Porous electrodes govern the electrochemical performance and pumping requirements in redox flow batteries, yet conventional carbon-fiber-based porous electrodes have not been tailored to sustain the requirements of liquid-phase electrochemistry. 3D printing is an effective approach to manufacture deterministic architectures, enabling the tuning of electrochemical performance and pressure drop. In this work, model grid structures are manufactured with stereolithography 3D printing followed by carbonization and tested as flow battery electrode materials. Microscopy, tomography, spectroscopy, fluid dynamics, and electrochemical diagnostics are employed to investigate the resulting electrode properties, mass transport, and pressure drop of ordered lattice structures. The influence of the printing direction, pillar geometry, and flow field type on the cell performance is investigated and mass transfer vs. electrode structure correlations are elucidated. It is found that the printing direction impacts the electrode performance through a change in morphology, resulting in enhanced performance for diagonally printed electrodes. Furthermore, mass transfer rates within the electrode are improved by helical or triangular pillar shapes or by using interdigitated flow field designs. This study shows the potential of stereolithography 3D printing to manufacture customized electrode scaffolds, which could enable multiscale structures with superior electrochemical performance and low pumping losses.
Supporting Information - Investigating mass transfer relationships in stereolithography 3D printed electrodes for redox flow batteries
In this document the Supporting Information can be found which includes information regarding the manufacturing of 3D printed electrodes (including: printed structures, structure deformation, resin spreading, pore sizes, scanning electron microscopy and X-ray tomographic microscopy images, and a clarification of the printing direction), the physiochemical analysis (including: elemental analysis, X-ray photoelectron spectroscopy, material characteristics, and cyclic voltammetry), mechanical stability, and the electrochemical performance (including: polarization curves, impedance spectroscopy, ohmic resistance, limiting current, and mass transfer correlations).