CoFe(2)O(4) Hollow Spheres-Decorated Three-Dimensional rGO Sponge for Highly Efficient Electrochemical Charge Storage Devices

[Image: see text] The energy demand, the crisis of fossil fuels, and the increasing popularity of portable and wearable electronics in the global market have triggered the demand to develop high-performance flexible all-solid-state supercapacitors that are capable of delivering high energy at high power density as well as being safely entrenched in those electronics. Herein, we have designed a nanocomposite, 80CF(hs)-20rGO(sp), which exhibits a high specific capacitance (C(S)) value of 1032 F g(–1) at 3 A g(–1). Utilizing this nanocomposite as the cathode and reduced graphene oxide sponge (rGO(sp)) as the anode, a flexible all-solid-state asymmetric device has been fabricated. In this device, poly(vinyl alcohol) (PVA) gel embedded with a mixture of 3 M KOH and 0.1 M K(4)[Fe(CN)(6)] was used as an electrolyte cum separator. The fabricated device showed the capability to deliver an energy density of 65.8 W h kg(–1) at a power density of 1500 W kg(–1) and retained its capability even after various physical deformations. The device also exhibited a long cycle life and retained ∼96% of its C(S) value after 5000 cycles. Moreover, the fabricated flexible all-solid-state device successfully illuminated light-emitting diodes, which proved its potential use in real-life supercapacitor applications. The obtained results revealed the excellent electrochemical performances of the fabricated device and rendered it a promising candidate in the energy sector.