Zincophilic/hydrophobic balanced binder enables highly stable Zn powder anode toward flexible zinc-ion batteries

Abstract

Zinc powder-based anodes are considered ideal candidates for flexible aqueous zinc-ion batteries (AZIBs) due to their tunability and scalability. However, the large surface area and intrinsic spherical morphology of zinc powder lead to increased side reactions and uncontrolled dendrite growth. This work proposes a groundbreaking binder design strategy that balances zincophilicity and hydrophobicity to achieve kinetically enhanced and thermodynamically stable Zn powder anodes. The strategy has been validated through diversified binder combinations, which create a balanced localized water (H₂O)-poor environment and incorporates zincophilic groups to effectively block water penetration onto zinc while allowing Zn^2 + conduction without compromising weight, volume, or cost. Consequently, Zn//Zn symmetric cells with zincophilic/hydrophobic balanced binder demonstrate stable cycling for 1600 hours at 1 mA cm⁻², 900 hours at 5 mA cm⁻², and even 220 hours at a high utilization rate of 50 % (6.6 mAh cm⁻²). Notably, a 10 × 10 cm² free-standing Zn powder electrode is fabricated exhibiting exceptional deformability and mechanical robustness due to the high ductility of the balanced binder. This characteristic allows the flexible ZnP//MnO₂ full battery to maintain stable capacity under various bending conditions. This work offers both theoretical and experimental insights into the development of high-performance binders for flexible AZIBs.