F-掺杂LiNi0.5Mn1.5O4材料的制备及性能研究

Synthesis and performance study of F-doped LiNi0.5Mn1.5O4 cathode material

摘要:

为改善LiNi0.5Mn1.5O4的倍率性能和循环性能，采用二步固相法制备了F-掺杂的LiNi0.5Mn1.5O4-xFx（x=0, 0.05，0.1，015，0.2）正极材料，讨论了不同F 掺杂量对材料性能的影响。X射线衍射、扫描电镜结果表明，掺杂和未掺杂的正极材料都为单一的尖晶石结构，粒度分布均匀。充放电测试、循环伏安和交流阻抗测试结果表明：当F-的掺杂量为x=0.1时（LiNi0.5Mn1.5O3.9F0.1）正极材料的性能最好，0.1C、0.5C、1C、2C及5C的首次放电比容量依次为129.07mAh/g、123.59mAh/g、118.49mAh/g、114.49mAh/g和92.57mAh/g。1C倍率下循环30次，容量保持率仍为98.84%。

Abstract:

Aiming at improving the electrochemical rate capability and cyclic performance of LiNi0.5Mn1.5O4，two step solid-state reaction was adopted to synthesize LiNi0.5Mn1.5O4-xFx（x=0, 0.05, 0.1, 0.15, 0.2）cathode materials.The effect of F-doped on the performance of LiNi0.5Mn1.5O4 was investigated. X-ray diffraction, scanning electron microscopy, the charging-discharging test, cyclic voltammetry tests, electrochemical impedance spectroscopy were employed to study their properties.The results showed both the doped and un-doped cathode materials were cubic spinel structure with clearly defined shape and uniform particle size distribution. For the cathode materials doped with 0.1F presents the best electrochemistry performance, at the charge-discharge rate of 0.1, 0.5, 1, 2 and 5C, its initial discharge specific capacity was 129.07, 123.59, 118.49, 114.49, 92.57mAh/g, respectively. When cycled at 1C rate, above 98.84% of its initial capacity can be retained after 30 cycles for LiNi0.5Mn1.5O3.9F0.1.