Multiphase manganese-based layered oxide for sodium-ion batteries: structural change and phase transition

Sodium-ion batteries (SIBs) are recognized as a leading option for energy storage systems, attributed to their environmental friendliness, natural abundance of sodium, and uncomplicated design. Cathode materials are crucial in defining the structural integrity and functional efficacy of SIBs. Recent studies have extensively focused on manganese (Mn)-based layered oxides, primarily due to their substantial specific capacity, cost-effectiveness, non-toxic nature, and ecological compatibility. Additionally, these materials offer a versatile voltage range and diverse configurational possibilities. However, the complex phase transition during a circular process affects its electrochemical performance. Herein, we set the multiphase Mn-based layered oxides as the research target and take the relationship between the structure and phase transition of these materials as the starting point, aiming to clarify the mechanism between the microstructure and phase transition of multiphase layered oxides. Meanwhile, the structure-activity relationship between structural changes and electrochemical performance of Mn-based layered oxides is revealed. Various modification methods for multiphase Mn-based layered oxides are summarized. As a result, a reasonable structural design is proposed for producing high-performance SIBs based on these oxides.