尖晶石LiMn2-x-yCoxLayO4-zClz/C复合电极的性能研究

采用高温固相法合成了掺杂改性的锂离子电池用尖晶石型LiMn_2-x-yCo_xLa_yO_4-zCl_z和复合型LiMn_2-x-yCo_xLa_yO_4-zCl_z/C正极材料. 通过X射线衍射和环境扫描电镜对材料的晶体结构和表观形貌进行了分析, 通过恒电流充放电测试和交流阻抗技术对材料的电化学性能进行了测试. 实验结果表明, 所制备的材料LiMn_2-x-yCo_xLa_yO_4-zCl_z和LiMn_2-x-yCo_xLa_yO_4-zCl_z/C均为单一的尖晶石结构, 其中以葡萄糖作为碳添加剂所得的复合材料的电性能最佳. 该材料具有良好的充放电循环可逆性能, 以0.2C倍率充放电, 首次放电比容量可达126.5mAh·g^-1, 充放电循环50次后平均放电比容量仍保持在123.5mAh·g^-1以上, 衰减不超过2.4%.

Properties of Spinel LiMn2-x-yCoxLayO4-zClz/C Composite Cathode for Lithium-ion Batteries

Modified spinel lithium manganese oxides LiMn_2-x-yCo_xLa_yO_4-zCl_z and LiMn_2-x-yCo_xLa_yO_4-zCl_z/C composite cathodes for lithium-ion batteries were prepared by the solid-state method. The structure and morphology of as-prepared cathode materials were characterized by XRD and ESEM. The electrochemical performances of the materials were tested by constant-current cyclic testing and electrochemical impedance spectroscopy. The results showed that the modified materials LiMn_2-x-yCo_xLa_yO_4-zCl_z and LiMn_2-x-yCo_xLa_yO_4-zCl_z/C were the simple spinel phase. Electrochemical tests showed that the material obtained by adding glucose as carbon additive gave an enhanced performance in terms of improved practical discharge capacity and good cyclability. The specific capacity was 126.5mAh·g^-1 at the first cycle. The cell was cycled for 50 cycles with an average specific capacity of about 123.5mAh·g^-1, the degrading rate of which was less than 2.4%.