Synthesis and characterization of Sn-doped LiMn₂O₄ cathode materials for rechargeable Li-ion batteries

Spinel Li Sn_xMn_2-xO₄ (x=0, 0.02, 0.04) was synthesized based on the controlled crystallization. The process started with the preparation of pristine or Sn-doped MnCO₃, followed by heat-treatment to produce the precursor Mn2O₃. Then, LiMn ₂O₄ was obtained by sintering of the mixture of Mn ₂O₃ and Li₂CO₃. The structural and electrochemical properties of as-prepared cathodes were investigated by X-ray diffraction, scanning electron microscopy, inductively coupled plasma-atomic emission spectrum, cyclic voltammetry, and charge-discharge cycling. The coin cells with Li Sn_xMn_2-xO₄ as the cathode were tested at a current density of 0.5 mA cm-2 in the voltage range of 3.35-4.35 V at room temperature and in the voltage range of 3.35-4.20 V at 55°C, respectively. The results show that the lattice constants of Sn-doped samples are reduced, but their cyclabilities are improved.