Facile synthesis of aluminum-doped LiNi_(0.5)Mn_(1.5)O_4 hollow microspheres and their electrochemical performance for high-voltage Li-ion batteries

摘要

This paper presents the preparation of LiNi_(0.5)Mn_(1.5)O_4 and aluminum (Al) doped LiNi_(0.5)Mn_(1.5)O_4 hollow microspheres as 5 V cathodes using monodisperse MnCO_3 microspheres as precursor and template, which were synthesized using MnSO_4-H_2O, NaHCO_3 and ethanol in water at room temperature. XRD and morphology characterization results indicated that the as-prepared LiNi_(0.5)Mn_(1.5)O_4 and Al doped LiNi_(0.5)Mn_(1.5)O_4 were both spinel structure, and have particle sizes of 2-3 μm. The cathode electrochemical properties of LiNi_(0.5)Mn_(1.5)O_4 and Al doped LiNi_(0.5)Mn_(1.5)O_4 hollow microspheres (as 5 V cathodes) were evaluated and compared by galvanostatic cycling (GC) vs. Li/Li~+ at the current rate 1C in 2.7-4.8 V. The specific initial capacities of all samples were in the range of 70-120 mA h g~(-1). Compared to undoped LiNi_(0.5)Mn_(1.5)O_4, Al doped LiNi_(0.5)Mn_(1.5)O_4 hollow structures can effectively improve discharge capacity (up to 140 (+5) mA h g~(-1)) and cycling stability (70% capacity retention after 200 cycles) as high voltage cathode materials.