Ultra-Long Lifespan Aqueous Zinc-Iodine Batteries Enabled by a Defect-Rich Covalent Triazine Framework

Aqueous Zinc-iodine batteries (ZIBs) are widely viewed as promising energy storage devices due to their high energy density and intrinsic safety. However, they encounter great challenges such as grievous polyiodides shuttle and sluggish iodine (I₂) redox reaction kinetics, thus undesirable cycling performance. Here a high-performance ZIB with an ultra-long lifespan is reported through the rational I₂ cathode catalyst design. Specifically, a covalent triazine framework with defect-rich sites and micro-mesoporous structure (i.e., CTF500) is developed as an effective I₂ cathode catalyst. Benefiting from the synergistic effect of micro-mesoporous structure and defect-rich sites for the confinement and conversion of I₂ species, the resulting ZIBs with I₂ loaded CTF500 (I₂@CTF500) cathode show an ultra-long lifespan over 75,000 cycles at 5 A g^-1, and an impressive cyclic performance over 15,000 cycles at high I₂ loading of 3.59 mg cm^-2, highlighting its commercial application prospect. In/ex situ spectral characterizations combined with theoretical calculations clearly reveal the reversible reaction mechanism of I₂ species in I₂@CTF500 cathode and the essential role of defect-rich sites in boosting the performance of ZIBs. This work not only guides the design of advanced I₂ cathodes for metal-iodine batteries but also expands the range of possible applications for defect-rich CTFs.