Hydrogen storage and electrochemical properties of annealed low-Co AB5 type intermetallic compounds

The structure, hydrogen storage and electrochemical properties of annealed low-Co AB5-type intermetallic compounds have been investigated. La-alloy, Nd-alloy and Cr-alloy are used to represent La0.8Ce0.2Ni4Co0.4Mn0.3Al0.3, La0.6Ce0.2Nd0.2Ni4Co0.4Mn0.3Al0.3 and La0.6Ce0.2Nd0.2Ni3.8Co0.4Mn0.3Al0.3Cr0....

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Bibliographic Details
Published in:	International journal of hydrogen energy Vol. 46; no. 25; pp. 13622 - 13631
Main Authors:	Kazakov, A.N., Blinov, D.V., Bodikov, V. Yu, Mitrokhin, S.V., Volodin, A.A.
Format:	Journal Article
Language:	English
Published:	Elsevier Ltd 09-04-2021
Subjects:	Electrochemical properties Hydrogen capacity Hydrogen diffusion Hydrogen storage Metal hydride Hydrogen diffusion Hydrogen storage Electrochemical properties Metal hydride Hydrogen capacity
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Summary:	The structure, hydrogen storage and electrochemical properties of annealed low-Co AB5-type intermetallic compounds have been investigated. La-alloy, Nd-alloy and Cr-alloy are used to represent La0.8Ce0.2Ni4Co0.4Mn0.3Al0.3, La0.6Ce0.2Nd0.2Ni4Co0.4Mn0.3Al0.3 and La0.6Ce0.2Nd0.2Ni3.8Co0.4Mn0.3Al0.3Cr0.2, respectively. The XRD results indicated that annealed samples are all single-phase alloys with CaCu5 type structure. The maximum of both hydrogen content and discharge capacity is obtained for La-alloy 1.23 wt%H2 and 321.1 mA h/g, respectively. All the investigated alloys are quiet stable with ΔH of hydrogen desorption about 36–38 kJ/mol H2. Cycle life of alloy electrode has been improved by partial substitution of La for Nd and Ni for Cr. The highest capacity retention of 92.2% after 100 charge/discharge cycles at 1C has been observed for Nd-alloy. The hydrogen diffusion coefficient measured by PITT is higher at the start of charging process and dramatically reduces by 2–3 order of magnitude with saturation of β-hydride. The highest value 6.9 × 10−13 cm2/s is observed for La alloy at 100% SOC. Partial substitution La for Nd and Cr for Ni in low-Co AB5 metal hydride alloys slightly reduces maximum discharge capacity, HRD performance and hydrogen diffusion kinetics. Low-Co alloys show good overall electrochemical properties compared to high-Co alloys and might be perspective materials for various electrochemical applications. •Low Co AB5 type alloys were studied as anode materials.•The maximum discharge capacity 321.1 mA h/g at 100 mA/g for La alloy.•The hydrogen diffusion coefficient at charging is measured by PITT.•High cycling retention of 92.2% after 100 cycles at 1C for Nd alloy.
ISSN:	0360-3199 1879-3487
DOI:	10.1016/j.ijhydene.2020.12.071