N-Doped Two-Dimensional Carbon Nanosheets with Micropore-Dominant Porosity for High-Performance Supercapacitor

Abstract

N-doped two-dimensional (2D) porous carbon nanosheets (PCNs) have been developed for high-performance supercapacitor through chemical crosslinking of biomass shell and γ-glutamic acid (γ-PGA) and followed by pyrolysis and activation. The C and N recomposition and pore formation processes occur within shell/γ-glutamic acid composite during pyrolysis. An optimized PCNs material has many advantages, including a large specific surface area (SSA) of 2393 m 2 g -1 , unique 2D nanosheet structure, and rich microporous structure. The rich oxygen/nitrogen functional groups and 2D nanosheet structure lead to the materials with super hydrophilicity, and also provide extra pseudocapacitance. With these added structural advantages and the component synergy, the PCNs show superior performance, for which the specific capacitance is 321 F g -1 in a three-electrode system, and only with a 7% capacitance loss after 13000 cycles at 5 A g −1 . Furthermore, a PCNs-based symmetric supercapacitor displays a high specific energy of 9.7 W h kg -1 at a power density of 275 W kg -1 . Biomass-derived materials have become promising electrode materials and their usage in energy storage devices is expected to increase.

Keywords: biomass, N-doped, porous carbon nanosheet, microporous structure, supercapacitor