Boosting zinc ion storage performance of sandwich-like V2O5/graphene composite by effectively inhibiting vanadium dissolution

Improving the stability of the layered structure and suppressing vanadium dissolution during repeated Zn2+ insertion/extraction processes are considered to be the key to promote the electrochemical stability of vanadium-based cathodes for ZIBs. In this work, a group of sandwich-like V2O5/graphene composites (V2O5/xG) were controllably fabricated by tuning the amount of hydrophobic graphene. With the increase of graphene content, the corresponding electrochemical properties show a parabolic trend that increase first and then decrease. A maximum capacity of 270 mAh g-1 after 100 cycles at 0.1 A g-1 and a superior cycle stability with 82.4% capacitance retention after 6000 cycles at 10 A g-1 are achieved when the amount of graphene is about 10.4% (that is V2O5/5G). The addition of graphene has been proven not only to act as an effective conductive network to promote charge transfer and enhance the pseudocapacitance effect on the electrode surface; but also to increase the electrode hydrophobicity, effectively inhibiting the dissolution of vanadium, and promoting the desolvation and diffusion kinetics of hydrated zinc ions. Moreover, the graphene layer, as a structural stabilizer, effectively prevents the structure of the active component V2O5 from collapsing during cycling, contributing to the long-term cycle life. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

In this study, sandwich-like V2O5/graphene composites were fabricated by controlling the graphene content. The addition of graphene not only enhanced the electrochemical stability and cycling life of the electrode, but also improved the charge transfer performance and suppressed vanadium dissolution.