Abstract:

 Sodium element has similar physical and chemical properties with lithium, and sodium resource is abundant in the earth, so research interest on sodium ion batteries has rapidly increased recently, particularly for the grid energy storage. Compared with aqueous sodium-ion batteries, non-aqueous sodium-ion batteries have attracted more attention due to its wider electrochemical window (1.5～4.5 V) and higher energy density (100～350 W·h·kg1). Generally, electrochemical performance of the non-aqueous sodium-ion batteries is evaluated using half cells with metallic sodium as a counter electrode. However, it may cause some potential safety risks when used metallic sodium in sodium-ion batteries, so research on non-aqueous sodium-ion batteries based on the anodes of non-metallic sodium deserves much more attention, which will promote the practical application of sodium-ion battery. Herein, we will introduce some typical sodium-ion batteries based on the anodes of non-metallic sodium, including carbon-based materials, Ti-based compounds, Na-alloys and transition metal oxides. In order to realize the commercialization of sodium-ion batteries, it is needed to explore new cathode and anode materials with better performance and low cost. In addition, mutual matching issues between cathode and anode, designing better electrolyte and binders and separator modification are also important in promoting the commercial applications of sodium-ion batteries in future.

Key words: sodium ion batteries, metallic sodium, negative electrode materials, organic electrolyte, full cell