Thermodynamic Reassessment of the La‐Mg‐Ni System and Its Application for Hydrogen Storage

An, Xiaowei; Wu, Kong-Bao; Zhang, Jieyu; Chen, Shuanglin; Li, Qian

doi:10.1002/9781118663547.ch105

Cited by 1 publication

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“…The PCI curves of samples #1 and #2 at 303, 318 and 333K are shown in Figure 1, from which it can be seen that the maximum hydrogen storage capacity of sample #1 (1.41 wt.%H 2 ) is larger than that of sample #2 (1.31 wt.%H 2 ). According to the updated La-Mg-Ni phase diagram [31], sample #1 is composed of LaNi 5 and La 4 MgNi 19 , and sample #2 contains LaNi 5 and LaMg 2 Ni 9 . As can be seen in Figure 2, the results of XRD patterns are agreed with the calculated phase diagram.…”

Section: Resultsmentioning

confidence: 99%

“…According to the thermodynamic description of the La-Mg-Ni system [31], two alloys, composition very close to nominal La 20.5 MgNi 78.5 (labeled as sample #1) and La1 5.5 Mg 6 Ni 78.5 (labeled as sample #2), locating at the LaNi 5 & (La,Mg) 5 Ni 19 and LaNi 5 & (La,Mg)Ni 3 binary zone, were selected and synthesized from the bulk of La (99.99 %), Mg (99.99 %), and Ni (99.999 %) using a medium frequency induction furnace. Before melting, the induction furnace was vacuumed to lower than 10 Pa and then injected with high purity argon (99.999 %) to 0.1 MPa.…”

Section: Methodsmentioning

confidence: 99%

“…In this work, on the basis of the more realistic physical assumptions, a model for PCI curves from the view of thermodynamic statistic as well as a kinetic model with the consideration of hydrogen-induced volume change is proposed for describing the hydrogen storage properties. The results of the models are compared with measurements on La 20.5 MgNi 78.5 and La1 5.5 Mg 6 Ni 78.5 alloys, which are selected according to the updated La-Mg-Ni phase diagram in our previous work [31].…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic and Kinetic Properties of La20.5MgNi78.5 and La15.5Mg6Ni78.5 Hydrogen Storage Alloys: The Theoretical Models and Their Verifications

An¹,

Pang²,

Li³

et al. 2016

Int J Metall Mater Eng

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In this paper, we present a statistic thermodynamic model quantitatively describing the pressurecomposition-isotherms (PCI) curve, which consists of hydrogen storage capacity, temperature, and equilibrium pressure in the hydriding and dehydriding (H/D) reactions, and a theoretical kinetic model to clarify the H/D kinetic mechanism of hydrogen storage alloys. The results of the calculations are well agreed with the experiments performed with La 20.5 MgNi 78.5 and La1 5.5 Mg 6 Ni 78.5 alloys, their maximum hydrogen storage capacities and the hydride formation enthalpies at 303~333 K are 1.41 wt.% H 2 and -31.64 kJ/mol H 2 for La 20.5 MgNi 78.5 and 1.31 wt.% H 2 and -27.23 kJ/mol H 2 for La1 5.5 Mg 6 Ni 78.5 , respectively. A new diffusion kinetic model is proposed with the consideration of Pilling-Bedworth Ratio, i.e. hydrogen-induced volume change used for studying the hydrogen absorption reaction kinetics. The activation energies are calculated to be 31.25 kJ/mol H 2 for La 20.5 MgNi 78.5 and 24.24 kJ/mol H 2 for La1 5.5 Mg 6 Ni 78.5 , respectively.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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