Dyeing I2 cathodes via densifying cationic groups in bifunctional binders for shuttling-free aqueous Zn-I2 batteries with high I2 utilization

Inspired by the dyeing technology, PAH with dense cationic groups is exploited as a bifunctional binder. • In-situ spectroscopic techniques and theoretical calculations demonstrate the robust electrostatic anchoring effect. • The quantitative nanomechanic techniques visually demonstrate the robust mechanical properties of the I 2 @PAH cathode. • I 2 @PAH cathode exhibits a capacity decay rate as low as 0.0019% per cycle over 12,000 cycles. • At a I 2 loading of 7.32 mg cm ‒2 , the Zn-I 2 pouch cell exhibits high I 2 utilization and cycling stability. Aqueous Zn-I 2 batteries have shown great promise for sustainable energy storage owing to their cost-effectiveness, environmental compatibility, and intrinsic safety. However, their practical application is restricted by the severe shuttle effect of polyiodides and significant capacity loss caused by volume changes, especially for high-loading and large-size pouch cells. Poly(allylamine hydrochloride) (PAH), a cationic polymer, is commonly used as the robust fixing agent in the dyeing process. Its dense –NH 3 + cationic groups can combine with anions on the dye to form insoluble colored precipitates. Herein, inspired by the dyeing technology, PAH is employed as a bifunctional binder to construct an I 2 @PAH cathode, which can effectively anchor polyiodides through cation–anion interactions to suppress the shuttle effect. Moreover, quantitative nanomechanical techniques demonstrate that PAH possesses superior mechanical properties to maintain the structural stability of the I 2 cathodes during the cycling process. The I 2 @PAH cathode delivers remarkable cyclic stability and a high discharge capacity (165 mAh g ‒1 over 12,000 cycles at 2.0 A g ‒1 ). Notably, at an I 2 loading equal to 7.32 mg cm ‒2 , the Zn-I 2 pouch cell exhibits an initial discharge capacity equal to 195mAh g ‒1 with a high I 2 utilization of 92.4% and remains stable for over 150 cycles, highlighting the considerable potential of PAH as a high-efficiency binder for aqueous Zn-I 2 batteries. Download: Download high-res image (103KB) Download: Download full-size image