Abstract:
Zinc-metal ion batteries (ZIBs) emerge as safer, cost-effective, and environmentally
sustainable alternatives to lithium-ion batteries. However, their progress is limited by low
ionic conductivity, dendrite formation, and poor electrolyte stability. Polyvinylpyrrolidone
(PVP) has been widely employed in polymer electrolytes due to its excellent film-forming
ability, strong coordination with metal ions, and high chemical stability. In this study, a high-
performance PVP-based gel polymer electrolyte (GPE) was developed using a mixed-cation
strategy involving Zn²⁺ and Cs⁺ ions. The GPE was fabricated by blending PVP with
propylene carbonate and ethylene carbonate, followed by incorporation of ZnCl₂ and CsCl
at varying ratios. Ionic conductivity was analyzed by the electrochemical impedance
spectroscopy (EIS), and structural interactions were examined by FTIR spectroscopy.
Results indicate that Zn²⁺ ions strongly coordinate with the carbonyl groups of PVP,
enhancing ion transport, while the addition of Cs⁺ ions further promote segmental motion
and mobility within the GPE matrix. The optimized Zn²⁺:Cs⁺ ratio of 3:2 exhibits the highest
ionic conductivity of 8.219 × 10⁻⁵ S cm⁻¹ with a corresponding activation energy of 0.407
× 10⁻⁴ eV. These findings confirm that the synergistic effect of mixed cations significantly
reduces ion migration barriers, enhances conductivity, and overcomes the limitations of
single-cation systems. Hence, the PVP-based GPE incorporating Zn²⁺/Cs⁺ offers a promising
electrolyte design for next-generation zinc-ion batteries with improved safety and
electrochemical stability.
