Redox Oligomer Assembling Hierarchical Reinforced Framework Cathodes for Ultra-Stable High-Performance Zinc-Ion...

Organic cathodes with maximal redox active-sites and structural tunability are in great demand for aqueous zinc-ion batteries (ZIBs). Currently, they are facing challenges of limited capacity, poor cycling stability, and sluggish ion transport in practical applications. In this work, we have developed a universal and efficient strategy to assemble a redox oligomer into a conductive substrate imitating a reinforced concrete framework as freestanding cathodes for high-performance ultrastable ZIBs. The signature molecule was specifically designed by sandwiching phenoxoline with two benzoquinone units to explore the most redox-active sites. 2D MXene nanosheets convalently bonded with single-walled carbon nanotubes to construct hierachical reinforced framework with superior porosity and structural rigidity. Benefiting from superior structural robustness and electrochemical dynamics, the cathodes deliver the highest specific capacity of 339.5 mAh g^-1 at 0.1 A g^-1, together with exceptional capacity retention of 87.5% over 65 000 cycles at 10 A g^-1. The calculated Zn²⁺ diffusion coefficient (10^-8-10^-7 cm² s^-1) indicates rapid charge transfer kinetics. The assembled pouch cell demonstrates stable power output under various bending angles for a flexible energy supply. This work provides not only a novel nanostructure engineering strategy for fabricating high-performance hierarchical electrodes but also insights into the design of redox-rich molecules for next-generation energy storage.