Multinitrogen π-Conjugated Conductive Polymer Stabilizing Ultra-Large Interlayer Spacing in Vanadium Oxides for High-Performance Aqueous Zinc-Ion Batteries

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 xerogels (designated as PBVO). 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 mAh 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.