Figure 5.

(a) Plot of cathode concentration versus time showing the general trends of K⁺ and CO₃^2– concentrations at the cathode when a BPM is used. (b) Schematic showing effects of a BPM on K⁺-comigration past the membrane by limiting free ion transport and electro-osmotic drag. Additionally, CO₃^2– concentrations are reduced by combining with H⁺ formed at the BPM junction to regenerate CO₂. While changing the MEA recipe delays the accumulation of ions, it does not necessarily prevent critical concentrations from being reached.