Formation‐Stage Interfacial Regulation of δ‐MnO 2 Enables Stable and Reversible Aqueous Zn‐Ion Storage
Fanghua Liang, Ling Wang, Junpeng Xiong, Chunqing Niu, Atsuya Kawai, Wei Zhang, Chunhong Zhu, Azeem Ullah, Mayakrishnan Gopiraman, Mingzheng Ge, Ick Soo KimABSTRACT
Layered δ‐MnO 2 is a promising cathode for aqueous zinc‐ion batteries, yet its practical application remains hindered by the coupled challenges of sluggish Zn 2+ storage kinetics and persistent Mn dissolution. Here, we develop a precursor‐embedded Fe interfacial regulation strategy to modulate the nucleation and growth of δ‐MnO 2 on porous carbon nanofibers (δ‐MnO 2 @Fe‐PCNFs). Rather than being dominated by homogeneous bulk substitution, the introduced Fe is predominantly present as low‐content, highly dispersed surface‐/interface‐associated species established during δ‐MnO 2 formation, where it regulates the local Mn─O environment and consequently modulates nanosheet growth and the accessibility of the reaction interface. The Fe‐regulated δ‐MnO 2 framework exhibits improved kinetic accessibility and suppresses Mn dissolution without altering its intrinsic Mn‐based redox chemistry. Consequently, the δ‐MnO 2 @Fe‐PCNFs electrode delivers an initial capacity of 409.29 mAh g −1 at 0.2 A g −1 and excellent long‑term cycling stability, maintaining a capacity of 243.64 mAh g −1 at 1 A g −1 after 1000 cycles and excellent capacity retention of 81.1% after 3000 cycles at 5 A g −1 . This work highlights formation‐stage interfacial regulation as an effective strategy to couple reaction accessibility with structural durability in Mn‐based aqueous zinc‐ion battery cathodes.