Incorporation of Homogeneous, Nanoscale MnO2 within Ultraporous Carbon Structures via Self-Limiting Electroless Deposition: Implications for Electrochemical Capacitors

Abstract

The self-limiting reaction of aqueous permanganate with carbon nanofoams produces conformal, nanoscopic deposits of birnessite ribbons and amorphous MnO₂ throughout the ultraporous carbon structure. The MnO₂ coating contributes additional capacitance to the carbon nanofoam while maintaining the favorable high-rate electrochemical performance inherent to the ultraporous carbon structure of the nanofoam. Such a three-dimensional design exploits the benefits of a nanoscopic MnO₂−carbon interface to produce an exceptionally high area-normalized capacitance (1.5 F cm^-2), as well as high volumetric capacitance (90 F cm^-3).