Facile synthesis of MnO2-Cu composite electrode for high performance supercapacitor

Abstract

Here, we report a facile approach for the development of unique nanoporous MnO2-Cu architecture through a combination of severe surface deformation and dealloying. The severe surface deformation of Cu-Mn alloy prior to selective dealloying resulted in the precipitation of nanoporous MnO2 in the Cu-rich substrate. The in situ grown nanoporous MnO2-Cu architecture demonstrated an areal capacitance of 2.8 F/cm2 at a current density of 5 mA/cm2 and exhibits an excellent cyclic stability of 95% retention for 4000 cycles at 15 mA/cm2 current density. The MnO2-Cu composite structure showed small charge transport resistance of 1.9 Ω as determined using impedance spectroscopy. The asymmetric supercapacitor fabricated using nanoporous MnO2-Cu as anode and reduced graphene oxide as cathode delivers specific energy of 5.55 Wh kg−1 at a specific power of 249.75 W kg−1. The superior performance of nanoporous MnO2-Cu architecture was attributed to its unique microstructure that ensures high surface area, small internal resistance with rapid charge transport. The current approach can be applied to different material systems and is potentially transformative in the emerging field of advanced supercapacitors.