High performance supercapacitors enabled by conducting polymer-nanomaterial composites*

Electrochemical double-layer capacitors (EDLCs) have attracted a great deal of attention in recent years due to their considerably high power density, long cycle life, and low maintenance cost. However, the small double layer capacitance often limits the application of EDLCs. Here we present EDLCs composed nanocomposites that exhibit considerably enhanced power density, capacitance, and cycling life. For example, EDLC composed of graphene-PdNPs show exhibit specific apacitance of 637 F g^-1, excellent cyclic performance, and maximum energy and power densities of 56 Whkg^-1 and 1166 Wkg^-1, respectively at a current density of 1.25 Ag^-1. An EDLC composed of graphene nanosheets, AgNPs, and polyparrole exhibits specific capacitance of 450 F g(-1) at current density of 0.9 mA g(-1) and high charge discharge reversibility, retaining over 92.0% of its initial value after 1000 cycles. In addition to their superior elctrochemical performance, these EDLCs also offer promises as structural material.