High-Efficiency Flexible Zn-Air Batteries Enabled by Agarose Based Oxygen Electrocatalyst and Gel Electrolyte Through Bidirectionally Synergistic Optimization Strategy.

Flexible Zn-air batteries (F-ZABs) typically suffer from limited cycle life due to sluggish oxygen electrocatalytic kinetics and unstable electrochemical interfaces. A bidirectionally synergistic strategy for profit is proposed from the unique elemental characteristics and molecular architecture of agarose to simultaneously construct a triple-doped N, P, O oxygen electrocatalyst with multiple active sites and gel electrolyte with exceptional mechanical robustness and weather resistance. The electrocatalyst demonstrates superior oxygen reduction reaction (ORR) activity (E_1/2 = 0.85 V) and stability (<5 mV decay after 10,000 cycles), outperforming commercial Pt/C. Density functional theory (DFT) calculations reveal that N, O, and P species enhance O-intermediate adsorption through optimized p-band center proximity to the Fermi level. This synergy enables aqueous Zn-air (ZABs) to achieve superior cyclability of 950 h. The dual helical structure of agarose synergizes with ethylene glycol (EG) to reconstruct hydrogen─bond networks of the polyacrylamide (PAM). This design yields F-ZABs with outstanding power density (144 mW cm^-2), operational stability (205 h), tolerance to mechanical stress and extreme temperatures (-20 °C for 420 h; 60 °C for 40 h). The work provides new insights into multidimensional marine biomass utilization, highlighting the critical role of intrinsic oxygen functionalities in ORR enhancement and the pivotal impact of electrolyte mechanics on flexible battery longevity.