A Review of Research Progress on Cathode Materials for Sodium-Ion Batteries: Practical Applications, Commercialization Challenge, and Future Directions

Abstract Sodium-ion batteries (SIBs), benefiting from the abundance and low cost of sodium resources, have emerged as highly promising complements to lithium-ion batteries, offering potential solutions to global energy and environmental challenges. This review systematically elucidates the structural characteristics, electronic properties, and sodium storage mechanisms of mainstream cathode materials, encompassing layered transition metal oxides, polyanion compounds, Prussian blue analogues, and emerging materials such as organics and sodium-rich layered oxides. Layered transition metal oxides exhibit diverse crystal structures (O-type/P-type), presenting a pronounced trade-off between capacity and stability. Polyanionic compounds possess stable structural frameworks and high redox potentials, yet are constrained by intrinsic conductivity limitations. Prussian blue analogues possess open framework structures that facilitate rapid ion transport. However, they suffer from issues related to structural defects and crystalline water. Organic materials and sodium-rich compounds offer high theoretical capacities and design flexibility, though improvements in conductivity and cycling performance remain necessary. Future directions involve exploring material systems (such as metal−organic framework-derived composites) through crystal field theory and band engineering, optimising preparation techniques, and fostering industry-academia-research collaboration. By offering crucial insights into the design of high-performance, low-cost, and eco-friendly cathode materials, this review can help expedite the research and development of sodium-ion batteries in a wide range of applications.