Self-discharge characteristics of vapor deposited polymer electrodes in an all-textile supercapacitor

Abstract

Despite the many efforts put toward developing flexible supercapacitors for wearable technology, few studies have focused on self-discharge, the spontaneous voltage decay of devices stored in their charged state. In this work, we characterize the self-discharge behavior of an all-textile supercapacitor utilizing oxidative chemical vapor deposited (oCVD) PEDOT-Cl electrodes. A significant portion of the voltage losses are found to arise from charge redistribution, a physical process involving the rearrangement of charges within the electrode material. Two means of mitigating this mode of self-discharge are presented. A post-charging hold step improves voltage retention by enabling spatially-uniform charge distribution within the electrode. Improving the ordering of polymer crystal domains via control over the polymer growth temperature during oCVD is also found to impact the self-discharge rate. Electrochemical and morphological characterizations of films grown at high and low temperature indicate that more ordered polymer films exhibit less self-discharge due to charge redistribution, perhaps a result of greater charge accessibility throughout the film. These results, including improved charging protocols and material optimizations, may help pave the way for practical, lightweight charge storage devices to power wearable electronics.