Carbon fabric-aligned carbon nanotube/MnO_2/conducting polymers ternary composite electrodes with high utilization and mass loading of MnO_2 for super-capacitors

摘要

3D porous ternary composite electrodes have been prepared by electrodepositing MnO_2 and poly(3,4-ethylenedioxythiophene) (PEDOT) successively on carbon fabric-aligned carbon nanotube (CF-ACNT) hybrids for the super-capacitors. MnO_2 petal-like nano-sheets are deposited on the ACNT surface with PEDOT uniformly encapsulated and interconnected MnO_2 nano-sheets and ACNTs. Cyclic voltammetry shows the MnO_2 utilization of ternary composites up to 77.7%, which far exceeds that of MnO_2/CNT-based materials reported recently. Moreover, the 3D porous ternary system allows large mass loading of MnO_2. And the ternary composites can remain a high MnO_2 utilization of 36% with the MnO_2 mass loading up to 3.11 mg cm~(-2) while achieve a reasonable area-normalized capacitance of 1.3 F cm~(-2) at 0.1 mV s~(-1). The ternary composites with substantially high mass loading exhibit an excellent rate capability and cycling stability, retaining over 95% of its initial charge after 1000 cycles. The excellent electrochemical performances are attributed to the synergetic effect of each component with unique properties and structures: high porosity and interconnectivity of CF, aligned ion diffusion channels along ACNTs, ultrathin MnO_2 nano-sheets and the improved conductivity by PEDOT.