Mg^(2+)掺杂对富锂层状氧化物材料Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)的影响

Effect of Mg^(2+)Doping on Li⁃Rich Layered Oxides Materials Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)

Mg^(2+)作为一种电化学惰性的阳离子,由于其离子半径(0.072 nm)与Li^(+)的离子半径(0.076 nm)相近,因此被广泛应用于取代富锂层状氧化物(LLOs)材料中Li^(+)的位置。然而,Mg^(2+)对LLOs材料晶体结构的影响还存在争议。利用溶胶凝胶法成功制备了一系列Mg^(2+)掺杂富锂正极材料Li_(1.2-x)Mg_(x)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2),通过X射线衍射仪和X射线光电子能谱等对其晶体结构和元素价态进行了系统的研究。结果表明,Mg^(2+)掺杂导致LLOs材料晶胞参数的增加。通过与Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)材料的电化学性能对比发现,Mg^(2+)掺杂有效地提高了LLOs材料的电化学性能。经过优化后,Mg-0.03样品展现出最优异的电化学性能,在0.1 C倍率下的初始放电比容量为291.9 mA•h/g,首圈库伦效率为78.40%。

As an electrochemical inert cation,Mg^(2+)has an ionic radius(0.072 nm)similar to that of Li^(+)(0.076 nm),which is widely used to replace Li^(+)in Li-rich layered oxides(LLOs)materials.However,the influence of Mg^(2+)on the crystal structure of LLOs materials is still controversial.In this work,the Mg-doped Li-rich cathode materials Li_(1.2-x)Mg_(x)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)were synthesized by a sol-gel and high-temperature calcination method.The crystal structure,and valence state of elements in synthesized materials were systematically studied via X-ray diffraction,and X-ray photoelectron spectroscopy.These results indicated that Mg^(2+)doping can increase the cell parameters of LLOs materials.At the same time,compared with Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2),Mg-doping can effectively improve the electrochemical performance of LLOs materials.After optimization,the Mg-0.03 sample exhibits anomalous electrochemical performance,that is,the initial discharge-specific capacity is 291.9 mA•h/g and the initial coulomb efficiency is 78.40%.