镱掺杂LiFePO_4/C正极材料结构和电化学性能  

Structure and Electrochemical Properties of Yb-doped Lithium Iron Phosphate Cathode Materials

作　　者：张秋明[1] 乔玉卿[1] 赵敏寿[1,2] 王立民[3] 

机构地区：[1]燕山大学环境与化学工程学院,河北秦皇岛066004 [2]燕山大学亚稳材料制备技术与科学国家重点实验室,河北秦皇岛066004 [3]中国科学院长春应用化学研究所,稀土资源与利用国家重点实验室,吉林长春130022

出　　处：《中国稀土学报》2012年第1期78-85,共8页Journal of the Chinese Society of Rare Earths

基　　金：河北省软科学计划(11457298);中国科学院创新工程项目(KJCX2-Y1W-H21);河北省自然科学基金项目(2008SYHZ0008);燕山大学博士基金项目(B330)资助

摘　　要：采用高温固相法制备LiFe1-xYbxPO4/C(x=0,0.06,0.08,0.10)锂离子电池正极材料,并用X射线衍射(XRD),扫描电镜(SEM),循环伏安测试(CV)及交流阻抗测试(EIS)等方法进行结构和电化学性能的测试。XRD分析结果表明LiFe1-xYbxPO4/C(x=0,0.06,0.08,0.10)样品具有橄榄石型晶体结构。Yb的掺杂导致LiFePO4晶格中c轴方向的P-O键长增加,其中x=0.08样品具有最长的P-O键长。SEM图表明Yb的掺杂可明显细化颗粒,其中x=0.08时样品粒径为200 nm,比未掺杂样品降低了约2.5倍。电化学性能测试表明,Yb的掺杂使样品的放电容量增加,循环稳定性能提高。在-20～40℃温度区间内,放电容量随温度的升高而增加,其中x=0.08的样品40℃时放电容量为150 mAh.g-1,但测试温度达到60℃时,放电容量急剧下降。EIS测试表明Yb的掺杂可以明显改善电极表面电化学反应的动力学性能,降低电荷转移电阻,提高交换电流密度。Microstructure and electrochemical properties of LiFe1-xYbxPO4/C（x=0,0.06,0.08,0.10） were investigated using XRD,SEM,CV,and EIS measurements.All the samples had the crystal structure of olivine.With increasing Yb substitution content,the particles of synthesized LiFe1-xYbxPO4/C maintained fine and homogeneous in size.The doping of Yb increased the bond length of P-O,which parallels c axis.The electrochemical test showed that the doping of Yb increased the discharge capacity and improved the cycle performance.The temperature effect indicated that the discharge capacity increased with the rise of temperature at-20~40 ℃.The sample with x=0.08 delivered the discharge capacity of 150 mAh · g-1 at 40 ℃,but the discharge capacity decreased drastically at 60 ℃.The EIS test demonstrated that the doping of Yb could improve the cycle performance of the sample,decreased the charge transfer resistance Rct and increased the exchange current density i0 greatly.

关 键 词：磷酸亚铁锂 镱 正极材料 锂离子电池 

分 类 号：O614.111[理学—无机化学] O614.811[理学—化学]