Li Lin, Li Zhongyu, Kuang Zhifan, Zheng Hao, Yang Minjian, Liu Jianwen, Wang Shiquan, Liu Hongying
School of Chemical Engineering, Guizhou University of Engineering Science, Bijie 551700, China.
Collaborative Innovation Center for Advanced Organic Chemical Materials Co-Constructed by the Province and Ministry, Ministry of Educational Key Laboratory for the Synthesis and Application of Organic Functional Molecules, College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, China.
Materials (Basel). 2024 Dec 19;17(24):6222. doi: 10.3390/ma17246222.
High-nickel ternary LiNiCoMnO (NCM622) is a promising cathode material for lithium-ion batteries due to its high discharge-specific capacity and energy density. However, problems of NCM622 materials, such as unstable surface structure, lithium-nickel co-segregation, and intergranular cracking, led to a decrease in the cycling performance of the material and an inability to fully utilize high specific capacity. Surface coating was the primary approach to address these problems. The effect of TiO coating prepared by the sol-gel method on the performance of LiNiCoMnO was studied, mainly including the morphology, cell structure, and electrochemical properties. LiNiCoMnO was coated by TiO with a thickness of about 5 nm. Compared with the pristine NCM622 electrode, the electrochemical performance of the TiO-coated NCM622 electrodes is improved. Among all TiO-coated NCM622, the NCM622 cathode with TiO coating content of 0.5% demonstrates the highest capacity retention of 89.3% and a discharge capacity of 163.9 mAh g, in contrast to 80.9% and145 mAh g for the pristine NCM622 electrode, after 100 cycles at 0.3 C between 3 and 4.3 V. The cycle life of the 5 wt% TiO-coated NCM622 electrode is significantly improved at a high cutoff voltage of 4.6 V. The significantly enhanced cycling performance of TiO-coated NCM622 materials could be attributed to the TiO coating layer that could block the contact between the material surface and the electrolyte, reducing the interface side reaction and inhibiting the transition metal dissolution. At the same time, the coating layer maintained the stability of layered structures, thus reducing the polarization phenomenon of the electrode and alleviating the irreversible capacity loss in the cycle process.
高镍三元LiNiCoMnO（NCM622）因其高放电比容量和能量密度，是一种很有前景的锂离子电池正极材料。然而，NCM622材料存在诸如表面结构不稳定、锂镍共偏析和晶间开裂等问题，导致材料的循环性能下降，无法充分利用高比容量。表面包覆是解决这些问题的主要方法。研究了通过溶胶 - 凝胶法制备的TiO包覆对LiNiCoMnO性能的影响，主要包括形貌、电池结构和电化学性能。LiNiCoMnO被包覆了厚度约为5nm的TiO。与原始NCM622电极相比，TiO包覆的NCM622电极的电化学性能得到了改善。在所有TiO包覆的NCM622中，TiO包覆含量为0.5%的NCM622正极在3至4.3V之间以0.3C循环100次后，表现出最高的容量保持率89.3%和放电容量163.9mAh/g，而原始NCM622电极分别为80.9%和145mAh/g。5wt%TiO包覆的NCM622电极在4.6V的高截止电压下循环寿命显著提高。TiO包覆的NCM622材料循环性能的显著增强可归因于TiO包覆层能够阻止材料表面与电解质之间的接触，减少界面副反应并抑制过渡金属溶解。同时，包覆层保持了层状结构的稳定性，从而减少了电极的极化现象并减轻了循环过程中的不可逆容量损失。
