Effect of Si on electrochemical hydrogen storage properties of crystalline Co

To investigate the effect of Si on the electrochemical properties of crystalline Co, Co–Si samples were synthesized by simple mixing of Co and Si, the electrochemical properties of them were studied as negative electrodes for nickel–metal hydride batteries in aqueous KOH solution. The results show that all the samples possess excellent electrochemical characteristics. When the weight ratio of Co to Si is 4:1, the sample electrode shows the best performance among the as-prepared materials, whose maximum discharge capacity is 419.9 mAh g - 1 and the capacity remains 352.2 mAh g - 1 after 50 cycles at the discharge current density 25 mA g - 1 , the retention rate is 83.9%. Analysis of electrode reaction mechanism demonstrates that the discharge capacity is attributed to hydrogenation of Co, where the crucial role Si has a catalytic activity.