Evaluation of water transportation in anion exchange membranes used for electrochemical CO₂ reduction

Abstract Electrochemical CO 2 reduction using a zero-gap reactor is promising for reducing power consumption compared with the other CO 2 electrochemical-reduced reactors due to its low applied voltage. However, the short lifetime caused by flooding and salt precipitation on the cathode is a problem. Several water transport mechanisms were proposed as the cause of flooding and salt precipitation, but the details are still obscure. We developed H-type cells capable of quantifying water transfer volumes and evaluated the permeability of water due to concentration differences of cations, the diffusion of water due to electrical conductivity without electrolyte concentration difference, and the migration of water due to electrical conductivity with electrolyte concentration difference.