The "two-step" method was adopted to realize the continuous gradient change of feed concentration and the gradient design of final material was derived from mathematical calculus formula. The full concentration-gradient precursor was prepared via co-precipitation method and technique of "Tubular synthesis". The final lithiated cathode material was obtained by calcination of the mixture of as-obtained full concentration-gradient precursor and 6.5％ excess LiOH·H2 O in oxygen, whose average chemical compositions was LiNi0.643Co0.055Mn0.302O2 analyzed by inductively coupled plasma-atomic emission spectrometry( ICP-AES) . The LiNi0.643Co0.055Mn0.302O2 particle was nearly spherical and had the size of 5 μm in diameter with narrow particle size distribution and its tap-density was approximately 2.029 g/cm3 . A well-ordered α-NaFeO2 layer-structured LiNi0.643Co0.055Mn0.302O2 was confirmed by Rietveld refinement of X-ray diffraction( XRD ) , in which the lattice parameters were a = 0.2877 ( 5 ) nm, c = 1.4242 ( 24 ) nm, V=0.102088(31) nm3, respectively. Energy dispersive spectrometory ( EDS ) and element mapping results verified that the concentration of Ni, Co and Mn changed gradually inside out of the particle. LiNi0.643Co0.055Mn0.302O2 delivered an initial discharge capacity of 187.68 mA · h · g-1 and coloumbic efficiency of 84.76％. After cycling at 1C rate for 200 cycles, the discharge capacity and capacity retention of LiNi0.643Co0.055Mn0.302O2 were 146.45 mA·h ·g-1 and 86.90％, respectively.%采用"两步"进料方式实现进料口浓度的连续梯度变换,并根据数学微积分公式完成材料的浓度梯度设计.通过共沉淀方法和"管道式合成"技术合成了浓度梯度前驱体,并与过量6.5％的LiOH·H2O在氧气气氛下混合煅烧得到浓度梯度正极材料.浓度梯度正极材料的平均化学成分由ICP-AES测得为LiNi0.643Co0.055Mn0.302O2.SEM照片显示,浓度梯度LiNi0.643Co0.055Mn0.302O2正极材料呈球状,粒径大小约5μm,其振实密度为2.029 g/cm3.XRD谱图表明,LiNi0643 Co0.055Mn0.302O2具有良好的α-NaFeO2层状结构;最小二乘法Rietveld精修得晶格参数a=0.2877(5)nm,c=1.4242(24)nm,V=0.102088(31)nm3.EDS和元素分布图共同验证了浓度梯度正极材料中Ni,Co,Mn的梯度变化.电化学测试结果表明,LiNi0.643Co0.055Mn0.302O2初始放电容量为187.68 mA·h·g-1,库仑效率为84.76％;1C倍率下充放电循环200周后放电容量为146.45 mA·h·g-1,容量保留率为86.90％.
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