Structure design enables stable anionic and cationic redox chemistry in a T2-type Li-excess layered oxide cathode
Structure design enables stable anionic and cationic redox chemistry in a T2-type Li-excess layered oxide cathode
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DOI：
10.1016/j.scib.2021.11.014
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发表时间：
2022-02-17
期刊：
影响因子：
18.9
通讯作者：
Zhou, Haoshen
中科院分区：
文献类型：
--
作者：
Cao, Xin;Li, Haifeng;Zhou, Haoshen
结合阴离子和阳离子氧化还原化学，富锂/过剩锂正极材料有望成为下一代锂离子电池的高能量密度候选者。然而，不可逆的晶格氧损失会加剧不可逆的过渡金属迁移，导致剧烈的电压衰减和容量退化。本文制备了一种亚稳态层状锂过量阴极材料t2型Li-0.72[Li0.12Ni0.36Mn0.52]O-2，其氧的堆叠排列和锂的配位环境与传统的o -3型层状结构有本质的不同。通过可逆的锂离子迁移过程和结构演化，不仅可以有效地抑制电压衰减，而且可以在长期循环后获得良好的容量保持。此外，不可逆/可逆阴离子/阳离子氧化还原活性已经通过各种原位/原位光谱技术进行了很好的分配和量化，进一步阐明了与（去）锂化相关的电荷补偿机制。这些具有增强阴离子氧化还原稳定性的新型T2结构的发现将为高能量密度富锂正极材料的发展提供新的领域。(C) 2021中国科学出版社。由爱思唯尔、中国科学出版社联合出版。版权所有。
Coupled with anionic and cationic redox chemistry, Li-rich/excess cathode materials are prospective high-energy-density candidates for the next-generation Li-ion batteries. However, irreversible lattice oxygen loss would exacerbate irreversible transition metal migration, resulting in a drastic voltage decay and capacity degeneration. Herein, a metastable layered Li-excess cathode material, T2-type Li-0.72[Li0.12Ni0.36Mn0.52]O-2, was developed, in which both oxygen stacking arrangement and Li coordina-tion environment fundamentally differ from that in conventional O-3-type layered structures. By means of the reversible Li migration processes and structural evolutions, not only can voltage decay be effectively restrained, but also excellent capacity retention can be achieved upon long-term cycling. Moreover, irreversible/reversible anionic/cationic redox activities have been well assigned and quantified by various in/exsitu spectroscopic techniques, further clarifying the charge compensation mechanism associated with (de)lithiation. These findings of the novel T2 structure with the enhanced anionic redox stability will provide a new scope for the development of high-energy-density Li-rich cathode materials. (C) 2021 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.