Wu Kang, Ran Peilin, Yin Wen, He Lunhua, Wang Baotian, Wang Fangwei, Zhao Enyue, Zhao Jinkui
Songshan Lake Materials Laboratory, Dongguan, 523808, China.
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
Angew Chem Int Ed Engl. 2024 Oct 14;63(42):e202410326. doi: 10.1002/anie.202410326. Epub 2024 Sep 13.
High-voltage ultrahigh-Ni cathodes (LiNiCoMnO, x≥0.9) can significantly enhance the energy density and cost-effectiveness of Li-ion batteries beyond current levels. However, severe Li-Ni antisite defects and their undetermined dynamic evolutions during high-voltage cycling limit the further development of these ultrahigh-Ni cathodes. In this study, we quantify the dynamic evolutions of the Li-Ni antisite defect using operando neutron diffraction and reveal its coupling relationship with anionic redox, another critical challenge restricting ultrahigh-Ni cathodes. We detect a clear Ni migration coupled with an unstable oxygen lattice, which accompanies the oxidation of oxygen anions at high voltages. Based on these findings, we propose that minimized Li-Ni antisite defects and controlled Ni migrations are essential for achieving stable high-voltage cycling structures in ultrahigh-Ni cathodes. This is further demonstrated by the optimized ultrahigh-Ni cathode, where reduced dynamic evolutions of the Li-Ni antisite defect effectively inhibit the anionic redox, enhancing the 4.5 V cycling stability.
高压超高镍阴极（LiNiCoMnO，x≥0.9）能够显著提高锂离子电池的能量密度和成本效益，使其超越当前水平。然而，严重的锂镍反位缺陷及其在高压循环过程中不确定的动态演变限制了这些超高镍阴极的进一步发展。在本研究中，我们使用原位中子衍射对锂镍反位缺陷的动态演变进行了量化，并揭示了其与阴离子氧化还原的耦合关系，阴离子氧化还原是限制超高镍阴极的另一个关键挑战。我们检测到明显的镍迁移与不稳定的氧晶格相关联，这伴随着高电压下氧阴离子的氧化。基于这些发现，我们提出，最小化锂镍反位缺陷和控制镍迁移对于在超高镍阴极中实现稳定的高压循环结构至关重要。优化后的超高镍阴极进一步证明了这一点，其中锂镍反位缺陷的动态演变减少，有效抑制了阴离子氧化还原，增强了4.5 V循环稳定性。
