Abstract
There is a need to understand the water dynamics of alkaline membrane fuel cells undervarious operating conditions to create electrodes that enable high performance and stable,long-term operation. Here we show, via operando neutron imaging and operando micro X-raycomputed tomography, visualizations of the spatial and temporal distribution of liquid waterin operating cells. We provide direct evidence for liquid water accumulation at the anode,which causes severe ionomer swelling and performance loss, as well as cell dryoutfrom undesirably low water content in the cathode. We observe that the operating conditionsleading to the highest power density during polarization are not generally the conditions thatallow for long-term stable operation. This observation leads to new catalyst layer designs andgas diffusion layers. This study reports alkaline membrane fuel cells that can be operatedcontinuously for over 1000 h at 600 mA cm−2with voltage decay rate of only 32-μVh−1–the best-reported durability to date.