Enhanced cycling stability of LiMn2O4 by surface modification with melting impregnation method

The surface of as-prepared LiMn₂O₄ was modified with Al₂O₃ by a melting impregnation method. X-ray diffraction, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) studies indicated that Al₂O₃ nano-particles are distributed around the spinel. X ray absorption fine structure analysis (XAFS) further demonstrated that Al atoms were also doped to the surface of LiMn₂O₄ particles. The nano-Al₂O₃ particle coating improves the capacity retention of spinel LiMn₂O₄ efficiently at both room temperature and 55 °C. The mechanism of improvement for surface modified LiMn₂O₄ can be attributed to the inhibition of a surface Jahn-Teller distortion and the decrease of manganese dissolution, leading to good electric contact among particles.