香港城市大学Yun-shan Jiang团队近日发现对称性破缺通过π型相互作用实现富锂阴极的稳定氧氧化还原。这一研究成果于2025年6月30日发表在《德国应用化学》杂志上。

有效稳定氧氧化还原是高能量密度富锂正极材料实际应用中最具挑战性的任务。然而，如何准确地调节氧能级以实现可逆氧化还原至今仍是一个难题。

在这项工作中，研究组通过调整与配体相邻的层间金属阳离子环境，在整个电压范围内实现了层状富锂材料中稳定的氧氧化还原，而不发生不可逆的O₂析出。结合同步加速器x射线吸收光谱和金属-配体轨道组合的理论分析，研究组证实了由于Ni三维自旋下t2g轨道和O 2p轨道之间的π型相互作用，O向Ni发生了明显的电荷转移。

此外，从头算分子动力学模拟揭示了Li萃取后Ni配位环境在π型相互作用下的自发对称性破缺，增强了阴离子和阳离子氧化的内在竞争，使O 2p态保持在金属能带以下，避免了过度氧化。结果表明，改性材料的电化学性能得到改善，结构/界面演化稳定。这项工作为相邻金属环境与配体O氧化还原反应之间的关系提供了新的见解。

附：英文原文

Title: Symmetry Breaking Enabled Stable Oxygen Redox in Li-Rich Cathodes via π-Type Interaction

Author: Fu-Da Yu, Zhe-Jian Yi, Hai-Nan Wang, Jia-Zhen Zhao, Yang-Qian Zhang, Yang Ren, Ji-Gang Zhou, Ji-Huai Wu, Zhang Lan, Yi-Ming Xie, Lan-Fang Que, Yun-shan Jiang, Zhen-Bo Wang

Issue&Volume: 2025-06-30

Abstract: Effectively stabilizing oxygen redox is the most challenging task for practical applications of high energy density Li-rich cathode materials. However, how to accurately tune the oxygen energy level to achieve reversible redox remains puzzling so far. In this work, we achieve stable oxygen redox in layered Li-rich materials over the whole voltage range without irreversible O2 release by adjusting the interlayer metal cation environment adjacent to the ligand. Combining synchrotron X-ray absorption spectroscopy and theoretical analysis of metal-ligand orbital combinations, we confirm the obvious charge transfer from O to Ni due to the π-type interaction between Ni 3d spin-down t2g orbitals and O 2p orbitals. Furthermore, Ab initio molecular dynamics simulations reveal the spontaneous symmetry breaking of the Ni coordination environment after Li extraction under the π-type interaction, which enhances the intrinsic competition between anion and cation oxidation, keeping O 2p state below the metal band to avoid over-oxidation. As a result, the modified material shows improved electrochemical performance and stable structural/interface evolution. This work provides new insights into the relationship between the adjacent metal environment and the ligand O redox reactions.

DOI: 10.1002/anie.202506507

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202506507