Molecularly engineered zwitterionic‑fluorinated hydrogel electrolyte for durable Ah-level zinc-ion batteries

Aqueous zinc-ion batteries are considered suitable candidates for grid storage but suffer from Zn dendrites and water-induced side reactions. Incorporating appropriate hydrophobic moieties into hydrogel electrolytes is an effective strategy to reduce water activity and widen the electrochemical stability window. To further advance this molecular design framework and enable precise interphase modulation, we report a molecularly engineered zwitterionic-fluorinated hydrogel electrolyte. Within the polymer network, the rationally introduced hydrophobic fluoroalkyl moieties (-CH₂CF₃) strengthen hydrogen bonds between hydrophilic units and water, thereby reducing water activity and mitigating parasitic reactions. Meanwhile, the zincophilic zwitterionic units (-SO₃^-, -N⁺(CH₃)₃) facilitate rapid and directional Zn²⁺ transport, with a Zn²⁺ transference number of 0.76. These tailored functional groups synergistically promote the in-situ formation of an organic-inorganic solid electrolyte interphase, enabling Zn negative electrode stability, achieving over 900 h of Zn plating/stripping at 5.0 mA cm^-2 and 5.0 mAh cm^-2. Furthermore, Zn | |MnO₂ pouch cells incorporating this electrolyte deliver a capacity of ~1 Ah and operate for over 700 h, indicating the potential of this electrolyte for large-scale energy storage applications.