title: Effect of percolation on the capacitance of supercapacitor electrodes prepared from composites of manganese dioxide nanoplatelets and carbon nanotubes.
abstract: Here we demonstrate significant improvements in the performance of supercapacitor electrodes based on 2D MnO2 nanoplatelets by the addition of carbon nanotubes. Electrodes based on MnO2 nanoplatelets do not display high areal capacitance because the electrical properties of such films are poor, limiting the transport of charge between redox sites and the external circuit. In addition, the mechanical strength is low, limiting the achievable electrode thickness, even in the presence of binders. By adding carbon nanotubes to the MnO2-based electrodes, we have increased the conductivity by up to 8 orders of magnitude, in line with percolation theory. The nanotube network facilitates charge transport, resulting in large increases in capacitance, especially at high rates, around 1 V/s. The increase in MnO2 specific capacitance scaled with nanotube content in a manner fully consistent with percolation theory. Importantly, the mechanical robustness was significantly enhanced, allowing the fabrication of electrodes that were 10 times thicker than could be achieved in MnO2-only films. This resulted in composite films with areal capacitances up to 40 times higher than could be achieved with MnO2-only electrodes.
authors.affiliation: CRANN and AMBER Research Centres, Trinity College Dublin , Dublin 2, Ireland.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Higgins
authors.forename: David
authors.initials: D
authors.lastname: McAteer
authors.forename: João Carlos Mesquita
authors.initials: JC
authors.lastname: Coelho
authors.forename: Beatriz
authors.initials: B
authors.lastname: Mendoza Sanchez
authors.forename: Zahra
authors.initials: Z
authors.lastname: Gholamvand
authors.forename: Greg
authors.initials: G
authors.lastname: Moriarty
authors.forename: Niall
authors.initials: N
authors.lastname: McEvoy
authors.forename: Nina Christina
authors.initials: NC
authors.lastname: Berner
authors.forename: Georg Stefan
authors.initials: GS
authors.lastname: Duesberg
authors.forename: Valeria
authors.initials: V
authors.lastname: Nicolosi
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Coleman
keywords: capacitance; carbon nanotube composite; electrode; manganese dioxide; nanosheet; nanotube; percolation; supercapacitor; thin film; two-dimensional