Mechanistic Insight into Polypyrrole Coating on V2O5 Cathode for Aqueous Zinc-Ion Battery

The aqueous zinc-ion batteries have been extensively studied among energy storage devices due to the excellent electrochemical performance, high safety, and low cost. Recently, vanadium oxide (V2O5) cathode materials have received much attention owing to the high theoretical capacity. However, it is still hindered by some drawbacks, including poor electronic conductivity, sluggish kinetics for zinc-ion diffusion, and cathode dissolution in the electrolyte. To address these issues, the cathode material of V2O5 particles coated by a layer of polypyrrole (V2O5/PPy) has been prepared by an environmental favorable route in this work. It was found that the PPy coating layer can efficiently enhance the cyclic and rate performance. The obtained V2O5@PPy cathode demonstrates a high capacity retention of 95.6 % after 300 cycles, and deliver a high-rate capacity of 68.4 mAh g(-1) at 5 A g(-1). The theoretical computation clarifies that PPy coating can weaken the electrostatic interaction between V2O5 matrix and zinc-ion and therefore boost the insertion/extraction process of Zn2+ ion. This work provides a valuable insight into the underlying action mechanism of polymer-coated cathode materials for Zn2+ storage in aqueous zinc-ion batteries.