新型富锂相层状正极材料的合成及电化学性能

Synthesis and electrochemistry of new Li-rich layered solid solution cathode materials for Li-ion batteries

以醋酸盐燃烧法按照相图(Li1.2Co0.4Mn0.4O2-Li1.2Ni0.4Mn0.4O2-Li1.2Ni0.2Mn0.6O2三角相图)设计合成了Li1.2-(Co0.4Mn0.4)1-x-y(Ni0.4Mn0.4)x(Ni0.2Mn0.6)yO2(0≤x+y≤1)系列固熔体锂离子电池正极材料。通过X射线衍射(XRD)和电化学性能测试对所得样品的结构及电化学性能进行了初步表征。XRD物相分析表明,温度对Li1.2(Co0.4Mn0.4)1-x-y(Ni0.4Mn0.4)x-(Ni0.2Mn0.6)yO2的合成有明显影响。可以判断:合成温度为950℃以上时,相图中所有成分点能够形成纯相,可鉴定为α-NaFeO2层状结构。初步的电化学性能测试表明,在2～4.8 V范围内,以20 mA/g的电流充放电,材料依据成分不同,有不同电化学性能(充电曲线形状、充放电容量等),最高放电容量达到228 mAh/g。

A series of layered（Li1.2Co0.4Mn0.4O2-Li1.2Nin4Mn0.4O2-Li1.2NiO2Mn0.6O2 （0≤x＋y≤1） solid solution cathode materials for Li-ion batteries were designed and attempted to prepare via a simple combustion method of acetates according to a triangle phase diagram of Li1.2-（Co0.4Mn0.4）1-x-y（Ni0.4Mn0.4）x（Ni0.2Mn0.5）yO2.. The products were analyzed by X-ray diffractometry （XRD） and electrochemical tests. XRD results show that sintering temperature has impacts on synthesis of materials, indicating that pure phase with a layered cx-NaFeO2 structure for all compositions can be obtained at a temperature of 〉1 950 ℃. Charge - discharge tests show that materials with different compositions present different electrochemical behaviors such as the shape of initial charge curve, capacity and cycleability in the voltage range of 2-4.8 V at a constant current of 20 mA/g. A maximal diacharge specific capacity of 228 mAh/g is observed.