Electrochemical properties of Co-S/x wt.% AB5 composite materials

Abstract

The Co-S/x wt.% AB5 (x=0, 10, 20, 30) composite materials were prepared by simply mixing Co-S material fabricated by hydrothermal method and AB5 alloy. The structure and morphology of the composite materials were characterized by XRD and SEM, respectively. The electrochemical properties of the composite electrodes were studied by the galvanostatic charge, discharge test and electrochemical impedance spectroscopy. The results showed that the Co-S/20 wt.% AB5 composite electrode showed the highest discharge capacity and the best cycling stability. The existence of the AB5 alloy improved the electrochemical activity of composite electrodes, reduced the electrochemical polarization resistances and promoted the electrochemical conversion reaction between Co and Co(OH)2. In order to improve the utilization rate of active materials, 0.01 mol/L Na2S2O3 was added into the electrolyte. The electrochemical properties of the composite electrode were significantly enhanced. After fifty cycles, the discharge capacity of the composite electrode increased from 407 to 481.7 mAh/g and the capacity retention increased from 79.7% to 91.2%.