Electrochemistry‐Driven Interphase Doubly Protects Graphite Cathodes for Ultralong Life and Fast Charge of Dual‐Ion Batteries

Abstract Dual‐ion batteries (DIBs) with graphite as cathode material, show superiority in terms of sustainability, affordability, and environmental impact over Li‐ion batteries that rely on transition‐metal based cathodes. However, graphite cathodes severely suffer from poor structural stability during anion storage at high potentials because of the co‐intercalation and oxidative decomposition of electrolytes. This work presents an in situ electrochemistry‐driven route to create a bifunctional interphase through implantation of diethylenetriaminepenta(methylene‐phosphonic acid) (DTPMP) on the surface of graphite particles. The reaction mechanisms and functions of DTPMP are investigated both experimentally and theoretically. The DTPMP‐derived interphase not only improves the antioxidative stability of electrolytes but also benefits the desolvation of PF 6 − anions, which doubly protect the graphitic structure and give rise to fast‐charge and ultralong cycling performance of graphite cathodes in DIBs.