Sr-doped Cu-MOF/PANI nanocomposites for high-performance supercapacitor application with enhanced capacitive and stability
摘要
Metal–organic frameworks (MOFs) are promising candidates for energy storage due to their tunable porosity. However, their practical application is often hindered by poor electrical conductivity and the blockage of active sites. In this study, a novel strontium-doped copper MOF (SR-doped Cu-MOF) was synthesized via a facile hydrothermal process and subsequently integrated with the emeraldine form of polyaniline (PANI) to form a high-performance composite. The structural and chemical properties of the materials were rigorously characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Electrochemical evaluation revealed that the Sr-doped Cu-MOF exhibited non-faradaic characteristics with a specific capacitance of 474 F/g; the Sr-doped Cu-MOF/PANI composite achieved a significantly enhanced specific capacitance of 688 F/g in a three-electrode system. In device fabrication, the Sr-doped Cu-MOF/PANI composite achieves a specific capacitance of 571 F/g. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) confirmed the synergistic effect of the composite, highlighting improved redox kinetics. Notably, the composite demonstrated exceptional cyclic stability, retaining 99% of its initial capacitance after 10,000 cycles. To differentiate between charge storage mechanisms, Dunn’s method was employed. The analysis revealed that diffusion-controlled (faradaic) processes dominated at low scan rates, accounting for 89% of the total charge storage at 5 mV s−1, with capacitive contributions increasing to 40% at 200 mV s−1. The device delivered a high energy density of 63.2 Wh/kg and power density of 1060 W/kg.