锂离子电池富锂锰基正极材料的制备与研究

Preparation and Study of Lithium-Ion-Based Cathode Materials for Lithium Ion Batteries

使用简单浸渍法合成xLi_2MnO_3·(1-x)LiNi_(0.8)Co_(0.2)O_2(x=0.3～0.7)正极材料前驱体,然后进行高温煅烧得到最终纳米颗粒。X射线衍射和扫描电子显微镜研究证实了xLi_2MnO_3·(1-x)LiNi0.8Co0.2O2(x=0.3～0.7)具有层状纳米材料的完整结构,随着Li_2MnO_3的增加,20°～23°之间的超晶格X射线衍射峰逐渐变得明显,这代表了单斜晶系(C2/m)的类Li_2MnO_3成分的形成,并且Li^+在过渡金属层中有序排列。进一步的电化学结果表明,0.5Li_2MnO_3·0.5LiNi_(0.8)Co_(0.2)O_2具有较好的放电容量,70次循环后放电容量保持在201mAh/g,容量保留率有95%。此外,0.7Li_2MnO_3·0.3LiNi_(0.8)Co_(0.2)O_2虽然放电容量较低,但是具有较好的循环稳定性。这项工作可能为富锂层状阴极材料的合成提供新的思路。

The precursor of xLi2MnO3·(1-x)LiNi0.8Co0.2O2(x=0.3~0.7)cathode material was synthesized by simple impregnation method,and the final nanoparticles were obtained by calcination at high temperature.X-ray diffraction and scanning electron microscopy studies have confirmed that xLi2MnO3·(1-x)LiNi0.8Co0.2O2(x=0.3~0.7)has a complete structure of layered nanomaterials.With the increase of Li2MnO3,the X-ray diffraction peaks of superlattices between 20 to 23 degrees gradually become obvious,which represents the formation of Li2MnO3-like components in monoclinic system(C2/m).Moreover,Li+are orderly arranged in the transition metal layer.Further electrochemical results show that 0.5Li2MnO3·0.5LiNi0.8Co0.2O2 has good discharge capacity.After 70 cycles,the discharge capacity remains at 201mAh/g,and the capacity retention rate is 95%.In addition,0.7Li2MnO3·0.3LiNi0.8Co0.2O2 has good cycle stability although its discharge capacity is low.This work may provide a new idea for the synthesis of lithium-rich layered cathode materials.