Investigation of Co-B-S system as anode material for secondary alkaline battery

A series of novel Co-S-B systems were prepared by simple chemical reduction method as the anode material for secondary alkaline batteries. The prepared samples were investigated by inductivity coupled plasma optical emission spectrum (ICP), Brunauer-Emmetr-Teller (BET) method, scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray energy dispersive spectroscopy (EDS) and charge-discharge method. It was found that the BET surface area of Co-S-B system increases and its particle size decreases with increasing the sulfur content. Sulfur incorporation suppresses initial capacity fading of Co-B compound due to irreversible dissolution of boron, and Co-S-B electrodes show enhanced electrochemical capacity and excellent cycle performance. The discharge capacity of Co75.4B17S7.6 reaches 513.6 mAh/g at a moderate current density of 100 mA/g and 470 mAh/g after 60 cycles, which is about 1.5 times that of conventional AB5-type alloy. A proper mechanism was proposed to explain the electrochemical reaction process of Co-S-B electrode.