Carbon-halogen bond substitution enables high-utilization four-electron iodine redox in noncorrosive dilute electrolytes.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41723120.
- Also identified by DOI 10.1038/s41467-026-69743-z and PMC identifier 13039508.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Aqueous Zn | |I<sub>2</sub> batteries, involving I<sup>-</sup>/I<sup>0</sup>/I<sup>+</sup> redox, are promising yet usually facing low I<sub>2</sub> utilization dominated by I<sup>0</sup>/I<sup>+</sup> redox, especially under high loadings. Unlocking alternative pathway to I<sup>0</sup>/I<sup>+</sup> redox, preferably in noncorrosive dilute electrolytes, is a crucial solution. Here, we report a pathway towards more thermodynamically favorable I<sup>0</sup>/I<sup>+</sup> redox, via a unique carbon-halogen bond substitution. This pathway is realized with a low-concentrated (0.7 M), noncorrosive organohalide additive (2-bromoacetamide, BrAce), triggering a reversible Br-C···I<sup>(0)</sup> and C-I<sup>(+)</sup>-Br bond substitution. Compared with conventional interhalogen bonding (I-Br) pathway, this pathway synchronously lowers the barrier for I⁰/I⁺ redox and strengthens the anti-hydrolysis of I<sup>+</sup> species, by elaborately regulating axial δ hole activity of interhalogen bond (I<sup>(δ+)</sup>-Br). Notably, this pathway enables sustainable operation of four-electron Zn | |I<sub>2</sub> batteries with high I<sub>2</sub> loading (8.6 ~ 24.0 mg cm<sup>-2</sup>), featuring improved performances: (1) high I<sub>2</sub> utilizations (55% ~ 80%) at high rates (5.8 ~ 46.4 mA cm<sup>-2</sup>), (2) long lifespan ( <math xmlns="http://www.w3.org/1998/Math/MathML"><mo>></mo></math> 400 cycles) with practical areal capacity ( ~ 3.85 mA h cm<sup>-2</sup>) and 99.5% retention even at 47.5 mA cm<sup>-2</sup>. This pathway opens an exciting research direction to unlock unusual halogen chemistry for scalable, high-energy, sustainable aqueous batteries.