▎ 摘　　要

Graphene-carbon nanofiber/MnO2 nanocomposite paper (GMP) is prepared via a simple chemical reaction between KMnO4 and carbon materials in acidic solution, in which MnO2 nanosheets are uniformly deposited on the graphene-carbon nanofiber paper. Owing to its freestanding structure, GMP is directly used as an electrode in the electrochemical tests without addition of any binders or conductive additives. Encouragingly, GMP exhibits an excellent capacitive performance with a high specific capacitance of 298.2 F g(-1) at 1 A g(-1) in 1 M Na2SO4 electrolyte. Meanwhile, this composite paper can withstand high scan rate loads without a large decrease of capacitance, the specific capacitance can be remaining at 370.4 F g(-1) even at 300 mV s(-1). In the cycling test, the composite paper presents an outstanding stability with 95.7 % capacitance retention after 3000 cycles. Additionally, the asymmetric supercapacitor is fabricated based on GMP electrode, it not only shows a high operating voltage of 2.0 V but also exhibits a high energy density of 23.0 Wh kg(-1) at 450.8 W kg(-1). Therefore, this kind of composite paper would be promising as electrode materials for flexible and high performance supercapacitors.