Dynamic transport of Zn2+ in ionic liquid intercalated V2O5 cathode for high-performance aqueous Zn-ion batteries

• We firstly reported the ionic liquids in the interlayers of V 2 O 5 cathode material for aqueous zinc ion batteries . • The ionic liquid between the V 2 O 5 layers optimized the interlayer charge distribution and widened the layer spacing. • We use in-situ spectroscopy to verify the dynamic response of ionic liquids during charging and discharging. • The intercalation of ionic liquids modifies the migration path of Zn 2+ , enlarging the channels and lowering the energy barrier. • 0.4Bmim + -V 2 O 5 || Zn of pouch full cells could stably cycled for 160 cycles at 50 mA g −1 , with an energy density of up to 310 W h kg −1 . Due to high safety and low-cost, aqueous Zn-ion batteries (ZIBs) are expected to be a promising next-generation energy storage technology. Exploiting high capacity and stable cathode materials are extremely important for the development of aqueous ZIBs. However, commercial V 2 O 5 despite its high theoretical specific capacity, suffers from structural instability during charging and discharging, and strong electrostatic forces seriously limit the diffusion of Zn 2+ . Herein, a novel dynamic transport mechanism of Zn 2+ is designed by intercalating organic cations (C 8 H 15 N 2 + ) from ionic liquids into the interlayers of V 2 O 5 . The electrostatic interaction between the C 8 H 15 N 2 + and the V-O layers enhance the structure stability of the layers and increase the interlayer spacing. Meanwhile, the C 8 H 15 N 2 + between the V-O layers reduce the diffusion energy barrier of Zn 2+ and enable the rapid dynamically transport of Zn 2+ . The diffusion coefficient is enhanced by an order of magnitude. The optimized V 2 O 5 cathode exhibits a high capacity of 268 mA h/g at 100 mA/g and excellent cycling stability (over 500 cycles at 200 mA/g with nearly 100 % coulombic efficiency). The home-made pouch cells deliver a high energy density of 310 W h kg −1 . This interesting idea opens up a new research direction for high-energy secondary batteries.