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International Journal of Metallurgical & Materials Engineering Volume 2 (2016), Article ID 2:IJMME-124, 7 pages
http://dx.doi.org/10.15344/2455-2372/2016/124
Research Article
Thermodynamic and Kinetic Properties of La20.5MgNi78.5 and La15.5Mg6Ni78.5 Hydrogen Storage Alloys: The Theoretical Models and Their Verifications

Xue-Hui An1, Yuepeng Pang1, Qin Li1, Jie-Yu Zhang1, Kuo-Chih Chou1, Qian Li1,2*

1State Key Laboratory of Advanced Special Steels & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China
2Materials Genome Institute, Shanghai University, Shanghai 200444, China
Dr. Qian Li, State Key Laboratory of Advanced Special Steels & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China; E-mail: shuliqian@shu.edu.cn
25 May 2016; 28 June 2016; 30 June 2016
An XH, Pang Y, Li Q, Zhang JY, Chou KC, et al. (2016) Thermodynamic and Kinetic Properties of La20.5MgNi78.5 and La15.5Mg6Ni78.5 Hydrogen Storage Alloys: The Theoretical Models and Their Verifications. Int J Metall Mater Eng 2: 124. doi: http://dx.doi.org/10.15344/2455-2372/2016/124
This work was financially sponsored by the Natural Science Foundation of China (No. 51501107, 51222402), “Shu Guang” project supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation (13SG39) and China Postdoctoral Science Foundation (2015M571541).

Abstract

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 La20.5MgNi78.5 and La15.5Mg6Ni78.5 alloys, their maximum hydrogen storage capacities and the hydride formation enthalpies at 303~333 K are 1.41 wt.% H2 and -31.64 kJ/mol H2 for La20.5MgNi78.5 and 1.31 wt.% H2 and -27.23 kJ/mol H2 for La15.5Mg6Ni78.5, 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 H2 for La20.5MgNi78.5 and 24.24 kJ/mol H2 for La15.5Mg6Ni78.5, respectively.