Keywords: Exchange Membrane Fuel Cell; Water; High Performance; Electrode; Flooding Introduction Anion exchange membrane fuel cells (AEMFCs) have experienced a surge of interest in the past decade as a lower cost alternative to proton exchange membrane fuel cells (PEMFCs) [1-3]. The increased pH in the alkaline AEMFC facilitates the use of a wider range of non-precious metal catalysts at the cathode due to favorable oxygen reduction reaction kinetics in alkaline acid media [4,5]. Anion exchange membranes (AEMs) vs. have also demonstrated a lower fuel permeability than proton exchange membranes when used in direct alcohol fuel cells [6]. Additionally, switching to AEMFCs enables the use of lower cost cell and stack components because of increased materials stability in alkaline acidic environment. Despite these significant advantages, PEMFCs have vs. remained favored due to a sizable performance gap between the two technologies Recently, this situation has improved [12-14], but the level of understanding on what factors are important for improved performances is still limited. Therefore, further studies are required to fully understand the fundamental and operational variables that limit AEMFC performance, and to develop strategies that overcome these limitations. One variable that has been mostly overlooked in the literature is the cell water content and balance. This is most likely because of the differences in the role of water in AEMFCs (Fig. 1A) PEMFCs (Fig. 1B). In PEMFCs, water is only generated (at the vs. cathode as a product of the oxygen reduction reaction, ORR) and not electrochemically consumed, such that its major role is the hydration of polymer electrolyte components to facilitate H+ conduction. Water is also moved to the cathode from the anode by drag as H+ produced by the hydrogen oxidation reaction (HOR) moves through
Keywords: Exchange Membrane Fuel Cell; Water; High Performance; Electrode; Flooding Introduction Anion exchange membrane fuel cells (AEMFCs) have experienced a surge of interest in the past decade as a lower cost alternative to proton exchange membrane fuel cells (PEMFCs) [1-3]. The increased pH in the alkaline AEMFC facilitates the use of a wider range of non-precious metal catalysts at the cathode due to favorable oxygen reduction reaction kinetics in alkaline vs. acid media [4,5]. Anion exchange membranes (AEMs) have also demonstrated a lower fuel permeability than proton exchange membranes when used in direct alcohol fuel cells [6]. Additionally, switching to AEMFCs enables the use of lower cost cell and stack components because of increased materials stability in alkaline vs. acidic environment. Despite these significant advantages, PEMFCs have remained favored due to a sizable performance gap between the two technologies Recently, this situation has improved [12-14], but the level of understanding on what factors are important for improved performances is still limited. Therefore, further studies are required to fully understand the fundamental and operational variables that limit AEMFC performance, and to develop strategies that overcome these limitations. One variable that has been mostly overlooked in the literature is the cell water content and balance. This is most likely because of the differences in the role of water in AEMFCs (Fig. 1A) vs. PEMFCs (Fig. 1B). In PEMFCs, water is only generated (at the cathode as a product of the oxygen reduction reaction, ORR) and not electrochemically consumed, such that its major role is the hydration of polymer electrolyte components to facilitate H+ conduction. Water is also moved to the cathode from the anode by drag as H+ produced by the hydrogen oxidation reaction (HOR) moves through
Importance%20of%20balancing%20membrane%20and%20electrode%20water%20in%20anion%20exchange%20membrane%20fuel%20cells%20-%20Accepted%20version.docx