In Situ Sodium Plating and Stripping at the Aluminum/Nasicon Interface

Abstract

Solid-state sodium metal batteries have emerged as compelling alternatives to lithium-ion batteries due to their abundance, geopolitical stability, and cost. However, the development of solid-state sodium metal batteries faces challenges such as achieving high ionic conductivity in solid electrolytes, ensuring stable interfaces between the solid electrolyte and sodium metal anode, as well as the complexity of manufacturing due to the air reactivity of sodium metal. To overcome these challenges, the anode-free manufacturing process to fabricate is a promising approach to enable the commercialization of sodium metal batteries.In this work Na3.4Zr2Si2.4P0.6O12 (NaSICON) was synthesized and densified to >99 % relative density with a total ionic conductivity of 5 mS cm-1 using a solution assisted solid-state reaction process followed by rapid induction hot-pressing, respectively. Using the hot-pressed NaSICON in an anode-free cell design, we demonstrate the feasibility and ease of using commercially available aluminum foil with a sputtered metal layer as the current collector (CC). We show stable sodium plating of several microns at the NaSICON | CC interface with a current density of 0.5 mA cm-2 at room temperature. In addition, this study demonstrates good reversibility after several cycles of plating and stripping.This study not only explores the electrochemical behavior of in situ sodium plating contributing to the advancement of cost-effective energy storage solutions, but also offers valuable insights into practical manufacturing processes for solid-state sodium metal batteries.