Constructing Face-Shared Configuration at the Hetero-Interface in Li-Rich Layered Oxide Cathodes

Lithium-rich cathodes are promising candidates for next-generation high-energy-density batteries owing to their high capacity and low cost. While the introduction of Li into the transition metal (TM) layers can trigger anion redox to provide additional capacity, the extraction of Li⁺ generates vacancies in the TM layers that facilitate out-of-plane TM migration, ultimately leading to gradual structural degradation. Herein, we synthesized a Li-rich heterostructure composed of a non-Li-rich O2 phase and a Li-rich O3 phase. The absence of Li vacancies in the non-Li-rich region suppresses out-of-plane TM migration from the Li-rich region. Additionally, the interface between the two phases adopts a homo-arranged, face-shared configuration, which also contributes to the suppression of out-of-plane TM migration, thus decreasing the formation of TM vacancies, thereby inhibiting the formation of vacancy clusters and associated O-O dimers within the TM layers and significantly enhancing Li⁺ deintercalation/re-intercalation reversibility. Benefiting from the introduction of the non-Li-rich O2 phase, the heterostructure improves the structural stability of the conventional O3 phase, yielding superior capacity/voltage retention. By elucidating the interaction mechanism at the heterointerface, this structural design provides a compelling strategy for developing practical Li-rich cathodes with high capacity and enhanced structural stability.