氧化钇包覆LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2的结构和电化学性能

Structure and electrochemical performance of yttrium oxide coated LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2

以氧化钇溶胶为包覆前驱物,利用氧化钇和正极材料表面带电状态不同制备氧化钇包覆LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2。采用X射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)及电化学测试等手段对LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2包覆前后的物相结构、表面形貌及电化学性能进行研究。结果表明:氧化钇包覆并未影响LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2的晶体结构,氧化钇以颗粒状分布在正极材料表面,氧化钇包覆层厚度在15~25nm,氧化钇在正极材料表面分布比较均匀。与未包覆LiNi_(0.5)Co_(0.2)Mn_(0.3)O_2相比,氧化钇包覆后,材料在高电压下的循环稳定性有所提高,最佳包覆量为0.4%。氧化钇包覆有效降低材料在充放电过程中的极化和电荷转移电阻。

Yttrium oxide coated LiNi_（0.5）Co_（0.2）Mn_（0.3）O_2 was successfully prepared based on the different surface potentials between the cathode material and yttrium oxide using yttrium oxide sol as coating precursor. The crystal structure, morphology and electrochemical properties of uncoated and yttrium oxide coated LiNi_（0.5）Co_（0.2）Mn_（0.3）O_2 were investigated by X-ray diffractometry（XRD）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and electrochemical measurements. The results indicate that the crystal structure is not affected by yttrium oxide coating, the yttrium oxide particles homogenously distribute on the surface of cathode materials and the thickness of coating layer is 15-25nm. Comparing with the uncoated LiNi_（0.5）Co_（0.2）Mn_（0.3）O_2, the cycle performance of the cathode material improves after yttrium oxide coating and the optimum coating amount is 0.4%. The charge transfer resistance and the polarization are suppressed after coating during the charge-discharge processes.