Synthesis and electrochemical performance of β-Co(OH)2

A novel electro-active material was synthesized by precipitation under high levels of supersaturation. The compound was pure β-Co(OH)2 with hexagonal crystal structure by XRD analysis, and it was flake-shaped, 50–200 nm in particle size and ∼20 nm in thickness by FE-SEM observation. The quasireversible electrochemical reaction between β-Co(OH)2 and Co upon charging/discharging produced a maximum discharge capacity of 462 mAh g−1, and furthermore the discharge capacity retained 97.6% of the initial capacity at the 100th cycle. These findings highlight the potential for β-Co(OH)2 compound in applications to negative electrode materials of alkaline rechargeable batteries.