Enhanced electrochemical properties of ball-milled LaY2Ni9.5Mn0.5Al0.5 hydrogen storage alloy with graphene

Appropriate graphene were added to the LaY2Ni9.5Mn0.5Al0.5 alloy by mechanical ball milling in order to enhance discharge performance of the raw alloy. The effects of the addition of graphene on the electrochemical and dynamic properties were discussed. The results showed that the LaY2Ni9.5Mn0.5Al0.5 alloy was composed of Gd2Co7 and Ce2Ni7 phase. The addition of graphene and ball milling treatment can significantly improve the electrochemical hydrogen storage capacity of the LaY2Ni9.5Mn0.5Al0.5 alloy. The LaY2Ni9.5Mn0.5Al0.5 milled alloy with the 3 wt % addition of graphene exhibits a superior maximum discharge capacity of 277.4 mAh.g(-1) with the capacity retention of 53.9% after 100 cycles, which is higher than that of the raw alloy. The exchange current density I-0 of the alloy electrodes and diffusion coefficient of hydrogen D were also improved significantly with graphene-additive. The addition of graphene exhibits obvious advantages for improving the high-rate dischargeability of alloy electrode.