Flash Nitrogen-Doped\nGraphene for High-Rate Supercapacitors

Abstract

Novel structured graphene produced by an environmentally-friendly\nand high-yielding method together with excellent electrochemical energy\nstorage performance is pursued. A one-pot, solvent- and catalyst-free\nflash Joule heating approach is developed for synthesizing nitrogen-doped\ngraphene and so named as flash nitrogen-doped graphene (FNG). The\nprecursors of amorphous carbon black and urea are quickly converted\ninto high-quality FNG in less than 1 s under a short electrical pulse\nwith a bright flash of blackbody radiation. The prepared FNG product\nfeatures high graphitization with a turbostratic structure. It delivers\na high surface-area-normalized capacitance of 152.8 μF cm^–2 at 1 A g^–1, an extraordinary rate\ncapability with prominent capacitance retention of 86.1% even at 128\nA g^–1, and a knockdown relaxation time of 30.2 ms.\nBesides, the assembled symmetric quasi-solid-state supercapacitor\nexhibits a high energy density of 16.9 Wh kg^–1 and\na maximum power density of 16.0 kW kg^–1, as well\nas desirable cyclic stability (91.2% of initial capacitance is maintained\nafter 10000 cycles). These outstanding performances show that FNG\nis a promising candidate for exploiting high-performance supercapacitors.