▎ 摘　　要

Due to the urgent demand for portable electronics, enormous research efforts are devoted for the development of flexible, wearable and lightweight supercapacitors. Herein, free-standing, binder-free and high-performance metal @ carbon sphere/graphene film electrodes (Fe@C/G and Co@C/G), consisting of beta-cyclodextrins (beta-CDs) as carbon sources, iron and cobalt as metal materials, and graphene sheets as "binders", have been synthesized and characterized. The resultant Fe@C/G and Co@C/G film electrodes exhibit maximum areal specific capacitances of 2.19 F cm(-2) and 0.80 F cm(-2) at 0.5 mA cm(-2) (438 F g(-1) and 160 F g(-1)), respectively. Furthermore, a flexible asymmetric all-solid-state supercapacitor (Fe@C/G//Co@C/G) is assembled and it displays a series of intriguing features including high volumetric specific capacitance of about 13.3 F cm(-3) at 0.5 mA cm(-2), excellent volumetric energy density of up to 5.99 mWh cm(-3) at a volumetric power density of 0.013 W cm(-3), and good cycle stability of 87.3% capacitance retention after 10,000 charge/discharge cycles. Even after 500 bending/unbending cycles, still about 80.5% of its initial capacitance is retained. Such results well demonstrate its strong potential for the practical applications of flexible energy storage devices.