Harnessing weak monomer miscibility to create porous microdomains in polymer electrolytes for zinc-ion batteries

Abstract

The practical deployment of aqueous zinc-ion batteries is fundamentally constrained by rampant dendrite growth and parasitic reactions at the anode. To address this, we design an amphiphilic ionogel electrolyte via molecular engineering. The material is synthesized by copolymerizing acrylamide and 2,2,3,4,4,4-hexafluorobutyl acrylate in a zinc salt/ionic liquid medium. During polymerization, in situ phase separation is triggered by the differing solubility of the two polymer components, followed by water-induced self-assembly driven by hydrophilic/hydrophobic interactions. This process ultimately yields gradient pore channels that enable fast and uniform Zn²⁺ transport. More importantly, the amphiphilic components synergistically modulate the interface: hydrophilic polyacrylamide chains anchor onto the zinc, immobilizing water and regulating solvation, while hydrophobic fluorinated domains form a barrier that excludes water and offers supplemental Zn²⁺ coordination. Consequently, the ionogel enables rapid, uniform zinc deposition, reduces the nucleation barrier, and promotes a robust fluoride- and Zn₃N₂-rich hybrid interphase. A Zn||Zn symmetric cell achieves stable cycling for over 2800 hours at 2 mA cm⁻², and a full cell with a Na₂V₆O₁₆·3H₂O cathode maintains a high capacity above 350 mAh g⁻¹ with prolonged cyclability. This work demonstrates a molecular-level design strategy for electrolyte matrices that simultaneously guide ion flux and tailor interfacial chemistry, providing a pathway towards durable metal batteries.