Quenching-Induced Spinel/Disorder Heterostructure for Stabilized Li-Rich Cathodes

Lithium-rich oxide (LRO) cathodes are considered promising candidates for next-generation lithium-ion batteries due to their low cost and high capacity but face challenges of cyclic decay caused by irreversible oxygen loss and structural degradation. Herein, a spinel/disorder heterostructure attached to the LRO surface is demonstrated by quenching high-temperature LROs in a MgCl₂ solution, based on the quenching regulation mechanism discovered from a thermodynamic perspective. High-temperature calcination promotes lattice expansion, weakens metal-oxygen bonds, and generates significant lattice distortion and defects. These metastable structures are effectively preserved by rapid cooling and further optimized by the MgCl₂ solution, ultimately forming a spinel/disorder heterostructure enriched with abundant defects and Mg doping on the LRO surface. This multifunctional interface enhances structural stability and improves the reversibility of oxygen-anion redox reactions, effectively suppressing irreversible oxygen release and interface side reactions. Moreover, the increased d-layer spacing-coupled spinel phase promotes Li⁺ transport, and the quenching-induced Mg doping and Li/O vacancies synergistically stabilize the bulk with an optimized electronic structure. Therefore, the modified LRO has a significantly improved cycling and rate performance as well as suppressed self-discharge. These findings deepen the understanding of quenching engineering of nanomaterials and demonstrate the feasibility of optimizing Li-rich cathodes through a spinel/disorder heterostructure for sustainable energy storage.