Leveraging Lewis Acid–Modulated Polymer–Inorganic Interface for High–Performance Solid–State Sodium Batteries

Abstract Solid–state sodium metal batteries with solid polymer electrolytes face significant challenges due to low ionic conductivity and limited electrochemical window. This study presents an innovative interface regulation strategy to expose Lewis–acidic hydroxyl (–OH) and fluoride (F − ) on the (110) and (111) planes of ZnOHF nanorods. By modulating the Lewis–acid intensity at the polymer–inorganic interface, ionic conductivity and Na + ion transfer number are increased, while Na dendrite is suppressed. Density Functional Theory (DFT) calculations indicate that a Na + ion engages with four –OH on the (110) plane, or with one –OH and three F − on the (111) plane. The (110) plane demonstrates a lower adsorption energy for Na + ions (−2.93 eV) compared to the (111) plane (−3.85 eV), but shows a stronger adsorption capability for FSI − ions, facilitating efficient Na + transport and strengthening FSI − ion interactions. Experimentally, the PN@ZnOHF–30 electrolyte, incorporating ZnOHF–30 nanorods primarily oriented with (110) planes, achieves an ionic conductivity of 5.74×10 −4 S cm −1 and a Na + ion transfer number of 0.42 at 80 °C. Na|PN@ZnOHF–30|Na symmetric cell maintains stable Na plating/stripping for 1000 h. Na 3 V 2 (PO 4 ) 3 |PN@ZnOHF–30|Na and Na 3 V 2 (PO 4 ) 3 |PN@ZnOHF–30|NaTi 2 (PO 4 ) 3 cells show excellent rate performance and cycling stability.