Guo-qing Wang

Microstructures and Electrochemical Properties of Cobalt-Free LaNi4.0Al0.2Fe0.4Cu0.4-xSnx (x = 0 ∼ 0.4) Electrode Alloys Prepared by Casting

Abstract The microstructure, hydriding performance, and electrochemical properties of LaNi 4.0 Al 0.2 Fe 0.4 Cu 0.4- x Sn x ( x = 0 ∼ 0.4) hydrogen storage alloys prepared by casting were investigated using XRD, SEM, pressure-composition isotherms, and electrochemical measurements. Substitution of Sn for Cu leads to the precipitation of LaNiSn phase. With increasing amount of tin substitution, cell volume, plateau pressures, and discharge capacities of the alloys decrease, whereas the cycle life of the alloys improves.

Effects of rapid quenching on microstructures and electrochemical properties of La0.7Mg0.3Ni2.55Co0.45Bx(x=0−0.2) hydrogen storage alloy

Abstract In order to improve the electrochemical performances of La-Mg-Ni based electrode alloys with PuNi3-type structure, a trace of boron was added in La0.7Mg0.3Ni2.55Co0.45 alloy. The La0.7Mg0.3Ni2.55Co0.45(x=0, 0.05, 0.1, 0.15 and 0.2) alloys were prepared by casting and rapid quenching. The electrochemical performances and microstructures of the as-cast and quenched alloys were investigated. The effects of rapid quenching on the microstructures and electrochemical performances of the above alloys were investigated. The results show that the as-cast and quenched alloys are composed of (La, Mg)Ni3 phase, LaNi5 phase and LaNi2 phase. A trace of the Ni2B phase exists in the as-cast alloys containing boron, and the Ni2B phase in the B-contained alloys nearly disappears after rapid quenching. Rapid quenching increases the amount of the LaNi2 phase in the B-free alloy, but it decreases the amount of the LaNi2 phase in the boron-containing alloys. The effects of rapid quenching on the capacities of the boron-containing and boron-free alloys are different. The capacity of the B-free alloy monotonously decreases with increasing quenching rate, whereas the capacities of the B-contained alloys have a maximum value with the change of the quenching rate. The rapid quenching can improve the stability of La-Mg-Ni based electrode alloy but lowers the discharge plateau voltage and decreases the plateau length. The effect of rapid quenching on the activation capabilities of the alloys was complicated.

Investigation of Cobalt-Free AB5-Type Hydrogen Storage Alloy

Co-free AB5-type LaxMm1-x(NiMnSiAlFe)4.9 (x = 0, 0.45, 0.75, 1) hydrogen storage alloys were prepared by casting and rapid quenching. The phase structures and microstructures of the as-cast and quenched alloys were analyzed and observed by XRD and SEM. The electrochemical performances of the as-cast and quenched alloys were measured. The effects of La content and quenching rate on the microstructures and electrochemical properties of the alloys were investigated comprehensivel y. The obtained results indicate that the Co-free AB5-type hydrogen storage alloy with excellent synthetical electrochemical performances can be prepared by adjusting La content and employing appropriate rapid quenching technique.