Structure and electrochemical performances of co-substituted LiSm x La0.2-x Mn1.80O4 cathode materials for rechargeable lithium-ion batteries

Abstract

Spinel LiMn2O4 and Sm, La co-substituted LiSm x La0.2-x Mn1.80O4 (x = 0.05, 0.10 and 0.15) cathode materials were synthesized by sol–gel method using aqueous solutions of metal nitrates and tartaric acid as chelating agent at 600 °C for 10 h. The structure and electrochemical properties of the synthesized materials were characterized by using thermogravimetric/differential thermal analysis, X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, charge/discharge and electrochemical impedance spectroscopy studies. XRD analysis indicated that all the prepared samples were mainly belong to cubic crystal form with Fd3m space group. LiSm0.10La0.10Mn1.80O4 exhibits capacity retention of 90 % and 82 % after 100 cycles at room temperature (30 °C) and at elevated temperature (50 °C) at a rate of 0.5-C, respectively, much higher than those of the pristine LiMn2O4 (74 % and 60 %). Among all the compositions, LiSm0.10La0.10Mn1.80O4 cathode has improved the structural stability, high-capacity retention, better elevated temperature performance and excellent electrochemical performances of the rechargeable lithium-ion batteries.