Bilayered nanostructured V 2 O 5 nH 2 O xerogel constructed 2D nano-papers for efficient aqueous zinc/magnesium ion storage.

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 V ₂ O ₅ nH ₂ O xerogel (BL-HVO _d NPS). This strategy employs O _d to improve Zn ²⁺ /Mg ²⁺ 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 Zn ²⁺ /Mg ²⁺ during insertion/extraction. The interlayer water molecules help shield the electrostatic interaction between Zn ²⁺ /Mg ²⁺ 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 Zn ²⁺ /Mg ²⁺ . More importantly, the successfully prepared unique 2D-on-2D homogenous nanopaper structure enhances electrolyte/electrode contact and reduces the migration/diffusion path of electrons/Zn ²⁺ and Mg ²⁺ , 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.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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