Flash Nitrogen-Doped Graphene for High-Rate Supercapacitors

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