Engineering Controls for Scaling CO2 Electrolyzers

Abstract

The electrochemical CO2 reduction (CO2R) to ethylene on copper-based catalysts has garnered significant attention for its potential in sustainable industrial practices. While substantial progress has been achieved in the development of small-scale electrolyzers with geometric areas ranging from 1 to 5 cm2, the imperative to address larger scales for industrial decarbonization necessitates a shift in focus. There are inherent critical risks when scaling a nascent technology like CO2 electrolysis. There can be emergent phenomena observed only at larger scales, that can prevent it from reaching commercialization, such as change in local CO2 concentration, defects in the porous transport layer, and temperature gradients The optimized conditions for operating a 5 cm2 electrolyzer may not work well with a 25 cm2 electrolyzer leading to failures. Therefore, there is a need to develop a systematic way to test for these phenomena to address these challenges to successfully operate a CO2R electrolyzer at an industrially relevant scale. In this work, we highlight the performance of a Cu-based catalyst designed for the selective reduction of CO2 to ethylene across varying scales, ranging from 5 to 100 cm2. This investigation shows the changes in the electrolyzer performance at different scales. Our findings highlight the critical importance of implementing engineering controls to overcome challenges associated with the scaling of electrolyzers. Specifically, we explore the impact of anolyte flow rate, gasket compression, and electrochemical pulsing techniques on maintaining the desired selectivity of the electrocatalyst across different scales. By systematically adjusting these parameters, we demonstrate the ability to mitigate non-linear effects and uphold the efficiency of CO2 reduction to ethylene, even on larger electrode surfaces.This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.