Electron Delocalization and Dissolution-Restraint in Vanadium Oxide Superlattices to Boost Electrochemical Performance of Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (ZIBs) have triggered a great deal of scientific research and become a promising alternative for large-scale energy storage applications, owing to the unique merits of high volumetric energy density, abundance of zinc resources, eco-friendliness, and safety. The pace of progress of ZIB development, however, is hindered by their poor reversibility and sluggish kinetics, derived from the dissolution of active materials in aqueous electrolytes and the strong electrostatic interactions between Zn2+ and the cathode lattice. Herein, a vanadium oxide (V2O5-x)/polyaniline (PANI-V) superlattice structure is demonstrated as a model of superlattice structural engineering to overcome these weaknesses. In this superlattice, the PANI layer not only plays the role of a spacer to expand the V2O5-x interlayer spacing but also serves as a conductive capacity contributor. Moreover, the PANI layer servers as structural stabilizer to restrain the dissolution of V2O5-x active materials in aqueous electrolytes. In addition, it introduces an interface effect to modulate the charge distribution of the V2O5-x monolayer, promoting Zn-ion diffusion into the structure. Correspondingly, weakening the electrostatic interactions and supressing the active materials dissolution synergistically boosts the electrochemical performance for Zn-ion storage. This work paves the way for the development/improvement of cathodes for aqueous zinc-ion batteries.