Gao Ang, Li Xinyan, Zhang Qinghua, Lin Ting, Wang Yichi, Chen Yujie, Lin Weiguang, Wang Shiyu, Ji Pengxiang, Luo Zhu, Wang Jinlong, Guo Yanbing, Gu Lin
Institute of Environmental and Applied Chemistry, College of Chemistry, Central China Normal University, Wuhan, 430079, China.
Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction, Ministry of Education, Central China Normal University, Wuhan, 430079, China.
Adv Mater. 2025 Jan;37(1):e2412673. doi: 10.1002/adma.202412673. Epub 2024 Nov 7.
Li-ion batteries employing stoichiometric layered Li metal oxides as cathodes are now reaching the energy density limits due to single cationic redox chemistry. Lattice oxygen redox (LOR) has been discovered in these materials, as a high-energy-density paradigm observed in Li-rich materials. Nevertheless, the origin of this process is not understood, preventing the rational design of better cathode materials. Here, employing stoichiometric Ni-based cathodes, it is demonstrated that LOR originates from a dynamic transition metal (TM) network caused by ion migration during the electrochemical process. This network is confirmed to be ribbon through both ex- and in-situ STEM observations, facilitating reversible LOR. Finally, a t orbital population rule is proposed to guide the design of ordered TM networks, supported by calculated structures and the synthesized ordered TM oxides reported. This work explains the mechanism of LOR in stoichiometric layered cathode materials, and sets a promising direction for the design of high-energy-density cathodes through the regulation of TM ordering.
由于单阳离子氧化还原化学，采用化学计量比层状锂金属氧化物作为阴极的锂离子电池目前正接近能量密度极限。在这些材料中发现了晶格氧氧化还原（LOR），这是在富锂材料中观察到的一种高能量密度模式。然而，这一过程的起源尚不清楚，阻碍了更好的阴极材料的合理设计。在此，采用化学计量比的镍基阴极，证明了LOR起源于电化学过程中离子迁移引起的动态过渡金属（TM）网络。通过非原位和原位扫描透射电子显微镜（STEM）观察证实该网络为带状，有利于可逆的LOR。最后，提出了一个t轨道占据规则来指导有序TM网络的设计，并得到了计算结构和报道的合成有序TM氧化物的支持。这项工作解释了化学计量比层状阴极材料中LOR的机制，并为通过调节TM有序性设计高能量密度阴极设定了一个有前景的方向。
