E everyday growing demand. electrical energy can be efficiently stored in electrochemical storage devices such as supercapacitors, batteries, and fuel cells. among them, rechargeable (metal-ion/ metal-air) batteries form the most promising and commercially viable solution. owing to the light weight and high energy density, li-ion battery (lib) has seen unprecedented commercial success. phosphate-based polyanionic materials (e.g. lifepo4) have been proposed as robust and safe cathode materials for the next generation lib . in addition to efficient intercalation chemistry, various phosphate-based compounds have been reported to exhibit efficient bi-functional catalysis for water splitting showing good oxygen evolution reaction (oer) with appreciable oxygen reduction reaction (orr) activity . also low theoretical capacity associated to the high molecular weight of such phosphate-based system has withdrawn attention towards electrocatalysis and found to shown activity close to conventional and commercial electrocatalysts such as pt/c and ruo2. so, these phosphate compounds can be used to develop metal-air batteries.