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

초록

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<middle dot>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<middle dot>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.

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