Novel chelating agent assisted dual doped spinel via sol–gel method for lithium rechargeable batteries

Abstract

LiMn2O4 and LiCuxAlyMn2−x−yO4 (x=0.50; y=0.05–0.50) powders have been synthesized via sol–gel method for the first time using Margaric acid as chelating agent. The synthesized samples have been used to physical and electrochemical characterization such as thermo gravimetric analysis (TG/DTA), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and electrochemical characterization viz., electrochemical galvanostatic cycling studies, electrochemical impedance spectroscopy (EIS) and differential capacity curves (dQ/dE). XRD patterns of LiMn2O4 and LiCuxAlyMn2−x−yO4 confirm high degree of crystallinity with better phase purity of synthesized materials. FESEM images of parent LiMn2O4 depict the most of the particles that are in 0.5μm while LiCu0.5Al0.05Mn1.45O4 powders exhibiting ice-cube surface morphology with good agglomerated less particle size of 50nm. TEM images of spinel LiMn2O4 and LiCu0.5Al0.05Mn1.45O4 corroborate that all the synthesized particles are nano-sized with uniform spherical and cloudy particle morphology. LiMn2O4 samples calcined at 850°C deliver the high discharge capacity of 130mAhg−1 in the first cycle while LiCu0.5Al0.05Mn1.45O4 samples deliver 120mAhg−1 during the first cycle. Inter alia all the dopant compositions investigated, LiCu0.5Al0.05Mn1.45O4 delivers the stable cycling performance of 119 and 115mAhg−1 in the 5th and 10th cycle with low capacity fade of 0.1 and 0.1mAhg−1cycle−1 corresponding to columbic efficiency of 99 and 99%.