An Excellent Air-Stable Layered Oxide Cathode Based on Morphological Regulation for High-Performance Sodium-Ion Batteries

The layered transition metal oxides have a promising future in sodium-ion batteries, but they also have problems, such as poor discharge capacity and air stability. To meet the challenges of O3-type layered oxides in sodium-ion batteries, NaNi0.47Cu0.03Mn0.48Ti0.02O2 (RNMCT) is synthesized by the molten salt method, and it has a unique cluster structure. The particles of submicrometer dimension can effectively enhance the electrochemical performance and air stability of cathode materials. The specific discharge capacity of RNMCT is 156.3 mA h g–1 at 0.1 C. After being exposed to air for 10 days with approximately 55% humidity, the specific capacity of RNMCT is 134.4 mA h g–1 (0.1 C). Meanwhile, in order to further improve air stability and the electrochemical properties of the cathode materials after exposure to air, a heat treatment strategy is introduced. The recovery rate of specific discharge capacity for RNMCT is 98% at 0.1 C. In this work, the performances of the two cathode materials are compared, and it can be seen that the properties of the material are different via various synthesis methods. This provides a very valuable reference for the subsequent research and application of layered oxide of sodium-ion batteries.