The synthesis and electrochemical properties of xLi2MnO3–(1 − x)MO2(M = Mn1/3Ni1/3Fe1/3) via co-precipitation method

The Co-free layered xLi2MnO3–(1 − x)MO2(M = Mn1/3Ni1/3Fe1/3) solid solution was synthesized by a two steps approach including co-precipitation and calcination. The samples were analyzed by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron miscroscopy (SEM), dQ/dV plots and electrochemical tests. The results indicated that the material possesses a layered α-NaFeO2 structure with R-3m space group and exhibits excellent electrochemical performances. The initial discharge capacity is 220 mAh g−1 in the voltage range of 2.0–4.8 V under current density of 30 mAh g−1 at 30 °C, and 232 mAh g−1 in the second discharge process. Meanwhile, the discharge capacity maintains 192.4 mAh g−1 after 20 cycles in the voltage range of 2.0–4.8 V. Moreover, the initial discharge capacity is 263 mAh g−1 in the cut-off voltage of 2.0–4.8 V at 50 °C. The high reversible capacities are attributed to reduction of Mn4+/Mn3+ during initial discharge process and the redox-reaction of Mn4+/Mn3+ during further cycles.