Aligned Nanostructures Resolve Zn2+ Transport Bottlenecks via Interfacial Kinetics–Diffusion Coupling in Aqueous Zinc‐Ion Batteries

It is revealed that limited solid‐state Zn2⁺ diffusion within the cathode leads to interfacial Zn2⁺ accumulation, forming a transport bottleneck that distorts Zn2⁺ flux directionality. Through advanced analytical techniques, including in situ electrochemical impedance spectroscopy (EIS), distribution of relaxation time (DRT) analysis, and COMSOL simulation, this study provides a detailed evaluation of synthesis‐driven evolution enhances electrochemical performance. Abstract Aqueous zinc‐ion batteries (AZIBs) have garnered significant attention as a safe and cost‐effective alternative to lithium‐ion batteries for grid‐scale energy storage. However, their performance is hindered by sluggish Zn2+ diffusion within the cathode and structural degradation. While pre‐intercalation strategies have demonstrated improvements in electrochemical performance, the comprehensive understanding between synthesis‐driven evolution, Zn2+ diffusion, and interphase kinetics remains underexplored. Herein, it is investigated how synthesis time influences the structure and morphology of K2V6O16·nH2O cathodes, as well as their Zn2+ diffusion and charge transfer kinetics. By coupling operando‐ electrochemical impedance spectroscopy (EIS) and COMSOL simulation, that interfacial Zn2⁺ accumulation, induced by limited solid‐state diffusion within the cathode, leads to pronounced transport bottlenecks—despite sufficient charge‐transfer kinetics is identified. This imbalance distorts the Zn2+ flux directionality and creates spatial heterogeneity in ion transport. Notably, these bottlenecks are effectively alleviated by 1D nanostructured architectures, which promote continuous ion transport and facilitate interfacial reaction kinetics. Consequently, K2V6O16·nH2O exhibits a tenfold increase in Zn2+ diffusivity and 97.26% capacity retention over 5000 cycles. These findings offer valuable insights into the rational design of high‐performance AZIB cathodes through synthesis‐driven structural control. It is revealed that limited solid-state Zn 2 ⁺ diffusion within the cathode leads to interfacial Zn 2 ⁺ accumulation, forming a transport bottleneck that distorts Zn 2 ⁺ flux directionality. Through advanced analytical techniques, including in situ electrochemical impedance spectroscopy (EIS), distribution of relaxation time (DRT) analysis, and COMSOL simulation, this study provides a detailed evaluation of synthesis-driven evolution enhances electrochemical performance. Abstract Aqueous zinc-ion batteries (AZIBs) have garnered significant attention as a safe and cost-effective alternative to lithium-ion batteries for grid-scale energy storage. However, their performance is hindered by sluggish Zn 2+ diffusion within the cathode and structural degradation. While pre-intercalation strategies have demonstrated improvements in electrochemical performance, the comprehensive understanding between synthesis-driven evolution, Zn 2+ diffusion, and interphase kinetics remains underexplored. Herein, it is investigated how synthesis time influences the structure and morphology of K 2 V 6 O 16 ·nH 2 O cathodes, as well as their Zn 2+ diffusion and charge transfer kinetics. By coupling operando- electrochemical impedance spectroscopy (EIS) and COMSOL simulation, that interfacial Zn 2 ⁺ accumulation, induced by limited solid-state diffusion within the cathode, leads to pronounced transport bottlenecks—despite sufficient charge-transfer kinetics is identified. This imbalance distorts the Zn 2+ flux directionality and creates spatial heterogeneity in ion transport. Notably, these bottlenecks are effectively alleviated by 1D nanostructured architectures, which promote continuous ion transport and facilitate interfacial reaction kinetics. Consequently, K 2 V 6 O 16 ·nH 2 O exhibits a tenfold increase in Zn 2+ diffusivity and 97.26% capacity retention over 5000 cycles. These findings offer valuable insights into the rational design of high-performance AZIB cathodes through synthesis-driven structural control. Advanced Science, EarlyView.