Interpenetrating Composite Hydrogel Electrolyte with Organic/Inorganic Polar Groups for Stable Zinc Metal Anode

Hydrogel electrolytes have been widely explored in flexible zinc batteries owing to their considerable mechanical strain and water-retaining properties. However, it is difficult to balance the contradiction between the ionic conductivity and the mechanical strength due to the deterioration of structural stability with the addition of electrolyte salts. To address this, we designed a coassembling organic–inorganic hydrogel (P–P/M) based on poly(vinyl alcohol)-polyacrylamide (P–P) interpenetrating matrix decorated with Zn-based montmorillonite (Zn-MMT). The Zn-MMT with overall negative potential can attract and regulate the transport of Zn2+, while the Brønsted/Lewis acid sites with positive polarizations offer anchoring sites for anions, which increases the cation transference number and reduces byproduct formation. Moreover, the formation of hydrogen bonds in the hydrogel can weaken the contact between free water molecules and the zinc cations, which effectively suppresses the corrosion of zinc foil. Consequently, the Zn//Zn cell with P–P/M electrolyte delivers a long cycle life of 2400 h at 0.5 mA cm–2. The good mechanical properties of the P–P/M hydrogel boost its application in flexible pouch cells even under bending and cutting conditions. This study provides an effective approach to designing organic–inorganic hydrogel electrolytes for long-life flexible zinc batteries.