Tb3+-doped LiCoO2 Produced by the Sol-Gel Method

Lithium cobaltate (LiCoO2) is a material that has been used for cathodes in rechargeable lithium-ion batteries since 1990. However, the materials currently in use have limitations, such as poor electrochemical response, low capacity (140 mAhg−1), cationic mixture, and undesirable structural changes. A group of elements called”rare earth”, are materials with promising properties. The terbium ion a rare earth used as a doping agent due to its thermomechanical stability and ionic radius, which are greater than those of cobalt (0.63 Å) and lithium (0.60 Å). The terbium ion in the crystal structure produces a deformation and shift of the Bragg reflections, expanding the volume of the lattice parameters, which can improve the electrochemical properties of the material. Therefore, for this study, ceramic powders of lithium cobaltate (LiCoO2) doped with terbium (Tb3+) at 0.01, 0.03, and 0.05 mol%, obtained by the sol-gel method, were analyzed, and characterized by x-ray diffraction (XRD), using Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Based on the diffraction patterns associated with the Bragg reflections of the space group R-3m, and Rietveld refinement, layered hexagonal structures were observed for the pure system and the system doped with terbium ions, under thermal treatment at 800 ℃. Chemical analysis (FT-IR) revealed the absorption of atomic vibrations, attributable to lithium cobaltate (LiCoO2) and the terbium ions, corresponding to a metal-oxygen (MO) band observed at approximately 560 nm. In low-resolution micrographs examined with an IMAGEJ image analyzer, pellet-like particles of nanometric dimensions are seen, with average sizes between 364 nm at 90 nm for the pure samples and the samples doped with terbium ions respectively. The materials were obtained using the sol gel method for future use applications as cathodes in lithium-ion batteries. The chemical, structural, and morphological properties found here can combat the limitations of current materials and speed the invention of energy storage systems with greater electrochemical capacity and thermal stability.