Bimetallic Ions Pre-Intercalated Hydrated Vanadium Oxides for High-Performance Aqueous Zinc-Ion Batteries

Abstract

A new generation of rechargeable batteries known as Aqueous Zinc-Ion Batteries (AZIB) offers benefits including affordability, eco-friendliness, dependability, and safety. Vanadium-based oxides show potential as cathodes for AZIB due to their layered structure and multivalent properties. However, the zinc storage performance is limited by the structural instability and the challenges posed by zinc ion diffusion. In this work, TiK-VOH (the bimetallic ions system of TI4+ and K+ co-pre-intercalated in V2O5·nH2O), is synthesized using a simple sol-gel method. TiK-VOH exhibits a lamellar structure in its morphology, with the layer spacing significantly increased to 12.1 Å. Specifically, the pre-intercalation of TI4+ mainly plays the role of expanding the layer spacing, which not only improves the diffusion kinetics of zinc ions, but also acts as a pillar to stabilize the layer structure. Additionally, TI4+ can make the VOH material appear layered morphology, enhances the contact area with the electrolyte, and improves the active sites. Meanwhile, the presence of K+ reduces electrochemical impedance and enhances the electrical conductivity of the VOH layer,, and further improves the reversibility and rate performance . Under the synergistic action of bimetallic ion pre-intercalating, the TiK-VOH material exhibits excellent electrochemical properties,The highest specific capacity of TiK-VOH reaches 393.4 mAh g-1 at a current density of 0.2 A g-1, even at 10 A g-1 (increased by 20 times), it still maintains a discharge specific capacity of 202 mAh g-1 with a capacity retention rate of 94% after 2000 cycles, the overall performance is much better than the Ti-VOH and K-VOH. This work offers an alternative perspective for the modification of vanadium-based cathode of AZIBs.

Keywords: Metal ions, Intercalation, Vanadium oxides, Electrochemical properties, Aqueous zinc-ion battery