Synthesis of nano-scale coated manganese oxide on graphite nanofibers and their high electrochemical performance

In this work, manganese dioxide (MnO2) was coated onto graphite nanofibers (GNFs), which were used as the substrate, by the direct coating method to improve their electrical performance. The effect of the thickness of MnO2 coated onto the GNFs on the electrochemical performance of the MnO2-GNFs was investigated. It was found that a nano-scale coating (about 10–20 nm) of MnO2 on GNFs can easily be achieved using the direct coating method. From cyclic voltammograms, the electrochemical performance of MnO2-GNFs was depended on the thickness of MnO2 coated onto GNFs, and in a current density of 0.1 A/g, the specific capacitance (252 F/g) of thin MnO2 (10 nm) coated GNFs was higher than that (113 F/g) of thick MnO2 (20 nm) coated GNFs. This indicated that an improvement in the electrochemical performance of MnO2-GNFs could be obtained by coating the GNFs with a nano-scale thickness of MnO2, leading to an improvement in the pseudocapacitive reaction of MnO2 during charge/discharge tests.