Jin Junteng, Wang Yao, Zhao Xudong, Hu Yang, Li Tianyu, Liu Hui, Zhong Yi, Jiao Lifang, Liu Yongchang, Chen Jun
Beijing Advanced Innovation Center for Materials Genome Engineering, Department of Physical Chemistry, University of Science and Technology Beijing, Beijing, 100083, China.
Institute for Advanced Materials and Technology, National Key Laboratory of New Metal Materials, University of Science and Technology Beijing, Beijing, 100083, China.
Angew Chem Int Ed Engl. 2025 Apr 11;64(16):e202423728. doi: 10.1002/anie.202423728. Epub 2025 Feb 14.
Layered manganese-rich oxides (LMROs) are widely recognized as the leading cathode candidates for grid-scale sodium-ion batteries (SIBs) owing to their high specific capacities and cost benefits, but the notorious Jahn-Teller (J-T) distortion of Mn always induces severe structural degradation and consequent rapid cathode failure, impeding the practical implementation of such materials. Herein, we unveil the "intrinsic distortion against J-T distortion" mechanism to effectively stabilize the layered frameworks of LMRO cathodes. The intrinsic distortion simply constructed by introducing bulk oxygen vacancies is systematically confirmed by advanced synchrotron X-ray techniques, atomic-scale imaging characterizations, and theoretical computations, which can counteract the J-T distortion during cycling due to their opposite deformation orientations. This greatly decreases and uniformizes the lattice strain within the ab plane and along the c axis of the material, thereby alleviating the P2-P'2 phase transition as well as suppressing the edge dislocation and intragranular crack formation upon repeated cycles. As a result, the tailored P2-NaMgMnO cathode featuring intrinsic distortion delivers a considerably enhanced cycling durability (91.9 % capacity retention after 500 cycles) without sacrificing the Mn/Mn redox capacity (186.5 mAh g at 0.3 C). This intrinsic distortion engineering paves a brand-new and prospective avenue toward achieving high-performance LMRO cathodes for SIBs.
层状富锰氧化物（LMROs）因其高比容量和成本优势而被广泛认为是大规模钠离子电池（SIBs）的主要阴极候选材料，但是锰臭名昭著的 Jahn-Teller（J-T）畸变总是会导致严重的结构退化以及随之而来的阴极快速失效，从而阻碍了这类材料的实际应用。在此，我们揭示了“抵抗 J-T 畸变的本征畸变”机制，以有效稳定 LMRO 阴极的层状结构。通过先进的同步辐射 X 射线技术、原子尺度成像表征和理论计算系统地证实了通过引入大量氧空位简单构建的本征畸变，由于其相反的变形取向，在循环过程中可以抵消 J-T 畸变。这极大地降低并均匀化了材料 ab 平面内和 c 轴方向的晶格应变，从而减轻了 P2-P'2 相变，并抑制了反复循环时的边缘位错和晶内裂纹形成。结果，具有本征畸变的定制 P2-NaMgMnO 阴极在不牺牲 Mn/Mn 氧化还原容量（0.3 C 下为 186.5 mAh g）的情况下，提供了显著增强的循环耐久性（500 次循环后容量保持率为 91.9%）。这种本征畸变工程为实现用于 SIBs 的高性能 LMRO 阴极开辟了一条全新的、有前景的途径。
