The compound β-Co(OH)2 was synthesized by solid-state chemical reaction of CoCl2·6H2O and NaOH at room temperature in air without inert gas present.Structure and electrochemical characteristics of β-Co(OH)2 were studied.XRD pattern is identical with that of pure β-Co(OH)2 with hexagonal crystal system.FE-SEM micrographs show that the β-Co(OH)2 is flaky,about 500 nm in diameter and several dozen nanometers in thickness.The thermal gravity analysis (TG) result shows that the compound is pure β-Co(OH)2,and the cyclic voltammetry indicates it undergoes reversible oxidation-reduction reaction upon charge/discharge process.Electrochemical experimental results demonstrate that the maximum discharge capacity of β-Co(OH)2 reaches 466 mAh·g-1,superior to that of the well-known AB5 alloys,showing great attractive in use as negative electrode materials of rechargeable batteries.Now main drawback of β-Co (OH)2 used as electrode materials is that the discharge platform is low and the discharge capacity decreases as a wave.But It is found that graphite and La2O3 additives can increase the discharge platform and smooth undulation in discharge capacity of β-Co (OH)2 electrodes.