Crystalline CoB: Solid state reaction synthesis and electrochemical properties

Using a facile and effective method based on the solid phase reaction between Co(OH)2 and KBH4, we successfully synthesize orthorhombic CoB. It is shown that this CoB obtained is of high purity and thermal stability. A possible formation process for orthorhombic CoB is discussed in detail. In addition, crystalline CoB shows excellent electrochemical reversibility and considerable high charge–discharge capacities when it is used as the anode material for nickel-based secondary batteries. The reversible discharge capacities of the CoB electrode are found to be about 380 mAh g−1 at a discharge current of 25 mA g−1 and 360 mAh g−1 at 100 mA g−1. Moreover, electrochemical reaction mechanism of CoB is investigated in detail.

► We report a new way to prepare orthorhombic CoB for the first time.
► The reversible discharge capacity of CoB electrode obtained is about 380 mAh g−1.
► The high capacity is attributed to the electrochemical oxidation of Co to Co(OH)2.