Print-and-plate architected electrodes for electrochemical transformations under flow

Flow cell electrodes are typically composed of porous carbon materials, such as papers, felts, and cloths. However, their random architecture hinders fundamental characterization of electrode structure-performance relationships during in situ operation of porous electrochemical flow systems. Here, we report a “print-and-plate” method that uses high-resolution direct ink writing to produce periodic lattices followed by a two-step metal plating process to convert these lattices into highly conductive (sheet resistance 40 milli-Ohm per square) electrodes. We assessed their in operando performance in an anthraquinone disulfonic acid half-cell using electrochemical fluorescence microscopy, where output current and fluorescence intensity are in excellent agreement. We then compared the pressure drop of three electrode designs simulated with a high-fidelity numerical solution to the governing PDEs. The most efficient design was then fabricated via the print-and-plate method and confocal fluorescence microscopy was used to generate a 3D map of the state of charge (SOC) inside the working electrode. The experimental state of charge map is in good agreement with our simulations. By unlocking programmable architectures, print-and-plate electrodes offer new opportunities for fundamental investigations relating porous electrode microstructure to performance and direct replication of simulated structures.