Effects of pretreatment on MlNi4.00Co0.45Mn0.38Al0.3 hydrogen storage alloy powders and the performance of 6 Ah prismatic traction battery

This paper investigates the effects of pretreatment of the MlNi4.00Co0.45Mn0.38Al0.3 (Ml: Lanthanum rich misch metal) alloy powders in 12 M NaOH solutions with 0.05 M NaBH4 at 110 °C for 3 h and the performance of 6 Ah prismatic traction battery. The alloy powders are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy with energy dispersive X-ray detector, inductively coupled plasma-atomic emission spectroscopy, laser particle size analyzer and BET chemisorptions analyzer. The electrochemical performance of the battery was effectively improved by the pretreatment of alloy powders with a NaOH/NaBH4 solution. It is found that the discharge efficiencies at 30C at room temperature and at 3C at −20 °C are increased from 5.6% to 88.1% and from 3.7% to 83.7%, respectively. The cycle lifetime at 3C of SOC of 80% is increased from 2200 to 4424. The enhanced performance is attributable to the change of the surface structure and properties of alloy powders by pretreatment.