An excellent cycle performance of asymmetric supercapacitor based on bristles like α-MnO2 nanoparticles grown on multiwalled carbon nanotubes

• Published in: Journal of power sources 2016-03, Vol.309, p.212-220
• Main Authors: Vinny, R.T., Chaitra, K., Venkatesh, Krishna, Nagaraju, N., Kathyayini, N.
• Format: Article
• Language: English
• Subjects: Asymmetric device; Cyclability; Nanocomposite; Power source; α-MnO2
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2016.01.098

Manganese oxide nanoparticles were grown on multiwalled carbon nanotubes (MWCNT) by a simple and cost effective reduction of KMnO4. Characterization of the material revealed the formation of α-MnO2 nanoparticles wound around MWCNT. This nanocomposite of α-MnO2/MWCNT was investigated for its hybrid supercapacitor performance in a three electrode system and exhibited a specific capacitance (Cs) of 255 F g−1 at a scan rate of 2 mV s−1. Further, an asymmetric supercapacitor (AS) device was designed using α-MnO2/MWCNT as positive electrode and activated carbon as negative electrode. The device showed Cs of 99.7 F g−1 at a scan rate of 1 mV s−1 in a wide potential window of 0–2 V in 1 M Na2SO4. The device also exhibited a high energy density of 26.3 Wh kg−1 with a maximum power density of 29.4 kW kg−1. Highlight of this work is that the device when subjected to 20,000 charge-discharge cycles at a high current density of 50 A g−1 retained 77% of its initial Cs. The AS device was efficiently used as power source to light four red LEDs arranged in parallel for about 12 min after charging the device for 30 s at a current density of 1 A g−1. [Display omitted] •Bristles like α-MnO2 was grown on MWCNT by reducing KMnO4.•AS device consisting of α-MnO2/MWCNTs//AC gave Cs of 99.7 F g−1.•AS device exhibited 20,000 cycle stability at 50 A g−1 with 77% Cs retention.•ED and PD of AS device was 26.3 Wh kg−1 and 29.4 kW kg−1.