Hydrothermally grown cobalt phosphate hydrate microflowers for supercapacitors: Effect of reaction temperature

In this work, cobalt phosphate hydrate (Co 3 (PO[Formula: see text]8H 2 O) was deposited on Ni-foam using the facile hydrothermal method with varied reaction temperatures as 120°C, 150°C and 180°C. The X-ray diffraction analysis reveals the C2/m space group of cobalt phosphate hydrate (CoPH) with a monoclinic crystal structure. Scanning electron microscopy (SEM) evaluates the effect of different reaction temperatures on the morphology of deposited thin film. The change in morphology from microflakes to three-dimensional (3D) microflowers is observed due to temperature variation. In the electrochemical study, the C2 (150°C) electrode delivers a specific capacitance of 8798[Formula: see text]mF/cm 2 (specific capacity 1.466[Formula: see text]mAh cm –2 ) at 30[Formula: see text]mA cm[Formula: see text] current density. Here, 70.65% of coulombic efficiency was observed over 1500 cycles. The energy density of 0.439[Formula: see text]Wh/cm 2 and power density of 9[Formula: see text]mW/cm 2 were delivered by optimized CoP electrodes, respectively. EIS study reveals the Rs values of C1, C2 and C3 electrodes are 1.49, 0.97 and 1.3 [Formula: see text], respectively.