Functional properties of ZnMn<inf>2</inf>O<inf>4</inf>/MWCNT/graphene nanocomposite as anode material for Li-ion batteries

Abstract

Nano-ZnMn2O4 and ZnMn2O4/MWCNT/graphene composites were prepared by solgel and ball-milling methods. The functional properties of the prepared samples were studied by applying various techniques. X-ray diffraction (XRD) Rietveld analysis indicated a single-phase ZnMn2O4 with a partially inverse spinel nanostructure (average size ≈ 7 nm), confirmed by TEM graphs, which revealed the morphology and particle nanosize distribution in samples. The samples were further characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). The Gaussian fitting of Zn 2p and Mn 2p narrow XPS spectrum confirmed the cation distribution obtained from XRD Rietveld analysis. The galvanostatic cycling of the pure ZnMn2O4 electrode exhibited higher initial discharge capacity (~ 1978 mAh g−1) when cycled at 100 mA g−1 versus Li/Li+. Meanwhile, the cyclic voltammetry tests evidenced the enhanced Li-ion diffusion during the oxidation and reduction processes. The assembled ZnMn2O4/MWCNT/G cell delivered about 190 mAh g−1 of specific discharge capacity over 100 cycles with 65% capacity retention.