Scalable Cross-Flow Multi-Tubular Electrochemical Cell for Electrochemically Mediated CO2 Capture

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The global concentration of carbon dioxide (CO2) in the atmosphere has increased by approximately 23 percent over the past 50 years, reaching an all-time record of 425 parts per million in March 2024. In efforts to achieve negative carbon emissions, electrochemically mediated CO2 separations have recently garnered increasing attention as a promising pathway due to their low energy requirements, modular scalability, and straightforward integration with renewable energies. Conventionally, flow systems requiring a membrane to prevent mixing of the anolyte and catholyte in the cell have been utilized in CO2 capture systems employing electrochemical reactions. However, the pumping costs and membrane have adverse impacts on energetics and CO2 transport in electrochemical systems.In this study, a cross-flow multi-tubular electrochemical cell based on supported liquid membranes (without a solid membrane) between two gas diffusion electrodes with porous and tubular structures is proposed. The conductive and tubular electrodes are manufactured through a facile two-step dip coating method employing Teflon AF 2400 and silver, which maximizes the stability and electrical conductivity of the electrodes. This novel cell architecture enables continuous operation through diffusion without pulsed flow or mixing, as well as a two-stage system combining activation/absorption and deactivation/release, thereby minimizing thermodynamic and operating energy consumption. Furthermore, the cylindrical diffusion profile and high surface area of the hollow fiber electrodes ensure superior CO2 fluxes compared to conventional flat plate electrodes. In particular, this proposed cross-flow system, where anodic and cathodic fiber electrodes are orthogonally arranged within the cell, can realize a compact design and ease of scaling up. Ultimately, this system not only serves as a "process-ready" separation device but also offers a cutting-edge perspective on the fabrication of electrochemical cell structures. Figure 1