Surface BO ₃ Configuration in Li‐Rich Cathode Materials Enabling Highly‐Stable Anionic Redox Reactions

Abstract

ABSTRACT Li‐rich Mn‐based layered oxides (LRMOs) are considered promising cathode candidates for next‐generation high‐energy‐density lithium batteries, owing to their high capacity and low cost. However, they are plagued by lattice‐oxygen release and surface‐driven structural degradation, which lead to low initial coulombic efficiency and poor cycling stability. Here, a B‐heterogeneous coordination structure is incorporated into the Li‐rich materials, forming a ≈4 nm surface layer enriched in BO 3 units while retaining BO 4 units within the bulk. Both of tetrahedral BO 4 and trigonal BO 3 display stronger bonding interaction than those of transition metal (TM)─O bonds (i.e., Mn─O, Ni─O, and Co─O), while surface BO 3 further strengthens the B─O bonds compared with bulk BO 4 , thus robustly anchoring lattice oxygen to suppress irreversible oxygen loss. Benefiting from this synergistic heterogeneous coordination, the modified LRMOs deliver a high reversible capacity of ∼300 mAh g −1 at 0.1C, an enhanced initial Coulombic efficiency of 93.5% and excellent capacity retention of 85.8% after 300 cycles at 1C. This work demonstrates the surface BO 3 structure as an effective paradigm to reconcile oxygen‐redox activity with long‐term stability in high‐energy‐density lithium batteries.