Synthesis and characterization of pristine Li2MnSiO4 and Li2MnSiO4/C cathode materials for lithium ion batteries

The cathode materials, pristine Li2MnSiO4 and carbon-coated Li2MnSiO4 (Li2MnSiO4/C), were synthesized by the sol-gel method. Power X-ray diffraction and scanning electron microscopy analyses show that the presence of carbon during synthesis can weaken the formation of impurities in the final product and decrease the particle size of the final product. The effects of carbon coating on electrochemical characteristics were investigated by galvanostatic cycling test and electrochemical impedance spectroscopy. The galvanostatic cycling test results indicate that Li2MnSiO4/C cathode exhibits better electrochemical performance with an initial discharge capacity of 134.4 mAh g(-1) and a capacity retention of 63.9 mAh g(-1) after 20 cycles. Electrochemical impedance analyses confirm that carbon coating can increase electronic conductivity, which results in good electrochemical performance of Li2MnSiO4/C cathode. The two semicircles and the large arc obtained in this study can be attributed to the migration of lithium ions through the solid electrolyte interphase films, the electronic properties of the material, and the charge transfer step, respectively.