Sonochemical synthesis of bilayer V2O5 for zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) hold significant promise for grid-scale energy storage, yet the lack of high-performance cathodes severely limits their viability. Here, we introduce an ultrafast, energy-efficient sonochemical synthesis to engineer bilayer vanadium pentoxide (V 2 O 5 ) nanobelts with precisely expanded interlayer spacing (11.2 Å). V K-edge extended X-ray absorption fine structure (EXAFS) analyses reveal a structural reconstruction from distorted VO 5 pyramids to symmetric VO 6 octahedra. Intercalated water molecules and sodium ions act as structural pillars, creating unimpeded zinc ions diffusion channels. This cathode delivers an exceptional specific capacity of 526.5 mAh g −1 (0.1 A g −1 ), outstanding rate capability (330.8 mAh g −1 at 2.0 A g −1 ), and ultralong cycling stability (260.6 mAh g −1 after 1000 cycles at 1.0 A g −1 ; 65.9% retention). Comprehensive kinetic studies demonstrate drastically reduced energy barriers, with an interfacial desolvation activation energy of 46.0 kJ mol −1 and solid-state diffusion energies of 33.3–38.7 kJ mol −1 . Operando studies further elucidate a synergistic Zn 2+ /H + co-intercalation mechanism, exclusive to the bilayer structure, which drives the reversible formation of a Zn x (OTf) y (OH) 2x−y ·nH 2 O byproduct that enhances structural resilience. These findings underscore the crucial importance of interlayer engineering in ZIB cathodes and provide new design principles for high-performance, durable zinc-ion storage systems.