Large Scale Preparation of Proton Pre‐intercalated δ‐MnO 2 Positive Material for Aqueous Zinc‐Ion Batteries

ABSTRACT Layered δ‐MnO 2 is regarded as one of the most promising positive materials for aqueous zinc‐ion batteries (ZIBs) owing to its unique 2D layered structure, large interlayer spacing, abundant ion storage sites, and eco‐friendly characteristics. However, current synthesis methods such as hydrothermal synthesis, electrochemical deposition, and solution precipitation suffer from various limitations, including safety concerns, low crystallinity, and difficulties in scaling up, which severely hinder their commercial application. Inspired by the H + /Na + ion exchange mechanism, this study successfully prepares large‐scale δ‐MnO 2 positive materials using a P2‐type Na 0.67 MnO 2 positive material for sodium‐ion batteries as a precursor, followed by a simple water treatment and ion exchange process. This method is straightforward to implement, and its key steps are based on the already mature industrial preparation route for sodium‐ion battery positives. The ion exchange process requires only water, and the by‐product sodium salts can be recycled, demonstrating strong potential for scalable application. Electrochemical tests reveal that the obtained material exhibits a high specific capacity exceeding 400 mAh/g at 0.1 A/g and an impressive rate capacity of 183 mAh/g at 2.0 A/g. This work proposes a simple and scalable strategy for preparing δ‐MnO 2 , contributing positively to advancing research on the application of aqueous ZIBs.