Bilayered nanostructured V₂O₅ nH₂O xerogel constructed 2D nano-papers for efficient aqueous zinc/magnesium ion...

Aqueous zinc ion batteries (AZIBs) and aqueous magnesium ion batteries (AMIBs) offer powerful alternatives for large-scale energy storage because of their high safety and low cost. Consequently, the design of high-performance cathode materials is essential. In this paper, we present a simple strategy that combines oxygen defect (O_d) engineering with a 2D-on-2D homogeneous nanopape-like bilayer V₂O₅ nH₂O xerogel (BL-HVO_d NPS). This strategy employs O_d to improve Zn²⁺/Mg²⁺insertion/extraction kinetics and reduce irreversible processes for high-performance AZIBs/AMIBs. And interlayer water molecules serve as an effective spacer to stabilize the expanded interlayer gap in BL-HVO_d NPS, thereby providing extended diffusion channels for Zn²⁺/Mg²⁺ during insertion/extraction. The interlayer water molecules help shield the electrostatic interaction between Zn²⁺/Mg²⁺ and BL-HVO_d NPS lattice, which improves diffusion kinetics during repeated. In addition, electrochemical characterization results indicate that the BL-HVO_d NPS can effectively the surface adsorption and internal diffusion of Zn²⁺/Mg²⁺. More importantly, the successfully prepared unique 2D-on-2D homogenous nanopaper structure enhances electrolyte/electrode contact and reduces the migration/diffusion path of electrons/Zn²⁺ and Mg²⁺, thus greatly improving rate performance. As a result, the BL-HVO_d NPS as AZIBs/AMIBs electrodes offer better reversible capacity of 361.8 and 162.8 mA h g^-1 (at 0.2 A g^-1), while displaying impressively long cycle lifes. This method provides a way to prepare advanced xerogel cathode materials for AZIBs and AMIBs.