Magnetic Field‐induced Disordered Phase of Spinel Oxides for High Battery Performance

• Published in: Advanced materials (Weinheim) Vol. 36; no. 35; pp. e2405876 - n/a
• Main Authors: Sun, Shuwei, Li, Xiaoning, Zhang, Chu, Wang, Xuefeng, Wang, Jianli, Wang, Chinwei, Xu, Zhichuan J., Cheng, Zhenxiang, Bai, Ying
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.08.2024
• Subjects: Aluminum oxide; Cathodes; cycling stability; Electrochemical analysis; Electrons; Heat treatment; Iron oxides; lithium‐ion battery; local magnetic field; Magnetic fields; Magnetic induction; Magnetic properties; Manganese ions; phase transition; Phase transitions; radical pair mechanism; Shell stability; Spinel; radical pair mechanism; local magnetic field; phase transition; lithium‐ion battery; cycling stability
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202405876

The disordered phase of spinel LiMn1.5Ni0.5O4 (LNMO) is more appealing as high‐voltage cathode due to its superior electrochemical performance compared to its ordered counterpart. Various methods are developed to induce a phase transition. However, the resulting materials often suffer from capacity degradation due to the adverse influence of accompanying Mn3+ ions. This study presents the utilization of local magnetic fields generated by a magnetic Fe3O4 shell to induce a disordered phase transition in LNMO at lower temperature, transitioning it from an order state without significantly increasing the Mn3+ content. The pivotal role played by the local magnetic fields is evidenced through comparisons with samples with nonmagnetic Al2O3 shell, samples subjected to sole heat treatment, and samples heat‐treated within magnetic fields. The key finding is that magnetic fields can initiate a radical pair mechanism, enabling the induction of order‐disorder phase transition even at lower temperatures. The disordered spinal LNMO with a magnetic Fe3O4 shell exhibits excellent cycling stability and kinetic properties in electrochemical characterization as a result. This innovation not only unravels the intricate interplay between the disordered phase and Mn3+ content in the cathode spinel but also pioneers the use of magnetic field effects for manipulating material phases. A locally generated magnetic field from a magnetic coating layer triggered a phase transition in lithium battery material spinal LiNi0.5Mn1.5O4 from an ordered to a disordered phase at temperatures as low as 300 °C. This innovative approach enriches the methods for fabricating novel energy materials, enhancing their performance in energy related applications.