Synergistic Dual-Plasticizer Engineering of Gel Polymer Electrolytes for Accelerated Zn²⁺ Transport and Stable Zinc Deposition

<title>Abstract</title> <p>Gel polymer electrolytes (GPEs) have emerged as promising alternatives to liquid electrolytes for aqueous zinc-ion batteries (AZIBs); however, achieving both high ionic conductivity and stable Zn deposition simultaneously remains a significant challenge. Herein, we report a dual-plasticizer engineering strategy by incorporating propylene carbonate (PC) and glycerol into a citric acid-crosslinked carboxymethyl cellulose (CMC) GPE. The synergistic plasticization effect reduces polymer crystallinity, increases interchain spacing, and enhances electrolyte uptake, resulting in an ionic conductivity of 9.06 mS cm⁻¹ and a Zn²⁺ transference number of 0.97. Consequently, the optimized electrolyte promotes rapid Zn nucleation, lowers interfacial resistance, and enables homogeneous Zn²⁺ transport, leading to uniform Zn deposition. Zn|Zn symmetric cells exhibit stable cycling for approximately 2500 hours, while Zn|V₂O₅ full cell maintains stable operation for 1000 cycles at 1 A g⁻¹. The enhanced electrochemical performance stems from the complementary roles of PC in facilitating ZnSO₄ dissociation and of glycerol in enhancing polymer chain mobility, thereby simultaneously optimizing ion transport and Zn/electrolyte interfacial stability. This work establishes dual-plasticizer engineering as a simple and effective strategy for designing high-performance GPEs for durable AZIBs.</p>