Tailoring crystallinity of 2D cobalt phosphate to introduce pseudocapacitive behavior

摘要

The latest technological developments have catalyzed the quest for efficient electrochemical energy storage devices. Tailoring the properties of the electrode materials, such as porosity, crystallinity, electrochemical surface area, etc., can enhance the performance of electrochemical energy devices. Herein, the sonochemical synthesis of cobalt phosphate (Co-3(PO4)(2)) followed by calcination at various temperatures (at 200, 400, 600, and 800 degrees C) is reported. The effect phase transformation of Co-3(PO4)(2) at various calcination temperatures on its electrochemical performance is evaluated. The prepared Co-3(PO4)(2) samples were characterized by analytical techniques such as X-ray diffraction spectroscopy (XRD), X-ray Photoelectron Spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), field emission scanning electrons microscopy (FESEM), and energydispersive X-ray spectroscopy (EDS). The FESEM results showed morphological changes when Co-3(PO4)(2) is calcined at 200, 400, 600, and 800 degrees C. XRD pattern revealed the phase transformations from crystalline to amorphous and then again crystalline due to the loss of water molecules from the crystal structure Co-3(PO4)(2). The EDS provided the elemental analysis and confirmed the high purity of the samples under investigation. The change in electrochemical behavior of the prepared samples was examined in a three-electrode cell using 1 M potassium hydroxide (KOH) electrolyte using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The Co-3(PO4)(2) calcined at 200 degrees C demonstrated excellent electrochemical performance, giving a specific capacity of 352.00 C.g(-1), selected for the fabrication of supercapattery. The fabricated supercapattery Co-3(PO4)(2):@200 degrees C//AC) produced 51.95 Wh.kg(-1) energy density corresponding to the power density of 346.00 W.kg(-1) at a current density of 1.0 A g(-1).