Effect of low-temperature ethanol-thermal treatment on the electrochemical properties of Co–B alloy as anode materials for alkaline secondary batteries

The crystallinity of amorphous Co–B alloy prepared from Co(NO3)2 and KBH4 was improved by low-temperature ethanol-thermal treatment without occurrences of decomposition and side reaction. All samples were characterized by X-ray powder diffraction (XRD), scanning electron micrograph (SEM), inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), specific surface area (SBET), cyclic voltammetry (CV), and charge–discharge test. It is found that Co–B alloy without ethanol-thermal treatment has poor electrochemical utilization and shows only an initial discharge capacity of 137 mAh g−1 at a constant current of 100 mA g−1. After being ethanol-thermal treated, the charge–discharge reversibility was improved. Among all the electrodes, the Co–B alloy treated for 12 h has the highest initial discharge capacity of 330 mAh g−1 due to the enhanced synergistic effect between Co and B. However, the Co–B alloy treated for 48 h shows very good cycling performance for its higher crystallinity. After 50 cycles, it still has a discharge capacity of 270 mAh g−1 with a capacity retention of 97.5%.