Covalent Graphene-MOF Hybrids for High-Performance Asymmetric Supercapacitors

• In this work, the covalent attachment of an amine functionalized metal-organic framework (UiO-66-NH2 = Zr6O4(OH)4(bdc-NH2)6; bdc-NH2 = 2-amino-1,4-benzenedicarboxylate) (UiO-Universitetet i Oslo) to the basal-plane of carboxylate functionalized graphene (graphene acid = GA) via amide bonds is reported. The resultant GA@UiO-66-NH2 hybrid displayed a large specific surface area, hierarchical pores and an interconnected conductive network. The electrochemical characterizations demonstrated that the hybrid GA@UiO-66-NH2 acts as an effective charge storing material with a capacitance of up to 651 F g−1, significantly higher than traditional graphene-based materials. The results suggest that the amide linkage plays a key role in the formation of a π-conjugated structure, which facilitates charge transfer and consequently offers good capacitance and cycling stability. Furthermore, to realize the practical feasibility, an asymmetric supercapacitor using a GA@UiO-66-NH2 positive electrode with Ti3C2TX MXene as the opposing electrode has been constructed. The cell is able to deliver a power density of up to 16 kW kg−1 and an energy density of up to 73 Wh kg−1, which are comparable to several commercial devices such as Pb-acid and Ni/MH batteries. Under an intermediate level of loading, the device retained 88% of its initial capacitance after 10 000 cycles. © 2020 The Authors. Advanced Materials published by Wiley-VCH GmbH

Nyckelord

2D materials

asymmetric supercapacitors

covalent assemblies

metal-organic frameworks

MXenes

Amides

Capacitance

Carboxylation

Charge transfer

Electrodes

Hybrid materials

Organic polymers

Organometallics

Supercapacitor

Asymmetric supercapacitor

Conductive networks

Conjugated structures

Covalent attachment

Electrochemical characterizations

Functionalized graphene

Large specific surface areas

Positive electrodes

Graphene

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