Preoxidation of Ni_0.8Co_0.17Al_0.03(OH)₂ with LiClO₄ to improve cycle stability of lithium-ion batteries

Layered Ni-rich anode material (LiNi_0.8Co_0.17Al_0.03O₂) is welcomed by the public because of its high nickel content, higher specific capacity and lower cost than LiCoO₂. However, the rapid capacity decline in the process of cycling prevents further commercial application of LiNi_0.8Co_0.17Al_0.03O₂. Among them, the mixing of Li⁺ /Ni²⁺ in Ni-rich anode materials is one of the main reasons for the poor cycle performance of materials. In this paper, LiNi_0.8Co_0.17Al_0.03O₂ precursor was preoxidized with highly oxidized LiClO₄. The X-ray diffraction (XRD) and Rietveld refinement results show that the LiNi_0.8Co_0.17Al_0.03O₂ (LiClO₄-NCA) sample after LiClO₄ treatment has a lower Li⁺/Ni²⁺ mixing degree, which is consistent with the results of Ni²⁺/Ni³⁺ in the anode material tested by X-ray photoelectron spectroscopy (XPS). The electrochemical test results show that LiClO₄-NCA has better cycling performance than the original sample LiNi_0.8Co_0.17Al_0.03O₂ (NCA). The capacity retention rate of LiClO₄-NCA (94.3%) is significantly higher than that of NCA (82.4%) after 100 cycles of 1 C. The excellent electrochemical performance of LiClO₄-NCA is attributed to the fact that LiClO₄ promotes the conversion of Ni²⁺ into Ni³⁺ in the material, reducing cation mixing phenomenon and maintaining a more complete layered structure. Therefore, LiClO₄ preoxidation of LiNi_0.8Co_0.17Al_0.03O₂ precursor can improve the mixing phenomenon of Li⁺/Ni²⁺ in the material and optimize the cycle stability of layered Ni-rich anode material.