A comprehensive review of layered transition metal oxide cathodes for sodium-ion batteries: The latest advancements and future perspectives

Sodium-ion batteries (SIBs) are emerging as a promising and cost-effective solution for large-scale energy storage systems and smart grids due to the abundant availability of sodium. The cathode materials in SIBs play a crucial role in providing free Na⁺ ions and determining battery potential. Among the various cathode candidates, Na⁺-based layered transition metal oxide cathodes (NTMOs) are considered promising options for practical SIB cathodes, with a high theoretical capacity and energy storage mechanism similar to commercial lithium-ion batteries (LIBs). However, challenges such as structural collapse, particle cracking, oxygen loss, and moisture stability need to be addressed for the full potential of NTMOs in practical SIB applications. This review investigates the underlying factors contributing to these challenges, analyzes the phases and electrochemical performance of NTMOs, and explores various strategies such as preparation technology, morphology control, and interface modulation. The optimization of sodium-ion full-cells composition, including anode selection, electrolyte composition, separator selection, and binders, is also discussed. Overall, this review highlights the potential advantages that NTMOs can offer to the industry by providing fresh perspectives and avenues for future research. Additionally, this comprehensive overview of NTMOs could potentially lead to advancements in the field of SIBs and contribute to the development of more efficient energy storage solutions.