| This article mainly reported the preparation method and structural evolution of high energy density anode materials rechargeable lithium battery:LiNixMn(2-x)O4 by X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS),Raman Spectroscopy(RS) and Fourier Transform Infrared Spectroscopy(FTIR) methods. It also discussed the possibility of its application as anode materials of rechargeable lithium batteries in view of their structures.Well-crystallized spinel LiMnO4 were obtained in the temperature range from 500℃ to 800℃ which was confirmed by XRD study. The morphology of the materials was obtained by SEM,which showed that undergo a crystallizing process from loose to aggregate, and finally to well-ordered crystalline grains with the increasing of sintering temperature. the sample sintered at 800℃ has the uniform particle size of about 0.5μm and the grains show a fine polyhedral shape and connected well with each other. XRD showed that the crystal structure was almost independent of the sintered time which implied that the sintered temperature was the key factor in materials crystallization. Furthermore, it was found out by XRD analysis that the lattice constant of nonstoichiometric spinel Li1+δMn2-δO4 decreased with lithium content, due to the larger Coulomb interaction of Mn4+-O than that of Mn3+-O.Substitutes of Mn by some other metal ions such as Al, Cr, Ti, Co, Ni et al. can improve the electrochemical performance of LiMn2O4. we synthesized the Ni-doped LiNixMn2-xO4 using drying emulsion method studied their structural and physical properties using varies of techniques. XRD analysis showed that the pure spinel LiNixMn2-xO4 crystal can be obtained within x<0.5, and the crystal lattice decreased with nickel doping. The (220) diffraction peak of spinel crystal appeared for LiNi0.4Mn1.6O4, which indicated partial occupation of the 8a sites by nickel atoms in the heavy doped LiNi0.4Mn1.6O4.The average valence of nickel and manganese ions and the ratio of Mn3+/Mn4+ can be studied by XPS. XPS spectra showed the average valence of nickel decreased from +3 to +2 with Ni content in LiNixMn2-xO4. However, the average valence of manganese increased from +3 to +4. The decreasing of Mn3+ ions amount can limit the Jahn-Teller distortion of [MnO6] octahedron. A1g, Eg, three F2g and four F1u modes of the spinel LiMn2O4 are Raman and IR active, respectively. From the Raman spectra of LiNixMn2-xO4, we found that the intensity of the shoulder peaks near 590 cm-1 became stronger with nickel doping, which confirms the increase of the average valence of Mn in LiNixMn2-xO4. The frequency of Raman vibrations in LiNixMn2-xO4 increased because the covalent interaction of Ni-O is larger than that of Mn-O, indicating a stronger stability of the [MnO6] octahedron framework. But there existed a critical Ni content (about x=0.2), which can give the strongest stability of the crystal framework.Four IR vibration bands can be observed in the FTIR spectra. It is noticed that when x increased to 0.4, the F2u IR vibration can be observed in the FTIR spectra, due to the occupancy of Ni atoms on the Li 8a sites in spinel.To summarize, both LiMn2O4 and LiNixMn2-xO4 were synthesized using drying emulsion method. A systematical study of the electronic properties and crystal structure of these materials were carried out by using of TG-DTA, XRD, XPS, Raman and FTIR. Results showed partial occupation of the 8a sites by nickel atoms in the heavy doped LiNi0.4Mn1.6O4. With nickel doping, the crystal lattice decreased, Mn3+/Mn4+ decreased and the covalent interaction of M-O in [MO6] became stronger, which indicated a stronger crystal stability and a better cycle performance. These results are very useful for us to improve the performance of these cathode materials.
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