Hydrothermal synthesis and electrochemical measurements of interconnected porous carbon/mno2 composites

Abstract

This article describes the electrochemical performance of a novel interconnected porous carbon/ MnO2 (IPC/MnO2) composite prepared by in situ self-limiting deposition under hydrothermal condition. The morphology and structure were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), and the electrochemical behavior was investigated using cyclic voltammetry (CV), charge-discharge tests, electrochemical impedance spectroscopy (EIS), and cycle life tests. The results showed that MnO2 grew homogeneously on the IPC surface, forming a hierarchical microstructure. The MnO2 had a typical K-Birnessite-type crystal structure and the MnO2 content was about 34%(w). At high synthetic temperatures, the MnO2 particles on the IPC surface were smaller. The prepared electrode material exhibited a good electrochemical capacitance performance. As the reaction temperature increased, the specific capacitance of the IPC/MnO2 composite first increased and then remained constant. The IPC/MnO2 composite synthesized at 100 °C had the maximum specific capacitance, 411 F-g-1, in a three-electrode system. An asymmetric supercapacitor was constructed with the IPC/MnO2 composite as the positive electrode and activated carbon (AC) as the negative electrode, in a 1 mol-L-1 Na2SO4 electrolyte. The results showed that the corresponding potential window increased from 1 to 1.8 V. The maximum specific capacitance of the asymmetric supercapacitor was 86 F-g-1 and a good rate capability was achieved. © Editorial office of Acta Physico-Chimica Sinica.