Ceramic Metallization Assisted Ultrasonic Welding Enabling the Effective Beta-Al2o3/Na Interface for Solid-State Sodium Metal Batteries

Abstract

The necessity for high energy density, safety, and cost-effective energy storage systems is propelling the advancement of solid-state sodium metal batteries (SSMBs). A critical challenge involves establishing an effective interface between the Na metal anode and solid-state electrolytes (SSEs), particularly with Beta-Al2O3 that exhibits both inadequate interfacial wettability and elevated resistance. Herein, a strategy integrating room-temperature ultrasonic welding with ceramic metallization (Au, In, Ge) has been developed to construct alloy interlayer between Beta-Al2O3 and Na anode. The effective interlayer formed by comprehensive strategy achieve intimate interfacial bonding through enhanced wettability and alloying reaction, optimizing Na+/e− flux distribution and guiding homogeneous Na plating/stripping. The optimized interface exhibits an impedance of 43 Ω cm2, while the critical current density of Na symmetric cells reaches 1.9 mA cm−2. Furthermore, the full cell assembled with Na3V2(PO4)3 as the cathode delivers a specific capacity of 102 mA h g−1 after 600 cycles at 0.5C, with a capacity retention rate of 92.7%. This work develops an interfacial engineering method that effectively resolves the Beta-Al2O3/Na compatibility issue, significantly improving the electrochemical performance of oxide electrolyte based SSMBs.

Keywords: Solid-state sodium batteries, NASICON electrolyte, Interface modification, Alloying reaction, Ultrasound welding