LiSixMn2−xO4 (x≤0.10) cathode materials with improved electrochemical properties prepared via a simple solid-state method for high-performance lithium-ion batteries

LiSixMn2−xO4 (x≤0.10) cathode materials were prepared via a simple solid-state process with tetraethylorthosilicate (TEOS) as the silicon source. The effects of Si-doping on the structure, morphology and electrochemical performance were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), galvanostatic charge-discharge tests and electrochemical impedance spectroscopy (EIS), respectively. All the Si-doped LiMn2O4 samples showed the intrinsic spinel structure. With the increasing of Si-doping concentration, the crystal lattice constant of LiSixMn2−xO4 samples increased and the particle size distribution becomes more uniform to some extent. Among these samples, the optimal Si-doped LiMn2O4 exhibited an initial discharge capacity of 134.6 mAh g−1 at 0.5 C, which was higher than that of the undoped spinel. After 100 cycles, the discharge capacity could still reach up to 114.5 mAh g−1 with capacity retention of 85.1%. Especially, at the high rate of 5.0 C, a high discharge capacity of 87.5 mAh g−1 was obtained while the undoped spinel only exhibited 33.7 mAh g−1. Such high performance indicated that doping the manganese sites with appropriate amount of silicon ions could effectively improve the specific capacity and cycling stability.