一种高{010}晶面族暴露的富锂层状材料制备与电化学性能研究

Preparation and Electrochemical Properties of a Lithium-Rich Layered Material with Highly Exposed{010}Crystallographic Planes

层状富锂氧化物具有超过250 mA·h/g的比容量,是提高锂离子电池能量密度的理想正极材料。但存在首圈库伦效率低、循环及倍率性能不佳等问题,限制了其实际应用。利用前驱体-模板法,通过调控前驱体共沉淀时间,结合固相烧结工艺合成了具有高{010}晶面族暴露的Li_(1.17)Ni_(0.4)Co_(0.05)Mn_(0.38)O_(2)(HLLO)富锂层状正极材料。X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等表征证明了合成的HLLO具有明显的晶面取向。电化学性能测试表明高暴露{010}晶面的存在能够加速锂离子的扩散,使得锂离子的扩散系数由原始的9.5×10^(-14)cm^(2)/s提升到3.9×10^(-13)cm^(2)/s,与传统Li_(1.17)Ni_(0.4)Co_(0.05)Mn_(0.38)O_(2)(LLO)相比,0.1 C下首圈库伦效率从70%提高至77%,1 C长循环500圈后容量保持率从43%提升至86%。

The layered lithium-rich oxide has a specific capacity of more than 250 mA·h/g,which make it one of the most promising cathodes for the high energy density lithium-ion batteries.However,the problems of low initial Coulombic efficiency,poor cycle,and rate performance limit its practical application.Here,a lithium-rich layered oxide Li_(1.17)Ni_(0.4)Co_(0.05)Mn_(0.38)O_(2)(HLLO)with highly exposed{010}crystallographic plane was synthesized by a precursor-template conversion and solid phase reaction method.The structural characterizations of X-ray diffractometer(XRD),scanning electron microscopy(SEM),and transmission electron microscopy(TEM)demonstrated that the exposed{010}crystallographic plane of HLLO was obvious.The electrochemical performance showed that such planes could accelerate lithium ions’diffusion,and lithium ions’diffusion coefficient was increased from 9.5×10^(−14) cm^(2)/s to 3.9×10^(−13) cm^(2)/s.Compared with the traditional Li_(1.17)Ni_(0.4)Co_(0.05)Mn_(0.38)O_(2)(LLO),the initial Coulombic efficiency of HLLO increased from 70%to 77%at 0.1 C,and its capacity retention rate increased from 43%to 86%at 1 C after 500 cycles.