ZIF-8 nanocrystals derived N-doped carbon decorated graphene sheets for symmetric supercapacitors

Sandwich-like ZIF-8 nanocrystal derived N-doped carbon decorated graphene sheets are developed through in-situ growth and followed by a thermal annealing treatment. The sandwich-like N-doped carbon decorated graphene sheets (NCGs) contain graphene substrate and the carbon nanoparticles with 30-50 nm in size. The sandwich-like NCGs generate a large specific surface area of 816.4 m(2) g(-1). With the high surface area and nitrogen doping, the as-fabricated NCGs as electrode materials for supercapacitor exhibit high specific capacitance of 225.0 F g(-1) at 0.5 A g(-1), an enhanced rate capability and excellent electrochemical stability with 96.8% retention after 10000 cycles even at 10 A g(-1). The symmetry supercapacitor based on NCGs delivers an energy density of 12.7 Wh kg(-1) at a specific power of 447 W kg(-1). When the power density increases to 15126 W kg(-1), the energy density can still keep 6.5 W h kg(-1). Furthermore, the symmetry supercapacitor shows an excellent cycle stability with 96.6% capacitance retention at 2 A g(-1) after 10000 cycles. (c) 2018 Elsevier Ltd. All rights reserved.