Supercapacitors based on composite material of MnO2 and carbon nanotubes

Nano MnO₂ powder produced by liquid coprecipitation method was absorbed on the surface of carbon nanotubes, which were synthesized by microwave plasma chemical vapor deposition, to form MnO₂-CNT composite material using ultrasonic mixing method for supercapacitor electrodes. The electrochemical performance of the prepared electrodes was measured by galvanostatic charge-discharge cycling test in 0.5 mol/L Na₂SO₄ aqueous solution. The results showed that MnO₂-CNT composite electrodes presented good electrochemical performance with specific capacitance of 238.7 F/g, much higher than that of MnO₂ electrodes which the specific capacitance only reached about 78.6 F/g, and the equivalent resistance of MnO₂-CNT composite electrodes was about 34.8 Ω, half less than that of MnO₂ electrodes with equivalent resistance of 87.6 Ω.