Microporous 3D Graphene‐Like Carbon as Iodine Host for Zinc‐Based Battery–Supercapacitor Hybrid Energy Storage with Ultrahigh Energy and Power Densities

Zinc (Zn)‐based aqueous battery‐supercapacitor hybrid (BSH) devices are considered promising energy storage devices benefiting from their high energy and power densities, low‐cost, safety, and environmental benignity. However, challenges remain in the development of efficient BSH electrodes due to poor reversibility in battery electrodes and lack of efficient supercapacitor electrodes to solve the problems of low power and energy densities. Herein, the loading of iodine (I 2 ) in the nanopores of 3D graphene‐like carbon (3DGC) for the fabrication of BSH electrodes and their device application with Zn are reported. The uniform micropores of 3DGC serve as nanocages to stabilize I 2 , the high surface area of 3DGC maximizes the dispersion, and the high conductivity of 3DGC provides a path for fast electron transfer. The resultant I 2 ‐loaded 3DGC (I 2 /3DGC) is applied to evaluate Zn‐based battery and BSH performance. The I 2 /3DGC‐based electrode exhibits excellent performance with ultrahigh energy and power densities resulting from the high reversibility of I 2 and supercapacitance of 3DGC. The device exhibits high cyclic stability in both battery and supercapacitor modes due to the confinement of I 2 in the micropores. It is demonstrated that this combination of 3DGC with I 2 provides an easy way to fabricate durable and economical BSH electrodes.