Confined Water Dynamics in Topological Networks Hydrogel for Aqueous Electrochemical Devices.

Abstract

The unique properties of confined water molecules within polymer networks have garnered extensive research interest in energy storage, catalysis, and sensing. Confined water molecules exhibit higher thermodynamic stability compared to free water, which reduces decomposition and evaporation of water in hydrogel electrolyte system. Herein, a facile strategy is developed to limit active water molecules in a hydrogel network via hydrogen bonding within a topological network. The design of this gel enhances hydrogen bonding between the gel network and water molecules, thereby improving stability by constructing interpenetrating networks. Using this design, the topological network gel is selected as the electrolyte for batteries, demonstrating an extended electrochemical window from 2.37 V with polyvinyl alcohol gel to 2.96 V, indicating superior confinement of water molecules by hydrogen bonds in the topological network. Additionally, batteries and capacitors assembled with the topological gel exhibit high-capacity retention rates of 94.25% after 20 000 cycles at a current density of 1.0 A g^-1 and 87.63% after 10 000 cycles at a current density of 0.5 A g^-1, respectively. This study demonstrates the feasibility of using a topological gel design to enhance gel electrolyte stability, offering a promising avenue for future research in regulating topological networks within gels for various applications.