Li 含量对球形富锂正极材料结构和电化学性能的影响

富锂正极材料已经成为高能量密度锂离子电池最具有前景的正极材料之一。然而,富锂正极材料电化学性能对其本体和表面的局域结构很敏感,而这些结构跟材料的合成过程密切相关。在目前的工作中,从合成的角度提出了新的思路,Li含量x将影响着富锂Li1.2x Mn0.54 Ni0.13 Co0.13 O2材料的结构特性和电化学性能。基于电化学,XRD,Raman, XPS技术的分析结果,改变Li含量将在材料的本体和表面产生尖晶石相和Li2 CO3物种,会造成所合成的材料局部组分发生变化,进而影响其电压容量曲线。实验结果表明,在正极材料合成的过程中,相比于其他含量,Li含量过量5%(摩尔分数)所合成的样品表现出更好的电化学性能,放电容量高达270 mAh/g。

Effects of Lithium Content on the Structure and Electrochemical Performance of Spherical Lithium-rich Cathode Materials

Lithium-rich cathode materials have become one of the most promising cathode materials for high-energy-density lithium-ion batteries. However, the electrochemical properties of lithium-rich cathode materials are highly sensitive to the local structure in the bulk and at the surface, which is closely associated with the synthesis process. In the present work, we provided new insights into the structural properties and corresponding electrochemical performance of Li1. 2xMn0. 54Ni0. 13Co0. 13O2 materials as a function of x (Li content) from a synthesis point of view. The spinel and Li2CO3 species in the bulk and at the surface arising from the varying amounts of lithium ions would result in the local compositional change within the as-prepared particles and provoke a change in the voltage-capacity profile as determined by electrochemical analysis, XRD, Raman, and XPS observations. Our results revealed that the as-prepared sample with 5% excess of Li in molar ratio utilized for the material synthesis showed better electrochemical performance in terms of discharge capacity ( ~270 mAh/ g) and voltage in comparison to other as-prepared samples with different Li contents.