F Doped δ‐MnO₂ Nanoflowers for High‐Performance Aqueous Zinc‐Ion Batteries

Abstract Aqueous zinc‐ion batteries (AZIBs) have attracted significant attention from researchers in recent years due to their low cost, high safety and high theoretical capacity. Among them, δ‐MnO₂ is considered one of the most promising cathode materials for aqueous zinc ion batteries because of its layered structure, which facilitates the intercalation and deintercalation of zinc ions. However, its narrow layer spacing and poor structural stability limit its future practical applications. To tackle these issues, herein, we report a two‐step strategy to introduce anionic fluoride ions into the δ‐MnO₂ nanoflowers. The flower‐like spherical structure, composed of interspersed nanosheets, increases the active sites for electrochemical reactions. Fluorine doping can expand the interlayer spacing available for ion insertion/extraction, and the formed fluorine‐manganese chemical bonds could stabilize the manganese‐oxygen octahedral ([MnO₆]) structure. The F‐doped δ‐MnO₂ nanoflowers show a reversible capacity of 435.1 mAh g⁻¹ at a current density of 0.1 A g⁻¹, which is obviously higher than that of undoped δ‐MnO₂ (212 mAh g⁻¹). These results indicate the potential of anion introduction in enhancing the electrochemical performance of δ‐MnO₂ in aqueous zinc‐ion batteries.