Water-Deactivated Polyelectrolyte Hydrogel Electrolytes for Flexible High-Voltage Supercapacitors

With the boom of flexible electronic products and wearable devices, flexible energy storage devices, for example, supercapacitors with high performance, are attracting increasing interest. A flexible water-deactivated polyelectrolyte hydrogel electrolyte with good mechanical properties and high ionic conductivity was prepared by using an anionic polymer, carboxy methyl cellulose, and a cationic monomer, methacrylamidopropyltrimethyl ammonium chloride. It was then applied in a supercapacitor with flexible activated carbon electrodes. This flexible supercapacitor possesses a high operating voltage of 2.1 V owing to the low electrochemical activity for water within the hydrogel as a result of the 'molecular cages' effect and hydrophilic interactions between functional groups and surrounding water molecules. Furthermore, this supercapacitor exhibits good flexibility and tailorability. As the first example of water-deactivated polyelectrolyte hydrogel electrolytes in applications involving flexible high-voltage supercapacitors, this work provides a platform for the design of energy storage devices with high energy density for flexible and wearable electronic devices.