Authors
Fu, Fang; Liu, Xiang; Fu, Xiaoguang; Chen, Hongwei; Huang, Ling; Fan, Jingjing; Le, Jiabo; Wang, Qiuxiang; Wang, Qiuxiang; Yang, Weihua; Ren, Yang; Amine, Khalil; Sun, Shi-Gang; Xu, Gui-Liang
Abstract
P2-type sodium manganese-rich layered oxides are promising cathode candidates forsodium-based batteries because of their appealing cost-effective and capacity features.However, the structural distortion and cationic rearrangement induced by irreversible phasetransition and anionic redox reaction at high cell voltage (i.e., > 4.0 V) cause sluggish Na-ionkinetics and severe capacity decay. To circumvent these issues, here, we report a strategy todevelop P2-type layered cathodes via configurational entropy and ion-diffusion structuraltuning. In situ synchrotron X-ray diffraction combined with electrochemical kinetic tests andmicrostructural characterizations reveal that the entropy-tunedNa0.62Mn0.67Ni0.23Cu0.05Mg0.07Ti0.01O2 (CuMgTi-571) cathode possesses more {010} activefacet, improved structural and thermal stability and faster anionic redox kinetics compared toNa0.62Mn0.67Ni0.37O2. When tested in combination with a Na metal anode and a non-aqueous NaClO4-based electrolyte solution in coin cell configuration, the CuMgTi-571-based positive electrode enables an 87% capacity retention after 500 cycles at 120 mA g-1 and about 75% capacity retention after 2000 cycles at 1.2 A g-1.