Additively Manufactured Binder-Free Electrodes for Supercapacitors

Abstract

Energy storage systems are of immense importance for energy transition. For a successful process, it is very important that energy storage technologies used are as environmentally friendly as possible. The electrodes of batteries and supercapacitors are produced by coating a slurry onto metal foils. To ensure that the active material adheres to the metal foil, fluorinated binders such as polyvinylidene difluoride (PVDF) and polytetrafluorethylene (PTFE) are necessary, which belong to the per- and polyfluoroalkyl substances (PFAS) and are considered to be harmful to the environment. This study presents a new process for electrode production, using additive manufacturing, to overcome these problems. Complete electrodes are printed from a single piece, eliminating the need for metal foil and binders. Masked stereolithography method guarantees a high resolution of the structure and a fast production time. The printed nonconductive polymer electrodes are converted into porous polymer electrodes after a pyrolysis and activation step. Gas adsorption measurements provide a sufficient high specific surface area of 499 m2 g−1 and a pore size distribution in the microporous range. Electrochemical experiments reveal that the printed electrodes are suitable for supercapacitor applications and are comparable to conventionally produced electrodes, especially for low current densities.