Regulating Extra-Layer Ion Channels in the Conductive V₂O₅ Hydrogel Cathode

High-power energy storage devices rely on the synergistic coordination of ion and electron transport. Here, an extra-layer channels engineering strategy is presented for developing high power and energy density cathode materials for aqueous zinc batteries (AZIBs). This approach utilizes a cation-induced self-assembly process to form conductive hydrogels with extra-layer channels by adding diverse cations (Li⁺, Na⁺, K⁺, Mg²⁺, Zn²⁺, Al³⁺, and NH₄ ⁺) into the carbon nanotubes (CNTs) ink dispersed hydrated V₂O₅ (h-V₂O₅) nanowires. The cations bridge h-V₂O₅ nanowires and create self-assembly network on the CNT surfaces, providing extra-layer ion channels beyond the intrinsic interlayer of h-V₂O₅. These external channels exhibit distinct properties depending on the cations, significantly influencing the performance of V₂O₅ hydrogel cathode for AZIBs. Larger cations reduce Zn²⁺ migration resistance enhancing diffusion kinetics; smaller cations strengthen the M─O bond, improving structural stability. For instance, K-V₂O₅/CNT demonstrates an initial specific capacity of up to 618 mAh g^-1 at 0.2 A g^-1 and retains a capacity of 248 mAh g^-1 even at 20 A g^-1. In contrast, the Zn-V₂O₅/CNT maintains excellent cycling stability, with 230 mAh g^-1 after 700 cycles at 1 A g^-1. This offers a versatile platform for tailoring ion transport channels in hydrogel cathodes for ZIBs.