The evolution of the performance of alkaline fuel cells with circulating electrolyte

摘要

The most recent information is presented concerning the development of the alkaline fuel cell (AFC) with circulating aqueous electrolyte technology at Eident Energy (EE). The latest version of this commercially sold sub-stack or "module" results in improved performance (400-430 to 590 W at 4 V and 51% total efficiency (η) versus LHV, i.e. from 100 to 137 mA cm~(-2) at 0.67 V per cell) and durability (2500 h expected with 10% decrease in power when operating at constant nominal current). The catalyst content in the module is also reduced from 1.2 to 0.5-0.6 mg cm~(-2). These improvements were achieved via an optimisation the porosity of the electrodes in order to obtain greater air diffusion inside the electrode. The authors also present the results of experiments that determine the origin of the performance loss of the AFC module over time. In contrast to much of the literature, the results do not support the irreversible corrosion of materials due to the oxygen reduction reaction. Indeed, over the investigated working period (i.e. ca. 1500-2000 h), the degradation of the performance was attributed to a slow and constant physical flooding due to imperfections in the wet proofing coating. Based on these facts, strategies are proposed to slow, avoid and even reverse to this flooding.