Bridging chemical relithiation and alloying reaction to engineer a Li-Al-F interface for enhanced lithium storage kinetics

Abstract

This study innovatively proposes a “chemical prelithiation/alloying-induced interfacial reconstruction” synergistic strategy that fundamentally improves the performance of Si-based anodes. Through a precisely controlled process leveraging orbital energetics and Lewis acid catalysis, we successfully engineer a Li-Al-F phase on the interface of SiO (denoted as Pre-SiO-Al) anodes via sequential chemical prelithiation and AlF₃-driven interfacial alloying reactions. This novel approach breaks through the ion transport limitations of traditional LiF-dominated solid electrolyte interphase (SEI) layers, while concurrently addressing the critical challenges of low initial Coulombic efficiency (ICE) and severe volume expansion. Mechanism studies reveal that the Li-Al-F offers an ultralow Li⁺ diffusion barrier (0.1 eV), significantly enhancing interfacial ion transport kinetics. Meanwhile, the high mechanical strength and dynamic stress dissipation capability of Li-Al-F effectively suppress SEI fracture caused by volume expansion, enabling coordinated deformation compatibility between the electrode and the interfacial layer. The Pre-SiO-Al anode maintains a high capacity of 682.6 mA h g⁻¹ after 2000 cycles at 1.0 A g⁻¹ with near 100% capacity retention. When paired with LiFePO₄ cathode, the Pre-SiO-Al||LFP full cell achieves impressive rate capability and cycling stability (93.8% capacity retention after 150 cycles at 0.5 C), demonstrating strong commercialization potential.