Spatial and Electrostatic Dual-Confinement in Hierarchical Hollow Bi-Bi₂O₃@Carbon Nanofibers for Dendrite Suppression and Side Reaction Mitigation in Aqueous Zinc-Ion Batteries

Abstract

The widespread application of aqueous zinc-ion batteries (AZIBs) is hindered by anode dendrite formation and side reactions, reducing cycling life and performance. This study introduces Bi-Bi₂O₃-loaded carbon nanofibers (Bi-Bi₂O₃@CNF) with hierarchical hollow structures and surface grooves fabricated via electrospinning, thermal treatment, and in situ growth. Experimental characterization and density functional theory reveal that the high surface area and fibrous network of Bi-Bi₂O₃@CNF enhance electron transport and electrolyte distribution, effectively reducing ohmic resistance and concentration polarization. This “Spatial Effect” provides ample space for uniform Zn deposition. Additionally, the in situ-grown Bi-Bi₂O₃, pyridinic nitrogen, pyrrolic nitrogen, and C─O─Bi bonds induce strong zinc affinity and electronegativity, generating an “Electrostatic Confinement Effect” that amplifies the “spatial effect” into a “Dual-Confinement Effect.” This synergy ensures uniform Zn deposition, suppresses dendrites and side reactions, and mitigates polarization. Compared to pure Zn anodes, Bi-Bi₂O₃@CNF reduces polarization overpotential by 17.6%, increases hydrogen evolution overpotential by 11.52%, and maintains a Coulombic efficiency of 98.8% for over 200 h. In full cells, Zn@Bi-Bi₂O₃@CNF//MnO₂ achieves 73.0% capacity retention after 1000 cycles at 1000 mA g⁻¹. This work provides a promising strategy for high-efficiency, durable, and safe AZIBs and offers valuable insights into the design of advanced aqueous energy storage materials.