Fe-doping effects on the structural and electrochemical properties of 0.5LiMnO·0.5LiMnNiO electrode material

With the aim of achieving a high-performance 0.5LiMnO·0.5LiMnNiO material, a series of 0.5LiMnO·0.5LiMnNiFeO (0.3 ≤  ≤ 0.5, 0.4 ≤  ≤ 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 and indicate that a low concentration of Fe incorporated in 0.5LiMnO·0.5LiMnNiO decrease a disordered cubic domain of the composite structure. The preferential distribution of Fe in cubic rock-salt contributes to an unimaginable decrease of -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 Mn/Mn and Ni/Ni. As a result, 0.5LiMnO·0.5LiMnNiFeO exhibits lower Warburg impedance and higher reversible capacity than the undoped material.