Preparation and Electrochemical Performance of an Aqueous Polymer Electrolyte for Highly Stable Zinc-Ion Batteries

Abstract

he electrochemical integrity of metallic zinc anodes in aqueous zinc-ion storage systems is fundamentally compromised by hydrogen evolution parasitism, oxidative corrosion, and dendritic morphogenesis—phenomena that collectively impede extended cycling stability and high-rate operational capability. In this investigation, an innovative polymeric electrolyte salt formulation (MS electrolyte) was architected to simultaneously modulate bulk electrolyte microstructure and anode-electrolyte interfacial chemistry through the dense functional group array and extended chain topology of poly(2-acrylamido-2-methylpropane sulfonic acid zinc). Successful synthesis of the polymer was confirmed by 1H NMR and FTIR spectroscopy, and the MS electrolyte was prepared by dissolving it in deionized water, with conventional 1 mol/L ZnSO₄ aqueous solution (ZS electrolyte) used as a control.      Electrochemical characterization demonstrates that the MS electrolyte formulation effectively mitigates parasitic interfacial reactions and dendritic proliferation at the zinc metal anode. Symmetric Zn-Zn configurations achieved extended cycling stability exceeding 600 h under moderate current density (1 mA/cm², 1 mAh/cm²), while sustaining 90 h of stable operation under aggressive conditions (10 mA/cm², 10 mAh/cm²). Asymmetric Zn-Cu cells delivered a mean Coulombic efficiency of 99.3% across 300 charge-discharge cycles. Full Zn-I₂ cells retained 86.1% of initial capacity after 1000 cycles at 1 A/g. Post-mortem analyses encompassing scanning electron microscopy, scanning electrochemical microscopy, X-ray diffraction, and Tafel polarization corroborate the suppression of surface corrosion and secondary reactions by the MS electrolyte system. This investigation furnishes a viable paradigm for aqueous zinc-ion electrolyte engineering that simultaneously realizes diminished water activity, enhanced ionic transport, and exceptional interfacial robustness, yielding consequential guidance for advancing high-performance aqueous zinc-ion battery technology.