Alkaline anion-exchange membrane fuel cell

Narducci and colleagues concluded that the water uptake, related to the type of anion, plays a very important role for the mechanical properties.

[5] The findings of Zhang et al. suggest that the crosslinking of anion conductive materials with stable sterically-protected organic cations is an effective strategy to produce robust AEMs for use in alkaline fuel cells.

The alkaline fuel cell used by NASA in 1960s for Apollo and Space Shuttle program generated electricity at nearly 70% efficiency using aqueous solution of KOH as an electrolyte.

This could overcome the problems of electrolyte leakage and carbonate precipitation, though still taking advantage of benefits of operating a fuel cell in an alkaline environment.

[10] The large majority of membranes/ionomer that have been developed are fully hydrocarbon, allowing for much easier catalyst recycling and lower fuel crossover.

A typical AEM is composed of a polymer backbone with tethered cationic ion-exchange groups to facilitate the movement of free OH− ions.

The challenge is to fabricate AEM with high OH− ion conductivity and mechanical stability without chemical deterioration at elevated pH and temperatures.

The main mechanisms of degradation are Hofmann elimination when β-hydrogens are present and direct nucleophilic attack by OH− ion at the cationic site.

[12] However, high ion-exchange capacity leads to excessive swelling of polymer on hydration and concomitant loss of mechanical properties.

Recent research has shown [13] that careful balancing of the humidity of the feed gases significantly improves fuel cell performance.