Designed Construction of a Graphene and Iron Oxide Freestanding Electrode with Enhanced Flexible Energy-Storage Performance

In this work, a bendable graphene@iron oxide hybrid film (GFeF) electrode was fabricated through a filtration assisted self-assembly method. Morphological characterization of GFeF revealed a uniform distribution of iron oxide nanoparticles between graphene nanosheets. Surface chemical characterization confirmed that graphene oxide in the as-prepared hybrid film was effectively reduced after thermal reduction. The electrochemical performance of a GFeF half-cell versus Li/Li+ exhibited high gravimetric capacity (855.2 mAh g(-1) at 0.02 A g(-1)), high volumetric capacity (1949.9 mAh cm(-3) at 0.02 A g(-1)), and superior cycling stability (93% capacitance retention after 500 cycles). On the basis of such a bendable electrode, a hybrid Li-ion supercapacitor that offers an operation voltage of 3.5 V and delivers a high energy density (129.6 Wh kg(-1)) like a Li-ion battery combined with a high power density (1870 W kg(-1)) like a supercapacitor was fabricated. In addition to the superior energy-storage capability, the as-fabricated prototype pouch cell also exhibited excellent mechanical flexibility and stable electrochemical performances under dynamic bending. The viability of such an energy-storage device provides a possible design pathway for future wearable electronics.