High elongation, low hysteresis, fatigue resistant gel electrolyte for supercapacitor and strain sensor

Abstract

With the arrival of the era of the Internet of Everything and the popularization of flexible wearable devices, energy supply devices serving flexible wearable devices have also become a research hotspot. Hydrogels are gaining ground in the field of flexible energy supply devices, especially supercapacitors, which have attracted wide attention due to the advantages of fast charging/discharging, high power density, and stability. However, flexible supercapacitor inevitably undergoes varying degrees of deformation during use, and their service life decreases dramatically with the prolongation of use. Therefore, the fabrication of a flexible supercapacitor that can be assembled from hydrogel electrolyte and is fatigue-resistant and stable has become a promising research direction. In this study, we constructed a gel electrolyte with high stretchability, low hysteresis, high stability, and fatigue resistance by designing a dual network structure, and assembled it into a supercapacitor. The device has many excellent features, providing a surface capacitance of 100 mF/cm2, a power density of 0.19 mW/cm2, and an energy density of 425 μWh/cm2 at a frequency of 1 mA/cm2. More importantly, it also exhibits superb stability when subjected to varying degrees of bending and compression. In addition, the gel electrolyte can detect small changes of the human body and quickly and sensitively convert motion signals into electrical signals, showing great potential as a flexible wearable device. This study provides an effective strategy for designing gel electrolytes with low hysteresis and high stability for wider application in flexible electronic devices.