Advances in sodium-ion battery cathode materials: exploring chemistry, reaction mechanisms, and prospects for next-generation energy storage systems

Lithium-ion batteries (LIBs) have been powering portable electronic devices and electric vehicles for over three decades. However, growing concerns regarding the limited availability of lithium resources and the subsequent surge in costs have prompted the exploration of alternative energy storage systems beyond LIBs. Among these alternatives, sodium-based batteries, with their similar intercalation chemistry, have emerged as the most promising alternative due to their cost-effectiveness and the abundance of sodium reserves in nature. Developing sodium-ion batteries (SIBs) that possess high energy density, long lifespan, and high-rate capability necessitates a comprehensive understanding of the reaction mechanisms, especially the intricate chemistry involved in cathode materials. In this review, we delve into the reaction mechanisms of the most commonly used cathode materials for SIBs, which include layered transition-metal oxides, polyanionic compounds, Prussian blue analogues, etc. We also highlight the specific physicochemical properties that have been uncovered through the application of advanced operando characterization techniques. Building upon the insights gained from this comprehensive review, we put forth future perspectives on the development of novel cathode materials for SIBs. By leveraging the extensive knowledge generated, we aspire to pave the way for further advancements in sodium-ion battery technology.