高温固相法合成LiNi_(0.25)Co_(0.5)Mn_(0.25)O_2及其结构性能研究

Synthesis and characterization of LiNi_(0.25)Co_(0.5)Mn_(0.25)O_2 by high temperature solid-state method

采用高温固相法合成了层状LiNi0.25Co0.5Mn0.25O2正极材料。通过X射线衍射(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)以及恒电流充放电测试,研究了LiNi0.25Co0.5Mn0.25O2材料的结构、形貌以及电化学性能。实验结果表明950℃7 h合成的样品具有最好的电化学性能,在0.1 C时2.5～4.3 V间,其首次充放电比容量分别为166.3 mAh/g和150 mAh/g,循环10周容量保持96%;XRD精修结果表明Li层中只有1.1%的位置被Ni所占据。

The layered LiNi0.25Co0.5Mn0.25O2 cathode material for Li-ion batteries was synthesized by high temperature solid-state method.XRD,SEM,XPS and charge-discharge cycling measurements were used to characterize the structure,morphology and electrochemical performance.The results show that the sample synthesized at 950 ℃ for 7 h exhibits excellent electrochemical performance.The initial charge capacity is 166.3 mAh/g and the initial discharge capacity is 150 mAh/g at the current density of 0.1 C between 2.5-4.3 V.The discharge capacity retention is 96% after 10 cycles.Rietveld analysis of the XRD pattern showed that only 1.1% sites in the Li plane occupies by Ni2＋ ions.