A multinitrogen π-conjugated conductive polymer stabilizing ultra-large interlayer spacing in vanadium oxides for high-performance aqueous zinc-ion batteries

Abstract

Rechargeable aqueous zinc-ion batteries (ZIBs) have attracted increasing attention in the field of electrochemical energy storage (EES) because of their remarkable features, including high theoretical capacity, cost-effectiveness, environmental friendliness, and inherent safety. However, the realization of high-performance cathodes with both high specific capacity and outstanding cycling stability in ZIBs remains challenging. In this work, we present the design of a novel conductive polymer, poly-[2,2′-bipyridin]-5-amine (PBpyA), and report the successful in situ intercalation synthesis of PBpyA-intercalated V₂O₅·nH₂O (designated as PBVO) xerogels. PBVO exhibits exceptional structural stability, attributed to the robust π-conjugation within PBpyA, which effectively stabilizes V₂O₅ bilayers. Moreover, PBVO features a significantly enlarged interlayer spacing of 14.1 Å, facilitating efficient intercalation/extraction of Zn²⁺. As a cathode material for ZIBs, PBVO demonstrates excellent electrochemical performance, delivering a high specific capacity of 454.6 mA h g⁻¹ at 0.1 A g⁻¹ and exhibiting remarkable cycling stability, with 97% capacity retention after 150 cycles at 0.2 A g⁻¹ and 84% capacity retention after 2000 cycles at 5 A g⁻¹. These findings position PBVO as a highly promising candidate for high-capacity and ultra-stable ZIB cathodes.