Rational Design of Copper Phosphate based Polyanionic Framework for High Performance Supercapacitor

The key to high-performing supercapacitors is their abundance, low cost, and ability to deliver high capacitance in a wide electrochemical window. A new class of phosphate-based polyanion material has been developed to deliver high capacitance via the effective utilization of their oxidation states. Cu3(PO4)2 was synthesized by the facile hydrothermal technique and delivers an ultra high specific capacitance of about 814 F/g with multiple discharge plateaus at a current density of 1 A/g within a voltage window ranging from 0.4 v to -1.2 V. This intriguing behavior is mainly due to the multi functional Cu while interacts with the electrolytic ions and also the inductive effect of a phosphate group (PO4)2− contributes to a high discharge voltage of -1.2V during charging and discharging process. It shows exceptional cyclic stability of 100 % over 10,000 cycles without sacrificing its coulombic efficiency and it is pertinent the structural stability of the system. The symmetric device was fabricated and delivered power density and energy density of 4.5 kW/kg and 31.5 Wh/kg, and also maintained excellent cyclic stability at 92% with high reversibility of charged ions. This offers new insights into the high potential of using polyanion-type compounds as high-capacity materials for advanced energy storage systems.