Rare earth metals ion intercalated hydrated vanadium oxides for high-performance aqueous zinc-ion batteries

Hydrated vanadium oxide (V2O5 & sdot;nH2O) is promising cathode candidates for aqueous rechargeable Zn-ion batteries (ZIBs) owing to its high theoretical specific capacity, abundant resources and environmentally friendly. However, the higher charge density of Zn2+ lead to its structural instability, cyclic degradation and sluggish Zn2+ diffusion kinetics. Herein, rare earth metal ions intercalated into the interlayer of V2O5 & sdot;nH2O materials (abbreviated as RE-VOH) are successfully synthesized to expand interlayer spacing and stabilize the layered structure via a simple sol-gel method, among, the yttrium ion intercalated V2O5 & sdot;nH2O (Y-VOH) exhibits a honeycomb porous microstructure and a remarkably enlarged interlayer distance (13.6 angstrom), which can not only increase the contact area between the electrode material and the electrolyte but also offer rapid diffusion channel for Zn2+. Meanwhile, the problem of vanadium dissolution of cathode materials is inhibited by the electrolyte additive strategy through adding suitable vanadium oxide sol to aqueous electrolyte, furthermore, the zinc anode modification strategy in electroplating process inhibits the formation of zinc dendrites. Benefitting from the synergistic effect of modification design for the ZIBs systems of cathode, electrolyte and anode, the overall electrochemical performance of Y-VOH electrode is significantly improved, delivering a large specific capacity of 337 mAh g-1 at the current density of 500 mA g-1 and excellent rate capability of 170 mAh g-1 at 10 A g-1, along with an outstanding capacity retention of 90 % over 3000 cycles. Additionally, systematical ex situ characterizations prove the (de)intercalation reversibility of Zn2+ storage mechanism for the Y-VOH cathode. This research may provide a new way for exploiting high performance vanadium-based materials for aqueous ZIBs.