Ag nanoparticles-decorated hierarchical porous carbon from cornstalk for high-performance supercapacitor

In this work, hierarchical porous carbon is successfully synthesized by a simple carbonization approach using cornstalk as the precursor. And then the decoration of Ag nanoparticles (NPs) to cornstalk-derived porous carbon (CSPC) is further performed through an in-situ reduction reaction to obtain the composite material (CSPC-Ag). By using electron transport channels and active sites of Ag NPs to promote the diffusion of electrolyte ions, the CSPC-Ag electrode exhibits an improved specific capacitance. When the loading amount of Ag NPs on CSPC is optimized to be 5 wt%, the most outstanding electrochemical performance could be achieved that the specific capacitance was up to 323.8 F∙g−1 at 0.5 A∙g−1, which have 1.8 times enhancement compared to the undecorated CSPC. In addition, the CSPC-Ag electrode shows an excellent cyclic stability that the specific capacitance was only reduced by 6.8% after 4000 cycles at 10 A∙g−1. Furthermore, the energy density of the CSPC-Ag based asymmetric supercapacitor reaches 15.9 Wh∙kg−1 at 11.2 kW∙kg−1 in the KOH electrolyte. Our work provides a facile strategy for developing high-performance Ag nanoparticles-decorated hierarchical porous carbon electrodes in supercapacitors as well as realizing the high value-added conversion and utilization of agricultural waste cornstalk.