Electron structure regulation via Co, in, Zn, and V in-situ substitution for high-quality cathode design of aqueous zinc-ion batteries

Abstract

Traditional manganese oxide cathodes for aqueous zinc-ion batteries usually suffer from sluggish kinetics and irreversible structure degradation, resulting in poor electrochemical activity and stability. The proposal of Zn₄SO₄·(OH)₆·xH₂O-assisted deposition-dissolution reaction model promotes the progress of non‑manganese oxide cathodes in certain systems, but the newly proposed model is of limited applications. Based on the model, exploiting high-quality cathodes and feasible performance regulation strategies are essential for the advancement of zinc batteries. Herein, a feasible method is proposed to realize in-situ substitution of Co, In, Zn, and V heteroatoms in Fe₃O₄ with N-doped carbon coated via the assistance of a Fe-based metal organic framework precursor. The in-situ adulterated metal heteroatoms are proved to have distinct effects on electron structure regulation, triggering more active electron transfer, thus enhancing the efficient interactions with charge carriers. Moreover, the polydopamine derived N-doped carbon shell and unique hollow bipyramidal hexagonal prism structure provide abundant active sites and guarantee sufficient space for electrolyte transport. The hollow structures could homogenize flux distribution and electric field distribution, facilitating high-efficiency and stable energy storage. Consequently, the electrochemical activity, kinetics, and stability could be remarkably optimized. In addition, electrochemical performance improvement mechanisms triggered by in-situ multiple heteroatoms substitution and structure design are revealed by systematic characterizations, computations, and simulations. This study proposes a feasible electron structure regulation strategy triggered by in-situ multiple heteroatoms substitution for non-MnO₂ cathode design, which is of great importance for the development of zinc batteries.