Study on the electrochemical performance of high-cycle LiMg0.08Mn1.92O4 cathode material prepared by a solid-state combustion synthesis

Abstract

LiMg0.08Mn1.92O4 cathode materials were prepared by a solid-state combustion synthesis at different calcination temperatures. The crystal structure was characterized by X-ray diffraction (XRD) analysis and the morphology was observed by scanning electron microscopy (SEM). All the calcined materials were identified as the spinel structure of LiMn2O4. The materials synthesized at 500°C, 600°C and 700°C were single phase, while Mn3O4 impurity phases can be detected in the other materials synthesized at 800°C and 900°C. The average particle size increased with the increase of calcination temperature. The effect of two-stage calcination temperature on the electrochemical properties of the LiMg0.08Mn1.92O4 materials was studied by galvanostatic charge/discharge tests, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. Results showed that the structural stability of the materials was improved due to Mg-doping. The LiMg0.08Mn1.92O4 materials calcined at 600°C and 700°C demonstrated excellent electrochemical performance with an initial discharge specific capacity of 101.3mAhg−1 and 107.6mAhg−1, and their capacity retention was 98.1% and 94.3% after 40 cycles at 0.2C, respectively.