Ningbo Institute of Materials Technology & Engineering (NIMTE), Chinese Academy of Sciences, Ningbo 315201, P. R. China.
College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences (UCAS), Beijing 100049, P. R. China.
J Phys Chem Lett. 2023 May 18;14(19):4575-4582. doi: 10.1021/acs.jpclett.3c00616. Epub 2023 May 10.
Li-rich layered oxides (LLOs) are regarded as one of the most desirable cathode materials due to their high specific capacity. Nevertheless, the irreversible oxygen release associated with low oxygen stability prevents their widespread application. Herein, an improved oxygen redox reversibility was achieved by constructing Ni-O-Ni configurations. Superconducting Quantum Interference Device (SQUID) magnetometry measurements are used to track the evolution of the Ni-O-Ni configuration during the electrochemical process. The strongest 180° superexchange interaction in the Ni-O-Ni configuration, derived from the inevitable Li/Ni mixing in LLOs, regulates the local structure to form the ferrimagnetic (FiM) structural units. Consequently, the FiM structural units prevent the irreversible oxygen release and endow LLOs with high initial Coulombic efficiency (ICE). This work emphasizes the importance of the Ni-O-Ni configuration for LLOs with high reversible capacity and proposes a synthesis approach to modulate the amount of FiM structural units.
富锂层状氧化物（LLOs）因其比容量高而被认为是最理想的阴极材料之一。然而，低氧稳定性导致的不可逆氧释放阻碍了其广泛应用。在此，通过构建 Ni-O-Ni 构型，实现了氧氧化还原可逆性的改善。超导量子干涉仪（SQUID）磁强计测量用于跟踪电化学过程中 Ni-O-Ni 构型的演变。Ni-O-Ni 构型中来自 LLO 中不可避免的 Li/Ni 混合的最强 180°超交换相互作用调节局部结构以形成亚铁磁（FiM）结构单元。因此，FiM 结构单元阻止了不可逆的氧释放，并赋予 LLOs 高初始库仑效率（ICE）。这项工作强调了 Ni-O-Ni 构型对于具有高可逆容量的 LLOs 的重要性，并提出了一种调节 FiM 结构单元数量的合成方法。
