Ultrathin CeO2 coating for improved cycling and rate performance of Ni-rich layered LiNi0.7Co0.2Mn0.1O2 cathode materials
Ultrathin CeO2 coating for improved cycling and rate performance of Ni-rich layered LiNi0.7Co0.2Mn0.1O2 cathode materials
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DOI：
10.1016/j.ceramint.2018.09.145
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发表时间：
2019-01
影响因子：
5.2
通讯作者：
Shengde Dong;Yuan Zhou;Chunxi Hai;Jinbo Zeng;Yanxia Sun;Yueying Shen;Xiang Li;Xiufeng Ren;
中科院分区：
文献类型：
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作者：
Shengde Dong;Yuan Zhou;Chunxi Hai;Jinbo Zeng;Yanxia Sun;Yueying Shen;Xiang Li;Xiufeng Ren;
采用湿化学法在富镍层状LiNi 0. 7 Co 0. 2 Mn 0. 1 O2正极材料表面包覆CeO 2纳米颗粒，有效提高了电极的结构稳定性。采用X射线粉末衍射（XRD）、透射电子显微镜（TEM）、扫描电子显微镜（SEM）和X射线光电子能谱（XPS）测定了原始和表面改性LiNi0.7Co0.2Mn0.1O2的结构、形貌、元素组成和电子态。电化学测试结果表明，0.3mol%CeO2包覆的LiNi0.7Co0.2Mn0.1O2具有优异的循环性能和倍率性能，在0.5C电流倍率下，放电比容量为161.7mA h g-1，100次循环后容量保持率为86.42%，相比之下，裸LiNi0.7Co0.2Mn0.1O2的分别为135.7 mA h g− 1和70.64%。即使在5 C下，放电比容量仍高达137.1 mA h g− 1，容量保持率为69.0%，而NCM仅提供95.5 mA h g− 1，容量保持率为46.6%。CeO 2具有良好的氧化能力，可将Ni 2+氧化为Ni 3+，将Mn 3+氧化为Mn 4+，从而抑制了Li+/Ni 2+混合和相转移的发生。此外，CeO 2涂层可以保护结构，避免副反应的发生。CeO 2包覆的复合材料具有更好的结构稳定性、循环性能和倍率性能，是一种很有前途的锂离子电池正极材料。
In this study, we have successfully coated the CeO2nanoparticles (CeONPs) layer onto the surface of the Ni-rich layered LiNi0.7Co0.2Mn0.1O2cathode materials by a wet chemical method, which can effectively improve the structural stability of electrode. The X-ray powder diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) are used to determine the structure, morphology, elemental composition and electronic state of pristine and surface modified LiNi0.7Co0.2Mn0.1O2. The electrochemical testing indicates that the 0.3 mol% CeO2-coated LiNi0.7Co0.2Mn0.1O2demonstrates excellent cycling capability and rate performance, the discharge specific capacity is 161.7 mA h g−1with the capacity retention of 86.42% after 100 cycles at a current rate of 0.5 C, compared to 135.7 mA h g−1and 70.64% for bare LiNi0.7Co0.2Mn0.1O2, respectively. Even at 5 C, the discharge specific capacity is still up to 137.1 mA h g−1with the capacity retention of 69.0%, while the NCM only delivers 95.5 mA h g−1with the capacity retention of 46.6%. The outstanding electrochemical performance is assigned to the excellent oxidation capacity of CeO2which can oxidize Ni2+to Ni3+and Mn3+to Mn4+with the result that suppress the occurrence of Li+/Ni2+mixing and phase transmission. Furthermore, CeO2coating layer can protect the structure to avoid the occurrence of side reaction. The CeO2-coated composite with enhanced structural stability, cycling capability and rate performance is a promising cathode material candidate for lithium-ion battery.