Flexible Polymer Hydrogels for Wearable Energy Storage Applications

Abstract The recent and fast‐growing trends related to the development of wearable technologies have raised the need for efficient and high‐performance energy storage devices having extra features such as flexibility and lightweight. Polymer hydrogels, as viscoelastic lightweight porous nanostructures with tunable surface and structural properties, can play a crucial role in the design of these future energy storage devices. Herein, recent developments and progress in the use of polymer hydrogels to design flexible and wearable energy storage devices are presented and discussed. The 3D structure of polymer hydrogels and porous nanostructures based on these hydrogels provides a platform to design flexible supercapacitors, batteries, and personal thermal management devices. Herein, different types of polymer hydrogels are presented, and their main fabrication techniques are reported. Moreover, the main structural properties affecting the energy storage performance of polymer hydrogels are discussed. In addition to recent progress in the design of polymer‐hydrogel‐based wearable devices, recent developments in polymer hydrogels for flexible applications (batteries, supercapacitors, and thermal energy storage systems) are reviewed in detail.