Rational design of practical layered transition metal oxide cathode materials for sodium-ion batteries

Sodium-ion batteries (SIBs), which serve as alternatives or supplements to lithium-ion batteries, have been developed rapidly in recent years. Designing advanced high-performance layered Na x TMO 2 cathode materials is beneficial for accelerating the commercialization of SIBs. Herein, the recent research progress on scalable synthesis methods, challenges on the path to commercialization and practical material design strategies for layered Na x TMO 2 cathode materials is summarized. Co-precipitation method and solid-phase method are commonly used to synthesize Na x TMO 2 on mass production and show their own advantages and disadvantages in terms of manufacturing cost, operative difficulty, sample quality and so on. To overcome drawbacks of layered Na x TMO 2 cathode materials and meet the requirements for practical application, a detailed and deep understanding of development trends of layered Na x TMO 2 cathode materials is also provided, including high specific energy materials, high-entropy oxides, single crystal materials, wide operation temperature materials and high air stability materials. This work can provide useful guidance in developing practical layered Na x TMO 2 cathode materials for commercial SIBs.