Fabrication of ternary hierarchical nanofibers MnO2/PANI/CNT and theirs application in electrochemical supercapacitors

•Ternary coaxial hierarchical nanofibers MnO2/PANI/MWCNT are synthesized.•MnO2/PANI/MWCNT exhibits high specific capacitance of 431.3 F g−1 at 0.5 A g−1.•MnO2/PANI/MWCNT maintains 88.2% initial capacity after 2000 cycles at 1 A g−1.•Ternary coaxial hierarchical nanostructures improve electrochemical properties.

In this article, ternary coaxial hierarchical nanofibers are prepared by a simple, repeatable, and scalable method. Polyaniline (PANI) is in-situ polymerized on multiwalled carbon nanotubes (MWCNT) to form PANI/MWCNT. Subsequently, manganese dioxide (MnO2) in-situ grows on PANI/MWCNT nanofibers to form ternary hierarchical nanofibers MnO2/PANI/MWCNT. The electrochemical performance of MnO2/PANI/MWCNT is investigated using cyclic voltammetry (CV), galvanostatic charge-discharge measurement, and electrochemical impedance spectroscopy. The results show that as-prepared ternary hierarchical nanofibers are all typical pseudo-capacitance capacitors. Compared with MWCNT, PANI nanofibers, and PANI/MWCNT composite nanofibers, the specific capacitance of MnO2/PANI/MWCNT composites exhibits the highest capacitance of 348.5 F g−1 at 1 A g−1, and 88.2% of which can still be maintained after 2000 consecutive cycles. The electrochemical measurements demonstrate that PANI layer and nanoflaky MnO2 can increase the specific capacitance of MWCNT. More important, MnO2 in-situ growth on PANI layer can effectively retain the structure of composites and improve the long-term cycle stability, which is conducive to obtain the new-type portable energy storage devices.

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