Directly Grown Multiwall Carbon Nanotube and Hydrothermal MnO(2) Composite for High-Performance Supercapacitor Electrodes

MnO(2)–MWNT–Ni foam supercapacitor electrodes were developed based on directly grown multiwalled carbon nanotubes (MWNTs) and hydrothermal MnO(2) nanostructures on Ni foam substrates. The electrodes demonstrated excellent electrochemical and battery properties. The charge transfer resistance dropped 88.8% compared with the electrode without MWNTs. A high specific capacitance of 1350.42 F·g(−1) was reached at the current density of 6.5 A·g(−1). The electrode exhibited a superior rate capability with 92.5% retention in 25,000 cycles. Direct MWNT growth benefits the supercapacitor application for low charge transfer resistance and strong MWNT–current collector binding.