Building a High-Performance Zn–I 2 Battery with a Green and Affordable Cationic Cellulose Binder

Despite showing low cost, inherent safety, and high suitability, the rechargeable Zn–I 2 aqueous batteries are still seriously suffering from self-discharge and energy density issues stemming from I 2 dissolution, polyiodide shuttling, and low I 2 mass loading. Herein, we develop a novel polyquaternium-10 (P10, a cationic cellulose)-based binding system to simultaneously circumvent these issues. The water-borne P10 binder can suppress I 2 dissolution and polyiodide shuttling by not only adsorbing polyiodides via its quaternary ammonium groups and oxygen heteroatoms but also eliminating the use of toxic, expensive, and I 2 -dissolving organic solvents (e.g., N -methylpyrrolidone, NMP), enabling a facile and green cathode-fabricating process. More importantly, the P10 binder is conducive to the preparation of thick cathode coatings with high I 2 mass loadings, thanks to its high elasticity and mechanical toughness after swelling by the electrolyte. As a result, Zn–I 2 batteries prepared with the P10 binder demonstrate much better anti-self-discharge performance than those prepared with conventional PVDF binders (capacity retention: 84 vs 63% after 200 h of open-circuit storage). Even at an ultrahigh I 2 mass loading of 14.5 mg cm –2, the batteries can still deliver significant specific capacity (216 mAh g –1 ) and cyclability (96.8% capacity remained after 385 cycles). This binder should be highly compatible with other performance-improving strategies, providing a green yet affordable approach for the construction of high-performance Zn–I 2 aqueous batteries.