Pseudocapacitive enhancement of brucite-like β-Co(OH)2 nanoflakes after the removal of intercalated water

Ultrathin brucite-like β-Co(OH)2 nanoflakes are prepared by a modified solvothermal method, and further thermal treatment is conducted at different temperatures to remove their intercalated and physically adsorbed water molecules and then enhance their pseudocapacitive performance. With the increase of the thermal treatment temperature from 60 to 140 °C, the morphology, size and crystalline phase of the pristine β-Co(OH)2 gradually change. The Sample-100 shows the best pseudocapacitive performance, without obvious changes in morphology, size and crystalline phase after being thermally treated at 100 °C, and it presents high pseudocapacitance of 659.1 Fg-1 at 1 A g−1, increasing by 44.2% comparing with that of the pristine β-Co(OH)2 nanoflakes. And it also exhibits superior cycling stability with capacitance retention of 95.7% after 8000 cycles at 10 A g−1. This study also demonstrates a facile strategy to improve the pseudocapacitive performance of materials with intercalated water.