An Oriented Cu₃(HHTP)₂@GO Free-Standing Cathode With Ultrafast Zn²⁺ Kinetics for High-Capacity and Durable Flexible Aqueous Zinc-Ion Batteries

Flexible aqueous zinc-ion batteries (AZIBs) offer critical safety and cost advantages for portable/wearable electronics, yet their widespread deployment remains constrained by energy density and cycle stability of cathode materials. Here, we fabricate a flexible free-standing cathode by integrating 2D conductive metal-organic framework (2D c-MOF, Cu₃(HHTP)₂) nanosheets with graphene oxide (GO). Eclipsed stacking in Cu₃(HHTP)₂ furnishes open 1D pathways for rapid Zn²⁺ diffusion, while robust π–π coupling with GO mitigates structural deterioration and volumetric strain during prolonged cycling. The optimized electrode demonstrates outstanding electrochemical performance, delivering a high specific capacity (358.2 mAh·g⁻¹ at 0.2 A·g⁻¹), exceptional cycling stability (213.3 mAh·g⁻¹ after 1140 cycles), and ultrafast ion diffusion (10⁻¹⁰-10⁻⁷ cm²·s⁻¹) among the highest reported for MOF-based cathodes in AZIBs. In situ spectroscopy and theoretical calculations unveil Zn²⁺ storage governed by CuO₄ redox centers, while the synergistic Cu₃(HHTP)₂@GO heterostructure creates confined microenvironments that boost ion-insertion kinetics and stabilize the structure. This work establishes a viable pathway for designing durable, high-capacity flexible electrodes for future energy storage applications.