LiNi0.5Co0.2Mn0.3O2@WO3复合正极材料的制备与性能

Preparation and properties of LiNi0.5Co0.2Mn0.3O2@WO3 composite cathode materials

  • 摘要: 为改善LiNi0.5Co0.2Mn0.3O2(NCM)锂离子电池三元正极材料的电化学性能,采用液相蒸发法将WO3包覆于NCM表面,得到NCM@WO3复合正极材料。通过XRD、SEM和TEM对NCM@WO3复合材料的结构和形貌进行表征,利用充放电测试、循环伏安及交流阻抗测试对其电化学性能进行表征。结果表明,当WO3包覆量为3wt%时,NCM@WO3复合材料性能最佳,在0.5 C下的首次放电比容量为179.9 mA·hg-1,不可逆容量损失降低至42.4 mA·hg-1,循环50圈后容量保持率为98.3%。WO3的包覆提高了锂离子扩散速率,减少了电极材料与电解液的副反应,NCM@WO3复合材料的电化学性能得到提升。

     

    Abstract: In order to improve the electrochemical performance of LiNi0.5Co0.2Mn0.3O2 (NCM), WO3 coated NCM (NCM@WO3) composite cathode materials were synthesized with a liquid phase evaporation process. The structure and morphology of the NCM@WO3 composite were characterized by XRD, SEM and TEM. The electrochemical performance of the NCM@WO3 composite was characterized by charge-discharge test, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the NCM@WO3 composite with 3wt% WO3 has the best performance, it delivers an initial discharge capacity of 179.9 mA·hg-1 with a low irreversible capacity loss of 42.4 mA·hg-1 at 0.5 C, and the capacity retention after 50 cycles is 98.3%. The improved electrochemical properties of the NCM@WO3 composite are mainly attributed to the WO3 coating, which improves the lithium ions diffusion rate and suppresses the interface reaction between the cathode and the electrolyte.

     

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