storage materials, Li-Mg-N-H combination systems are regarded as one of the most potential candidates for the vehicular applications owing to their high hydrogen storage capacity (>5 wt% H) and a more appropriate thermodynamic properties of hydrogen absorption and desorption. In the Li-Mg-N-H systems, tremendous efforts have been devoted to improving the hydrogen storage properties by adjusting composition, revealing reaction mechanisms, adding catalysts and refining the microstructures, etc. During the studies, different mechanisms, such as the coordinated two-molecule or multimolecule reaction mechanism and the ammonia-mediated mechanism, are proposed and applied under some certain conditions. Catalysis and nanosizing are very effective in enhancing the kinetic properties and thermodynamic destabilization of Li-Mg-N-H systems. Due to nano effects, the space-confinement and nanoconfinement seems to be more effective for improving the hydrogen storage performance, and it is great significant to develop hydrogen storage materials by studying the nanoconfined effects on the Li-Mg-N-H systems.     

Recent advances in hydrogen storage technologies based on nanoporous carbon materials

Hydrogen is a promising energy carrier that can potentially facilitate a transition from fossil fuels to sustainable energy sources without producing harmful by-products. Prior to realizing a hydrogen economy, however, viable hydrogen storage materials must be developed. Physical adsorption in porous solids provides an opportunity for hydrogen storage under low-stringency conditions. Physically adsorbed hydrogen molecules are weakly bound to a surface and, hence, are easily released. Among the various surface candidates, porous carbons appear to provide efficient hydrogen storage, with the advantages that porous carbon is relatively low-cost to produce and is easily prepared. In this review, we summarize the preparation methods, pore characteristics, and hydrogen storage capacities of representative nanoporous carbons, including activated carbons, zeolite-templated carbon, and carbide-derived carbon. We focus particularly on a series of nanoporous carbons developed recently: metal–organic framework-derived carbons, which exhibit promising properties for use in hydrogen storage applications.     

Hydrogen storage performance of LaNi3.95Al0.75Co0.3 alloy with different preparation methods

Rare-earth AB₅-type La–Ni–Al hydrogen storage alloys are widely studied due to their extensive application potentials in hydrogen isotope storage, hydrogen isotope isolation and hydrogen compressors, etc. Good hydriding/dehydriding kinetics, easily activation, high reversibility are important factors for their practical application. However, their overall hydrogen storage performance, especially plateau pressure and hydrogen absorption/desorption durability need to be further optimized. In this study, the microstructures and the hydrogen storage properties of as-cast, annealed, and melt-spun LaNi_3.95Al_0.75Co_0.3 alloys were investigated. The experimental results of XRD and SEM showed that all alloys contained a pure CaCu₅ type hexagonal structure LaNi₄Al phase. The cell volume increased in an order of annealed ?> ?melt-spun ?> ?as-cast, resulting in a lower hydrogen absorption/desorption plateau pressure and a more stable hydride phase. The hydrogen storage capacity of three alloys was almost the same. The slope factor of the annealed and melt-spun alloys is smaller than the as-cast alloy, indicating that heat-treatment process can make the alloys more uniform. For the cycle stability of the alloys, the hydrogen absorption rate of the annealed alloy and melt-spun alloy was much faster than that of the as-cast alloy after 500 cycles. The melt-spun alloy showed high pulverization resistance during hydrogen absorption/desorption, and exhibited an excellent cycling retention of 99% after 500 cycles, suggesting that melt-spinning process can enhance the cycle stability and improve the cycle life of the alloy.     

Influence of heat exchanger structure on hydrogen absorption-desorption performance of hydrogen storage vessel

The influence of heat exchanger structure on hydrogen absorption-desorption performance of hydrogen storage vessel was studied, in which the AB₅ (La_0.25Ce_0.75Ni_4.4Al_0.1Mn_0.1Co_0.4) hydrogen storage alloy was used as a typical representative. In order to obtain the data on reaction enthalpy, the PCT curve of the alloy was measured with three different temperatures, and the linear fitting was carried out according to the Van't Hoff relation curve. The SMCR (Spiral-mini-channel Reactor) reactor structure was adopted. The heat transfer method and its simplified model were studied by finite element method to explore the effect of size of heat transfer structure, particularly for heat pipe diameter, on the hydrogen absorption-desorption performance of hydrogen storage alloy in the vessel.     

储氢研究进展概况

氢能将是21世纪重要的二次能源。概要介绍几种不同的储氢方法(压缩存储、液氢存储、金属氢化物、配位氢化物等)及储氢的现状,指出了差距和存在的问题。     

Li原子修饰缺陷蓝磷单层储氢性能的第一性原理研究

本文基于第一性原理计算,系统地研究了碱金属Li原子修饰缺陷蓝磷单层体系的储氢性能. 研究结果表明,双空位缺陷DV2的引入可以有效增强Li原子与蓝磷单层间的相互作用,能够有效阻止单层表面Li团簇的形成. 单个Li原子可以稳定吸附3个H2分子,H2分子平均吸附能为0.248 eV/H2. 电子结构分析表明,H2分子主要通过极化机制和轨道杂化作用吸附在Li修饰的缺陷蓝磷单层体系上. 此外,本文还研究了温度和压强对Li/DV2体系储氢性能的影响. 结果表明,在室温和低压条件下,H2分子可以稳定吸附在Li/DV2体系表面,从而实现室温条件下的可逆储氢.     

Hydrogen absorption-desorption cycle decay mechanism of palladium nanoparticle decorated nitrogen doped graphene

As a hydrogen storage material, palladium nanoparticle decorated nitrogen doped graphene (Pd/N-rGO) has drawn much attention owing to its high absorption capacity at moderate conditions. However, its hydrogen absorption-desorption cycle performance, which is essential for their practical application, has been rarely studied. In this paper, a simple and convenient high temperature thermal reduction method was used to synthesize nitrogen-doped graphene decorated with Pd nanoparticles (Pd/N-rGO). Taken it as a representative, the hydrogen absorption-desorption cycle performance of Pd/N-rGO was investigated. The results showed that after three cycles the hydrogen storage capacity dropped from 2.9 ​wt% to 0.8 ​wt% at 25 ​°C and 4 ​MPa pressure. It was found that the palladium nanoparticles shed from Pd/N-RGO sheet after cycle performance test, and then agglomerated. These phenomena will weaken the hydrogen spillover effect, leading to the decrease of hydrogen storage capacity. Meanwhile, decreased defects reduce the hydrogen absorption sites, which will thus deteriorate the hydrogen storage capacity.     

LaNi_4Cu金属间化物的贮氢和结构分析

用化学共沉淀法,在氢气氛下,进行高温还原扩散,制得LaNi_4Cu金属间化物,经活化后具有良好的贮氢性能,经化学分析、X射线晶体衍射和红外光谱测定,确定该化合物的组成、晶体结构,并阐明贮氢原理。     

快淬对贮氢合金组织和电化学性能的影响

通过XRD、TEM、DTA分析和电化学实验 ,研究了快淬对贮氢合金组织和电化学性能的影响。研究表明 ,成分均匀性改善和单胞体积减小是影响快淬贮氢合金电化学性能的主要因素 ,其中 ,前者使充放电循环稳定性提高 ,后者使放电容量降低。在本研究中 ,快淬速度为 10m/s时 ,合金成分的均匀性已较铸态有明显改善 ,更高的快淬速度并不能使成分的均匀性进一步大幅度提高 ,反而使单胞体积减小 ,因此 ,快淬速度为 10m/s时 ,快淬合金的综合电化学性能最佳。     

Nanomaterials for renewable hydrogen production, storage and utilization

An ever growing demand for energy coupled with increasing pollution is forcing us to seek environmentally clean alternative energy resources to substitute fossil fuels. The rapid development of nanomaterials has opened up new avenues for the conversion and utilization of renewable energy. This article reviews nanostructured materials designed for selected applications in renewable energy conversion and utilization. The review is based on the authors’ research, with particular focus on solar hydrogen production, hydrogen storage and hydrogen utilization. The topics include photoelectrochemical (PEC) water splitting and photocatalytic hydrogen production, solid-state hydrogen storage, and proton exchange membrane fuel cells (PEMFCs). It is expected that the rational design of nanomaterials could play an important role in achieving a renewable energy based economy in the coming decades.