Chemically Anchored Lattice Oxygen Enables Stability in Layered Sodium Cathodes
Zhiyu Song, Shivam Kansara, Shuoshuo Cheng, Miaorui Yang, Fan Li, Chao Qi, Shiyu Li, Jang‐Yeon Hwang, Ying Bai
Abstract
The long-term performance of P2-type layered transition metal oxides is often compromised by irreversible oxygen redox and lattice instability, resulting in rapid capacity degradation. This work proposes a dual-site La 3+ substitution strategy to stabilize the lattice oxygen and improve the electrochemical durability. The substitution of La 3+ into the transition metal layer forms strong La─O covalent interactions that anchor lattice oxygen while simultaneously lowering the O 2p orbital energy to suppress parasitic oxygen evolution. This electronic and structural modulation enables controlled anionic redox behavior and enhances phase reversibility under deep charge. In situ XRD reveals a minimal volume change (0.9%) during cycling, indicative of an apparent structural resilience. The optimized 0.02La-doped cathode exhibits stable full-cell performance when paired with commercial hard carbon, achieving 80.2% capacity retention over 600 cycles at 5C. These findings demonstrate a viable path toward stable sodium-ion cathodes via rare-earth-assisted lattice oxygen regulation.