Coaxial MnO2 Nanoshell/CNFs Composite Film Anode for High-Performance Lithium-Ion Batteries

A flexible freestanding coaxial MnO2 nanoshell/CNFs (carbon nanofibers) composite film was prepared by electrospinning and electrochemical deposition in three-electrode systems. Scanning electron microscopy (SEM), thermogravimetric analysis (TG), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were employed to analyze the microstructure and morphology of the MnO2 nanoshell/CNFs composite film. The electrochemical performances were tested by galvanostatic charge-discharge tests, cyclic voltammograms (CVs) and electrochemical impedance spectra (EIS). The results show that MnO2 nanoshell can be uniformly deposited on the surface of CNFs and the thickness of MnO2 shell is about 70-90 nm. The unique 3D network structure of CNFs hinders the large volume change of MnO2 during charge/discharge process. The capacity of the as-synthesized MnO2 nanoshell/CNFs composite film anode is 1076 mAh g(-1) for 2nd cycle at 50 mA g(-1), and the capacity loss rate per cycle is 0.1392% from 2nd to 200th cycles. The results exhibit as-prepared MnO2 nanoshell/CNFs composite film with excellent electrochemical performance is a promising anode in lithium-ion batteries. (C) 2018 The Electrochemical Society.