Surface modification of metal phosphate Binder-Free electrode with metal hydroxides for supercapattery

Supercapattery is one of the emerging alternative energy storage technologies and numerous recent studies have been done in search of good electrode material for its application. Cobalt phosphate (Co3(PO4)2) is a promising candidate due to its abundance, low cost, valence states variation, and good faradaic property. However, cobalt phosphates have limited surface area, affecting its electrochemical performance. To overcome that, herein Co3(PO4)2 was synthesized via sonochemical method and calcined at various temperatures to obtain the best calcination temperature followed by coating of cobalt hydroxide (Co(OH)2) layer. The synthesis of Co3(PO4)2 and coating of Co(OH)2 over cobalt phosphate was observed through X-ray diffraction analysis (XRD) and the morphology of the synthesized nanostructures was observed using Field emission scanning electron microscopy (FESEM). Cyclic voltammetry, galvanostatic charge discharge, and electrochemical impedance spectroscopy analyses were carried out. The results showed calcination temperature of 200 degrees C followed by coating of Co(OH)2 using 2 mM metal precursor as the optimized sample. This sample exhibited the fascinating electrochemical performance of specific capacitance (2111.83F g-1 at 1 A g-1), energy density (72.51 Wh kg- 1 at 1 A g-1), and power density (2357 W kg- 1 at 10 A g-1) and fabricated supercapattery demonstrated outstanding cyclic stability up to 84 % over 15,000 charge/discharge cycles.

Automated summary

Supercapattery is an emerging alternative energy storage technology, and cobalt phosphate (Co3(PO4)2) is a promising electrode material due to its abundance, low cost, valence states variation, and good faradaic property. To improve its electrochemical performance, Co3(PO4)2 was synthesized via sonochemical method, calcined at different temperatures, and coated with cobalt hydroxide (Co(OH)2) layer. The optimized sample showed fascinating electrochemical performance and outstanding cyclic stability over 15,000 charge/discharge cycles.