Recent advances and prospects of layered transition metal oxide cathodes for sodium-ion batteries

Due to the high safety, long service life and outstanding energy density, lithium ion batteries (LIBs) have been widely used in portable energy storage devices. However, the uneven distribution and increasingly high price of lithium resources have hindered the further use of LIBs, particularly for large-scale energy storage. Sodium-ion batteries (SIBs) that have the same working principle as LIBs have, emerged as some of the most promising candidate devices for use in large-scale energy storage applications and low-speed electric automobiles, due to the low cost and abundant reserves of sodium resources. As a key component of SIBs, the cathode materials have a remarkable effect on the electrochemical performance. Layered transition metal oxides have been considered to be some of the most promising cathodes for SIBs due to their flexibility, versatility, and excellent electrochemical performances. Although layered materials face several challenges such as irreversible phase transition, inferior capacity retention and poor air stability, recent experimental studies have proposed corresponding strategies to solve these problems. Herein, we will survey the latest progress in the development of high-energy SIBs cathodes focusing on high-voltage, high-capacity and composite-structure cathode materials.