High-Performance Supercapacitors of N-Doped Graphene Aerogel and Its Nanocomposites with Manganese Oxide and Polyaniline

Nitrogen-doped graphene aerogel (NG(ae)) with a three-dimensional (3D) interconnected structure with ca. 3.5 at% of nitrogen content was synthesized by a hydrothermal reduction of graphene oxide with hydrazine and a following freezing-dry method. The 3D morphology of conductive NG(ae) provides fast ion diffusion leading to nearly steady specific capacitances (ca. 450 F g(-1)) when increasing scan rates (10-100 mV(-1)) or applied currents (0.5-2.5 A g(-1)). Not only can the nitrogen-containing groups improve the electrical conductivity of NG(ae) but also they can store charges via their reversible surface redox reactions. The as-fabricated symmetric supercapacitor of NG(ae) in 1 M H2SO4 electrolyte provides a maximum specific energy and power of 42 Wh kg(-1) and 2077 W kg(-1), respectively. In addition, incorporating pseudocapacitor materials i.e., MnO2 and polyaniline to NG(ae) structure can also provide higher specific energy owing to surface redox reactions. The as-fabricated supercapacitors in this work may be practically used in high energy and power applications. (C) 2018 The Electrochemical Society.