Negating Na||Na3Zr2Si2PO12 interfacial resistance for dendrite-free and Na-less solid-state batteries

Solid electrolytes hold promise in safely enabling high-energy metallic sodium (Na) anodes. However, the poor Na||solid electrolyte interfacial contact can induce Na dendrite growth and limit Na utilization, plaguing the rate performance and energy density of current solid-state Na-metal batteries (SSSMBs). Herein, a simple and scalable Pb/C interlayer strategy is introduced to regulate the surface chemistry and improve Na wettability of Na3Zr2Si2PO12 (NZSP) solid electrolyte. The resulting NZSP exhibits a perfect Na wettability (0 degrees contact angle) at a record-low temperature of 120 degrees C, a negligible room-temperature Na||NZSP interfacial resistance of 1.5 omega cm(2), along with an ultralong cycle life of over 1800 h under 0.5 mA cm(-2)/0.5 mA h cm(-2) symmetric cell cycling at 55 degrees C. Furthermore, we unprecedentedly demonstrate in situ fabrication of weight-controlled Na anodes and explore the effect of the negative/positive capacity (N/P) ratio on the cyclability of SSSMBs. Both solid-state Na3V2(PO4)(3) and S full cells show superior electrochemical performance at an optimal N/P ratio of 40.0. The Pb/C interlayer modification demonstrates dual functions of stabilizing the anode interface and improving Na utilization, making it a general strategy for implementing Na metal anodes in practical SSSMBs.

Automated summary

Solid electrolytes hold promise for high-energy metallic sodium anodes, but the poor contact between sodium and the solid electrolyte limits the performance of solid-state sodium-metal batteries (SSSMBs). In this study, a Pb/C interlayer strategy is introduced to improve the wetting behavior of Na3Zr2Si2PO12 (NZSP) solid electrolyte. The modified NZSP exhibits excellent wetting properties at low temperature and a negligible interfacial resistance, leading to a longer cycle life. In addition, the study explores the effect of the negative/positive capacity ratio on the performance of SSSMBs and demonstrates the dual functions of the Pb/C interlayer in stabilizing the anode interface and improving sodium utilization.