Achieving Enhanced Reversible Anionic Redox Activity in Li‐Rich Layered Oxides via LiCoMn ₅ Superstructure Design

Abstract

Abstract The Li‐rich layered oxide (LRLO) cathode drives the development of low‐cost and high‐energy‐density Li‐based batteries, owing to its ultrahigh capacity contributed from cationic redox and extra oxygen anionic redox reaction (ARR). However, unlocking higher ARR activity without compromising reversibility remains challenging. Herein, a series of LRLO samples with varying Ni‐Co‐Mn compositions is designed to synergistically enhance ARR activity and reversibility. On the one hand, the absence of Co results in suppressed ARR activity for traditional Li 1.2 Mn 0.6 Ni 0.2 O 2 with LiMn 6 superstructures, causing inferior O‐related capacity and cycling stability. On the other hand, excessive Co/Mn atomic exchange within the honeycomb structure by forming LiCo n Mn 6‐n ( n ≥ 2) units activates more O‐redox capacity for another typical Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 , but induces oxygen instability and low ARR reversibility. Notably, moderate incorporation of Co into LiMn 6 mainly produces LiCoMn 5 (n = 1) superstructures in Li 1.2 (Mn 0.65 Ni 0.25 Co 0.1 ) 0.8 O 2 (LRLO‐Co10) with Li 3 ‐O‐LiCoMn coordination. This unique structure enables highly reversible ARR activity. Consequently, LRLO‐Co10 exhibits a reversible capacity exceeding 300 mAh g −1 at 0.1C and retains 95.7% of the initial capacity (271.1 mAh g −1 ) after 300 cycles at 1C. These findings provide a valuable insight into compositional optimization and a strategy for achieving high‐capacity Li‐rich cathodes.