Constructing Kosmotropic Salt-Compatible PVA Hydrogels for Stable Zinc Anodes via Strong Hydrogen Bonds Preshielding Effect

Physical hydrogels crosslinked by noncovalent interactions are promising in flexible zinc-metal batteries for their component controllability and environmental friendliness. However, the compatibility of PVA-based electrolyte and kosmotropic salt remains a challenge, which shows an unclear mechanism. Here, a "good-to-poor" solvent substitution strategy is adopted to develop a PVA hydrogel electrolyte with good compatibility with kosmotropic salt (ZnSO4). Stretching the polymer conformation by preshielding the strong intrachain hydrogen bonds with good solvents and activating the polymer interchain interaction in situ with poor solvents will induce the formation of a homogeneous polymer network and the release of hydrated hydroxyl groups for fast ion transport. This multiscale microstructure improves the ionic conductivity and liquid retention of PVA hydrogels with kosmotropic salt. Additionally, this strong hydrogen bonds preshielded hydrogel electrolyte offers great battery performance, with 1300 h of stable cycling at 1 mA cm-2 with low voltage hysteresis; and an extended cycle life of 220 h at 68.4% zinc utilization. Importantly, the Zn//MnO2 pouch cell maintains 98.4% capacity after 100 cycles at 0.2 A g-1 and features strong environmental reliability. These concepts address the inherent barriers of kosmotropic salt-based hydrogel electrolytes and advance their development in soft electronics. Flexible electrolytes require fundamental mechanical flexibility and electrochemical properties. This work pioneers a novel strong hydrogen bonds preshielding strategy that overcomes the inherent incompatibility of polyvinyl alcohol (PVA) and ZnSO4 salts, and stimulates high ionic conductivity and low polarization property in this system. This functional hydrogel electrolyte leverages and extends the advantages of PVA-based electrolytes for stable and flexible zinc-metal batteries. image