Facile Zn²⁺ Desolvation Enabled by Local Coordination Engineering for Long-Cycling Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (AZIBs) have aroused continuously increasing attention for grid-scale energy storage applications. However, the progress of AZIBs is largely plagued by their sluggish reaction kinetics and poor structural reversibility, which are closely related to the desolvation process of hydrated Zn²⁺. Herein, a strategy of local coordination engineering is proposed to modulate both surface and bulk structure of a conventional α-MnO₂ cathode to overcome these issues. Theoretical simulations and experimental characterizations reveal that the surface F coordinations effectively adjust the absorption strength toward H₂O and Zn, which facilitates the desolvation of hydrated Zn²⁺ and thus improves the interfacial ion diffusion rate and reaction kinetics. Meanwhile, the structural integrity is largely enhanced with suppressed irreversible phase evolution over cycling benefiting from the presence of robust Mn-F bonds in the bulk lattice. As a consequence, the achieved cathode exhibits almost no capacity degradation after 400 cycles at a low current density of 0.5 A g^-1 and long-term durability over 3500 cycles at a high current density of 5 A g^-1. The proposed modulation strategy provides new opportunities for designing long-cycling and high-energy cathodes for AZIBs and beyond.