A piezoelectric interlayer design between an Na3Zr2Si2PO12 solid electrolyte and sodium metal is demonstrated to solve the interfacial issues against low-temperature solid-state sodium batteries. A piezoelectric ZnO layer proves a favorable interlayer with matched modulus, high Na-adhesion, sufficient piezoelectricity to thoroughly reduce the interfacial resistance and promote a quasi-solid-state Na2MnFe(CN)6-based full cell operating at a harsh condition of 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.
