摘要
富锂层状氧化物作为锂离子电池正极材料具有高比容量优势.采用草酸盐共沉淀法制备Li(Li0.22Ni0.17Mn0.61)O2,并用YF3包覆电极.采用X射线衍射(XRD)、扫描电子显微镜(SEM)和X射线能谱分析(EDS)表征材料结构、观察材料形貌.结果表明,材料颗粒尺寸在100～200 nm范围,YF3包覆不会改变材料结构和形貌.电化学恒流充放电测试表明,YF3包覆Li(Li0.22Ni0.17Mn0.61)O2电极的比容量,尤其倍率比容量明显提高.60 mA·g-1电流密度下包覆电极材料30周循环后其比容量保持在220 mAh·g-1以上,1500 mA·g-1电流密度下其比容量仍可达150 mAh·g-1.电化学阻抗谱(EIS)测试结果表明,YF3包覆电极电荷转移电阻和扩散阻抗均明显降低,有利于电化学性能改善.
The Li（Li0 22 Ni0.17 Mn0. 61 ）O2 was prepared with oxalic co-precipitation and coated with an YF3 layer by a chemical deposition method. The as-prepared and YF3-coated Li-rich materials were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy-dispersive X-ray spectroscopy （EDS）. The results demonstrate that the as-prepared and YF3-coated Li（ Li0.22Ni0 17Mn0.61 ）O2 materials have a typical layered structure and are composed of sphere-like particles with a diameter of 100-200 nm. Gal-vanostatic charge-discharge tests show that the discharge capacity of the YF3-coated Li （ Lio. 22 Nio. 17 Mno 6l ） 02 is obviously improved. At the low current density of 60 mAh·g^-1, the discharge capacity reaches 240 mAh·g^-1, and remains 220 mAh·g^-1 after 30 cycles. At the high current density of 1500 mAh·g^-1, the discharge capaci-ty still keeps 150 mAh·g^-1, showing an excellent high-rate capability. Electrochemical impedance spectra （EIS） reveal that the YF3-coated Li （Li0.22 Ni0. 17 Mn0.6l ）O2 shows lower charge-transfer resistance and diffu-sion impedance as compared with the as-prepared Li（ Li0.22Ni0.17Mn0. 61 ）O2.
出处
《电化学》
CAS
CSCD
北大核心
2012年第4期322-327,共6页
Journal of Electrochemistry
基金
国家973计划项目(No.2009CB220100)资助
