Effect of Ni content on the structure, thermodynamic and electrochemical properties of the non-stoichiometric hydrogen storage alloys

• Published in: Journal of alloys and compounds Vol. 308; no. 1; pp. 163 - 171
• Main Authors: Ye, H, Zhang, H, Cheng, J.X, Huang, T.S
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 10.08.2000; Elsevier
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Electrochemical impedance spectroscopy; Electrochemical performance; Energy; Exact sciences and technology; Fuels; Hydrogen; Hydrogen storage materials; Thermodynamic property; X-ray diffraction; Hydrogen storage materials; X-ray diffraction; Electrochemical performance; Thermodynamic property; Electrochemical impedance spectroscopy; Manganèse alloy; Electrochemical properties; Storage; Hydrogen; Cobalt alloy; Aluminium alloy; Thermodynamic properties; Misch metal; Nickel alloy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/S0925-8388(00)01049-5

Commercial MmNi x Co 0.75Mn 0.40Al 0.30 hydrogen storage alloys have been investigated to examine the effect of non-stoichiometry on the microstructure, thermodynamic and electrochemical properties, where Ni content, x, is tuned from 3.05 to 4.05. It is found that for the stoichiometric and B-rich compound, only single phase with CaCu 5-type exists. However, for B-poor compounds, there is principal a CaCu 5-type phase with small amount of Ln 2Ni 7 type phase (Ln: rear earth elements) and the amount of Ln 2Ni 7 phase reduces with Ni. With the increase of Ni content, the lattice parameter along a and c axis, thus the cell volume, of the hexagonal CaCu 5-type phase decrease monotonously. The hydrogen desorption pressure and enthalpy of hydride increase with Ni increasing. The electrochemical properties of the non-stoichiometric compounds with different Ni content are well related to the structure and thermodynamics of compound.