LAUSR

Abstract The metallic Cu material is synthesized via pyrogenic decomposition of Cu2(OH)2CO3 and ammonia reduction of CuO. The ammonia-induced solid phase transition process converts the material from semiconductor to conductor, and the internal chemical bond from ionic bond and covalent bond to metal bond, which makes it have high conductivity and more active sites as well as a rapid Faraday electrode reaction kinetics. Besides, the synthesized metallic Cu material can be used as positive materials for supercapacitors, which has high conductivity and displays a great specific capacity of 15 mAh g−1 (98.5 F g−1) at 0.5 A g−1. The hybrid supercapacitor device is further fabricated with activated carbon as cathode materials and it exhibits a good specific capacitance and excellent cycling performance (cost 16.7% of initial capacitance over 40,000 cycles). The electrochemical character of hybrid supercapacitor presents maximum specific energy of 6.5 Wh kg−1 at a specific power of 200.1 W kg−1. These results suggest the metallic material is a very promising electrode material for supercapacitors with superior electrochemical properties.