Dynamic Transition Metal Network via Orbital Population Design Stabilizes Lattice Oxygen Redox in Stoichiometric Layered Cathodes
Ang Gao, Xinyan Li, Qinghua Zhang, Ting Lin, Yi‐Chi Wang, Yujie Chen, Weiguang Lin, Shiyu Wang, Pengxiang Ji, Zhu Luo, Jinlong Wang, Yanbing Guo, Lin Gu
Abstract
Abstract 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 2g 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.