Lin Y.-P.Tsai C.-B.Ho W.-H.Wu N.-L.2019-05-172019-05-17201102540584https://scholars.lib.ntu.edu.tw/handle/123456789/409002MnO2 has been deposited onto two types of carbon (C) substrates, including a non-porous multi-wall carbon nano-tube (CNT) and a porous carbon black (CB) powder, by a solution reduction process where MnO4 - was reduced at 80 ¢XC by the C substrate so as to give nano-crystalline MnO2 directly at the C surface. The nature of the C substrate has profound effects on polymorphicity, microstructure and electrochemical properties, in terms of supercapacitor application, of the resulting oxide. Deposition on CNT produces meso/macro-porous layer containing predominantly spinel MnO2 strongly bonded to the CNTs and having a larger surface area, while that on CB results in birnessite granules with a lower surface area. In addition to having a higher specific capacitance (309 F g-1), the MnO2/CNT electrode exhibits superior power performance (221 F g-1 at 500 mV s-1 or ca. 20 Wh kg -1at 88 kW kg-1) to MnO2/CB due to reduced electronic and ion-diffusion resistances. Furthermore, the MnO2/CNT electrode also exhibits slower self-discharging rate and greater cycling stability. The results indicate that the MnO2 spinel/CNT holds promise for supercapacitor applications. ? 2011 Elsevier B.V. All rights reserved.Chemical synthesisComposite materialsNanostructuresSupercapacitorjournal article10.1016/j.matchemphys.2011.06.0502-s2.0-80052577161https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052577161&doi=10.1016%2fj.matchemphys.2011.06.050&partnerID=40&md5=839d2132db131053b251bade07b008c4