Bifunctional mechanism of immobilized organic molecule to steer Zn2+ and polyiodides transport kinetics toward ultra-stable aqueous ZnI2 batteries

Aqueous zinc‑iodine batteries (AZIBs) have been considered due to the significant potential for multi-electron transfer reactions and a high theoretical capacity of 211 mAh g −1 and a considerable output potential. Nevertheless, aqueous Zn I 2 batteries face some formidable challenges in conventional aqueous electrolytes, including catastrophic Zn dendrite hyperplasia and severe parasitic reactions, and terrible shuttle effect of polyiodides. To address these concerns, it has been recognized that hydrogel electrolyte (HE) can effectively block the active water molecules and coordinate with Zn 2+ , thus inhibiting the growth of zinc dendrites and meanwhile can mitigate the shuttle effects. Herein, anionic polyacrylamide (PAM) hydrogel electrolyte with immobilization of organic molecule of amber acid with carboxyl functional groups elaborately designed with bifunctional mechanism to address the adverse reactions simultaneously on both Zn anode and I 2 cathode. The immobilization of organic additives can build suitable ion transport highways for the modulation of Zn 2+ and polyiodides transport kinetics toward ultra-stable aqueous Zn I 2 Batteries. Eventually, as a proof of demonstration, the assembled PAM/AA based aqueous Zn I 2 cell can yield an remarkable rate performance and a high and maintained capacity of 138 mAh g −1 over 15,000 cycles with a negligible decay rate of 0.005 ‰ per cycle at a high current of 5 Ag −1 .