▎ 摘　　要

It is extremely important to design and fabricate high capacitance and stable Coulombic efficiency capacitors for energy storage. Herein, nitrogen-doped graphene coated on flexible tantalum foil is developed as a cathode for aluminum-ion hybrid supercapacitors which are based on an ionic liquid electrolyte with 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl)/AlCl3. The results demonstrate that the nitrogen-doped graphene cathode offers a high capacitance of 254 F g(-1), a Coulombic efficiency of similar to 90% and a cycle life of 1000 at a current density of 0.3 A g(-1). Meanwhile, the nitrogen-doped graphene cathode shows a capacitance of similar to 130 F g(-1), a Coulombic efficiency of almost 100% and a cycle life of 2000 at a higher current density of 2.0 A g(-1). Moreover, the energy storage mechanism of the nitrogen-doped graphene in the aluminum-ion hybrid supercapacitors, that is, the dominant electrical double-layer capacitance (the adsorption and desorption of AlCi(4)(-) on the surface), and the intercalation/deintercalation in the nitrogen doped graphene, are confirmed.