Single-Ion Conducting Polymer Electrolytes for Sodium Batteries

Abstract

Sodium-ion batteries have attracted extensive attention recently owing to the announcements of several companies to commercialize this technology in the (very) near future. Just like commercial lithium-ion batteries, though, these batteries are comprising and/or will comprise a liquid electrolyte – with all its advantages and challenges. Thinking one step ahead (as also done by a few companies already), the next step might be the transition to (“zero-excess”) sodium-metal batteries, which will require fundamentally new electrolyte solutions, and just like for lithium-metal batteries, these might be based, e.g., on polymers.Herein, we present our latest results on single-ion conducting polymer electrolytes for sodium-metal batteries. These polymer electrolytes do not only show higher ionic conductivity than its lithium analogues (>2.5 mS cm-1 at 40 °C), but moreover the same beneficial properties in terms of high electrochemical stability towards oxidation, highly reversible sodium plating and stripping, and excellent cycling stability of Na‖Na3V2(PO4)3 cells for more than 500 cycles. The results thus show that single-ion conducting polymer electrolytes are very promising candidates for high-performance sodium batteries.