Development of Polymer Electrolyte Fuel Cells with Excellent Sub-zero Start-up Performance
Elucidation of micro-nano freezing phenomena in fuel cells
We are visualizing the freezing phenomenon near the reaction layer in fuel cells, which cannot normally be observed, using an ultracold electron microscope. By combining electrochemical measurements, we are also elucidating the freezing phenomenon of produced water, which becomes a problem in cold climate applications, and are developing fuel cells with excellent sub-zero activation performance.
Content of research
In the polymer electrolyte fuel cell (PEFC), which is a highly efficient and clean energy conversion device, the water produced by the reaction passes through a catalyst layer pores of several tens of nanometers in diameter and is discharged into the gas diffusion layer and gas supply channel through the microporous layer (MPL), which is a porous layer with pores of several micrometers in diameter, as shown in the left figure below. In the activation in a sub-zero environment in cold regions, the produced water freezes, causing the power generation to stop and degrade. However, the phenomenon is on a micro-nano scale and is thus difficult to measure, so the phenomenon is still insufficiently understood. This study is aimed to clarify where the water freezes and what mechanism leads to performance shutdown and aging degradation. We will conduct microscopic observation, electrochemical measurement and catalyst layer model analysis to contribute to the improvement of activation resistance and extension of the service life. The middle figure below shows the catalyst layer filled with ice, and the right figure is a structural schematic of the catalyst layer modeled in the analysis.
Potential for social implementation
- ・Visualization of condensate distribution in a fuel cell
- Using this method, we have successfully frozen, immobilized and visualized the condensate in the fuel cell, which interferes with the oxygen supply to the reaction layer. Using this method, we are now developing high-performance fuel cells for normal operation.
Appealing points to industry and local governments
We believe that this highly original project, which makes full use of microscopic observation and electrochemical measurement/analysis, will be useful to develop fuel cells for cold regions like Hokkaido. At our laboratory research is also conducted from a broad perspective to realize a sustainable energy system by developing high-efficiency equipment and analyzing social energy systems, so that we can contribute to solve energy and global warming problems.