Hierarchical core/shell structure of MnO2@polyaniline composites grown on carbon fiber paper for application in pseudocapacitors

Abstract

Hierarchical core/shell structured arrays of MnO₂@polyaniline (PANI) nanosheets are successfully deposited on the surface of carbon fiber paper (CFP) by a two-step method of a redox reaction-assisted deposition of MnO₂ and post electrodeposition of PANI. The CFP is used as a three-dimensional (3D) current collector to ensure 3D transport of ions and electrons with a large surface area. In addition, the electrodeposition technique enables conformal and thin coating of a layer of PANI across the entire MnO₂ nanosheet. The MnO₂@PANI on the CFP shows a unique architecture for efficient ion diffusion pathways in hierarchical porous structures and rapid electron transfer through PANI coated layers. The MnO₂@PANI/CFP can be applied as a binder- and carbon-free electrode for supercapacitors. Evaluation of the electrochemical performance revealed that the as-prepared electrodes have a high value of specific capacitance (437 F g⁻¹ at 1 A g⁻¹), high rate capability (62.4% retention at 15 A g⁻¹), and good cycle life (∼100% at sequential current densities of 1 and 5 A g⁻¹ over 3000 cycles).