1. Layered oxide cathode material

Layered oxides  in sodium ion batteries material have inherent cost advantages, not only because these materials can learn from the highly mature solid-state or co precipitation methods commonly used in lithium-ion batteries to achieve low-cost large-scale production, but also because they have a rich selection of active elements.

The chemical formula of layered oxide positive electrode materials for sodium ion batteries can be expressed as NaxTMO2 (x ≤ 1, where TM is one or more of the 3D transition metals such as Ni, Mn, Fe, Co, Cu, etc.). By studying the coordination environment of sodium ions and the stacking mode of oxygen, layered oxides can be classified into the following categories:

2. Polyanionic positive electrode material

Polyanion positive electrodes have better thermal stability and thus better safety, but their biggest drawback is their low electronic conductivity, which prevents them from charging and discharging under high currents, and their specific capacity is low. Therefore, its conductivity is often improved by coating and doping, thereby improving its electrochemical performance.

The general formula of polyanionic compounds can be expressed as NaxMy [(XOm) n –] z, where M is an electrically active transition metal and X is a non-metallic element such as P, S, Si, etc. Among them, sodium vanadium phosphate [Na3V2 (PO4) 3] material with NASCON (Na Super ionic conductor) structure has high voltage and specific capacity.

1.3 Prussian Blue Cathode Materials

The Prussian blue cathode material has a perovskite like structure and a face centered cubic structure. The molecular formula is AxM [Fe (CN) 6] y · zH2O (0