AlF3-Stabilized Cathode Electrolyte Interphase with Superior PF6- Affinity and PF6- -Transferred Characteristics for Dual-Ion Batteries

Abstract

High-voltage and high-power dual-ion batteries (DIBs) face significant challenges due to the severe oxidative decomposition of the electrolyte and pronounced structural degradation of the graphite cathode. In this context, we introduce Al₂O₃ as a surface modifier, which facilitates the establishment of a stabilized cathode electrolyte interphase (CEI). Al₂O₃ functions as a protective coating and engages in a chemical reaction with the corrosive HF to produce AlF₃, thereby alleviating HF-induced degradation of the graphite cathode. Furthermore, the resulting AlF₃ layer preferentially adsorbs PF₆^- anions, thereby promoting their rapid transfer and aiding in the formation of a LiF-rich, stable CEI. This interphase substantially mitigates both the structural deterioration of graphite and the decomposition of the electrolyte. Consequently, the Al₂O₃-modified graphite cathode (A-Gr) exhibits exceptional rate performance and long-term cycling stability, retaining 78% of its initial capacity after 3500 cycles. This research presents an effective surface modification strategy that enhances electrode performance through interfacial chemistry engineering, providing a promising approach for advancing next-generation, durable energy storage systems.