高致密球形LiNi0.8Co0.1Mn0.1O2颗粒的合成及性能研究

以氨水为络合剂,NaOH为沉淀剂,通过共沉淀制备了高致密、粒度均匀的球形前驱体Ni0.8Co0.1Mn0.1(OH)2.通过焙烧该前驱体和LiOH.H2O的混合物制备出球形锂离子电池正极材料LiNi0.8Co0.1Mn0.1O2.采用XRD、SEM、TEM、TGA/DSC以及恒流充放电测试对材料的结构、形貌和电化学性能进行表征.结果表明,球形前驱体是由纳米级一次颗粒团聚形成,而不是晶粒的长大,且反应时间对前驱体的形貌、粒径分布及振实密度有显著影响.750℃焙烧16 h后的正极材料,保持了完好的球形形貌,具有最佳的层状结构和电化学性能,振实密度最大(2.98 g/cm3),首次放电容量为202.4 mAh/g,倍率性能佳,在3C的放电电流下容量为174.1 mAh/g,且循环性能优良,在40次循环以后,放电容量保持率为92.3%.

Synthesis and Characterization of Spherical LiNi0.8Co0.1Mn0.1O2 Particles with a High Tap-density

Spherical Ni0.8Co0.1Mn0.1(OH)2precursors with a high tap-density and a narrow size-distribution were synthesized via coprecipitation using NaOH and NH3.H2O as the precipitation and complexing agents.Spherical LiNi0.8Co0.1Mn0.1O2 particles were then prepared by sintering the mixture of this precursor and LiOH.H2O.The prepared materials were characterized by XRD,SEM,TEM,TGA/DSC and galvanostatically charge/discharge tests.The results indicate that secondary spherulites of the precursors are formed by aggregation of crystals but not by elongated crystals.The reaction time shows a significant effect on the morphology,size-distribution and tap-density of the precursor.The LiNi0.8Co0.1Mn0.1O2powders calcined under 750℃ for 16 h exhibit a spherical morphology with the highest tap-density(2.98 g/cm3) and the largest initial discharge capacity(202.4 mAh/g).More than 92.3% of the capacity is retained after 40 cycles.In addition,the cell delivers a discharge capacity of 174.1 mAh/g at 3C rate.