Cracking a tough nut: Challenges, strategies, and development of layered transition-metal oxide-based cathode materials for commercialization of sodium-ion batteries

In advancing sodium-ion battery (SIB) as a practical complementary technology for lithium-ion battery (LIB), layered transition-metal oxides (LTMO) are revered for their commercial potential as cathode active materials (CAM) due to their similar working principle and scalable synthesis method with LIB's commercial CAMs. Although these Na-based CAMs have high theoretical energy densities, they suffer from chemical instability due to air exposure during manufacture and storage and from capacity degradation during cycling operation. This review outlines the causes of these issues and explores improvement strategies, which are then translated as considerations for commercialization (e.g., performance improvement) of LTMOs as CAMs for SIBs. This review also discusses information on the material-related scale-up processes such as CAM synthesis and storage and slurry coating and loading. Lastly, the SIBs' industrial development is highlighted by providing information and insights on the high-level supply chain of minerals and materials, development roadmaps, and key market players that link material research and development endeavors to the commercialization of SIBs. • LTMOs, as CAM for both LIB and SIB, suffer from air and cycling stability issues. • Improvement strategies include elemental substitution and architecture design. • Scaling up requires reassessing CAM synthesis and storage conditions. • Mineral and material supply chain for SIBs are geographically concentrated. • Electrode-specific improvements may make SIBs competitive with LFPs.