Homeostatic Solid Solution in Layered Transition-Metal Oxide Cathodes of Sodium-Ion Batteries

• Published in: Journal of the American Chemical Society Vol. 145; no. 1; pp. 224 - 233
• Main Authors: Ren, Meng, Zhao, Shuo, Gao, Suning, Zhang, Tong, Hou, Machuan, Zhang, Wei, Feng, Kun, Zhong, Jun, Hua, Weibo, Indris, Sylvio, Zhang, Kai, Chen, Jun, Li, Fujun
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 11.01.2023
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.2c09725

Two-phase transformation reaction is ubiquitous in solid-state electrochemistry; however, it usually involves inferior structure rearrangement upon extraction and insertion of large-sized Na+, thus leading to severe local strain, cracks, and capacity decay in sodium-ion batteries (SIBs). Here, a homeostatic solid solution reaction is reported in the layered cathode material P′2-Na0.653Ni0.081Mn0.799Ti0.120O2 during sodiation and desodiation. It is induced by the synergistic incorporation of Ni and Ti for the reinforced O­(2p)-Mn­(3d-eg*) hybridization, which leads to mitigated Jahn–Teller distortion of MnO6 octahedra, contracted transition-metal oxide slabs, and enlarged Na layer spacings. The thermodynamically favorable solid solution pathway rewards the SIBs with excellent cycling stability (87.2% capacity retention after 500 cycles) and rate performance (100.5 mA h g–1 at 2500 mA g–1). The demonstrated reaction pathway will open a new avenue for rational designing of cathode materials for SIBs and beyond.