Advanced Polymeric Binders in Aqueous Zinc Ion Batteries: Dynamic Diselenide Bonds as Unique Cofactors for Improving Redox Kinetics

Abstract

Aqueous zinc ion batteries (AZIBs) show significant advantages in the field of current energy storage. This work has focused on the binder, which is one of the components of the cathode, which enhances the electrochemical behavior of sustainable high-capacity batteries. The polyurea-containing diselenide or disulfide units have been synthesized as a binder for AZIBs, which are named PICSe and PICS. Compared with PVDF, the critical contents of polyurea binders are diselenide/disulfide units, which act as cofactors to coordinate with cation charge carriers, facilitate Zn²⁺ transfer, and improve redox kinetics. Furthermore, the binders achieve physical cross-linking through free-radical-mediated mechanisms and hydrogen bonding interactions, which result in high mechanical properties of the cathodes. Therefore, the resultant AZIBs based on a PICSe binder show that the discharge specific capacity can be stabilized at about 100 mA h g^–1 after 500 cycles at 1 C, and the capacity retention rate is 84.9%.