Stable, high-rate, organic zinc-ion batteries accomplished using an ion-conducting marine-inspired binder

Abstract

Aqueous zinc-ion batteries (AZIBs) are promising for a range of future energy storage needs. However, their widespread adoption is hindered by the cathode's poor conductivity and high solubility in the aqueous electrolyte, resulting in low energy density and poor cycle life. Most research has focused on improving the active material performance, with less emphasis on optimizing other electrode components. Binders, which are essential for maintaining electrode integrity during cycling, can also play a crucial role in enhancing conductivity and mitigating dissolution. In this study, we introduce a novel dual-functional polymer, POxaPG, incorporating gallol (a marine adhesive) and polyethylene gallol (PEG) as a binder that addresses these challenges. Due to the strong adhesion and excellent mechanical stability provided by the robust bonding between the gallol groups and the carbonyl active material, and high ionic conductivity provided by the PEG groups, an organic AZIB incorporating this binder achieves capacities ranging from ∼350 mAh g⁻¹ (0.01 A g⁻¹) to 200 mAh g⁻¹ (20 A g⁻¹), among the highest reported for organic materials at these rates. Furthermore, the cathode with the conductive gallol binder demonstrates exceptional cycling performance compared to electrodes using the conventional polyvinylidene fluoride (PVDF) binder, demonstrating outstanding capacity retention after over 8000 cycles at 1 A g⁻¹. This work provides a valuable new approach for designing adhesive, conductive, and environmentally-friendly binders, thereby enhancing the commercial potential of organic materials in AZIBs.