Rapid ultrasound welding toward compact Na/Beta-Al2O3 interface realizing room-temperature solid-state sodium metal battery

Interfacial regulation on Na metal/solid electrolytes benefits for realizing room temperature solid-state sodium metal battery for energy storage technique, yet remains challenging due to rigid solid-solid contact and unmanageable dendrite growth. To suit the remedy to the annoying interfacial trouble, a highly efficient ultrasound welding (UW) strategy is rolled out and successfully verified by Na/Beta-Al2O3 interface in one minute. The UWNa/Beta-Al2O3/UW-Na symmetric cell accompanied by a critical current density of 0.65 mA cm-2 can be cycled stably for over 800 h at 0.1 mA cm-2 at room temperature. Integrating into polyanion-typed Na3V2(PO4)3 cathode with three-dimensional Na+ transport, the room-temperature sodium metal full battery delivers a high energy density of 234 Wh kg- 1 under a high power density of 1773 W kg- 1. Such full battery provides a reversible capacity of 86 mA h g- 1 after 700 cycles at 0.5 C with a capacity retention of 86.66%. This work elucidates the atom-level ultrasonic welding strategy for constructing compact Na/Beta-Al2O3 interface, providing rational design on engineering Na/solid electrolyte interface for solid-state sodium metal battery.