Research progress in O3-type phase Fe/Mn/Cu-based layered cathode materials for sodium ion batteries

Abstract

Sodium ion batteries have become one of the research hotspots in the field of energy storage. Due to their comprehensive advantages in specific capacity, the working voltage, and cost, layered oxides have become one of the most promising cathode materials. Among them, O3-type materials show higher energy density and capacity in full cells. Fe/Mn/Cu-based materials have more advantages than other layered oxides in terms of cost and resource. This review focuses on layered oxide cathode materials including Na_xMnO₂, Na_xFeO₂, Na_xFe_yMn_1−yO₂, and Na_xMn_1−y−zFe_yCu_zO₂. The research status with respect to competitive advantages, existing challenges, and solution strategies was systematically analyzed. Furthermore, the effects of phase transition, and air stability of the layered oxide cathode on the electrochemical performance were discussed. Based on the in-depth analysis of modification methods, promising optimization strategies of electrochemical performance were proposed, hoping to provide guidance for the future design of O3-type Na_xMn_1−y−zFe_yCu_zO₂ materials.