Abstract
With the promising future of wearable electronics, a challenge is to find a suitable form of energy storage. Various forms of fiber-based batteries and supercapacitors, including parallel, coaxial, and twisted fiber structures have been suggested. In this work, we have studied the electrical properties of three different twisted fiber supercapacitors made of different commercially available conductive threads and a polyvinyl alcohol (PVA)-based gel electrolyte. The large signal capacitance and the electrochemical impedance of all three samples were studied for 1 to 6 turns of twists in 10-cm long threads. While the results showed a linear increase in the capacitance with the number of turns in a nylon-based thread, a stainless steel fiber-based device showed almost no change in its electrical properties with an increase in the number of turns. The image processing tool from MATLAB was used to study the structure of twisted threads. Analyzing the images showed that the change in the nylon-based capacitance was related to the length of the overlapped two threads. However, the hairy and intertwined structure of the threads containing stainless steel fibers had dominated the capacitive behavior of the devices. The applied image processing method not only is useful for analyzing fiber-based devices but also can be applied to design an optimum structure for high energy storage capacitances.
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