Microstructures and electrochemical properties of LaNi3.8-xAlx hydrogen storage alloys

The microstructures and electrochemical properties of LaNi_3.8–xAl_x (x=0.0, 0.1, 0.2, 0.3 and 0.4) alloys were studied systematically. The microstructures were identified by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The main phases were not changed with the substitution of Ni by Al, but minor phases appeared when x=0.4. With Al content increasing, the cell volume increased and the hydrogen storage capacity increased first and then decreased, and the maximum discharge capacity increased from 209.4 mAh/g (x=0.0) to 285.3 mAh/g (x=0.3) and then decreased to 241.3 mAh/g (x=0.4). Meanwhile, the exchange current density (I₀) increased and the diffusion coefficient (D) decreased with the addition of Al.