Sandwich-Like Sulfur-Doped V2O5/Reduced graphene Oxide/Sulfur-Doped V2O5 Core-shell structure boosts Zinc-Ion storage

Abstract The synthesis of V2O5 with novel architectures for aqueous Zn-ion batteries (AZIBs) has been developed great advances but is still a huge challenge. Herein, a sandwich-like composite, sulfur-doped V2O5/reduced graphene oxide/sulfur-doped V2O5 (denoted as S-V2O5/rGO) core–shell structure, is synthesized by the combination of hydrothermal and calcining processes, and this material exhibits improved electrochemical properties for Zn2+ storage. The rGO in the middle and S-dopant facilitate ion diffusion and electron transport and make the material easier for the electrolyte to enter, resulting in outstanding Zn2+ storage of S-V2O5/rGO. The Zn//S-V2O5/rGO battery delivers a high capacity up to 610 mAh·g−1 at 0.1 A·g−1 and stable cycle performance. The battery also delivers excellent rate stability with about 467, 458, 454, 447 and 442 mAh·g−1 at 0.4, 0.8, 1.0, 1.5 and 2.0 A·g−1. The energy densities are achieved as high as 333 Wh·kg−1 at 286 W·kg−1 and 306 Wh·kg−1 at 1392 W·kg−1 based on the mass of S-V2O5/rGO. The results prove that this sandwich-like structure combination with S-dopant can improve the electrical conductivity and facilitate the migration of Zn2+ and electrons, leading to fast redox reaction kinetics. These findings provide a novel strategy for designing novel V-based architectures for aqueous multivalent ions batteries.