采用固相法制备了LiNixCoyMn1-x-yO2(x=0.5,y=0.2;x=0.8,y=0.1)三元正极材料,利用X射线衍射仪、扫描电子显微镜以及充放电测试仪对这2种材料的晶体结构、形貌及电化学性能进行了研究。结果表明:2种材料均具有相同的α-NaFeO2层状结构,经充放电循环后特征峰对应的强度均明显下降;2种材料均为球形或类球形细小颗粒,高镍材料有轻微的团聚现象。电化学测试结果表明,2种材料表现出不同的电化学行为,LiNi0.5Co0.2Mn0.3O2在循环过程中其主体结构非常稳定,且电压提高后结构未发生变化;在较低电压循环时 LiNi0.8Co0.1Mn0.1O2多次发生微结构的相变,说明镍含量的增加虽然可以提高材料的电化学性能,但会导致充放电过程中高镍材料结构稳定性下降。
LiNixCoyMn1-x-yO2 (x=0.5,y=0.2;x=0.8,y=0.1) ternary cathode materials were prepared by solid phase method.The crystal structures,morphologies and electrochemical properties of the two materials were studied by X-ray diffraction (XRD),scanning electron microscopy (SEM) and galvanotactic charge-discharge test.The results indicated that the two materials had the same α-NaFeO2 layered structure,and the intensity corresponding to the characteristic peaks decreased obviously after cycling.All materials were spherical or quasi-spherical formed by the tiny particles,and rich-nickel materials particles had a certain agglomeration phenomenon.The electrochemical tests exhibited the different electrochemical behaviors for the two materials.The main structure of LiNi0.5Co0.2Mn0.3O2 was very stable during the cycle,and the structure did not change after the voltage was raised.LiNi0.8Co0.1Mn0.1O2 had multiple phase transformation processes of microstructure in low voltage cycle,which indicated that although the improvement of nickel content can improve the electrochemical performance of the material,however,it also caused the stability of high nickel materials to decrease during the process of charge-discharge.
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