Preparation of supercapacitor electrode material based on the cobalt hydroxide nanoplates via cathodic electrodeposition and investigation of its supercapacitive performance

In this study, cobalt hydroxide nanoplates were prepared from nitrate bath by electrochemical deposition method. Electrodeposition experiments were performed at a current density of 0.5 mA cm-2 in RT condition. The structure and morphology of the prepared sample were investigated via XRD, FT-IR, SEM and TEM analyses. The structural analyses by XRD and IR showed that the prepared deposit has pure β phase of Co(OH)2. Also, SEM and TEM observations revealed that the prepared sample has hexagonal plate-like morphology at nano-scale. The edge lengths of the plates range from 100 to 200 nm. The supercapacitive behavior of the prepared nanoplates was evaluated by cyclic voltammetry (CV) and charge-discharge tests. For this purpose, CV and charge-discharge tests of the electrode prepared from hydroxide nanoplates were conducted in the potential window of -0.2-0.55 V vs. Ag/AgCl at 1M KOH electrolyte. For first cycle of charge-discharge, the capacity as high as 915.5 F g-1 was measured which is in agreement with the values calculated form CV curves. Also, the capacity of 894.7 F g-1 was calculated for the 500th cycle, which only 2% capacity decay. These results confirmed that the β-Co(OH)2 nanoplates have excellent supercapacitive behavior and high cycle life, which can be a promising candidate for the electrochemical supercapacitors.