Flexible solid-state supercapacitor fabricated by metal-organic framework/graphene oxide hybrid interconnected with PEDOT

Abstract

We have successfully synthesized the Hong Kong University of Science and Technology-1 (HKUST-1) metal organic framework (MOF)-graphene oxide (GO) hybrids (noted as H-G) onto carbon nanotube film (CNTF) and further electrochemically deposited poly(3,4-ethylenedioxythiophene) (PEDOT) to give a flexible conductive porous electrode (noted as PEDOT/H-G-CNTF), which shows excellent electrochemical performance due to the mesoporous structure of H-G in PEDOT/H-15G-CNTF hybrid. Electrochemical studies show that the PEDOT/H-15G-CNTF exhibits an exceptional areal capacitance of 128 mF cm−2 at 10 mV s−1 than that of PEDOT/HKUST-1-CNTF (81 mF cm−2) in a three-electrode system, indicating that the incorporation of GO into the hybrids effectively boosts the capacitive performance of PEDOT/HKUST-1-CNTF. To further explore the capacitive performance of PEDOT/H-15G-CNTF electrode, a symmetric flexible solid-state supercapacitor has also been assembled and tested. The assembled optimum flexible supercapacitor shows superior areal capacitance (37.8 mF cm−2) at the scan rate of 5 mV s−1, and good charge/discharge capability using PVA/H3PO4 gel electrolyte. The volumetric energy density for this device is calculated to be 0.051 mWh cm−3, with a volumetric power density is 2.1 mW cm−3 at current density of 0.4 mA cm−2. The device exhibits the excellent electrochemical property and mechanical properties under different bending angles.