Authors
Rujiao Ma, Shao-Jian Zhang, Xun Zhao, Yiyang Hu, Han Wu, Junnan Hao
Published in
Angewandte Chemie (International ed. in English). Oct 28, 2026. Epub Oct 28, 2026.
Abstract
Aqueous four-electron zinc-iodine (Zn-I2) batteries offer high capacity and operating voltage, yet most reported systems rely on Cl- to activate the I0/I+ conversion, generating hydrolysis-prone ICl2 - intermediates that cause rapid capacity decay. However, how inner I-X bond polarization (X = F, Cl, and Br) governs the hydrolytic stability of interhalogen intermediates remains unclear. Here, we conduct both experimental and computational analyses, revealing Br- as the most effective halide. Compared with F- and Cl-, Br- forms less-polarized and more hydrolytically stable IBr2 - intermediates, markedly improving high-voltage iodine reversibility. Building on this Br--mediated stabilization, we further design a multifunctional PNA-PyBr hydrogel electrolyte by incorporating pyridine hydrobromide into a sulfonate-rich poly(sodium p-styrenesulfonate-co-acrylamide) network. Pyridinium cations immobilize IBr2 - as water-insoluble Py+IBr2 - complexes, protecting I+ species from hydrolysis, while sulfonate groups regulate the aqueous hydrogen-bond network and establish Zn2+-selective transport pathways. The resulting cells deliver a near-theoretical capacity of 422.6 mAh g-1 and a record lifespan of over 20 000 cycles at 20 C. Moreover, a 500 mAh pouch cell with an areal capacity of 3.5 mAh cm-2 sustains 600 cycles with negligible capacity decay, demonstrating the practical potential of Br--activated four-electron Zn-I2 chemistry.
PMID:
42949622
Bibliographic data and abstract were imported from PubMed on 28 Oct 2026.
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