Inconsistency between superstructure stability and long-term cyclability of oxygen redox in Na layered oxides

作者：Liu, Hui; Zhao, Chong; Wu, Xiang; Hu, Chunjing; Geng, Fushan; Shen, Ming; Hu, Bei; Hu, Bingwen; Li, Chao^*

来源：Energy & Environmental Science, 2024, 17(2): 668-679.

DOI：10.1039/d3ee02915h

• LI
• INTERCALATION
• CATHODES
• NMR

Reversibility of oxygen anionic redox (OAR) in 3d transition-metal layered oxides holds the key to its practical utilization in sustainable batteries. However, the influence of cationic superstructure ordering on the reversibility of OAR during long-term battery operation remains unclarified. Herein we explore an inconsistency between the superstructure stability and long-term cyclability of OAR by comparing two contrasting systems, i.e., ribbon superstructured P2- and P3-Na0.6Li0.2Mn0.8O2. The "less Li and more Na" feature of the O-type domain formed in desodiated P3-Na0.6Li0.2Mn0.8O2 provides the driving force for the reconstruction of the ribbon superstructure, while the "more Li and less Na" feature formed in desodiated P2-Na0.6Li0.2Mn0.8O2 does not, thereby bringing about a better stability of the superstructure and a decent reversibility of local Mn-O coordination for P3-Na0.6Li0.2Mn0.8O2. More importantly, we reveal that the progressive loss of the ribbon superstructure and the accompanying sluggish local structural rearrangements occurring in P3-Na0.6Li0.2Mn0.8O2 result in a worse cyclability of OAR relative to P2-Na0.6Li0.2Mn0.8O2. It is thus reasonable to conclude that it is the reversible out-of-plane displacement of Li+ that intrinsically governs the cyclability of OAR rather than the stability of the superstructure. These findings represent a conceptual breakthrough towards the impact of the superstructure on the behavior of OAR. @@@ The preservation of LiTM (i.e., Na-O-Li configurations) determines the cyclability of oxygen redox rather than the stability of the superstructure.

• 单位
  上海交通大学