Synthesis and electrochemical performance of Li_(3-2x)Mg_xV_2(PO_4)_3/C composite cathode materials for lithium-ion batteries  

锂离子电池复合正极材料Li_(3-2x)Mg_xV_2(PO_4)_3/C的合成及其电化学性能（英文）

作　　者：尹武梅 张婷婷[1] 朱庆[2] 陈权启[1,2] 李谷才[3] 张灵志[2] 

机构地区：[1]湘潭大学化学学院,湘潭411105 [2]桂林理工大学化学与生物工程学院,桂林541004 [3]湖南工程学院化学化工学院,湘潭411104

出　　处：《Transactions of Nonferrous Metals Society of China》2015年第6期1978-1985,共8页中国有色金属学报（英文版）

基　　金：Project(12JJ3017) supported by the Natural Science Foundation of Hunan Province,China;Project(2013GXNSFAA019304) supported by the Natural Science Foundation of Guangxi Province;Project(51364007) supported by the National Natural Science Foundation of China

摘　　要：The Li3 2xMgxV2（PO4）3/C （x-=0, 0.01, 0.03 and 0.05） composites were prepared by a sol-gel method and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electrochemical measurements. The XRD results reveal that a small amount of Mg2＋ doping into Li sites does not significantly change the monoclinic structure of Li3V2（PO4）3, but Mg-doped Li3W2（PO4）3 has larger cell volume than the pristine Li3V2（PO4）3. All Mg-doped composites display better electrochemical performance than the pristine one, and Liz.94Mgo.03Vz（P04）3/C composite exhibits the highest capacity and the best cycle performance among all above-mentioned composites. The analysis of Li＋ diffusion coefficients in Li3V2（PO4）3/C and Li2.94Mgo.03V2（P04）3/C indicates that rapid Li＋ diffusion results from the doping of Mg2＋ and the rapid Li＋ diffusion is responsible for the better electrochemical performance of Mg-doped Li3V2（PO4）3/C composite cathode materials.采用溶胶-凝胶法制备Li3-2xMgxV2(PO4)3/C(x=0、0.01、0.03、0.05)复合材料,并通过X射线衍射(XRD)、扫描电镜(SEM)和电化学测试等测试手段对合成材料进行表征。XRD结果表明:在Li3V2(PO4)3的锂位掺杂少量Mg2+,并没有明显改变Li3V2(PO4)3晶体的单斜结构,但镁掺杂Li3V2(PO4)3的晶胞体积大于未掺杂Li3V2(PO4)3的晶胞体积。所有镁掺杂复合材料Li3-2xMgxV2(PO4)3/C(x=0.01、0.03、0.05)的电化学性能均优于Li3V2(PO4)3/C复合材料,其中,Li2.94Mg0.03V2(PO4)3/C在上述所有材料中具有最高的容量和最好的循环性能。对Li3V2(PO4)3/C和Li2.94Mg0.03V2(PO4)3/C的锂离子扩散系数及电化学性能进行对比分析,结果表明:Li+在镁掺杂Li3V2(PO4)3材料中的快速扩散是由Mg2+在锂位的掺杂造成,Li+在活性材料中的快速扩散使镁掺杂Li3V2(PO4)3材料具有优良的电化学性能。

关 键 词：lithium-ion batteries lithium vanadium phosphate diffusion coefficient sol gel method 

分 类 号：TQ131.11[化学工程—无机化工] TM912[电气工程—电力电子与电力传动]