Crystal structure and hydrogen storage properties of (La,Ce)Ni_5−xM _x (M = Al, Fe, or Co) alloys

Abstract

The effects of partial substitution of La by Ce and Ni by Al, Fe, or Co in LaNi₅-based alloys on hydrogen storage performance were systematically studied. All samples were prepared using vacuum arc melting in an argon atmosphere. The results showed that for La-Ni_5−xM _x (M = Al, Fe, or Co) alloys, the lattice constants and unit cell volumes increased with an increasing amount of Al and Fe. On the other hand, these parameters decreased upon partial substitution of La by Ce. In addition, the lattice constant remained almost constant in the La_0.6Ce_0.4Ni_5–xCo _x alloys regardless of the value of x (x = 0.3, 0.6, or 0.9), as Ce might enhance the homogeneity of the CaCu₅-type phase in Co-containing alloys. The hydrogen storage properties of the alloys were investigated using pressure, composition, and temperature isotherms. The experimental results showed that the plateau pressure decreased with an increasing content of Al, Fe, or Co, but it increased with Ce addition. Furthermore, the plateau pressures of all Co-containing alloys were almost identical upon substitution with Ce. Finally, the enthalpy (ΔH) and entropy (ΔS) values for all alloys were calculated using van’t Hoff plots. The relationship between the lattice parameters and enthalpy changes for hydrogenation will be discussed.

Keywords

metal hydride / LaNi₅ / hydrogen storage alloys / partial substitution / P−C−T curves / thermodynamics

References

[1] Schlapbach L., Züttel A. Hydrogen-storage materials for mobile applications. Nature, 2001, 414(6861): 353.

[2] Ding Y.F., Wen C.E., Hodgson P., Li Y.C. Effects of alloying elements on the corrosion behavior and biocompatibility of biodegradable magnesium alloys: a review. J. Mater. Chem. B, 2014, 2(14): 1912.

[3] Yang X.W., Zhu Y.F., Zhang J.G., Zhang Y., Liu Y.N., Lin H.J., Wang T.M., Li L.Q. Effect of partial substitution of Ti for Al on the phase structure and electrochemical hydrogen storage properties of Mg3AlNi2 alloy. J. Alloys Compd., 2018, 746, 421.

[4] Valøen L.O., Zaluska A., Zaluski L., Tanaka H., Kuriyama N., Ström-Olsen J.O., Tunold R. Structure and related properties of (La,Ce,Nd,Pr)Ni₅ alloys. J. Alloys Compd., 2000, 306(1–2): 235.

[5] Kumar M.P.S., Zhang W.L., Petrov K., Rostami A.A., Srinivasan S., Adzic G.D., Johnson J.R., Reilly J.J., Lim H.S. Effect of Ce, CO and Sn substitution on gas phase and electrochemcal hydriding/dehydriding properties of LaNi₅. J. Electrochem. Soc., 1995, 142(10): 3424.

[6] Mendelsohn M.H., Gruen D.M., Dwight A.E. The effect on hydrogen decomposition pressures of group IIIa and IVa element substitutions for Ni in LaNi alloys. Mater. Res. Bull., 1978, 13(11): 1221.

[7] Vogt T., Reilly J.J., Johnson J.R., Adzic G.D., McBreen J. Crystal structure of nonstoichiometric La( Ni,Sn ) 5+x alloys and their properties as metal hydride electrodes. Electrochem. Solid-State Lett., 1999, 2(3): 111.

[8] Mendelsohn M.H., Gruen D.M., Dwight A.E. LaNi_5-xAl _x is a versatile alloy system for metal hydride applications. Nature, 1977, 269(5623): 45.

[9] Mendelsohn M.H., Gruen D.M., Dwight A.E. The effect of aluminum additions on the structural and hydrogen absorption properties of AB5 alloys with particular reference to the LaNi_5-xAl _x ternary alloy system. J. Less-Common Met., 1979, 63(2): 193.

[10] Pourarian F., Wallace W.E. Hydrogen storage in Ce-Ni_5-xCu _x. J. Less-Common Met., 1982, 87(2): 275.

[11] Jain R.K., Jain A., Agarwal S., Lalla N.P., Ganesan V., Phase D.M., Jain I.P. Characterization and hydrogenation of CeNi_5-xCr _x (x = 0, 1, 2) alloys. J. Alloys Compd., 2007, 430(1–2): 165.

[12] Aybar A.B., Anik M. Direct synthesis of La-Mg-Ni-Co type hydrogen storage alloys from oxide mixtures. J. Energy Chem., 2017, 26(4): 719.

[13] Pandey S.K., Srivastava A., Srivastava O.N. Improvement in hydrogen storage capacity in LaNi₅s through substitution of Ni by Fe. Int. J. Hydrogen Energy, 2007, 32(13): 2461.

[14] Walker G. Solid-state Hydrogen Storage: Materials and Chemistry, 2008, Cambridge, Woodhead Publishing Ltd.

[15] Aylward G.H., Findlay T.J.V. SI Chemical Data, 1973, New York, J. Wiley & Sons, Ltd..

[16] Asano K., Yamazaki Y., Iijima Y. Hydriding and dehydriding processes of LaNi_5-xCo _x (x = 0–2) alloys under hydrogen pressure of 1–5 MPa. Intermetallics, 2003, 11(9): 911.

[17] Van Mal H.H., Buschow K.H.J., Kuijpers F.A. Hydrogen absorption and magnetic properties of LaCo_5xNi_5-5x compounds. J. Less-Common Met., 1973, 32(2): 289.