Gradiently Sodiated Alucone as an Interfacial Stabilizing Strategy for Solid-State Na Metal Batteries

摘要

All-solid-state metal batteries (ASSMBs) are attracting much attention due to their cost effectiveness, enhanced safety, room-temperature performance and high theoretical specific capacity. However, the alkali metal anodes (such as Li and Na) are active enough to react with most solid-state electrolytes (SSEs), leading to detrimental reactions at the metal-SSE interface. In this work, a molecular layer deposition (MLD) alucone film is employed to stabilize the active Na anode/electrolyte interface in the ASSMBs, limiting the decomposition of the sulfide-based electrolytes (Na3SbS4 and Na3PS4) and Na dendrite growth. Such a strategy effectively improves the room-temperature full battery performance as well as cycling stability for over 475 h in Na-Na symmetric cells. The modified interface is further characterized by X-ray photoelectron spectroscopy (XPS) depth profiling, which provides spatially resolved evidence of the synergistic effect between the dendrite-suppressed sodiated alucone and the insulating unsodiated alucone. The coupled layers reinforce the protection of the Na metal/electrolyte interface. Therefore, alucone is identified as an effective and bifunctional coating material for the enhancement of the metal/electrolyte interfacial stability, paving the way for rapid development and wide application of high-energy ASSMBs.