β‐MnOOH Converted δ‐MnO 2 with New Layer‐to‐Layer Charge Storage as Cathode for Zinc‐Ion Batteries

transformed into β-MnOOH during the reversible charge and discharge process. This work uncovers a new phase transformation in Mn-based cathodes and can pave the way for the development of more efficient layered materials for ZIBs.