PEO-NaPF₆ Blended Polymer Electrolyte for Solid State Sodium Battery

Solid-state polymer electrolytes (SPEs) are proposed as promising candidates for application in sodium batteries to replace the organic liquid electrolytes for enhanced safety. In this study, we first verified the feasibility of PEO-NaPF 6 SPE in solid-state sodium batteries (SSBs). The explored PEO-NaPF 6 SPEs exhibit a relatively high ionic conductivity of ∼6.3 × 10 −4 S cm −1 at 80 °C, a large Na + transference number ( t Na+ ) of 0.58, and sufficient thermal stability at around 200 °C for SSBs. More importantly, the PEO-NaPF 6 SPEs afford excellent long-term cycling performances for the Na∣∣Na 3 V 2 (PO 4 ) 3 @C cell at 80 °C (85.8% capacity retention at 2 C after 200 cycles) and the Na∣∣NaNi 2/9 Cu 1/9 Fe 1/3 Mn 1/3 O 2 cell at 80 °C (77% capacity retention at 0.5 C after 100 cycles). All of the properties make the PEO-NaPF 6 SPE a potential alternative for application in SSBs.