阳离子无序和表面化学残留物对层状氧化物阴极初始库仑效率影响的研究  

Insight into the Effects of Cation Disorder and Surface Chemical Residues on the Initial Coulombic Efficiency of Layered Oxide Cathode

作　　者：刘晋利 吴涵峰 刘志北 吴英强 王莉[1] 卑凤利[2] 何向明[1] Jin-Li Liu;Han-Feng Wu;Zhi-Bei Liu;Ying-Qiang Wu;Li Wang;Feng-Li Bei;Xiang-Ming He(Institute of Nuclear and New Energy Technology,Tsinghua University,Beijing 100084,P.R.China;China National Quality Supervision Testing Center for Industrial Explosive Materials,Nanjing University of Science and Technology,Nanjing 210094,Jiangsu P.R.China;School of Chemical&Environmental Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)

机构地区：[1]清华大学,核能与新能源技术研究院,北京100084 [2]南京理工大学,国家民用爆破器材质量监督检验中心,江苏南京210094 [3]中国矿业大学,化学与环境工程学院,北京100083

出　　处：《电化学》2022年第11期99-109,共11页Journal of Electrochemistry

基　　金：supported by the National Natural Science Foundation of China(No.U21A20170);the Ministry of Science and Technology of China(No.2019YFE0100200,2019YFA0705703,and 2021YFB2501900)。

摘　　要：锂层状氧化物LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622)是电动汽车高能锂离子电池中最有前途的正极材料之一。然而,目前NCM622的一个问题是其初始库仑效率(ICE)只有约87%,比LiCoO_(2)或LiFePO_(4)至少低6%。在本工作中,我们研究了在烧结过程中形成的表面化学残留物(如LiOH和Li_(2)CO_(3))和Li/Ni阳离子混排对ICE的影响。结果表明,当烧结温度从825℃提高到900℃时,样品的ICE从80.80%提高到86.68%,而相应的Li/Ni阳离子混排和表面化学残留物也有所减少。进一步地,我们使用HNO_(3)溶液洗涤去除825℃烧结后的样品的表面残留物,发现尽管Li/Ni阳离子紊乱有所增加,但ICE提高3.57%。这些结果表明,通过适当的烧结工艺和后处理技术将表面残留量和Li/Ni阳离子混排降至最低是获得高ICE并改善NCM622电化学性能的关键。Lithium layered oxide LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622)is one of the most promising cathode materials in high-energy lithium-ion batteries for electric vehicles.However,one drawback for NCM622 is that its initial coulombic efficiency(ICE)is only about 87%,which is at least 6%lower than that of LiCoO_(2)or LiFePO_(4).In this work,we investigated the effects of surface chemical residues(e.g.,LiOH and Li_(2)CO_(3))and Li/Ni cation disorder resulted during the sintering on the ICE.We found that the ICE of the as-prepared samples could be boosted from 80.80%to 86.68%as the sintering temperatures were increased from 825 to 900℃.The corresponding Li/Ni cation disorder and surface chemical residues were also reduced with the increasing sintering temperatures.Furthermore,the ICE of the sample sintered at 825℃ could be enhanced by 3.57%after washing with HNO3solution to remove the surface residues despite the Li/Ni cation disorder being increased.These results demonstrate that minimizing the amount of surface residuals and the degree of Li/Ni cation disorder through an appropriate sintering process and post-treatment technology is critical to achieve a high ICE and improve the electrochemical performances of NCM622.

关 键 词：锂层状氧化物 首圈库仑效率 表面残碱 锂镍阳离子混排 

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