Facile synthesis and capacitive characteristics of Co(OH)2 nanoflakes via a solid-reaction route at room temperature

Flake-like β-Co(OH)2 with dimension around 20–50 nm was conveniently synthesized via a simple, low cost and practical room-temperature solid-state reaction with the assistance of polyethylene glycol (PEG) 400 and its electrochemical properties were evaluated using cyclic voltammetry (CV) and galvanostatic charge–discharge technology. A high specific capacitance of 658.4 F g− 1 at 5 mA was observed for the β-Co(OH)2 nanoflakes, compared to 302.7 F g− 1 for the block-like β-Co(OH)2 obtained without the PEG-400, showing the morphological function of nanoflakes for improving the capacitive performance. Furthermore, the β-Co(OH)2 nanoflakes can offer a good specific capacitance retention of ca. 80% after 1000 cycles, suggesting its potential application in supercapacitors.