Atomically bonding Na anodes with metallized ceramic electrolytes by ultrasound welding for high‐energy/power solid‐state sodium metal batteries

Abstract A solid‐state sodium metal battery has cut a striking figure in next‐generation large‐scale energy storage technology on account of high safety, high energy density, and low cost. Nevertheless, the large interfacial resistance and sodium dendrite growth originating from the poor interface contact seriously hinder its practical application. Herein, a modified ultrasound welding was proposed to atomically bond Na anodes and Au‐metalized Na 3 Zr 2 Si 2 PO 12 electrolytes associated with the in situ formation of Na–Au alloy interlayers. Thereupon, intimate Na 3 Zr 2 Si 2 PO 12 –Au/Na interfaces with a low interfacial resistance (~23 Ω cm 2 ) and a strong dendrite inhibition ability were constructed. The optimized Na symmetric battery can cycle steadily for more than 900 h at 0.3 mA cm −2 under a low overpotential (<50 mV) of Na electroplating/stripping and deliver a high critical current density of 0.8 mA cm −2 at room temperature. By incorporating the above interface into the solid‐state Na metal battery, taking three‐dimensional Na 3 V 2 (PO 4 ) 3 as the cathode, the full battery offers a high energy density of 291 Wh kg −1 at a high power density of 1860 W kg −1 . A pouch‐type solid‐state sodium metal full battery based on a ceramic electrolyte was assembled for the first time, and it lit a 3 V LED lamp. Such a strategy of the ultrasound welding metalized solid‐state electrolyte/Na interface by engineering the Na–Au interlayer would pave a new pathway to engineer a low‐resistance and highly stable interface for high‐energy/density solid‐state sodium metal batteries.