Park Hyeokjun, Park Hayoung, Song Kyung, Song Seok Hyun, Kang Sungsu, Ko Kun-Hee, Eum Donggun, Jeon Yonggoon, Kim Jihoon, Seong Won Mo, Kim Hyungsub, Park Jungwon, Kang Kisuk
Department of Materials Science and Engineering & Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul, Republic of Korea.
Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul National University, Seoul, Republic of Korea.
Nat Chem. 2022 Jun;14(6):614-622. doi: 10.1038/s41557-022-00915-2. Epub 2022 Apr 21.
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 LiNiCoMnO 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.
富镍层状氧化物被视为近期高能量锂离子电池的关键阴极材料。然而，其实际应用受到较差的循环稳定性的阻碍，这种稳定性源于化学机械故障。在这里，我们实时探测LiNiCoMnO的固态合成，以更好地理解相演变过程中的结构和/或形态变化。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射线衍射进行的多尺度观察表明，整体合成受核心处前驱体的固有热分解与界面附近的拓扑锂化之间的动力学竞争控制，这导致了空间上不均匀的中间体。热分解导致晶间空隙和晶内纳米孔的形成，这对循环稳定性不利。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。
