摘要
Layered Li[Ni1/3Co1/3Mn1/3]O2 was synthesized with complex metal hydroxide precursors that were prepared by a co-precipitation method.The influence of coordination between ammonia and transition-metal cations on the structural and electrochemical properties of the Li[Ni1/3Co1/3Mn1/3]O2 materials was studied.It is found that when the molar ratio of ammonia to total transition-metal cations is 2.7：1,uniform particle size distribution of the complex metal hydroxide is observed via scanning electron microscopy.The average particle size of Li[Ni1/3Co1/3Mn1/3]O2 materials was measured to be about 500 nm,and the tap-density was measured to be approximately 2.37 g/cm3,which is comparable with that of commercialized LiCoO2.XRD analysis indicates that the presently synthesized Li[Ni1/3Co1/3Mn1/3]O2 has a hexagonal layered-structure.The initial discharge capacity of the Li[Ni1/3Co1/3Mn1/3]O2 positive-electrode material is determined to be 181.5 mA·h/g using a Li/Li[Ni1/3Co1/3Mn1/3]O2 cell operated at 0.1C in the voltage range of 2.8-4.5 V.The discharge capacity at the 50th cycle at 0.5C is 170.6 mA·h/g.
以共沉淀法制备的过渡金属氢氧化物前驱体合成锂离子电池层状正极材料Li[Ni1/3Co1/3Mn1/3]O2。考察氨与过渡金属阳离子的配位效应对Li[Ni1/3Co1/3Mn1/3]O2材料的结构和电化学性能的影响。SEM分析结果表明,当NH3·H2O与过渡金属阳离子的总摩尔比为2.7:1时,获得了分布均一的颗粒为过渡金属氢氧化物共沉淀,合成的Li[Ni1/3Co1/3Mn1/3]O2材料的平均粒径约为500nm,振实密度接近2.37g/cm3,接近商品化的LiCoO2正极材料的振实密度。XRD分析结果表明,合成的Li[Ni1/3Co1/3Mn1/3]O2材料具有六角晶格层状结构。Li/Li[Ni1/3Co1/3Mn1/3]O2电池在2.8-4.5V电压范围内的0.1C倍率测试结果表明,首次放电容量达181.5mA·h/g,0.5C倍率循环50次后的放电容量为170.6mA·h/g。
基金
Project(50721003)supported by the National Natural Science Foundation of China
Project(07JJ6082)supported by the Natural Science Foundation of Hunan Province,China
Project supported by the Open Project of State Key Laboratory of Powder Metallurgy in Central South University,China
