The Negative Electrode Developement for a Ni-MH Battery Prototype

D. J. CUSCUETA; A. A. GHILARDUCCI; H. R. SALVA; R. H. MILLOCCO; E. B. CASTRO

PHYSICA B - CONDENSED MATTER

ELSEVIER SCIENCE BV

Año: 2009 vol. 404 p. 2848 - 2850

0921-4526

The negative electrode development for anickel-metalhydride battery(Ni–MH) prototype was performed with the following procedure:(1)the Lm0.95Ni3.8Co0.3Mn0.3Al0.4 (Lm = lanthanum rich mischmetal) intermetallic alloy was elaborated by melting the pure elements in an induction furnace inside a boron nitride crucible under an inert atmosphere,(2)the obtained alloy was crushed and sieved between  44 and 74  mm and mixed with teflonized carbon;(3)the compound was assembled together with a current collector and pressed in acylindrical matrix.The obtained electrode presented a disc shape, with 11 mm diameter and approximately 1mm thickness. The crystalline structure of the hydrogen storage alloy was examined using X-ray diffractometry. The measured hcp lattice volume was 1.78 % larger than the precursor LaNi5 intermetallic alloy, increasing the available space for hydrogen movement. Energy dispersive spectroscopy (EDS) and scanning electronic microscopy (SEM) measurements were used before and after hydriding in order to verify the alloy sample homogeneity. The negative electrode was electrochemically tested by using a laboratory cell. It activates almost totally in its first cycle, which is an excellent characteristic from the commercial point of view. The maximumdischarge capacity reached was 314.2 mAh/g in the 10thcycle.