Recent progress in layered oxide cathodes for sodium-ion batteries: stability, phase transition and solutions

Abstract

Due to their cost efficiency and the sustainable availability of sodium resources, sodium-ion batteries (SIBs) are regarded as an economical alternative or additional choice to the well-established lithium-ion batteries (LIBs), particularly within extensive energy storing configurations. Sodium-based layered transition metal oxides have received a significant amount of focus among the several cathode possibilities for SIBs due to their convenient synthesis, elevated operating potential, and relatively high specific capacity. However, layered oxide cathodes suffer from a string of deadly problems, such as poor air stability, erratic electrolyte/cathode interface, and irreversible phase transition, from preparation to application, leading to inferior battery performance. This seriously limits their practical application and commercialization. The objective of this study is to examine the critical issues concerning layered oxide cathode materials with the aim of comprehending their underlying root causes and degradation mechanisms. Furthermore, this study seeks to elucidate the major challenges and corresponding solutions pertaining to diverse types of layered oxides over the past five years. Specifically, the emphasis is on enhancing air stability, mitigating phase transitions, and attaining superior structural reversibility, rapid Na⁺ kinetics, and overall enhanced electrochemical performance. Various solution strategies tailored to address distinct issues are also deliberated upon.