Ultrahigh capacitance of nanoporous metal enhanced conductive polymer pseudocapacitors

A high energy density is critical for supercapacitors to supersede conventional batteries for the applications where both high power and high energy are demanded. Here we report nanoporous metal/conductive polymer hybrid electrodes fabricated by electrochemically plating conductive polypyrrole into nanoporous channels of a dealloyed nanoporous metal. The low electric resistance and open porosity of the nanoporous metal give rise to excellent conductivity of electrons and ions and hence dramatically improved electrochemical performances of the pseudocapacitive polypyrrole. Supercapacitors based on the hybrid electrodes show an ultrahigh energy density of ∼100 Wh kg−1 in a three-electrode, comparable to NiMH batteries, as well as high power density of ∼57 kW kg−1. Cycling stability measurements demonstrate that the hybrid electrode can retain 85% of the maximum capacitance after 3000 cycles and the degeneration is mainly caused by the dissolution of polypyrrole during charge/discharge cycling. ► NPG-PPy hybrid electrodes are fabricated by combining dealloying and electropolymerization. ► Nanoporous hybrid structure facilitates charge transport and thus has low internal resistance. ► Ultrahigh energy densities of ∼100 Wh kg−1 in a 3-electrode configuration, comparable to NiMH batteries, can be achieved. ► High power density of ∼57 kW kg−1 is retained along with ultrahigh capacitance. ► The hybrid electrodes keep up to 85% the maximum capacitance after 3000 cycles.