Dual-Electrode Synergistic Electrolyte Enabling Highly Reversible Multi-Electron Redox in Aqueous Zinc-Iodine Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 41194374.
- Also identified by DOI 10.1002/adma.202513389.
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Abstract
Multi-electron redox strategies offer promising approaches to achieve high energy density in aqueous Zn-iodine (Zn─I<sub>2</sub>) batteries, yet the development is impeded by unstable intermediate species, slow redox kinetics, and poor reversibility, particularly at low current densities. Herein, 1-pentyl-3-methylimidazolium bromide ([PeMIM]<sup>+</sup>Br<sup>-</sup>) is employed to develop a dual-electrode synergistic electrolyte (DESA-E), which enables the multi-electron conversion of Zn─I<sub>2</sub> batteries with high specific capacity and long-term cycling stability. The Br<sup>-</sup> in DESA-E induces dual-halogen synergy, accelerating cascade I<sup>-</sup>/I<sup>0</sup>/I<sup>+</sup> four-electron conversion kinetics and activating the Br<sup>-</sup>/Br<sup>0</sup> redox reactions for ultra-high specific capacity. Meanwhile, hydrophobic [PeMIM]<sup>+</sup> alkyl chains stabilize interhalogen intermediates, suppress I<sup>+</sup> hydrolysis, and guide Zn deposition along the (002) plane via electrostatic effect. Consequently, the DESA-E enables Zn─I<sub>2</sub> batteries with a specific capacity of 557 mA h g<sup>-1</sup> after 500 cycles at 0.5 A g<sup>-1</sup> with an average coulombic efficiency of 99.97%, and maintains a low degradation rate of 0.00055% per cycle over 60 000 cycles at 8 A g<sup>-1</sup>. This work presents a facile and cost-effective electrolyte design to enable durable multi-electron Zn─I<sub>2</sub> batteries for high-energy-density systems.