The Synergistic Suppression of Hydrogen Evolution and Dendrite Formation through Multihydroxyl-Induced Disruption of the Solvation Structure for Ultrastable Solid-State Zinc Ion Batteries

The practical implementation of zinc-ion batteries has been hindered by the reversibility and stability of zinc anodes, owing to uncontrollable zinc dendrite formation, corrosion phenomena, and hydrogen generation. Herein, a PC pseudopolyrotaxane synthesized by threading poly(ethylene oxide) (PEO) molecular chains into the cavities of multiple cyclodextrin (CD) macromolecules is introduced into polyacrylamide (PAM) to form a hydrogel electrolyte for use. A PC with high electronegativity and strong affinity for zinc can not only reconfigure the solvation structure of Zn2+ and modulate the hydrogen bond network among water molecules but also serve as Zn ion transport channels. This coupling reduces the water activity and mitigates the side reactions of active H2O decomposition while accelerating the Zn ion deposition kinetics and facilitating the oriented growth of Zn along the (002) crystallographic plane without dendrite formation. Consequently, the PC–PAM hydrogel exhibits satisfactory ionic conductivity (25.3 mS cm–1). The Zn//Zn symmetric battery assembly demonstrates stable cycling performance, lasting over 1510 h at 1 mA cm–2. The zinc–manganese oxide full battery retains a significant specific capacity of 102.5 mAh g–1 after 1000 cycles at 5 A g–1 without obvious zinc dendrites. This study offers a noteworthy perspective on the design of high-performance hydrogel electrolytes for Zn-ion batteries.