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 MnO ₂ 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 MnO ₂, leading to an improvement in the pseudocapacitive reaction of MnO₂ during charge/discharge tests.