A fuel cell is a defined as a device that converts the chemical energy from a fuel into electricity through a chemical reaction of positively charged hydrogen ions with oxygen or another oxidizing agent. They are very different from batteries in requiring a continuous source of fuel and oxygen or air to sustain the chemical reaction, whereas in a battery the chemicals present in the battery react with each other to generate an electromotive force (emf) or voltage.
Fuel cells can produce electricity continuously for as long as these inputs are supplied.
There are several different types of fuel cells such as proton exchange membrane, solid oxide, methanol and others. Recently researchers have developed a new class of fuel cells based on a newly discovered polymer-based material could bridge the gap between the operating temperature ranges of two existing types of polymer fuel cells, a breakthrough with the potential to accelerate the commercialization of low-cost fuel cells for automotive and stationary applications.
A Los Alamos National Laboratory team, in collaboration with Yoong-Kee Choe at the National Institute of Advanced Industrial Science and Technology in Japan and Cy Fujimoto of Sandia National Laboratories, has discovered that fuel cells made from phosphate-quaternary ammonium ion-pair can be operated between 80°C and 200°C with and without water, enhancing the fuel cells usability in a range of conditions. The research is published in the journal Nature Energy.
“Polymer-based fuel cells are regarded as the key technology of the future for both vehicle and stationary energy systems,” said Yu Seung Kim, the project leader at Los Alamos.
There’s a huge benefit to running fuel cells at the widest possible operating temperature with water tolerance. But current fuel-cell vehicles need humidified inlet streams and large radiators to dissipate waste heat, which can increase the fuel-cell system cost substantially, so people have looked for materials that can conduct protons under flexible operating conditions. It is very exciting that we have now found such materials.
A Leader In Fuel Cell Research.
Los Alamos has been a leader in fuel-cell research since the 1970s. Fuel cell technologies can significantly benefit the nation’s energy security, the environment and economy through reduced oil consumption, greenhouse gas emissions, and air pollution. The current research work supports the Laboratory’s missions related to energy security and materials for the future.
Currently, two main classes of polymer-based fuel cells exist. One is the class of low-temperature fuel cells that require water for proton conduction and cannot operate above 100°C. The other type is high-temperature fuel cells that can operate up to 180°C without water; however, the performance degrades under water-absorbing conditions below 140°C.
The research team found that a phosphate-quaternary ammonium ion-pair has much stronger interaction, which allows the transport of protons effectively even under water-condensing conditions.
“The discovery happened when we were investigating alkaline hydroxide conducting membranes, which have quaternary ammonium groups,” said Kim.
While the alkaline membranes work only under high pH conditions, the idea came across that alkaline membranes can be used under low pH conditions by combining with phosphoric acid.
This was a breathtaking moment, when Choe brought the calculation data that showed the interaction between quaternary ammonium and biphosphate is 8.7 times stronger than conventional acid-base interaction.
The Los Alamos team collaborated with Fujimoto at Sandia to prepare quaternary ammonium functionalized polymers. The prototype fuel cells made from the ion-pair-coordinated membrane demonstrated excellent fuel-cell performance and durability at 80-200°C, which is unattainable with existing fuel cell technology.
The performance and durability of this new class of fuel cells could even be further improved by high-performing electrode materials.
said Kim, citing an advance expected within five to ten years that is another critical step to replace current low-temperature fuel cells used in vehicle and stationary applications.
About Gordon Smith Gordon's expertise in the area of industrial energy efficiency and alternative energy. He is an experienced electrical engineer with a Masters degree in Alternative Energy technology. He is the co-founder of several renewable energy media sites including Solar Thermal Magazine.