Flexible Hydrogel Electrolytes for Organic Batteries with High Cyclability

The growing interest in organic batteries for the sustainable storage of energy is giving rise not only to new polymeric active materials for batteries but also to new electrolyte systems. Water-based electrolytes are particularly interesting due to the sheer abundance of water on our planet and its cost-effective, sustainable, nonhazardous, and nonflammable nature. To further increase the safety of aqueous battery cells, various strategies have been pursued, of which the use of solid and gel electrolytes is one of the most prominent. Here, we present an efficient approach for a new environmentally friendly hydrogel electrolyte with high ionic conductivity (20 ± 1 mS cm–1 at room temperature) and medium ionic conductivity at low temperature (5.3 ± 0.3 mS cm–1 at −20 °C) based on commercially available monomers and a zinc salt compatible with the redox chemistry of the 2,2,6,6-tetramethylpiperidine-N-oxyl radical in a semiorganic battery setup. We investigate its battery cycling behavior and compare its performance with that of a previously analyzed analog that does not contain a hydrogel.