AlF_3包覆改性LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2正极材料的制备与性能  

Synthesis and characterization of AlF_3-coated LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2 cathode materials for Li-ion batteries

作　　者：张倩[1] 李建刚[2] 谢娇娜[2] 何向明[3] 

机构地区：[1]北京化工大学化学工程学院,北京100029 [2]北京石油化工学院应用化学系,北京102617 [3]清华大学核能与新能源技术研究院,北京100084

出　　处：《化工新型材料》2009年第12期26-29,共4页New Chemical Materials

基　　金：北京市教委科技发展规划项目(KM200710017001)

摘　　要：制备了4．6V高截至电压下具有良好循环表现的AlF23覆改性LiNi0.4Co0.2Mn0.4O2正极材料，通过XRD、SEM、交流阻抗（IMP）分析、充放电测试研究了不同用量AlF3包覆LiNi0.4Co0.2Mn0.4O2正极材料的结构与电化学性能。结果表明，AlF3以非晶态形式包覆于LiNi0.4C0.2Mn0.4O2材料颗粒的表面。当包覆量〈1．0％（摩尔分数，下同）时，AlF2包覆导致轻微的初始容量损失，但显著抑制了高充电电压下膜阻抗和电荷传递阻抗的增加，较好改善了LiNi0．4Co0.2Mn0.4O2材料的循环稳定性；当包覆量达到2．0％以上时，因AlF3无电化学活性，使得初始容量损失过大。综合各方面表现，0．5％AlF3包覆样品的电化学性能较佳，2．5～4．6V范围0．5C放电容量为182．2mAh·g^-1循环30次后容量保持率达88．1％。AlF3-coated LiNi0.4 Co0.2 Mn0.4 O2 powders with improved cycling performance at 4. 6V cut-off voltage were synthesized. The structural and electrochemical properties of AlF3-coated LiNi0.4 Co0. 2 Mn0. 4 O2 electrodes was studied as function of the level of AlF3 coating by using X-ray diffraction（XRD）, scanning electron microscope（SEM）, charge-discharge tests and electrochemical impedance spectra（EIS）. The results showed that the uncrystalline AlF3 uniformly distributed on the surface of the LiNi0. 4 Co0. 2 Mn0. 4 O2 particles. As the coating amount less than 1.0% （mol）, the initial capacity of the coated LiNi0. 4 Co0. 2 Mn0. 4 O2 decreased slightly, however the cycling stability was improved at 4. 6V cut-off cycling by reducing the increase of film resistance and charge transfer resistance. The sample with more than 2.0% （mol） AlF3 coating show remarkable decrease of the initial capacity due to too much inactive AlF3 coating. In view of the initial capacity and cycling performance, 0.5 % （mol） coated sample exhibited the best electrochemical performance. It showed initial discharge capacity of 182.2mAh（g ^-1 at 0.5℃ rate, and 88.1% of initial capacity retention after 30 cycles at 4.6V cut-ff cycling.

关 键 词：锂离子电池 正极材料 LiNi0.4Co0.2Mn0.4O2 ALF3 包覆 

分 类 号：TM912[电气工程—电力电子与电力传动]