Formation andVariation of the Superstructure of CationOrdering in Layered Cathode Materials

This study employs aberration-corrected transmission electron microscopy to provide definitive evidence of cation ordering within the superstructure of LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523), a prominent Ni-rich ternary cathode material, characterized by wave vector <b><i>q</i></b> = 1/3(2<b>a</b>* – <b><i>b</i></b>*). We show that this ordering can be enhanced through controlled heating. Comparative analysis of LiNi_<i>x</i>Co_<i>y</i>Mn_<i>z</i>O₂ samples with different compositions revealed that Mn ions are crucial for superstructure formation. The battery performance test shows that the superstructure has no obvious effect on the voltage platform during the charge–discharge cycle, but has a negative effect on the cycle performance and structural stability. This study elucidates the origin and detrimental effects of superstructures, advancing the understanding of their impact on battery performance, which is vital for the future development of ternary cathode materials.