Researchers have identified a chemical, triazole, that could allow PEM fuel cells to operate more efficiently. Polymer electrolyte membrane (PEM) fuel cells are the the most promising fuel cells for portable use such as automobiles. A team lead by Dr. Meilin Liu, a professor in the School of Materials Science and Engineering at Georgia Tech, has discovered that a chemical called triazole is significantly more effective than similar chemicals researchers have explored to increase conductivity and reduce moisture dependence in polymer membranes.
A fuel cell essentially produces electricity by converting the chemicals, hydrogen and oxygen, into water. Proton exchange membranes used in fuel cells are a specially treated material that looks a lot like plastic wrap. It allows protons to pass through it virtually unimpeded, while electrons are blocked. The membrane is the key to building a better fuel cell.
Replacing water in the membrane with triazole has several positive effects:
- Previously membranes needed to operate at temperatures below 100 °C, usually about 80 °C, in order to retain the moisture needed to conduct protons. Replacing the water in the membrane with triazole allows the fuel cell to operate at higher temperatures and thus more efficiently.
- The conductivity of the membrane is increased.
- The triazole-containing membranes operating at 120 °C eliminated the need for a water management system and dramatically reduced the cost and complexity of the membrane cooling system.
- The higher operating temperature, allows the use of lower purity hydrogen. When operationg at lower temperatures; expensive, very high purity hydrogen, without traces of carbon monoxide, is required to prevent poisoning of the very sensitive catalyst required at these conditions.
While they have pushed their polymer fuel cells to 120 degrees Celsius with triazole, Liu’s team is looking into better polymers to get those temperatures even higher, he said.