Building a High-Performance Zn–I2 Battery with a Green and Affordable Cationic Cellulose Binder
Despite showing low cost, inherent safety, and high suitability, the rechargeable Zn–I2 aqueous batteries are still seriously suffering from self-discharge and energy density issues stemming from I2 dissolution, polyiodide shuttling, and low I2 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 I2 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 I2-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 I2 mass loadings, thanks to its high elasticity and mechanical toughness after swelling by the electrolyte. As a result, Zn–I2 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 I2 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–I2 aqueous batteries.
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