A layer separated V2O5-PEG-amine hybrid cathode material for high capacity zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (ZIBs) have significant potential for advancing energy storage technologies. However, the instability of cathode materials, such as V₂O₅, under operating conditions is a bottleneck for commercializing aqueous ZIBs. Here, we have devised an innovative approach to pillaring the V₂O₅ layers by inserting polyethylene glycol amine (PEG-amine), creating a layer-separated V₂O₅ ultrathin nanosheet (expanded interlayer spacing to 1.21 nm) composite cathode material (VOPxA). First-principles calculations verified the most stable orientation and bonding configuration of PEG-amine within the V₂O₅ host structure. The stable anchoring of PEG-amine is facilitated by the interaction of the C–H and N–H groups with the V₂O₅. The distinctive V₂O₅-PEG-amine hybrid structure led to a narrower band gap (0.72 eV), expediting efficient electron transport. This configuration resulted in a high storage capacity of 515 mA h g⁻¹ at 0.1 A g⁻¹, stability over 2000 cycles at 3 A g⁻¹, and a high energy density of 396 W h kg⁻¹ at 113 W kg⁻¹. The pillared PEG-amine between the V₂O₅ layers significantly enhanced the electrochemical kinetics of the intercalating/de-intercalating zinc ions and mitigated the collapse of the V₂O₅ layer structure. The post-stability analyses of the cathode electrode revealed retention of good structural integrity and excellent stability of the employed cathode material.