Promoted ion conductivity of sodium salt–poly(ethylene oxide) polymer electrolyte induced by adding conductive beta-alumina and application in all-solid-state sodium batteries

Abstract

Solid polymer electrolytes can significantly improve the safety and energy density of sodium-ion batteries compared with the liquid electrolytes. However, the low ionic conductivity and poor mechanical properties inhibit the practical application. In this paper, poly(ethylene oxide) (PEO) solid polymer electrolytes with enhanced ion conductivity are demonstrated by introducing inorganic solid electrolyte (beta-alumina) filler. With the presence of conductive beta-alumina filler, the ion conductivity of the resultant PEO polymer electrolyte is enhanced from 2.5*10–4 to 3.95*10–4 S cm−1. Applied in sodium-ion batteries (SIBs), the cell delivers an initial discharge capacity of 93.1 mAh g−1 and acceptable cycling performance (77.8 mAh g−1 after 100 cycles), which are significantly superior to that of the PEO solid polymer electrolyte without beta-alumina filler modification. The presented results prove that the ion conductivity of PEO polymer electrolyte can be enhanced by adding conductive beta-alumina, promoting its practical application in Na-ion all-solid-state batteries or other electrochemical energy storage systems.