Synthesis and characterization of acrylamide/zeolite nanocomposite hydrogels for aqueous zinc-ion batteries

Abstract

Polyacrylamide (PAM)/zeolite nanocomposite hydrogels were synthesized as novel gel polymer electrolytes (GPEs) for flexible zinc-ion batteries. The hydrogels were prepared by in-situ free radical polymerization of acrylamide in the presence of dispersed zeolite nanoparticles. Fourier transform infrared spectroscopy confirmed the formation of crosslinked PAM and its interaction with zeolite nanoparticles. Scanning electron microscopy revealed increased porosity and improved zeolite dispersion with higher nanoparticle content. Thermogravimetric analysis indicated enhanced thermal stability with zeolite incorporation. The compressive modulus increased from 0.25 MPa for the neat hydrogel to 1.12 MPa for the nanocomposite containing 20 wt% zeolite, demonstrating improved mechanical strength. Electrochemical impedance spectroscopy showed that the ionic conductivity increased from 0.75 mS/cm for pristine PAM hydrogel to 1.85 mS/cm for the nanocomposite hydrogel with 15 wt% zeolite, attributed to increased porosity and zeolite's ion-exchange capacity. Cyclic voltammetry revealed faster redox kinetics with increasing zeolite content. Galvanostatic cycling demonstrated that the PAM/zeolite nanocomposite GPE with 15 wt% zeolite delivered the optimal zinc-ion battery performance, with a high initial discharge capacity of 125 mAh/gZn, coulombic efficiency exceeding 98 %, and capacity retention of 87 % after 100 cycles. The results indicate that zeolite incorporation significantly enhanced the thermal, mechanical and electrochemical properties of the PAM hydrogels for application as GPEs for flexible zinc-ion batteries.