Unraveling the Role of Nitrogen‐Doped Carbon Nanowires Incorporated with MnO₂ Nanosheets as High Performance Cathode for Zinc‐Ion Batteries

Manganese‐based cathode materials are considered as a promising candidate for rechargeable aqueous zinc‐ion batteries (ZIBs). Suffering from poor conductive and limited structure tolerance, various carbon matrix, especially N‐doped carbon, were employed to incorporate with MnO₂ for greatly promoted electrochemical performances. However, the related underlying mechanism is still unknown, which is unfavorable to guide the design of high performance electrode. Herein, by incorporating layered MnO₂ with N‐doped carbon nanowires, a free‐standing cathode with hierarchical core‐shell structure (denoted as MnO₂@NC) is prepared. Benefiting from the N‐doped carbon and rational architecture, the MnO₂@NC electrode shows an enhanced specific capacity (325 mAh g⁻¹ at 0.1 A g⁻¹) and rate performance (90 mAh g⁻¹ at 2 A g⁻¹), as well as improved cycling stability. Furthermore, the performance improvement mechanism of MnO₂ incorporated by N‐doped carbon is investigated by X‐ray photoelectron spectroscopy (XPS), Raman spectrums and density functional theory (DFT) calculation. The N atom elongates the Mn‐O bond and reduces the valence of Mn⁴⁺ ion in MnO₂ crystal by delocalizing its electron clouds. Thus, the electrostatic repulsion will be weakened when Zn²⁺/H⁺ insert into the host MnO₂ lattices, which is profitable to more cation insertion and faster ion transfer kinetics for higher capacity and rate capability. This work elucidates a fundamental understanding of the functions of N‐doped carbon in composite materials and shed light on a practical pathway to optimize other electrode materials.