Enhancing the Electrochemical Performance of Disordered Spinel Cathodes via Cationic Substitution Strategy for High Voltage Lithium Batteries

Abstract

Lithium ion batteries (LIBs) are regarded as a promising energy storage solution for transport and stationary applications like electric vehicles, uninterrupted power supply or photovoltaics and have drawn increasing attentions. In this regard, pure spinel nanopowders of LiNi0.5Mn1.5O4 (LNMO) and LiNi0.25M`0.25 Mn1.5O4 (M` = V, Cr or Co) have been prepared via sol-gel auto-combustion method as high voltage cathode materials. The changes in the crystallographic symmetry and space group were detected by X-ray diffraction technique (XRD). The surface morphology and particle size of the as-prepared materials were characterized by field emission scanning electron microscope (FE-SEM) and high resolution transmission electron microscope (HR-TEM). The ionic conductivity of Li+ ions in both bulk materials and assembled model electrodes were measured using electrochemical impedance spectroscopy analysis (EIS) at room and high temperatures The obtained results indicated a remarkable improvement in both electronic and ionic conductivies of metal ions-substituted LNMO spinel materials, showing lower charge transfer resistance and higher lithium ion diffusion coefficient, leading to better electrochemical kinetics. Finally, the galvanostatic cycling tests have been carried out for the assembled batteries in the potential range of 3.0–4.8 V (vs. Li+/Li).