碳包覆改性制备高倍率性能的锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2
Preparation of Carbon-Coated LiNi1/3Co1/3Mn1/3O2 Cathode for High-Rate Lithium Ion Batteries
作者单位E-mail
郑卓 四川大学高分子研究所, 成都 610065  
郭孝东 四川大学化学工程学院, 成都 610065  
吴振国 四川大学化学工程学院, 成都 610065  
向伟 成都理工大学材料与化学化工学院, 成都 610059  
滑纬博 四川大学化学工程学院, 成都 610065  
钟本和 四川大学化学工程学院, 成都 610065  
杨秀山 四川大学化学工程学院, 成都 610065 yangxs@scu.edu.cn 
摘要: 采用碳酸盐共沉淀-高温固相法制备了一系列表面碳包覆改性(w=1.0%,2.0%,3.0%)的LiNi1/3Co1/3Mn1/3O2正极材料,借助X射线衍射(XRD)分析、扫描电镜(SEM)、透射电镜(TEM)、电化学阻抗谱(EIS)和恒电流充放电测试等表征手段对材料的晶体结构、微观形貌和电化学性能进行了较系统的研究。结果表明,碳成功地包覆在了材料颗粒的表面,碳包覆改性后的材料具有良好的α-NaFeO2结构(空间群为R3m),且随着包碳量的增加,一次颗粒平均尺寸逐渐增大(从177 nm增至209 nm)。表面的无定形碳层可以提高材料的电子导电率,减少电极材料与电解液的副反应,故而碳包覆材料的电化学性能都有了一定程度提升。包覆碳量为2.0%的样品高倍率和长循环性能最好,在2.7~4.3 V,1C下循环100次后,容量保持率为93%;在0.1C、0.2C、0.5C、1C、3C、5C、10C和20C时的放电比容量分别为:155、148、145、138、127、116、104和96 mAh·g-1。在超高倍率50C(9 A·g-1)时,其放电比容量还能达到62 mAh·g-1(原始LiNi1/3Co1/3Mn1/3O2材料仅为30 mAh·g-1),倍率性能十分优异。
关键词: 碳酸盐共沉淀法  碳包覆  高倍率性能  LiNi1/3Co1/3Mn1/3O2  锂离子电池
基金项目: 国家自然科学基金(No.21506133)和四川省科技支撑计划(No.2014GZ0077)资助项目。
Abstract: A series of carbon-coated LiNi1/3Co1/3Mn1/3O2 cathodes (w=1.0%, 2.0%, 3.0%) have been prepared by the carbonate co-precipitation, high temperature solid state method. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge tests were employed to analyze the crystal structure, micromorphology and electrochemical properties of the as-prepared materials. The results indicate that carbon was successfully coated on the particle surface, and the carbon-coated LiNi1/3Co1/3Mn1/3O2 cathodes have well-ordered α-NaFeO2 structure (space group is R3m). The average primary particle sizes were gradually increased (from 177 to 209 nm) with the increased carbon coating. The amorphous carbon layer on the surface could enhance the electronic conductivity and decrease the side reactions between electrolyte and electrodes, thus improving the electrochemical performance. The 2.0% carbon-coated sample has the best high rate and long-term cycling stability. After 100 cycles at 1C between 2.7 and 4.3 V, the material retained 93% of its initial capacity. At 0.1C, 0.2C, 0.5C, 1C, 3C, 5C, 10C and 20C, the specific capacities of the material were 155, 148, 145, 138, 127, 116, 104 and 96 mAh·g-1, respectively. This sample exhibits an excellent ultra-high rate performance with a high discharge capacity of 62 mAh·g-1 (the pristine LiNi1/3Co1/3Mn1/3O2 barely delivers 30 mAh·g-1) even at the ultra-high rate 50C (9 A·g-1).
Keywords: carbonate co-precipitation  carbon-coated  high rate performance  LiNi1/3Co1/3Mn1/3O2  lithium-ion battery
投稿时间:2016-08-23 修订日期:2016-11-18
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