Highly flexible and non-toxic natural polymer gel electrolyte for printed supercapacitors for IoT

Gelatin offers a safe and sustainable alternative for gel electrolytes in printed supercapacitors. In this work, the performance of a non-toxic natural polymer electrolyte is studied in screen and stencil-printed supercapacitors. The basic electrical properties are determined with samples prepared on laboratory scale; subsequently, roll-to-roll printed samples are used to observe behavior of the samples under severe mechanical stress. With a 2 M NaCl gel electrolyte, electrical performance equal to that of a 1 M liquid electrolyte is reached, and the devices endure bending down to a 10 mm radius. Even below that, functional devices are successfully measured, although leakage current levels deteriorate somewhat during bending. However, even these samples recover to baseline levels after they are straightened and can be thus used in various applications, since devices with no short circuits or permanent degradation can be successfully prepared.