LaMgNi4.xCox合金的氢储性能研究
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"这篇论文详细探讨了LaMgNi4.xCox合金的制备方法及其储氢性能。研究者采用悬浮熔炼和烧结工艺，成功制备出LaMgNi4.xCox合金系列（x=0, 0.3, 0.5），并对其进行了X射线粉末衍射（XRD）分析。结果显示，这些合金均呈现单一相，具有SnMgCu4结构，即AuBe5型结构。通过压力-容量-温度（PCI）实验，研究了LaMgNi4在不同温度下的吸放氢行为，发现其在373 K和4.3 MPa氢气压力下，吸氢量达到最高，约为1.45%（5.79 H/M）。在这一过程中，材料的结构经历了从立方结构的α-LaMgNi4转变为正交结构的β-LaMgNi4H3.41，最后又回到立方结构的γ-LaMgNi。"
这篇2013年的论文聚焦于金属间化合物在氢能存储中的应用，特别是LaMgNi4.xCox合金系列。悬浮熔炼是一种高级金属合金制备技术，它能够确保均匀的成分分布，避免传统铸造方法可能导致的杂质或不均匀性。烧结过程则有助于提高合金的密度和力学性能。XRD分析是材料科学中常用的一种表征工具，用于确定物质的晶体结构和相组成。
论文指出，LaMgNi4.xCox合金在吸收氢气时，其结构会发生相变，这表明合金的储氢机制可能与结构变化有关。这种相变对于理解材料的储氢机理至关重要，因为不同的相可能具有不同的氢吸附能力。PCI测量法是一种评估材料吸放氢性能的有效手段，它可以提供关于氢气在材料中吸附和脱附的详细信息。
在实际应用中，储氢材料的性能取决于其在特定温度和压力下的吸氢容量，以及吸放氢的可逆性。373 K（100°C）和4.3 MPa的压力条件是模拟实际储氢系统工作环境的常见选择。LaMgNi4合金在这些条件下显示出较高的储氢容量，这表明它可能适用于高温氢能源存储系统。
这篇论文揭示了LaMgNi4.xCox合金作为储氢材料的潜力，它的结构特性与储氢性能之间的关系，以及优化合金成分对改善储氢效率的影响。这些研究结果为设计和开发更高效的储氢材料提供了理论依据，并对未来的氢能技术发展具有重要意义。
Trans. Nonferrous Met. Soc. China 23(2013) 2307−2311
Preparation of LaMgNi
4−x
Co
x
alloys and hydrogen storage properties
Jian-bo TAN
1
, Xiao-qin ZENG
1,2
, Jian-xin ZOU
1
, Xiao-mei WU
1
, Wen-jiang DING
1
1.
Shanghai Engineering Research Center of Magnesium Materials and Applications,
School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;
2. State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering,
Shanghai Jiao Tong University, Shanghai 200240, China
Received 2 July 2012; accepted 28 September 2012
Abstract: The LaMgNi
4−x
Co
x
(x=0, 0.3, 0.5) compounds were prepared by the method of levitation melting and a subsequent heat
treatment at 1073 K for 10 h. XRD analysis shows that the obtained LaMgNi
4−x
Co
x
alloys consist of a single phase with the structure
of cubic SnMgCu
4
(AuBe
5
type). The hydrogen absorption/desorption properties of LaMgNi
4
were investigated by PCI measurement
at various temperatures (T=373, 398, 423 K) and the results show that the maximum absorbed hydrogen capacity reaches 1.45%
(5.79H/M) under a hydrogen pressure of 4.3 MPa at 373 K. The XRD patterns during absorbing procedure at 373 K indicate the
phase structure changing from cubic (α-LaMgNi
4
) to orthorhombic (β-LaMgNi
4
H
3.41
) and after hydrogenation finally back to cubic
(γ-LaMgNi
4
H
4.87
), and a partial desorption was also observed under this condition. With increasing temperature, a slight decrease of
the absorbed hydrogen content was observed and the number of plateaus reduces from two to one, but the hydrogen absorption
kinetics improves. The electrochemical properties of the LaMgNi
4-x
Co
x
were measured by simulated battery test, which shows that
the discharge capacity of the alloys significantly improves with the increase of Co content.
Key words: hydrogen storage alloy; electrochemical properties; LaMgNi
4−x
Co
x
1 Introduction
Hydrogen storage alloy has aroused great interest in
view of its potential as a new energy storage material.
During the last years, magnesium based alloys showed
large potential for hydrogen storage applications due to
their high hydrogen capacity and low costs [1,2], but
because of the high temperature of dehydrogenation and
poor kinetics, the applications of these alloys are still
limited [3,4]. Recently, a lot of investigations have been
done on the RE−Mg−Ni (RE=rare earth) system [5−8],
and it has been shown that the ternary compounds
RE
1−x
Mg
x
Ni
2
based on Laves structure are new
promising in hydrogen-absorbing capacity and
electrochemical properties [9−12].
In previous works, BOBET et al [13] reported that
LaMgNi
4
compound absorbs 3.8H/M at room
temperature but no desorption has been observed even at
temperature up to 473 K under primary vacuum.
Nevertheless CHOTARD et al [14] reported that
LaMgNi
4
H
4.85
formed at a pressure of more than 2 MPa
and a subsequent decrease of hydrogen pressure to
ambient conditions led to hydrogen desorption of
1.5H/M hydrogen at 373 K. WANG et al [15] also
reported about electrochemical properties of LaMgNi
4
that the discharge capacity reaches 400 mA·h/g which is
much higher than that of the commercial AB
5
alloys (330
mA·h/g).
To the best of our knowledge, there are neither
related investigations on the reversible properties of
LaMgNi
4
hydrogen absorption/desorption at different
temperatures, nor complete pressure-composition
isotherm (PCI) curves about the compound available.
Also a lot of contradictory conclusions were made
whether LaMgNi
4
can desorb hydrogen or not. For these
reasons, the compounds LaMgNi
4−x
Co
x
(x=0, 0.3, 0.5)
were synthesized by levitation melting first and then the
thermodynamic and kinetic hydrogen storage properties
of LaMgNi
4
were investigated systematically at different
temperatures. Finally, the effects of Co addition on the
electrochemical properties of LaMgNi
4−x
Co
x
by partial
Foundation item: Projects (10JC407700, 11ZR1417600) supported by the Science and Technology Committee of Shanghai, China; Project (12ZZ017)
supported by the Shanghai Education Commission, China
Corresponding author: Xiao-qin ZENG; Tel: +86-21-54742301; Fax: +86-21-34203730; E-mail: xqzeng@sjtu.edu.cn
DOI: 10.1016/S1003-6326(13)62733-8
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