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

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.