Negating Na|NaZrSiPO 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 Na 3 Zr 2 Si 2 PO 12 (NZSP) solid electrolyte. The resulting NZSP exhibits a perfect Na wettability (0° contact angle) at a record-low temperature of 120 °C, a negligible room-temperature Na|NZSP interfacial resistance of 1.5 Ω 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 °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 Na 3 V 2 (PO 4 ) 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. A novel Pb/C interlayer is introduced on Na 3 Zr 2 Si 2 PO 12 solid electrolyte, which offers perfect Na wettability, negates interfacial resistance, and allows in situ fabrication of "Na-less" anodes for stable solid-state Na-metal batteries.