Stabilizing sodium metal anodes by functional polymers

With the development of the next-generation energy storage systems, rechargeable secondary batteries that improve energy density and safety are necessary to achieve energy iteration. Because of their low cost and high energy density, sodium metal batteries (SMBs) have great potential in the future. However, due to the instability of the solid electrolyte interface (SEI), the growth of sodium dendrites, and the volume expansion of the sodium metal anodes (SMAs) during planting and stripping, its practical implementation is hindered. In recent years, with the deepening of polymer chemistry research, polymers have been widely used to improve the batteries’ actual performance, safety, and durability as a result of their strong chemical stability, processability, structural designability, and functional diversity. Based on the basic understanding of the relationship between polymer structure and properties, polymer design and common processing methods of stable SMAs are systematically summarized. Furthermore, the strategies of polymers to stabilize SMAs were reviewed from five aspects: artificial SEI, separators, gel polymer electrolytes, solid polymer electrolytes, and anode hosts. The current research status and difficulties in optimizing SMAs to achieve high stability are discussed. Finally, the challenges and potential development directions of SMAs are discussed.