Spatially Decoupled Redox Activities Enable High Capacity and Fast Kinetics in Co-Free Li-Rich Cathodes

Cobalt-free lithium-rich layered oxides (Co-free LLOs) represent promising high-capacity and cost-effective cathode chemistries for next-generation lithium-ion batteries. However, their practical application is still limited by sluggish interfacial kinetics and complex redox regulation in the absence of cobalt, which hinders the efficient activation of the Li-rich layered framework and bulk charge transport, resulting in unsatisfactory initial capacity utilization and rate capability. Here, we demonstrate that these intrinsic limitations can be effectively addressed through a spatially decoupled redox strategy in which distinct redox functionalities are assigned to different regions within a single particle. Specifically, a three-region functional architecture is constructed in Co-free LLOs: the bulk region preserves the original layered framework and maintains reversible oxygen redox contribution as the primary source of high capacity; the near-surface bulk region undergoes fluorine substitutional regulation, which effectively modulates oxygen redox behavior by suppressing irreversible oxygen overoxidation while enhancing transition-metal cationic redox to maintain charge compensation; meanwhile, a localized spinel-like reconstructed region formed in the near-surface area provides additional low-voltage capacity through Mn³⁺/Mn⁴⁺ redox and accelerates interfacial Li⁺ transport via three-dimensional diffusion pathways. The outermost surface is further protected by an in situ formed LiF-rich amorphous layer, which stabilizes the electrode/electrolyte interface. This spatially graded architecture, enabled by fluorine-induced local electronic structure modulation, creates distinct functionalities across different length scales. As a result, the optimized cathode delivers a high reversible capacity of 310.11 mAh g^-1, an initial Coulombic efficiency of 87.7%, and a superior rate capability. This work provides a spatially decoupled redox design strategy for developing high-energy cobalt-free cathodes and offers insights into multiscale functional regulation in Li-rich layered oxides.