The effect of aluminum precursors on the structural and electrochemical properties of spinel LiMn2 − xAlxO4 (x = 0, 0.05, 0.1, 0.15) cathode materials

In this paper, the effect of different aluminum precursors, i.e., Al(OH)3 and Al2O3, on the structural and electrochemical properties of spinel LiMn2 − xAlxO4 (x = 0, 0.05, 0.1, 0.15) is investigated by X-ray diffraction (XRD), micro-Raman spectroscopy (RS), field-emission scanning electron microscopy (FE-SEM) and charge–discharge cycling test. In particular, the ratio of Raman intensity at 625 cm− 1 to Raman intensity at 585 cm− 1 provides crucial insights into the Al substitution in spinel LiMn2O4 lattice. The XRD patterns and FE-SEM images show that the crystal structure and the particle morphologies of LiMn2 − xAlxO4 are not altered by use of either Al(OH)3 or Al2O3 as Al precursors. However, the Raman spectra show that Al doping behavior is significantly affected by Al precursors, with Al(OH)3 serving as a more effective Al precursor than Al2O3. Such conclusion is further supported by the electrochemical cycling results.