MIT engineers have improved the power output of one type of fuel cell by more than 50 percent through technology that could help these environmentally friendly energy storage devices find a much broader market, particularly in portable electronics.
The new material key to the work is also considerably less expensive than its conventional industrial counterpart, among other advantages.
“Our goal is to replace traditional fuel-cell membranes with these cost-effective, highly tunable and better-performing materials,” said Paula T. Hammond, Bayer Professor of Chemical Engineering and leader of the research team. She noted that the new material also has potential for use in other electrochemical systems such as batteries.
The work was reported in a recent issue of Advanced Materials by Hammond, Avni A. Argun and J. Nathan Ashcraft. Argun is a postdoctoral associate in chemical engineering; Ashcraft is a graduate student in the same department.
Like a battery, a fuel cell has three principal parts: two electrodes (a cathode and anode) separated by an electrolyte. Chemical reactions at the electrodes produce an electronic current that can be made to flow through an appliance connected to the battery or fuel cell. The principal difference between the two? Fuel cells get their energy from an external source of hydrogen fuel, while conventional batteries draw from a finite source in a contained system.
The MIT team focused on direct methanol fuel cells (DMFCs), in which the methanol is directly used as the fuel and reforming of alcohol down to hydrogen is not required. Such a fuel cell is attractive because the only waste products are water and carbon dioxide (the latter produced in small quantities). Also, because methanol is a liquid, it is easier to store and transport than hydrogen gas, and is safer (it won't explode). Methanol also has a high energy density-a little goes a long way, making it especially interesting for portable devices.
The DMFCs currently on the market, however, have limitations. For example, the material currently used for the electrolyte sandwiched between the electrodes is expensive. Even more important: that material, known as Nafion, is permeable to methanol, allowing some of the fuel to seep across the center of the fuel cell. Among other disadvantages, this wastes fuel-and lowers the efficiency of the cell- because the fuel isn't available for the reactions that generate electricity.Using a relatively new technique known as layer-by-layer assembly, the MIT researchers created an alternative to Nafion. “We were able to tune the structure of [our] film a few nanometers at a time,”
Hammond said, getting around some of the problems associated with other approaches. The result is a thin film that is two orders of magnitude less permeable to methanol but compares favorably to Nafion in proton conductivity.
To test their creation, the engineers coated a Nafion membrane with the new film and incorporated the whole into a direct methanol fuel cell. The result was an increase in power output of more than 50 percent.
The team is now exploring whether the new film could be used by itself, completely replacing Nafion. To that end, they have been generating thin films that stand alone, with a consistency much like plastic wrap.
This work was supported by the DuPont-MIT Alliance through 2007. It is currently supported by the National Science Foundation.
In addition, Hammond and colleagues have begun exploring the new material's potential use in photovoltaics. That work is funded by the MIT Energy Initiative. This Institute-wide initiative includes research, education, campus energy management and outreach activities, an interdisciplinary approach that covers all areas of energy supply and demand, security and environmental impact.
Written by Elizabeth Thomson, MIT News Office
Elizabeth A. Thomson | MIT News Office
Engineers program tiny robots to move, think like insects
15.12.2017 | Cornell University
Electromagnetic water cloak eliminates drag and wake
12.12.2017 | Duke University
DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.
Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
15.12.2017 | Power and Electrical Engineering
15.12.2017 | Materials Sciences
15.12.2017 | Life Sciences