Fabrication of hybrid supercapacitor based on rod-like HKUST-1@polyaniline as cathode and reduced graphene oxide as anode

Rod-like HKUST-1 (MOF-199) was hydrothermally synthesized, and the electrochemical capacitance properties of this MOF composited with polyaniline (PANI) were studied. The electrode was characterized by X-ray diffraction technique (XRD), Brunauer, Emmett, and Teller (BET) and scanning electron microscopy (SEM). The electrochemical performance of the HKUST-1 and PANI, as well as HKUST-1/PANI (HP) composite was investigated by cyclic voltammetry and galvanostatic charge-discharge. Pure HKUST-1 showed a low specific capacitance at a current density of 1 A/g, because of its poor conductivity. However, due to the high surface area (190 m2/g) of the rod-like HKUST-1, its composite with PANI led to an improvement in electrochemical performance. The specific capacitance of HP was achieved to be 270 F/g at the current density of 1 A/g, which is much higher than that of HKUST-1 (70 F/g) and PANI (227 F/g). An asymmetric supercapacitor (ASC) was fabricated by using the HP as cathode and rGO nanosheets as anode. This ASC provided a maximum specific power of 7497 W/kg and a specific energy of 6.22 Wh/kg with a wide working potential of 1.5 V and 87% capacity retention after 2000 cycles. Two ASCs connected in series were applied, which without recharging, lightened green and red LEDs up for 3 and 5 min, respectively.