Dynamic Polyiodide-Trapping and Proton-Capturing Dual-Network Engineering for High-Areal-Capacity, Long-Cycling and High-Temperature Zn─I₂ Batteries.

Abstract

Aqueous zinc-iodine (Zn─I₂) batteries demonstrate great potential in the large-scale grid-scale energy storage. However, severe polyiodide shuttling and interfacial parasitic reactions limit the practical application of aqueous Zn─I₂ batteries with high iodine loading. Here, aminonicotinic acid (AMI) is first introduced in this work to address these issues by dynamic polyiodide-trapping and proton-capturing dual-network engineering. The abundant active sites on AMI effectively trap the I₃ ^- ions for inhibiting the polyiodide dissolution and migration in the electrolyte. Moreover, AMI reversibly captures H⁺ ions and neutralizes OH^- ions, thereby effectively mitigating pH fluctuations to suppress the interfacial side reaction on the Zn anode. Consequently, the Zn//Zn symmetrical battery demonstrates prolonged cycling stability over 7000 h at 1 mA cm^-2 and 1 mAh cm^-2. The Zn─I₂ battery maintains stable cycling for over 2800 cycles based on an ultrahigh I₂ cathode loading of 23.8 mg cm^-2 (3.1 mAh cm^-2), and 3000 cycles at a high temperature of 50°C at 2 A g^-1. This work pioneers a novel electrolyte additive strategy for polyiodide-trapping and pH-buffering dual-network engineering, providing a straightforward and innovative approach toward energy-dense, endurable, and high-temperature Zn─I₂ batteries.