Liquid-crystal mediated assembly of iodinated graphene oxide for ultra-dense supercapacitors as safe power source for Internet of Things data transmission

Dense iodinated reduced graphene oxide (rGO) with outstanding electrical and electrochemical properties is produced through a green method comprising liquid crystal-mediated assembly of polyiodides and GO, and subsequent UV irradiation. The dense rGO electrode (1.46 g/cm³) exhibited a very high volumetric capacitance of 226 F/cm³, a factor of three larger than commercial activated carbon, and amongst the highest reported for graphene. The scalability is demonstrated by the fabrication of supercapacitor pouch cells that realized a volumetric energy density of 0.94 Wh/l, comparable to market products with similar footprint, while advantageously using a safe and green aqueous electrolyte. Our pouch cell powered battery-less Internet of Things (IoT) sensor nodes and demonstrated sensing and transmission of over 40 temperature and relative humidity data packets. Our work establishes the critical advantages graphene-based materials have over activated carbons in terms of ease of fabrication, tailorability, and enhanced volumetric energy density to advance the state-of-art in supercapacitor device research.