ABSTRACT
The Mn0.720Ni0.175Co0.105(OH)2 precursor was co-precipitated by the Couette-Taylor reactor. The 0.3Li2MnO3 x 0.7LiMn0.60Ni0.25Co0.15O2 of the high capacity cathode material for a Li-ion battery was synthesized according to the amount of lithium excess (5-20 mol.%). X-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM) were used to characterize the 0.3Li2MnO3 x 0.7Li-Mn0.60Ni0.25Co0.15O2. Based on the XRD patterns and FE-SEM images, the 5 and 10 mol.% lithium excess samples were observed for spinel structure. The 15 and 20 mol.% lithium excess samples were not observed for the structure. We can conclude that the spinel structure was made in 0.3Li2MnO3 x 0.7LiMn0.60-Ni0.25Co0.15O2, due to a lack of lithium. The discharge specific capacity of 5, 10, 15, and 20 mol.% lithium excess were measured at 216, 246, 262, and 261 mA h g(-1), respectively. Cyclic voltammograms show that the Li2MnO3 has a lower lithium influence than a spinel or layered structure. Based on these experiment results, we can conclude that the best Li source amount of the 0.3Li2MnO3 x 0.7LiMn0.60-Ni0.25Co0.15O2 synthesis is a 15 mol.% excess.
Subject(s)
Electric Power Supplies , Electrodes , Lithium/chemistry , Metal Nanoparticles/chemistry , Metal Nanoparticles/ultrastructure , Crystallization/methods , Electric Conductivity , Equipment Design , Equipment Failure Analysis , Ions , Macromolecular Substances/chemistry , Materials Testing , Molecular Conformation , Particle Size , Surface PropertiesABSTRACT
Core-shell structures were prepared from synthesized SiO2-LiMn2O4 with manganese oxide as shell on the silica core by a precipitation method, which allowed control of core structure in terms of thickness and particle size. X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), field emission-transmission electron microscopy (FE-TEM), and energy dispersive spectroscopy (EDS) were used to characterize the SiO2-LiMn2O4. According to FE-SEM images, particle growth was controlled by controlling the amount of manganese precursor and the temperature. The synthesized core-shell structure was composed of silica, lithium silicate, Mn2O3, and the spinel phase of lithium manganese oxide. Electrochemical measurements show that the synthesized core-shell structure has poorer electrochemical performance than that of LiMn2O4.
