Tailored crosslinking of Poly(ethylene oxide) enables mechanical robustness and improved sodium-ion conductivity

Sodium-based energy storage systems are promising candidates for electric vehicles and grid-level energy storage applications. The advancement of sodium-based energy storage systems relies on the development of high performance sodium-ion conducting electrolytes and membranes that exhibit high ionic conductivity and mechanical stability. A crosslinked poly(ethylene oxide) based polymer electrolyte was developed that demonstrates high ionic conductivity, as well as excellent mechanical stability over a wide temperature range. Ionic conductivities up to 2.0 x 10(-4) S/cm at 20 degrees C and 7.1 x 10(-4) S/cm at 70 degrees C are achieved for the plasticized membrane, almost four orders of magnitude greater than that of the non-plasticized membrane. The membranes are mechanically robust, and the storage modulus of the membrane is maintained at similar to 1 MPa from -20 to 180 degrees C even with the addition of plasticizer. This study provides a synthesis approach towards the design of highly ion conducting, mechanically robust gel polymer electrolytes for Na-ion batteries, non-aqueous flow batteries, and many other applications.