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 (S-BET), 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 mAg(-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%. (C) 2008 Elsevier B.V. All rights reserved.