Pre‐Activated Cascade Redox Enables High‐Voltage Multi‐Electron Anion Storage in Graphite

Abstract

ABSTRACT Graphite cathodes enable high‐voltage operation in dual‐ion batteries but are intrinsically constrained by a single‐electron chemistry and sluggish anion intercalation. Here, an iron‐chloride‐intercalated graphite  stabilized by oxygen functional groups is shown to establish a pre‐activated, cascade multi‐electron redox pathway. Sequential oxidation of iron and chlorine at intermediate potentials simultaneously expands interlayer spacing and redistributes electronic density, creating a favorable host for high‐voltage PF 6 − intercalation. This synergistic activation enables an average transfer of 2.61 electrons per redox event, breaking the intrinsic one‐electron limit of graphite. As a result, the cathode delivers up to 5 V (vs. Na/Na + ) with a stable capacity of 52 mAh g −1 at 3 A g −1 , significantly outperforming conventional graphite cathodes (15 mAh g −1 ). By integrating multi‐electron redox chemistry with anion storage, this approach unlocks a new direction for high‐power electrochemical energy storage.