A Robust and Tough Composite Hydrogel Electrolyte with Anion-Locked Supramolecular Network for Zinc Ion Batteries

Abstract

Hydrogel electrolytes have garnered extensive attention in zinc ion batteries due to their excellent flexibility and good safety. However, their limited mechanical properties, low ionic conductivity, and poor Zn²⁺ transference number pose significant challenges for developing high-performance zinc ion batteries. Herein, this work constructs a 3D supramolecular network capable of locking anions and active water molecules through the abundant hydrogen bonding interactions between aramid nanofibers, polyvinyl alcohol, and anions. This network synergistically enhances the mechanical properties (with a mechanical strength of 0.88 MPa and a toughness of 3.28 MJ m⁻³), ionic conductivity (4.22 S m⁻¹), and Zn²⁺ transference number (0.78). As a result, the supramolecular composite hydrogel electrolyte can effectively inhibit dendrite growth and side reactions, facilitate interface regulation, and enable uniform zinc deposition. The Zn anode exhibits a cycle life of 1500 h at 5 mA cm⁻² and 5 mAh cm⁻², with an average coulombic efficiency of 99.1% over 600 cycles. Additionally, the Zn||polyaniline full cell maintains a high capacity retention of 78% after 9100 cycles at 1 A g⁻¹. The assembled pouch cells demonstrate good flexibility, deformability, and compression resistance. This work provides valuable insights into the design of high-performance hydrogel electrolytes for zinc ion batteries.