A New High-Current Electrochemical Capacitor Using MnO2-Coated Vapor-Grown Carbon Fibers

Abstract

Composites of MnO2 nanosheet arrays vertically grown on the surface of vapor-grown carbon fibers (VGCFs) are fabricated by a low-temperature redox reaction between KMnO4 and the VGCFs. An assembled AC/0.5 M K2SO4/MnO2@VGCF electrochemical capacitor exhibits a higher specific capacitance, as well as a better rate capability, at a fast-current density compared to the capacitor built on hydrothermally prepared, standalone MnO2. Electrochemical tests revealed that VGCFs act as a conducting matrix, which effectively improves the conductivity of MnO2 nanosheets during cycling.