Advance and Prospect of Functional Materials for Sodium Ion Batteries

Sodium ion batteries (SIBs) as a new chemical power source have recently attracted a great attention for large-scale energy storage owing to the abundance and low cost of sodium resources. In order to achieve advanced SIBs with high specific energy, long cycling lifetime and fast charge/discharge ability, efforts have been devoted to developing advanced electrode materials with large specific capacity, robust cycling stability and good rate capability, as well as functional electrolytes with high ion-conductivity and wide electrochemical window. Promising cathode materials include high-capacity layered oxides, high-potential fluorophosphates and long-lifetime phosphates. Available anode materials consist of highly stable Ti-based layered oxides and carbon materials, high-capacity elemental metals/non-metals and low-cost metal-based compounds. Effective electrolytes involve ester-based electrolytes and ether-based electrolytes. This review summarizes the recent advance of electrode materials and electrolytes for SIBs, mainly focusing on their electrochemical properties, existing challenges and resolution strategies.