Tang Pei, Guan Siqi, Wu Chen, Wu Huize, Lu Ni, Tan Jun, Wang Chunyang, Cheng Hui-Ming, Li Feng
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China.
School of Materials Science and Engineering, University of Science and Technology of China, Shenyang, 110016, China.
Angew Chem Int Ed Engl. 2025 Jun 24;64(26):e202503108. doi: 10.1002/anie.202503108. Epub 2025 May 2.
Layered oxide cathode materials with primary-secondary architecture face challenges of inhomogeneous Li diffusion and chemomechanical degradation due to misorientations between equiaxed primary particles. Although a radial architecture, featuring elongated grains, is widely believed to enhance diffusion, it does not address the root cause of chemomechanical failure-crystallographic misorientation. The impact of crystallography on the electrochemical performance of radially architectured secondary particles, compared to conventional designs, remains poorly understood. Here, by combining transmission Kikuchi diffraction with multimodal characterization, we decipher the crucial role of crystallography in the performance and stability of polycrystalline high-Ni layered oxide cathode materials. Contrary to the conventional belief that a preferential texture induced by the radial architecture is the key to performance enhancement, we uncover that the radial architecture primarily alters the misorientation distribution by introducing substantially increased low-angle grain boundaries and twin boundaries that significantly mitigate chemomechanical cracking and phase degradation. This crystallographic refinement facilitates enhanced Li diffusion between primary particles, ultimately boosting the rate capability and long-term stability of the cathodes. By quantitatively uncovering the crystallographic influence on performance, this work provides a new avenue for optimizing Li diffusion kinetics and chemomechanical resilience in polycrystalline cathode materials through crystallographic engineering.
具有主次结构的层状氧化物阴极材料面临着由于等轴状一次颗粒之间的取向错误而导致的锂扩散不均匀和化学机械降解的挑战。尽管具有细长晶粒的径向结构被广泛认为可以增强扩散，但它并没有解决化学机械失效的根本原因——晶体取向错误。与传统设计相比，晶体学对径向结构二次颗粒的电化学性能的影响仍知之甚少。在这里，通过将透射菊池衍射与多模态表征相结合，我们破译了晶体学在多晶高镍层状氧化物阴极材料的性能和稳定性中的关键作用。与传统观点认为径向结构诱导的择优织构是性能增强的关键相反，我们发现径向结构主要通过引入大量增加的低角度晶界和孪晶界来改变取向错误分布，从而显著减轻化学机械开裂和相降解。这种晶体学细化促进了一次颗粒之间锂扩散的增强，最终提高了阴极的倍率性能和长期稳定性。通过定量揭示晶体学对性能的影响，这项工作为通过晶体学工程优化多晶阴极材料中的锂扩散动力学和化学机械弹性提供了一条新途径。
