Highly amorphous cobalt phosphate synthesized via microwave route as a superior positive electrode material for asymmetric supercapatteries

Supercapattery has emerged as a promising energy storage solution, combining the attributes of batteries and supercapacitors to deliver a system with outstanding power and energy density. This study involved the synthesis of four cobalt phosphate (Co₃(PO₄)₂) samples using sonochemical and microwave-assisted hydrothermal methods, with two samples undergoing post-calcination at 200 °C. Among these samples, the one synthesized through microwave-assisted hydrothermal synthesis followed by calcination at 200 °C (CM-200) exhibited the highest specific capacity of 272.74C/g, surpassing the others. The exceptional performance of CM-200 can be attributed to its amorphous nature, offering abundant redox-active sites for efficient redox reactions. In constructing a supercapattery, CM-200 served as the positive electrode alongside activated carbon as the negative electrode, resulting in an energy density of 18.85 Wh/kg and a power density of 750 W/kg. Moreover, this supercapattery displayed impressive durability, enduring up to 3000 cycles while retaining 98.55 % of its initial capacity.