Tuning the crystallinity of ZrO2 nanostructures derived from thermolysis of Zr-based aspartic acid/succinic acid MOFs for energy storage application

Abstract

This paper investigated the effect of calcination temperatures on the structural, and capacitance of Zr-MOFs as an electrode material for supercapacitor applications. MIP-202 and 203 were prepared solvothermally, using zirconium clusters with aspartic acid and succinic acid as ligands, respectively. These MOFs are subject to heat treatment at 350 and 500 °C to be converted to ZrO2 derived from MOFs. As a result, we have six materials: MIP-202 (bare), MIP-202 (350 °C), MIP-202 (500 °C), MIP-203 (bare), MIP-203 (350 °C), and MIP-203 (500 °C). The structure of compounds were confirmed by X-ray diffraction analysis (XRD), N2 adsorption–desorption measurements, scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS). We investigated the differences in electrochemical properties in the amorphous and crystalline phases. The electrochemical performances of fabricated electrodes, including as-prepared Zr-based MOFs before heat treatment (MIP-202, MIP-203) and after that, at 350 and 500 °C, are demonstrated via electrochemical tests in a three-electrode configuration. Among the materials, MIP-202 (350) exhibits the best electrochemical efficiency due to its amorphous structure and high specific surface area, delivering a high specific capacitance of 308 F g−1 at a current density of 2 A g−1. To further identifying electrochemical properties of the electrode, an asymmetric supercapacitor was constructed utilizing graphene oxide (GO) as the anode and MIP-202 (350) as the cathode. The device provided long cyclic life durability (86 % specific capacitance maintenance after 3000 cycles) and high energy density of 16.06 Wh kg−1 and high-power density 40,000 W kg−1.