锂离子电池浓度梯度正极材料LiNi_(0.643)Co_(0.055)Mn_(0.302)O_2的合成与表征  

Synthesis and Characterization of Full Concentration-gradient LiNi_(0.643)Co_(0.055)Mn_(0.302)O_2 Cathode Material for Lithium-ion Batteries

作　　者：罗熳 蒋文全[1] 韩雪[1] 郭荣贵[1] 李涛[1] 于丽敏[1] 

机构地区：[1]北京有色金属研究总院,北京100088

出　　处：《高等学校化学学报》2018年第1期148-156,共9页Chemical Journal of Chinese Universities

摘　　要：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Li OH·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LiNi_(0.643)Co_(0.055)Mn_(0.302)O_2.SEM照片显示,浓度梯度LiNi_(0.643)Co_(0.055)Mn_(0.302)O_2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,LiNi_(0.643)Co_(0.055)Mn_(0.302)O_2具有良好的α-Na Fe O2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,LiNi_(0.643)Co_(0.055)Mn_(0.302)O_2初始放电容量为187.68 m A·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 m A·h·g-1,容量保留率为86.90%.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 Li OH·H2 O in oxygen, whose average chemical compositions was LiNi_（0.643）Co_（0.055）Mn_（0.302）O_2 analyzed by inductively coupled plasma-atomic emission spectrometry（ ICP-AES）. The LiNi_（0.643）Co_（0.055）Mn_（0.302）O_2 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-Na Fe O2 layer-structured LiNi_（0.643）Co_（0.055）Mn_（0.302）O_2 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.LiNi_（0.643）Co_（0.055）Mn_（0.302）O_2 delivered an initial discharge capacity of 187. 68 m A · h · g-1 and coloumbic efficiency of 84. 76%. After cycling at 1 C rate for 200 cycles,the discharge capacity and capacity retention of LiNi_（0.643）Co_（0.055）Mn_（0.302）O_2 were 146. 45 m A·h ·g-1 and 86. 90%,respectively.

关 键 词：共沉淀 浓度梯度 锂离子电池 正极材料 

分 类 号：O646[理学—物理化学]