锆酸镧锂包覆富锂锰基正极材料的结构及性能研究

Study on structure and properties of lithium lanthanum zirconate coated lithium rich manganese-based cathode material

采用共沉淀法制备了二次颗粒为球形且颗粒粒径均匀的Li_(1.2)Ni_(0.2)Co_(0.08)Mn_(0.52)O_(2)(LLMO)前驱体,并将前驱体、固态电解质锆酸镧锂(LLZO)和氢氧化锂混合均匀后煅烧合成出不同LLZO包覆量的LLMO正极材料(LLZO@LLMO)。利用XRD、SEM等测试方法研究LLMO的微观结构;利用EIS研究改性前后LLMO的电化学性能。结果表明,在质量分数为1%的包覆量下LLZO@LLMO电化学性能最佳;0.1 C下首次放电容量达到了253.1 mAh/g,首次库伦效率达到了81.1%;1 C下循环100圈放电容量为162.3 mAh/g,容量保持率达到了89.0%;即使5 C大倍率下放电容量达到了120.4 mAh/g。相对于原始样品循环性能及倍率性能得到了显著提升。

Li_(1.2)Ni_(0.2)Co_(0.08)Mn_(0.52)O_(2)(LLMO)precursor with uniform secondary spherical particles is prepared via co-precipitation method.Subsequently,LLMO precursor,solid lithium lanthanum zirconate(LLZO)electrolyte,and lithium hydroxide are mixed uniformly together and then calcined to synthesize LLMO cathode materials with different LLZO coating amounts(LLZO@LLMO).The microstructure of LLMO precursor is studied by using X-ray diffraction(XRD),scanning electron microscopy(SEM),and other testing methods.Results indicate that the optimal electrochemical performance of LLZO@LLMO is achieved with 1wt.%of LLZO coating amount.Under a 0.1 C rate,its initial discharge capacity reaches 253.1 mAh·g^(-1),with an initial Coulombic efficiency of 81.1%.After 100 cycles at 1 C rate,the discharge capacity is 162.3 mAh·g^(-1),with a capacity retention rate of 89.0%.Even under a rate as high as 5 C,the discharge capacity remains at 120.4 mAh·g^(-1).The modified samples exhibit significantly improved cycling and rate performance compared to the original samples.