High-Entropy Mn/Fe-Based Layered Cathode with Suppressed P2-P'2 Transition and Low-Strain for Fast and Stable Sodium Ion Storage

• Published in: ACS applied materials & interfaces 2024-01, Vol.16 (2), p.2378-2388
• Main Authors: Wang, Ziqing, Zhang, Shengfeng, Fu, Xiaoguang, Huang, Rui, Huang, Ling, Zhang, Junyu, Yang, Weihua, Fu, Fang, Sun, Shigang
• Format: Article
• Language: English
• ISSN: 1944-8252
• DOI: 10.1021/acsami.3c16333

Mn/Fe-based layered oxides are deemed to be a highly suitable cathode for sodium-ion batteries (SIBs) due to their high capacity and abundant Mn/Fe resources, but they still suffer from a complicated phase transition and large volume variation. To conquer these problems, high-entropy Mn/Fe-based layered oxide P2-Na Mn Fe Cu Mg Ti Al Zr Sn O (Mn-Fe-HEO) is rationally designed and fabricated. When used as a cathode for SIB, high-entropy Mn-Fe-HEO exhibits much higher reversible capacity and better rate capability than low-entropy Na Mn Fe Cu O (Mn-Fe-LEO) within a wide voltage range of 1.5-4.3 V. Ex situ X-ray diffraction combined with diffusion kinetics tests and microstructural characterizations demonstrate that high-entropy enhanced structural stability effectively prevents the Jahn-Teller distortion of Mn , stabilizes the Na diffusion channels, and enables the smooth transfer of more working Na . These lead to a stable and fast redox electrochemistry in high-entropy Mn-Fe-HEO. This work deepens the understanding of the relationship between high-entropy structure and performance and provides important guidance for the rational design of future high-entropy layered cathodes.