PEDOT-Based Stackable Paper Electrodes for Metal-Free Supercapacitors

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.