With the aim of achieving a high-performance 0.5Li(2)MnO(3)center dot 0.5LiMn(0.5)Ni(0.5)O(2) material, a series of 0.5Li(2)MnO(3)center dot 0.5LiMn (x) Ni (y) Fe(1-x-y)O2 (0.3 <= x <= 0.5, 0.4 <= y <= 0.5) samples with low Fe content was synthesized via coprecipitation of carbonates. Its crystal structure and electrochemical performance were characterized by means of powder X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, galvanostatic charge/discharge testing, cyclic voltammetry, and electrochemical impedance spectra. Rietveld refinements with a model integrating R (3) over barm and Fm (3) over barm indicate that a low concentration of Fe incorporated in 0.5Li(2)MnO(3)center dot 0.5LiMn(0.5)Ni(0.5)O(2) decrease a disordered cubic domain of the composite structure. The preferential distribution of Fe in cubic rock-salt contributes to an unimaginable decrease of c-axis parameter of the predominant layered structure as the Fe content increases. Moreover, including Fe as a dopant can kinetically improve crystallization and also change the ratio of Mn3+/Mn4+ and Ni3+/Ni2+. As a result, 0.5Li(2)MnO(3)center dot 0.5LiMn(0.4)Ni(0.5)Fe(0.1)O(2) exhibits lower Warburg impedance and higher reversible capacity than the undoped material.