Intermediate-Temperature SOFCs Using Proton-Conducting Perovskite

Today, most vehicles are driven by internal combustion engines with liquid fuel. The efficiency of internal combustion engines is only 15%–25%, and a power source with higher efficiency is needed from the aspects of energy conservation and CO₂ emissions. A fuel cell is one leading candidate for this alternative power source. There are several types of fuel cells, but the polymer electrolyte membrane fuel cell (PEFC) is the top runner now, and auto makers are putting most of their research and development resources into a PEFC + on-board hydrogen storage system [1]. Regarding the PEFC, it is well known that several problems remain, such as high cost due to the use of platinum, liquid water management, and the durability of the polymer electrolyte. However, the two major issues of this system lie on the fuel side, hydrogen infrastructure and hydrogen storage. Although hydrogen itself has very high power density, it is very difficult to store hydrogen with high physical density. Many researchers are working on the search for better hydrogen storage technology, such as a high-pressure tank, hydrogen storage metal, carbon nano-tubes, and liquid hydrogen. However, so far the driving range of fuel cell (FC) vehicles is much less than that of vehicles with internal combustion engines. The issue regarding hydrogen infrastructure is more a political and economic one. “The hydrogen economy” needs a huge expenditure to build up the network of hydrogen distribution and refueling stations, but no one has a vision of this huge cost yet.