MEMS Fuel Cells--Low Temp--High Power Density

Lawrence Livermore National Laboratory

Technology Marketing Summary

Rechargeable batteries presently provide limited energy density and cyclical lifetime for portable power applications, with only incremental improvements forecasted in the foreseeable future. Furthermore, recharging requires access to electrical outlets via a tethered charger. The MEMS Fuel Cell represents a disruptive power source technology that can avoid many of these problems. It uses easy-to-store liquid fuels such as methanol and provides more than three times the operating time possible with rechargeable batteries. In addition, one can “refuel” the Fuel Cell by instantaneously swapping out the fuel cartridge. Finally, it is much easier to recycle than a battery and contains fewer toxic chemicals.

Description

The miniature fuel-cell technology uses thin-film fuel cells which combine microcircuit processes, microfluidic components, and micro-electrical-mechanical systems (MEMS) technology. The MEMS based fuel cell uses a thin layer of electrolyte material sandwiched between electrode materials containing appropriately proportioned catalyst materials. Microfluidic control elements distribute fuel mixtures through a silicon chip over one electrode surface while air is simultaneously distributed over the other electrode. In addition, new LLNL technology has a three-dimensional microfluidic flow field architecture, along with the porous electrolyte support structures, which offers significant advantages to increase the volumetric power density of the fuel cell, as well as to manufacture the fuel cell via a continuous integration approach. Combining this high power density architecture with the microfluidic fuel processor and advanced thermally insulated packaging provides a scalable, high energy density portable power source.

Benefits

MEMS based fuel cells offer the following advantages over batteries:

Instantaneous recharge via fuel cartridge swapping
Lighter weight, higher volumetric power, energy density
Longer lasting
Reduced life cycle cost in comparison to rechargeable batteries

The MEMS based fuel cell offers the following advantages over other micro-fuel cells:

Fewer individual parts
Easier to produce
Can take advantage of the economy of scale offered by silicon fabrication

Applications and Industries

With the advantage listed above, MEMS based fuel cells could replace rechargeable batteries in a number of applications:

Power for portable computers
Power for cell phones and other handheld devices
Power for remote sensors and electronics
Backup power for emergencies

Patents and Patent Applications

ID Number	Title and Abstract	Primary Lab	Date
Application 20050207953	High aspect ratio chemical microreactor A chemical microreactor with a high aspect ratio. In one embodiment the chemical microreactor has a chemical microreactor section with channels having a height and with spacings having a width. There is a high aspect ratio of the height to the width. The high aspect ratio in one embodiment is more than substantially 5:1. The high aspect ratio in another embodiment is more than substantially 10:1. The high aspect ratio another embodiment is more than substantially 15:1. The high aspect ratio in one embodiment is substantially 20:1.	Lawrence Livermore National Laboratory	07/20/2004 Filed
Patent 5,601,938	Carbon aerogel electrodes for direct energy conversion A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome.	Lawrence Livermore National Laboratory	02/11/1997 Issued
Patent 6,921,603	Microfluidic fuel cell systems with embedded materials and structures and method thereof Described herein is a process for fabricating microfluidic systems with embedded components in which micron-scale features are molded into the polymeric material polydimethylsiloxane (PDMS). Micromachining is used to create a mold master and the liquid precursors for PDMS are poured over the mold and allowed to cure. The PDMS is then removed form the mold and bonded to another material such as PDMS, glass, or silicon after a simple surface preparation step to form sealed microchannels.	Lawrence Livermore National Laboratory	07/26/2005 Issued
Patent 6,960,235	Chemical microreactor and method thereof A chemical microreactor suitable for generation of hydrogen fuel from liquid sources such as ammonia, methanol, and butane through steam reforming processes when mixed with an appropriate amount of water contains capillary microchannels with integrated resistive heaters to facilitate the occurrence of catalytic steam reforming reactions. One such microreactor employs a packed catalyst capillary microchannel and at least one porous membrane. Another employs a porous membrane with a large surface area or a porous membrane support structure containing a plurality of porous membranes having a large surface area in the aggregate, i.e., greater than about 1 m.sup.2 /cm.sup.3. The packed catalyst capillary microchannels, porous membranes and porous membrane support structures may be formed by a variety of methods.	Lawrence Livermore National Laboratory	11/01/2005 Issued
Patent 6,960,403	Bonded polyimide fuel cell package and method thereof Described herein are processes for fabricating microfluidic fuel cell systems with embedded components in which micron-scale features are formed by bonding layers of DuPont Kapton.TM. polyimide laminate. A microfluidic fuel cell system fabricated using this process is also described.	Lawrence Livermore National Laboratory	11/01/2005 Issued
Patent 7,122,261	Metal hydride fuel storage and method thereof Disclosed herein is a metal hydride fuel storage cartridge having integrated resistive heaters that can be used in conjunction with fuel cells such as MEMS-based fuel cells. The cartridge is fabricated using micromachining methods and thin/thick film materials synthesis techniques.	Lawrence Livermore National Laboratory	10/17/2006 Issued
Patent 7,186,352	Microfluidic systems with embedded materials and structures and method thereof Described herein is a process for fabricating microfluidic systems with embedded components in which micron-scale features are molded into the polymeric material polydimethylsiloxane (PDMS). Micromachining is used to create a mold master and the liquid precursors for PDMS are poured over the mold and allowed to cure. The PDMS is then removed form the mold and bonded to another material such as PDMS, glass, or silicon after a simple surface preparation step to form sealed microchannels.	Lawrence Livermore National Laboratory	03/06/2007 Issued
Patent 7,527,659	Metal hydride fuel storage and method thereof Disclosed herein is a metal hydride fuel storage cartridge having integrated resistive heaters that can be used in conjunction with fuel cells such as MEMS-based fuel cells. The cartridge is fabricated using micromachining methods and thin/thick film materials synthesis techniques.	Lawrence Livermore National Laboratory	05/05/2009 Issued
Patent 7,534,402	Method for forming a chemical microreactor Disclosed is a chemical microreactor that provides a means to generate hydrogen fuel from liquid sources such as ammonia, methanol, and butane through steam reforming processes when mixed with an appropriate amount of water. The microreactor contains capillary microchannels with integrated resistive heaters to facilitate the occurrence of catalytic steam reforming reactions. Two distinct embodiment styles are discussed. One embodiment style employs a packed catalyst capillary microchannel and at least one porous membrane. Another embodiment style employs a porous membrane with a large surface area or a porous membrane support structure containing a plurality of porous membranes having a large surface area in the aggregate, i.e., greater than about 1 m.sup.2/cm.sup.3. Various methods to form packed catalyst capillary microchannels, porous membranes and porous membrane support structures are also disclosed.	Lawrence Livermore National Laboratory	05/19/2009 Issued
Patent 7,732,086	Bonded polyimide fuel cell package Described herein are processes for fabricating microfluidic fuel cell systems with embedded components in which micron-scale features are formed by bonding layers of DuPont Kapton.TM. polyimide laminate. A microfluidic fuel cell system fabricated using this process is also described.	Lawrence Livermore National Laboratory	06/08/2010 Issued
Patent 7,744,830	Catalyst for microelectromechanical systems microreactors A microreactor comprising a silicon wafer, a multiplicity of microchannels in the silicon wafer, and a catalyst coating the microchannels. In one embodiment the catalyst coating the microchannels comprises a nanostructured material. In another embodiment the catalyst coating the microchannels comprises an aerogel. In another embodiment the catalyst coating the microchannels comprises a solgel. In another embodiment the catalyst coating the microchannels comprises carbon nanotubes.	Lawrence Livermore National Laboratory	06/29/2010 Issued
Patent 7,931,993	Method of preparation of bonded polyimide fuel cell package Described herein are processes for fabricating microfluidic fuel cell systems with embedded components in which micron-scale features are formed by bonding layers of DuPont Kapton.TM. polyimide laminate. A microfluidic fuel cell system fabricated using this process is also described.	Lawrence Livermore National Laboratory	04/26/2011 Issued
Patent 8,057,988	Catalyst for microelectromechanical systems microreactors A microreactor comprising a silicon wafer, a multiplicity of microchannels in the silicon wafer, and a catalyst coating the microchannels. In one embodiment the catalyst coating the microchannels comprises a nanostructured material. In another embodiment the catalyst coating the microchannels comprises an aerogel. In another embodiment the catalyst coating the microchannels comprises a solgel. In another embodiment the catalyst coating the microchannels comprises carbon nanotubes.	Lawrence Livermore National Laboratory	11/15/2011 Issued

Technology Status

Technology ID	Development Stage	Availability	Published	Last Updated
21209	Prototype	Available	04/22/2011	04/22/2011

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MEMS Fuel Cells--Low Temp--High Power Density

Lawrence Livermore National Laboratory

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