Unleashing the Power of Zn-Rich Cathodes: A Polydopamine-Driven Reduced Graphene-Oxide Zn3V3O8 Coating for Aqueous Zn-Ion Batteries

Zn3V3O8 (ZVO) is a widely used high-capacity cathode material in aqueous zinc-ion batteries (AZIBs), particularly serving as a zinc-rich cathode in anode-free AZIBs. However, the irreversible zinc intercalation in ZVO leads to rapid depletion and reduced capacity. To address this issue, we propose the uniform coating of ZVO with reduced graphene oxide (RGO) using polydopamine (PDA). Our approach enhances the hydrophobicity and electrical conductivity of the cathodes, enabling the reversible dissolution of Zn2+ ions. We observed that the ZVO sample coated with RGO using PDA (ZVO@PDA@RGO) demonstrated significantly higher capacity retention (93.1% after 1000 cycles at 5 A g(-1)) compared to pristine ZVO. In an anode-free cell, it retained an impressive capacity of 134.5 mAhg(-1) after 100 cycles. Thus, this study provides a design that enhances the reversibility, lifespan, and performance of Zn-rich cathodes in AZIBs, potentially rendering them more suitable for anode-free battery applications.