Polyamine Compound with High-Density N-H Proton Arrays Enables High-Loading and Long Lifespan Zinc-Iodine Batteries

Aqueous zinc-iodine (Zn-I₂) batteries, despite their cost-effectiveness and safety, are plagued by zinc anode corrosion and the polyiodide shuttle effect. Herein, trace tetraethylenepentamine (TEP), with a high-density N-H proton array, is employed to regulate the running environment of Zn-I₂ batteries, which suppresses anode corrosion and polyiodide formation, enabling long-term cycling under high-loading conditions. For the zinc anode, TEP's high-density N-H array facilitates preferential surface adsorption, optimizing the interfacial Helmholtz layer. Rich in lone-pair electrons, its -NH₂ and -NH- groups as Lewis bases coordinate with Zn²⁺ ions to regulate interfacial ion dynamics, enabling dendrite-free Zn deposition. For the iodine cathode, TEP coordinates with I₂ via the lone pair electrons of N atoms and forms strong electrostatic hydrogen bonds between H protons and I^-, synergistically suppressing polyiodides formation, thereby enhancing the utilization of the iodine cathode. Consequently, TEP enables the Zn||Zn battery to achieve a stable cycling for over 2333 h (1 mA cm^-2, 1 mAh cm^-2). The Zn-I₂ battery with a high iodine loading (15.9 mg cm^-2) retains 91.3% capacity after 8900 cycles. This study demonstrates that incorporating a trace amount of TEP provides a new insight into the development of sustainable, long-life Zn-I₂ batteries.