Self-Supporting Electrode of High Conductive PEDOT:PSS/CNTs Coaxial Nanocables Wrapped by MnO2 Nanosheets

A free-standing film of manganese oxide/poly(3,4-ethylenedioxythiophene):poly (styrene sulfonate)/ carbon nanotubes (MnO2/PEDOT:PSS/CNTs) is obtained and directly applied as self-supporting electrode of supercapacitors. CNTs (modified by ionic liquid) are homogeneously wrapped by conducting polymer PEDOT:PSS. The presence of PEDOT:PSS prevents ultrathin MnO2 nanosheets from restacking as well as promotes them vertical growth and uniform distribution on the surface of PEDOT:PSS/CNTs. The MnO2/PEDOT:PSS/CNTs hybrid electrode which possesses coaxial nanocable structure exhibits significant improvement both in specific capacitance and conductivity compared with CNTs or MnO2/CNTs electrodes. This specific hybrid structure greatly accelerates electrons transport. The specific capacitance of MnO2/PEDOT:PSS/CNTs electrode is 533 Fcm(-3) at the current density of 1 mAcm(-2), while the specific capacitance values of CNTs and MnO2/CNTs electrodes at the same current density only show 15 and 150 Fcm(-3), respectively. The as-fabricated MnO2/PEDOT:PSS/CNTs hybrid film also exhibits excellent rate capability and cycle stability. For example, the hybrid film shows a specific capacitance of 265 Fcm(-3) at current density of 20 mAcm(-2), and the high capacitance retention ratio of 129% is achieved after 20000 cycles. Due to its excellent electrochemical properties and good flexibility, MnO2/PEDOT:PSS/CNTs self-supporting electrode presents promising applications in flexible supercapacitors.