Electrochemical studies of LiCr x Fe x Mn2−2x O4 in an aqueous electrolyte

Abstract

In this paper, LiCr x Fe x Mn2−2x O4 (x = 0, 0.05, 0.1) electrode materials were prepared by sol–gel technique and characterized by X-ray diffraction (XRD) and transmission electron microscopy or high-resolution transmission electron microscopy techniques. XRD results reveal that the Cr–Fe-co-doped LiCr x Fe x Mn2−2x O4 materials are phase-pure spinels. The electrochemical properties of the LiMn2O4, LiCr0.05Fe0.05Mn1.9O4, and LiCr0.1Fe0.1Mn1.8O4 electrodes in 5 M LiNO3 aqueous electrolyte were investigated using cyclic voltammetry, AC impedance, and galvanostatic charge/discharge methods. In the current range of 0.5–2 A g−1, the specific capacity of the LiCr0.05Fe0.05Mn1.9O4 electrode is close to that of the LiMn2O4 electrode, but the specific capacity of the LiCr0.1Fe0.1Mn1.8O4 electrode is obviously lower than that of the LiMn2O4 electrode. When the electrodes are charge/discharge-cycled at the high current rate of 2 A g−1, the LiCr0.05Fe0.05Mn1.9O4 electrode exhibits an initial specific capacity close to that of the LiMn2O4 electrode, but its cycling stability is obviously prior to that of the LiMn2O4 electrode.