Study on the electrochemical performance of high-cycle LiMg_(0.08)Mn_(1.92)O_4 cathode material prepared by a solid-state combustion synthesis

摘要

LiMg_(0.08)Mn_(1.92)O_4 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 LiMN_2O_4. The materials synthesized at 500 °C, 600 °C and 700 °C were single phase, while Mn_3O_4 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 LiMg_(0.08)Mn_(1.92)O_4 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 LiMg_(0.08)Mn_(1.92)O_4 materials calcined at 600 °C and 700 °C demonstrated excellent electrochemical performance with an initial discharge specific capacity of 101.3 mAh g~(-1) and 107.6 mAh g~(-1), and their capacity retention was 98.1% and 94.3% after 40 cycles at 0.2 C, respectively.