Piezoelectric Interlayer Enabling a Rechargeable Quasisolid‐State Sodium Battery at 0 °C

Abstract Solid‐state sodium (Na) batteries (SSNBs) hold great promise but suffer from several major issues, such as high interfacial resistance at the solid electrolyte/electrode interface and Na metal dendrite growth. To address these issues, a piezoelectric interlayer design for an Na₃Zr₂Si₂PO₁₂ (NZSP) solid electrolyte is proposed herein. Two typical piezoelectric films, AlN and ZnO, coated onto NZSP function as interlayers designed to generate a local stress‐induced field for alleviating interfacial charge aggregation coupling stress concentration and promoting uniform Na plating. The results reveal that the interlayer (ZnO) with matched modulus, high Na‐adhesion, and sufficient piezoelectricity can provide a favorable interphase. Low interfacial resistances of 91 and 239 Ω cm² are achieved for the ZnO layer at 30 and 0 °C, respectively, which are notably lower than those for bare NZSP. Moreover, steady Na plating/stripping cycles are rendered over 850 and 4900 h at 0 and 30 °C, respectively. The superior anodic performance is further manifested in an Na₂MnFe(CN)₆‐based full cell which delivers discharge capacities of 125 mA h g⁻¹ over 1600 cycles at 30 °C and 90 mA h g⁻¹ over 500 cycles at 0 °C. A new interlayer‐design insight is clearly demonstrated for SSNBs breaking low‐temperature limits.