Nickel-rich layered oxides are envisaged as key near-future cathode materials for high-energy lithium-ion batteries. However, their practical application has been hindered by their inferior cycle stability, which originates from chemo-mechanical failures. Here we probe the solid-state synthesis of LiNi_0.6Co_0.2Mn_0.2O₂ in real time to better understand the structural and/or morphological changes during phase evolution. Multi-length-scale observations—using aberration-corrected transmission electron microscopy, in situ heating transmission electron microscopy and in situ X-ray diffraction—reveal that the overall synthesis is governed by the kinetic competition between the intrinsic thermal decomposition of the precursor at the core and the topotactic lithiation near the interface, which results in spatially heterogeneous intermediates. The thermal decomposition leads to the formation of intergranular voids and intragranular nanopores that are detrimental to cycling stability. Furthermore, we demonstrate that promoting topotactic lithiation during synthesis can mitigate the generation of defective structures and effectively suppress the chemo-mechanical failures.

富镍层状氧化物被设想为高能锂离子电池的关键近期阴极材料。然而，它们的实际应用受到其较差的循环稳定性的阻碍，这源于化学机械故障。_{在这里，我们探讨了LiNi 0.6} Co _0.2 Mn _0.2 O ₂的固态合成。实时更好地了解相演化过程中的结构和/或形态变化。多尺度观察——使用像差校正透射电子显微镜、原位加热透射电子显微镜和原位 X 射线衍射——揭示了整个合成过程是由前体在核心和界面附近的拓扑锂化，导致空间异质中间体。热分解导致形成不利于循环稳定性的晶间空隙和晶内纳米孔。此外，我们证明在合成过程中促进拓扑锂化可以减轻缺陷结构的产生并有效抑制化学机械故障。