Effects of Al on Cycling Stability of a New Rare-Earth Mg-Based Hydrogen Storage Alloy

Abstract:

In order to improve the cycling stability of a new rare-earth Mg-based hydrogen storage alloys, La0.7Mg0.3Ni2.65-xMn0.1Co0.75Alx (x=0.0-0.4) alloys were prepared to investigate the structure and electrochemical properties of these alloys. XRD and Rietveld analyses reveal that the alloys consist of a (La,Mg)Ni3 phase with rhombohedral PuNi3-type structure and a LaNi5 phase with hexagonal CaCu5-type structure. Electrochemical studies on these alloys indicate that their maximum discharge capacities were decreased from 400.7 mAh/g (x=0.0) to 335.6 mAh/g (x=0.4). However, the cycling stability of the alloy electrodes was significantly improved after Ni was partially replaced by Al. After 100 charge/discharge cycles, the discharge capacity retention was increased from 32.0% (x=0.0) to 73.8 % (x=0.3), which can be attributed to the formation of a dense oxide film on the alloy surface. Moreover, the high rate dischargeability measurements indicate that the electrochemical kinetic properties were deteriorated with increasing Al content owing to the presence of a dense oxide film of Al.

• Periodical: Materials Science Forum (Volumes 475-479)
• Pages: 2457-2462
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.475-479.2457
• Online since: January 2005
• Authors: Y.F. Liu, H.G. Pan, Rui Li, Y.Q. Lei
• Keywords: Electrochemical Property, Hydrogen Storage Alloy, Ni-MH Battery, Structure

References

[1] G. Sandrock: J. Alloy Comp., 293-295(1999) p.877.

[2] K. Kadir, T. Sakai, I. Uehara: J. Alloys Compd., 257(1997) p.115.

[3] K. Kadir, T. Sakai, I. Uehara: J. Alloys Compd., 302(2000) p.112.

[4] T. Kohno, H. Yoshida, F. Kawashima, T. Inaba, I. Sakai, M. Yamamoto, M. Kanda: J. Alloys Compd., 311(2000) p. L5.

DOI: 10.1016/s0925-8388(00)01119-1

[5] H. G. Pan, Y. F. Liu, M. X. Gao, Y. Q. Lei, and Q. D. Wang: J. Electrochem. Soc., 150 (2003) p. A565.

[6] H.G. Pan, Y.F. Liu, M.X. Gao, Y.F. Zhu, Y.Q. Lei, Q.D. Wang: J. Electrochem. Soc., 151(2004) p. A374.

[7] T. Sakai, H. Miyamura, N. Kuriyama, A. Kato, K. Oguro, H. Ishikawa: J. Electrochem. Soc., 137(1990) p.795.

DOI: 10.1149/1.2086557

[8] M. Jurczyk, M. Nowak, E. Jankowska, J. Jakubowicz: J. Alloys Comp., 339(2002) p.339.

[9] T. Takeshita, W. E. Wallace, R. S. Craig: Inorg. Chem., 13(1974) p.2282. 5.

[10] M.H.J. Van Rijswick, Hydrogen for Energy Storage, A.F. Anderesen and A.J. Maeland, Editors, P. 261, Pergamon Press, Oxford (1978).