Structure design of MOF-derived Fe2O3 for high-performance asymmetric supercapacitors

Abstract

The enhancement of electrochemical performance in supercapacitors is significantly dependent on the development of electrode materials characterized by optimized morphology and size. Fe₂O₃ is a promising material among various candidates, but its practical applications are hindered by internet challenges such as poor conductivity. In this study, Fe-MOF was employed as a precursor template for synthesizing Fe₂O₃, and polyvinylpyrrolidone (PVP) was introduced to regulate crystal growth. This approach led to the successful synthesis of Fe₂O₃ particles with three distinct morphologies. The MFO-2 material, characterized by a large surface area, exhibited an impressive specific capacitance of 96.8 mAh g⁻¹ at a current density of 1 A g⁻¹. To further explore its practical application, an asymmetric supercapacitor was assembled with MFO-2 as the negative electrode and super-activated carbon (AC) as the positive electrode. The resulting AC//MFO-2 supercapacitor demonstrated a maximum energy density of 20.12 Wh kg⁻¹ at a power density of 140 W kg⁻¹. It retained 90.5 % of its capacity after 10,000 charge-discharge cycles at 2 A g⁻¹, confirming its excellent cycling stability. Additionally, the two devices were connected in parallel and successfully powered an LED light, providing strong evidence for the practical applicability of the proposed system.