ABSTRACT
In this chapter, we bring an overview of sodium-ion batteries and the electrochemical performances of promising layered cathode materials used for Na-ion batteries. The benefits of using sodium, the working principle of Na-ion batteries were introduced. Furthermore, the properties of the two common sodium layered metal oxides O3-type and P2-type were presented. Also, we interpret how ex-situ and in situ techniques are being used for in-depth studying of the structure evolution and phase transition of layered structure materials for Na-ion batteries. The issues related to the phase transition of the two-layered structure types and strategies to prevent it were details discussed to find out the solution for long-cycling performance. Therefore, different synthesis methods utilized for doping/substituting in the original cathode such as solid-state reaction, sol-gel, and co-precipitation which helps to eliminate phase transition and enhance the structural stability were so far mentioned. After all, the structure and electrochemistry of layered structure materials of single transition metal (NaxMO2), two transition metals (NaxMMʹO2), and three transition metals (NaxMMʹMʺO2) are summarized. The last paragraphs mainly described our recent work of synthesizing NaNi1/3Mn1/3Co1/3O2 material with different phase components such as: single-phase (O3, P2, and P3), bi-phase P2/O3, and multiple-phase P2/O1/O3.
