PEDOT-Based Stackable Paper Electrodes for Metal-Free Supercapacitors

Abstract

Paper-based electrodes are promising candidates for energy storage devices due to its availability in nature, low cost, sustainability, intrinsic porosity/fibrous structure, and mechanical properties. In this work, we implemented a straightforward method to control the capacitive response of paper electrodes modified by deposition of PEDOT-polyamine composites. These composite materials were characterized by TGA, SEM-EDS, and Raman spectroscopy, proving the homogeneous functionalization and proper integration of the polymers within the paper microstructure. The electrochemical evaluation by cyclic voltammetry (CV) and galvanostatic charge-discharge curves (GCD) revealed the stable electroactivity of the paper electrodes in a neutral 0.5 M NaCl solution, whereas the introduction of polyamine yielded an enhancement of the capacitive performance. Furthermore, the stacking of paper sheets on a current collector was proved to be an efficient strategy for building electrodes with tunable pseudocapacitance with adequate electrochemical connectivity across the whole architecture. A linear increase in the total capacitance measured by both CV and GCD (60-400 mF/cm2) on the number of stacked PEDOT-modified paper sheets was determined (1-6 sheets). The stacking strategy was comparatively tested using both plastic (PET) and metallic (Au) substrates for preparing the current collectors with similar results and excellent cyclability and capacitance retention (97% after 1000 GCD cycles for three stacked sheets) in 0.5 M NaCl as a harmless and environmentally friendly electrolyte. The stacking of paper sheets modified by polyamine-doped PEDOT coatings constitutes a simple and promissory strategy facing the construction of lightweight metal-free electrodes for harmless supercapacitors in wearable devices.