A Novel Aqueous Asymmetric Supercapacitor based on Pyrene-4,5,9,10-Tetraone Functionalized Graphene as the Cathode and Annealed Ti3C2Tx MXene as the Anode

Asymmetric supercapacitors (ASCs), employing two dissimilar electrode materials with a large redox peak position difference as cathode and anode, have been designed to further broaden the voltage window and improve the energy density of supercapacitors. Organic molecule based electrodes can be constructed by combining redox-active organic molecules with conductive carbon-based materials such as graphene. Herein, pyrene-4,5,9,10-tetraone (PYT), a redox-active molecule with four carbonyl groups, exhibits a four-electron transfer process and can potentially deliver a high capacity. PYT is noncovalently combined with two different kinds of graphene (Graphenea [GN] and LayerOne [LO]) at different mass ratios. The PYT-functionalized GN electrode (PYT/GN 4-5) possesses a high capacity of 711 F g(-1) at 1 A g(-1) in 1 M H2SO4. To match with the PYT/GN 4-5 cathode, an annealed-Ti3C2Tx (A-Ti3C2Tx) MXene anode with a pseudocapacitive character is prepared by pyrolysis of pure Ti3C2Tx. The assembled PYT/GN 4-5//A-Ti3C2Tx ASC delivers an outstanding energy density of 18.4 Wh kg(-1) at a power density of 700 W kg(-1). The PYT-functionalized graphene holds great potential for high-performance energy storage devices.

Automated summary

Asymmetric supercapacitors (ASCs) have been designed to increase the voltage window and energy density of supercapacitors by using two dissimilar electrode materials. In this study, the combination of redox-active organic molecule (pyrene-4,5,9,10-tetraone) with graphene-based materials resulted in a high capacity electrode. The assembled ASC using PYT-functionalized graphene as cathode and annealed-Ti3C2Tx MXene as anode achieved an outstanding energy density of 18.4 Wh kg(-1) at a power density of 700 W kg(-1). PYT-functionalized graphene shows great potential for high-performance energy storage devices.