Low-Self-Discharge Nanoconfined Hydrogel Electrolyte for Stable High-Energy-Density Aqueous Zinc-Iodine Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 41623162.
- Also identified by DOI 10.1021/acsnano.5c20669.
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Abstract
Aqueous zinc-iodine batteries (AZIBs) leveraging four-electron I<sup>-</sup>/I<sup>0</sup>/I<sup>+</sup> redox chemistry show great promise in safe energy storage systems. However, realizing Ah-level AZIBs with industrial-grade parameters (≥10 mg cm<sup>-2</sup> mass loading) remains fundamentally challenging. Here, we prepare the hydrogel electrolyte with mesoporous nanoparticles SBA-15 (MNPHE) by a nanoconfined polymerization strategy. The framework confinement effect, anion confinement effect, and free water confinement effect are achieved through Lewis acid-base interactions and hydrogen bond networks. The multiconfinement effects yield simultaneous ultrahigh mechanical strength (501 kPa tensile strength) and a record-high Zn<sup>2+</sup> transference number (<i>t</i><sub>Zn<sup>2+</sup></sub> = 0.95), which collectively suppressed polyiodide generation and I<sup>+</sup> species hydrolysis. This results in markedly enhanced reversibility and kinetics for four-electron I<sup>-</sup>/I<sup>0</sup>/I<sup>+</sup> redox chemistry under a high-I<sub>2</sub>-mass-loading cathode. Based on MNPHE, the Zn||I<sub>2</sub> full cells display a record-low self-discharge rate with only 20% capacity loss after three months and a prolonged lifetime of 100,000 cycles at 25 C. Furthermore, Ah-level four-electron Zn||I<sub>2</sub> pouch cells achieve excellent cyclability of 800 cycles and an ultrahigh cathode-mass-specific energy density of 466.7 Wh kg<sup>-1</sup>, surpassing all aqueous Zn-based systems in the Ah-level regime.