二元掺杂对LiFePO_4结构及电化学性能的影响  

Influence of doping with two elements on structure and electrochemical performance of LiFePO_4

作　　者：冯传启[1,2,3] 李琳[1,2] 李华 陈骁[2,3] 王石泉[2,3] 

机构地区：[1]安顺学院功能材料与资源化学重点实验室,贵州安顺561000 [2]有机化工新材料湖北省协同创新中心,湖北武汉430062 [3]湖北大学有机功能分子合成与应用教育部重点实验室,湖北武汉430062

出　　处：《电源技术》2016年第4期755-757,762,共4页Chinese Journal of Power Sources

基　　金：贵州省科技厅;安顺市人民政府和安顺学院三方联合基金项目(黔科合J字LKA[2012]02号);贵州省教育厅"功能材料与资源化学特色重点实验室"开放基金项目(GAFMRC201301)

摘　　要：采用流变相法合成了锂离子电池正极材料LiFePO_4,并对其进行Ga3+和F-离子同时掺杂改性。用X射线衍射光谱法(XRD)、透射电子显微镜法(TEM)等测试手段对改性材料进行表征,并对LiFe_(1-x)Ga_x(PO_4)1-xF_(3x)(x=0,0.02,0.06,0.10,0.14)正极材料进行了电化学性能测试。结果表明:正、负离子同时掺杂后的LiFe_(1-x)Ga_x(PO_4)1-xF_(3x)仍具有橄榄石结构,但能明显地改善LiFePO_4的电化学性能,尤其是改善其倍率性能。当掺杂量x为0.06时,样品LiFe_(0.94)Ga_(0.06)(PO_4)_(0.94)F_(0.18)表现出最优的电化学性能,以0.1 C进行充放电时,初始放电比容量为155 m Ah/g,经100次循环后,仍然保持为147m Ah/g;以1 C进行充放电时,首次放电比容量达到142 m Ah/g,经100次循环后,仍保持为130 m Ah/g。To improve the performance of LiFePO_4 as cathode material,the compounds LiFe_（1-x）Ga_x（PO_4）_（1-x）F_（3x）（x=0,0.02,0.06,0.10,0.14） were synthesized by reheological phase reaction method（RPR）. The samples were characterized by X-ray diffraction（XRD） and transmission electron microscope（TEM） techniques. The electrochemical properties of different samples were investigated by battery testing system. The results show that the samples doped by Ga^（3＋） and F- keep a well-ordered olivine phase, but the doping of Ga^（3＋） and F- in LiFePO_4[Li Fe_（1-x）Ga_x（PO_4）_（1-x）F_（3x）]can improve the electrochemical performance of LiFePO_4, especially the rate performances. The Li Fe0.94Ga0.06（PO4）0.94F0.18（x=0.06） behaves the best electrochemical performance among all samples. At 0.1 C, the initial discharge specific capacity of the LiFe_（0.94）Ga_（0.06）（PO_4）_（0.94）F_（0.18） is 155 m Ah/g,and remains 147 m Ah/g after 100 cycles; At 1 C,the initial discharge specific capacity of the sample is 142 m Ah/g,and remains 130 m Ah/g after 100 cycles.

关 键 词：锂离子电池 磷酸铁锂 正极材料 掺杂 

分 类 号：TM912.9[电气工程—电力电子与电力传动]