Anion-reduction catalytic centres regulate interfacial solvation structures for fast-charging Si anodes

Abstract

Anion-rich interfacial solvation structures (ISS) are critical for stable fast charging of anodes. Here we propose interfacial anion-reduction catalysis as a new paradigm, in which catalytic centres regulate the ISS to direct solid electrolyte interphase formation. Using S vacancies as prototypical catalytic sites, we demonstrate that electrostatic potential wells induced by these centres attract bis(fluorosulfonyl)imide (FSI−) to the interface and form contact ion pairs during charging, creating FSI−-rich ISS in commercial electrolytes. This catalytically regulated ISS promotes preferential FSI− reduction and ultrafine LiF grain formation, generating a compact LiF-rich solid electrolyte interphase with rapid Li+ transport pathways. Si-based anode with catalytic interface demonstrates stable cycling with an average coulombic efficiency of ~99.94%. Pouch cells achieve ~91.4% and ~85.3% charge in 10 min and 6 min, respectively, while providing ~240.4 Wh kg−1 under 6 min charging. This work establishes catalytic regulation of ISS as a promising strategy for fast battery charging.