磷酸铝纳米包覆对三元材料性能的影响

Effect of AlPO_4 nano-coating on electrochemical property of LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2

为提高三元正极材料的性能,采用纳米AlPO4包覆。并用X射线衍射(XRD),扫描电镜(SEM),透射电镜(TEM)和恒流充放电对包覆和未包覆的材料进行结构表征与性能测试分析。结果表明,AlPO4包覆并没有改变电极材料的晶体结构,仅在电极材料表面形成均匀的包覆层,厚度约为4nm。包覆后的电极材料在3～4.5V的充放电电压范围内,循环性能明显优于未包覆的材料,并且包覆量越高,材料的性能越好。但是包覆量太高会影响其初始容量,研究表明,0.2%的包覆浓度能够提高材料的电化学性能。

The performance of LiNi1/3 C01/3 Mn1/3 02 anode material was improved by A1PO4 nano-coating. A1PO4- coated LiNi1/3 Co1/3 Mn1/3 02 was obtained by suspension solution of nano A1PO4. Related characters were investigated by X- ray powder diffraction （XRD）, scanning electron microscope imaging （SEM）, transmission electron microscope imaging （TEM） and charge-discharge cycling test. The results showed that the coating do not change the structure of LiNi1/3 C01/3 Mn1/3 02, its surfaces were covered uniformly by nano A1PO4, and the thickness of coating layer was about 4nm. To enhance the electrochemical performance, A1PO4-coated LiNi1/3 Co1/3 Mn1/3 02 markedly improved capacity retention compared to pristine material upon cycling at 3. 0-4. 5 V. Higher was the weight proportion of coating, better was the performance. However,high weight proportion of coating reduced the capacity. 0. 2wt coating was selected, because it not only im- proved capacity retention upon cycling at 3-4. 5V,but also retained the best capacity of positive material.