Enhanced electrochemical performance of LiMn 2 O 4 by SiO 2 modifying via electrostatic attraction forces method

SiO 2 -modified LiMn 2 O 4 materials were synthesized by the electrostatic attraction forces with the followed heat treatment. The surface morphology, structure, and electrochemical performance were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), CV, and electrochemical impedance spectroscopies (EIS), respectively. SEM and XRD patterns revealed that SiO 2 was not only coated on the surface, but also partial Si 4+ ions diffused into the crystal structure. As a result, the spinel LiMn 2 O 4 modified with 2.0 wt.% SiO 2 (LiMn 2 O 4 @SiO 2 -2.0 wt.%) exhibits a discharge specific capacity of 101.2 mAh g −1 over 3.0–4.3 V and with a capacity retention of 97.6% after 100 cycles at 25 °C. Even cycled at 55 °C, its capacity retention is still 88.7%. The excellent electrochemical performance is attributed to the improved reversibility and dynamic behaviors after SiO 2 modification. Partial Si 4+ doping in LiMn 2 O 4 assists to stabilize its crystal structure, while the SiO 2 coating layer on the surface of LiMn 2 O 4 materials helps to reduce the attacks of electrolyte and the dissolution of Mn 2+ .