Corresponding Author

Quang-chao ZHUANG(zqc209@126.com)


Composite electrode of CuF2/MoO3/C was fabricated through high energy mechanical milling. The properties of CuF2/MoO3/C were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (TEM), galvanostatic charge-discharge measurements, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the grain sizes of CuF2 and MoO3 after milling were 200 ~ 300 nm, and the initial discharge capacity of CuF2/MoO3/C was 647 mAh?g-1 at room temperature and at a current density of 10 mA.g-1. However, the capacity decayed rapidly in the next cycles. CV curves showed one reduction peak at 2.2 V in the first cycle and another one at 3.2 V in the following cycles. The Nyquist diagram of CuF2/MoO3/C electrode consisted of two semicircles and one line. During the discharge process, the high frequency semicircle (HFS) may be associated with not only the Li+ migration through the SEI film, but also contact resistance between the CuF2/MoO3/C composites and the current collector. The middle frequency semicircle (MFS) should be related to the Schottky contact between CuF2 and conductive agents, which may be the important feature of such composites materials with big band gap. Besides the low frequency line may be related to the diffusion step. A very large value of charge transfer resistance for the CuF2/MoO3/C electrode may induce the rapid decay in capacity.

Graphical Abstract


CuF2/MoO3/C composite electrode, conversion reactions, electrochemical impedance spectra, Schottky contact impedance

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