热处理温度对TiO2包覆LiNi0.8Co0.15Al0.05O2的电化学性能影响

采用共沉淀法制备了镍基正极材料LiNi0.8Co0.15Al0.05O2(LNCA),通过浸渍-水解法在LNCA表面包覆了1%的TiO2,研究了热处理温度对1%TiO2@LiNi0.8Co0.15Al0.05O2的电化学性能的影响。通过扫描电镜(SEM)、X射线衍射(XRD)、电化学工作站和电池测试仪等对材料进行表征。结果表明,提高热处理温度,可以使样品表面的包覆层均匀致密,但750℃热处理样品的阳离子混排程度有所增加;TiO2表面包覆并热处理后提高了材料的热稳定性能,有利于提高样品在大倍率放电时的循环性能,热处理温度为650℃时具有最佳的电化学性能。当包覆层为TiO2和Li2TiO3混合物时,对循环性能的改善能力优于包覆层为单纯的TiO2或Li2TiO3。

Study on effect of heat treatment temperature on electrochemical performance of 1%TiO2 coated LiNi0.8Co0.15Al0.05O2

The Ni-rich cathode material LiNi0.8Co0.15Al0.05O2 was prepared by coprecipitation method, and 1% TiO2 was coated on the surface of LiNi0.8Co0.15Al0.05O2 by impregnation-hydrolysis method. The effect of heat treatment temperature on the electrochemical properties of 1%TiO2@LiNi0.8Co0.15Al0.05O2 was studied. The materials were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD), electrochemical workstation and battery tester. The results show that the cover layer became more uniform and denser with the increase of the heat treatment temperature, but the cation mixing increased after heat treatment at 750 ℃. The thermodynamic stability of the material was improved after TiO2 surface coated and heat treatment, which was beneficial to improve the cycling performance of samples at high rate discharge. The best electrochemical performance was obtained with the heat treatment at 650 ℃. When coated with the mixture of TiO2 and Li2TiO3, the cycling performance was better than that of the coating coated with pure TiO2 or Li2TiO3.