二氧化铈包覆LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)材料制备及电化学性能研究

Synthesis and electrochemical performance of CeO_(2)-LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode material

采用共沉淀法制备了Ni_(0.8)Co_(0.1)Mn_(0.1)(OH)_(2)前驱体,以Ce(NO_(3))_(3)·6H_(2)O和C6H12N4为反应试剂,通过化学浴法制得CeO_(2)包覆的Ni_(0.8)Co_(0.1)Mn_(0.1)(OH)_(2)材料,进一步地,在氧气氛围下将CeO_(2)包覆的前驱体混合Li_(2)CO_(3)煅烧得到CeO_(2)-LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)复合正极材料。利用X射线衍射、扫描电镜等手段对材料的物相、形貌和元素分布等进行表征,并测试其电化学性能。结果表明:2%CeO_(2)包覆的正极材料在0.2C下首次放电比容量由未包覆的186.1mAh/g增加到195.8mAh/g;0.5C下循环150次后容量保持率为85.0%,其优异的电化学性能主要归因于CeO_(2)阻止了电解液与电极材料的直接接触、降低了电化学电阻,并可抑制副反应的发生。

The Ni_(0.8)Co_(0.1)Mn_(0.1)(OH)_(2)precursor was firstly prepared by the coprecipitation method,and then the CeO_(2)coated Ni_(0.8)Co_(0.1)Mn_(0.1)(OH)_(2)material was obtained via a chemical bath method by using Ce(NO_(3))_(3)·6H_(2)O and C6H12N4 as reagents.Further,the CeO_(2)-coated precursor and Li_(2)CO_(3)were evenly mixed and calcined under oxygen atmosphere to get CeO_(2)coated LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(CeO_(2)-LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2))cathode material.The phase,morphology and element distribution of the cathode material were characterized by XRD,SEM and other technologies,and also investigated their electrochemical performances via galvanostatic charge/discharge instrument and electrochemical workstation.The results shown that the 2wt%CeO_(2)coated composite presented superior initial discharge capability(195.8mAh/g at 0.2C),compared with uncoated cathode material(186.1mAh/g at 0.2C).Further,the 2wt%CeO_(2)coated composite also exhibited better cycle property(with capacity retention of 85.0%after 150 cycles at 0.5C)to that of the uncoated cathode material.The presence of moderate CeO_(2)layer between the electrolyte and electrode material can decrease the electrochemical resistance of the cathode,thus enhancing its discharge capability and stability.A reliable strategy was provided to enhance the electrochemical properties of high nickel ternary cathode materials.