Electrochemical Performance Enhancement of 3D Printed Electrodes Tailored for Enhanced Gas Evacuation during Alkaline Water Electrolysis

摘要

A zero-gap cell with porous electrodes is a promising configuration for alkalinewater electrolysis. However, gas evacuation becomes a challenge in that case,as bubbles can get trapped within the electrode’s 3D structure. This workconsiders a number of 3D printed electrode geometries with so-called triplyperiodic minimal surfaces (TPMS). The latter is a mathematically definedstructure that repeats itself in three dimensions with zero mean curvature, andcan therefore be expected to be particularly well-suited to enhance gas evacuation.Another advantage as compared to other state-of-the-art 3D electrodeslike foams or felts lies in the fact that their porosity, which determines theavailable surface area, and their pore size or flow channel dimensions, whichdetermines the degree of bubble entrapment, can be varied independently.By a combined experimental and modeling approach, this work then identifiesthe structural parameters that direct the performance of such 3D printedTPMS geometries toward enhanced gas evacuation. It is demonstrated thatan optimal combination of these parameters allows, under a forced electrolyteflow, for a reduction in cell overpotential of more than 20%. This indicates thatefforts in optimizing the electrode’s geometry can give a similar electrochemicalperformance enhancement as optimizing its electro-catalytic composition.