Electron-deficient boron-containing additive induced Lewis acid interface with O-S/B-S chemical adsorption of polysulfides for durable sodium-sulfur batteries.

Abstract

Room-temperature sodium‑sulfur (RT Na-S) batteries hold great promise for large-scale energy storage, yet they face severe challenges from polysulfide shuttling and sodium dendrite growth. To address these challenges, this study proposes an innovative strategy by introducing a boron-based additive, 2,4,6-trimethoxyboroxine (TMBX), into the propylene carbonate (PC)/NaClO₄ electrolyte to in-situ construct a boron-rich interphase. On the cathode side, the cathode electrolyte interface (CEI) layer is enriched with electron-deficient Lewis acidic B₂O₃, which chemisorbs soluble sodium polysulfides via BS and OS bonds. Simultaneously, this interphase forms a physical barrier due to its high mechanical strength and favorable structural properties, and the two effects work synergistically to suppress the shuttle effect. On the anode side, the inner solid electrolyte interface (SEI) layer that rich in boron-containing inorganic components can effectively inhibits sodium dendrite nucleation. Benefiting from the synergistic regulation of the boron-containing interphase, the TMBX-modified electrolyte endows Na-S cells with excellent performance. This work establishes a rational electrolyte design principle of leveraging boron-centered Lewis acidity for targeted polysulfide anchoring, coupled with a high-modulus interphase, offers a scalable and efficient strategy toward durable RT Na-S batteries.