Interfacial H-Bonding Enables Fatigue-Resistant Gel Electrolytes for Flexible Zinc-Ion Batteries

The insufficient interfacial adhesion between the electrode and electrolyte, which compromises the stability of ion transport under dynamic mechanical conditions, remains a critical technical challenge for flexible zinc-ion batteries (ZIBs). Dynamic hydrogen bonding and hydrophobic inclusion can effectively enhance the adhesion between gel molecules and electrodes. Here, a cyclodextrin (CD)-modified polyacrylamide/carboxymethyl cellulose (PAM/CMC) dual-network gel electrolyte with fatigue resistance is successfully developed, which is based on the host-guest interactions from CD. This design effectively resolves the separation problem caused by interfacial slippage in conventional gel electrolytes under repeated bending, exhibiting an enhanced interfacial load-bearing capacity of 11 N, high stretchability of 162%, and retained structural integrity after folding cycles. Notably, the PAM/CMC/CD gel delivers a breakthrough ionic conductivity of 32.01 mS cm^-1 and a Zn²⁺ transference number of 0.9062. Interfacial H-bonds regulate Zn²⁺ solvation structures, reducing coordination numbers and desolvation energy to 4.54 eV. Simultaneously, they suppress Zn dendrite growth by promoting preferential (002) plane deposition, evidenced by a higher adsorption energy (-2.97 eV) versus the (100) plane. The assembled Zn||Zn symmetric batteries have only 1.8% capacity decay after 1200 h of cycling, and the Zn||MnO₂ full batteries retain a specific capacity of 275 mAh g^-1 after 120 cycles at 0.2 A g^-1, exhibiting robust electrochemical stability even under repeated mechanical deformation. This work overcomes critical challenges in interfacial stability and mechanical endurance for flexible ZIBs, providing a reliable energy storage solution for wearable electronics.