A Universal Compensation Strategy to Anchor Polar Organic Molecules in Bilayered Hydrated Vanadates for Promoting Aqueous Zinc-Ion Storage.

Abstract

The electrochemical performance of layered vanadium oxides is often improved by introducing guest species into their interlayer. Guest species with high stability in the interlayer and weak interaction with Zn²⁺ during charge/discharge process are desired to promoting reversible Zn²⁺ transfer. Herein, a universal compensation strategy was developed to introduce various polar organic molecules into the interlayer of Al_x V₂ O₅ ·nH₂ O by replacing partial crystal water. The high-polar groups in the organic molecules have a strong electrostatic attraction with pre-intercalated Al³⁺ , which ensures that organic molecules can be anchored in the interlayer of hydrated vanadates. Simultaneously, the low-polar groups endow organic molecules with a weak interaction with Zn²⁺ during cycling, thus liberalizing reversible Zn²⁺ transfer. As a result, Al_x V₂ O₅ with polar organic molecules displays enhanced electrochemical performance. Furthermore, based on above cathode material, a pouch cell was assembled by further integrating a dendrite-free N-doped carbon nanofiber@Zn anode, displaying an energy density of 50 Wh kg^-1 . This work provides a path for designing stable guest species with a weak interaction with Zn²⁺ in the interlayer of layered vanadium oxide towards high-performance cathode materials of aqueous Zn batteries.