固相燃烧法快速合成LiNi0.03Mg0.10Mn1.87O4正极材料及电性能研究

Rapid Synthesis of LiNi0.03Mg0.10Mn1.87O4 Cathode Material by Solid-state Combustion Method and its Electrochemical Properties

摘要:

采用固相燃烧法在500℃反应1 h后然后进一步在650℃二次焙烧6 h,快速合成了Ni、Mg共掺杂的LiNi0.03Mg0.10Mn1.87O4正极材料。借助X射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射光谱仪(XPS)和电化学测试等对材料的结构、形貌、物相和电化学性能进行测试。结果表明：LiNi0.03Mg0.10Mn1.87O4正极材料为立方尖晶石型结构,颗粒尺寸在100-200 nm之间,为多面体形貌。合成的LiNi0.03Mg0.10Mn1.87O4材料有良好的电化学性能,在1 C时首次放电比容量为107.6 mAh.g-1,10 C首次放电比容量有68.7 mAh.g-1,在55℃、1 C首次放电比容量有103.7 mAh.g-1,CV和EIS测试得出该材料有较大的锂离子扩散系数为1.038×10-11 cm2s-1和较小的活化能32.69 kJ.mol-1,对循环1000次后的极片进行剖面分析,该材料的晶体结构和颗粒形貌基本没有变化,适量Ni、Mg共掺杂能够有效提高尖晶石型LiMn2O4在循环过程中的容量衰减和结构稳定性,抑制了Jahn-Teller效应。

Abstract:

Ni-Mg co-doped LiNi0.03Mg0.10Mn1.87O4 cathode material was synthesized by solid-state combustion method at 500℃ for 1 h and further calcined at 650℃ for 6 h. The structure, morphology, phase and electrochemical properties of the material were tested by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectrometry (XPS) and electrochemical tests. The results show that the LiNi0.03Mg0.10Mn1.87O4 has a cubic spinel structure with a particle size of 100-200 nm, which is a polyhedral morphology. The synthesized LiNi_0.03Mg0.10Mn1.87O4 has good electrochemical performance with initial discharge capacity of 107.6 mAh.g-1 at 1 C, and the first discharge capacity of 10 C is 68.7 mAh.g-1. The initial discharge capacity is 103.7 mAh?g-1 at a high temperature of 55℃. CV and EIS tests show that the LiNi0.03Mg0.10Mn1.87O4 has a large lithium ion diffusion coefficient of 1.038×10-11 cm2.s-1 and a small activation energy of 32.69 kJ.mol-1. The material after 1000 cycles shows that the crystal structure and particle morphology are basically unchanged, doping appropriate amounts of Ni and Mg ions can effectively improve the capacity attenuation and structural stability of the spinel LiMn2O4, thereby suppressing the Jahn-Teller effect.