The LLNL Center for Microtechnology Engineering has developed and demonstrated a laboratory prototype miniature thin-film fuel cell power source, which provides portable electrical power for a range of consumer electronics. With the LLNL fuel cell, a typical cell phone battery could be projected to last more than 300 percent longer, extending standby time from four days to two weeks, and talk time from six hours to two days.
The miniature fuel cell technology incorporates a thin-film fuel cell and microfluidic fuel-processing components integrated into a common package. Using easy-to-store liquid fuels, such as methanol, the fuel cell power module provides greater than three times longer operating time than present rechargeable batteries.
“LLNL’s fuel cell can be cheaper, smaller, with more energy capacity than any battery or alternative fuel cell technology,” said Jeff Morse, principle investigator on the fuel cell project.
“Additionally, the higher energy capacity of such a product will lead to further new classes of personal electronics,” Morse explained, “such as autonomous sensors and communication devices that are not currently possible with existing battery technologies. This will facilitate the integration of voice, data and computing technologies that cannot be achieved with today’s technologies.”
The patented design and method for making thin-film fuel cells combines microcircuit processes, microfluidic components, and micro-electrical-mechanical systems (MEMS) technology. This solution provides the consumer a lighter-weight, longer-lasting power source for replacement of existing rechargeable batteries.
Morse predicts the MEMS-based fuel-cell power source will replace rechargeable batteries, such as lithium-ion and lithium-ion polymer, in a range of consumer electronics, including cell phones, handheld computers and laptops. The MEMS fuel cell is designed to be 50 percent of the cost with 30 percent of the weight, size or volume of existing rechargeable portable power sources.
“The MEMS-based fuel cell has been designed to compete with existing re-chargeable batteries in their respective marketplaces,” said Morse. Current estimates suggest a price of $1.50-$3 per watt-hour.
LLNL’s miniature fuel cell product incorporates integrated microfluidic fuel distribution architecture within a miniature fuel cell package. This feature enables the fuel cell to operate from highly concentrated methyl alcohol fuel mixtures supplied from a replaceable fuel cartridge.
The impact to the consumer will be greater than three times longer periods between recharging for initial products, with foreseeable improvements of up to 15 times longer. Furthermore, recharging is instantaneous by simply plugging in a new fuel cartridge.
The heart of this miniature power source utilizes a thin layer of electrolyte material sandwiched between electrode materials containing appropriately proportioned catalyst materials. Microfluidic control elements distribute methyl alcohol fuel mixtures through a silicon chip over one electrode surface while air is simultaneously distributed over the other electrode. Integrated resistive heaters allow heating of the electrolyte-electrode layers, thereby increasing the conduction of catalytically generated protons from the fuel supply across the electrolyte to the air breathing electrode, where they combine with oxygen to generate electrical current. Optimization of current output through control of the catalyst and electrode surface area, and microfluidic fuel distribution, offer a miniature energy source providing continuous power for greater than three times longer than existing rechargeable batteries.
The miniature fuel cell power source will find applications in the complete range of consumer electronics as a replacement for rechargeable batteries. These include cell phones, personal digital assistants, laptops and other portable electronics.
Other applications include military electronics and sensors for remote and autonomous application in which extremely long lasting power is required.