Polyethylene Glycol Diacid−Engineered Semi-Interpenetrating Hydrogel Electrolyte for Durable Aqueous Zinc-Ion Batteries

Designing hydrogel electrolytes that simultaneously enhance Zn2+ transport and mitigate parasitic reactions remains an important challenge for durable aqueous zinc-ion batteries (ZIBs). Here, a semi-interpenetrating polymer network (SIPN) hydrogel electrolyte composed of polyacrylamide (PAM), sodium alginate (SA), and polyethylene glycol diacid (PEGDA) is developed to regulate interfacial Zn deposition and ion transport. PEGDA incorporation results in a more uniform, interconnected porous structure, leading to enhanced electrolyte uptake and improved Zn2+ transport characteristics. The optimized hydrogel exhibits a high ionic conductivity of 19.36 mS cm−1, a Zn2+ transference number of 0.56, good mechanical flexibility, and a reduced corrosion current density. Structural and electrochemical analyses indicate more uniform Zn deposition accompanied by enhanced growth along the Zn (002) crystallographic orientation. Consequently, Zn||Zn symmetric cells operate stably for over 3500 h at 0.5 mA cm−2, while Zn||Cu cells deliver an average Coulombic efficiency of 99.05%. When coupled with a MnO2−partially oxidized graphene (POG) cathode, the resulting full cell achieves a reversible capacity of 290.73 mAh g-1 at 0.1 A g-1 and retains 88.72% capacity after 500 cycles at 0.5 A g-1. These findings demonstrate the potential of PEGDA-modified SIPN hydrogels as effective electrolytes for stable and long-life aqueous ZIBs.