Harnessing hydrogels for electrochemical energy and environmental sustainability

The emergence of hydrogel as a multifunctional material suited for energy storage and environmental remediation is driven by the material's inherent high-water content and structurally stable three-dimensional polymeric crosslinks. This review work provides a comprehensive account of the recent advances in hydrogels. The review will concentrate on the potential of hydrogel as a material for next-generation sustainable technologies in electrochemical and environmental applications. The review tackles a wide range of synthesis methods, including polymerization and crosslinking. More advanced techniques such as microfluidics, 3D printing, and supramolecular self-assembly are also explored. These advanced methods are amenable to property tuning of the hydrogel to modify properties such as sensitivity, conductivity, and mechanical strength. The basic features of hydrogels, such as swelling, ionic transport, chemical stability, and functionalizability, are explored in terms of reported improved performance for advanced applications. This review outlines the recent progress in developing and applying hydrogels in electrochemical energy systems, from advanced processes in energy storage devices such as supercapacitors, lithium-ion and sodium-ion batteries, and emerging applications in redox flow batteries. Furthermore, we investigate the potential application of hydrogel in environmental remediation, tracking its use in heavy metal and organic pollutant adsorption in wastewater treatment. The review concludes by addressing challenges such as long-term stability, scalability, and environmental safety, while also identifying future opportunities in bioinspired design, smart hydrogel integration, and circular material strategies.