Nowadays, due to the use of fossil fuels, environmental pollution, global warming, and rapid resource depletion, the technological advances in modern society have driven the development of a variety of electrochemical power sources, which offer "clean energy". The exponential growth in various portable electronic devices, as well as interest in electric vehicles for clean air, has created intense worldwide activity in electrochemical power sources. Among several existing power sources, supercapacitors are gaining much attention due to their excellent power density along with moderate energy...

In recent years, supercapacitors are leading among electrochemical energy storage devices since they can efficiently store energy produced from renewable energy sources. Moreover, supercapacitors attract more attention than batteries because of safety and numerous advantages over batteries as high power, instant charging, and long cycle life. Nowadays, metal phosphates have been attracting much attention for application in energy storage devices and catalysis due to their low cost, high conductivity, and redox reversibility. Besides such excellent properties, very few metal phosphate...