Microstructured Cathode for Self-Regulated Oxygen Generation and Consumption

Self-supplies oxygen onboard on-demandComplete fuel cell with no ancillary partsDoes not depend on the surrounding environment and does not need to “breathe” airStackable for higher power outputAbility for sub-centimeter sizingImproved oxygen reduction rate balances anodic and cathodic reactionsMembrane-less packaging and gravity-independent operationMonolithic, standalone system is simple and mechanically robustFlexibility in fuel/oxidant sourcesHigh energy density and high power density

Complete, miniaturized fuel cell with no ancillary partsPortable devices such as laptops, cell phones, and global positioning systemsCharging portable devices in the outdoor area (for soldiers or campers) to replace heavy batteries for given energy.Stacked system for higher power output

Researchers from the UCLA mechanical and aerospace engineering department have designed and fabricated a microstructured cathode capable of generating oxygen bubbles, consuming the oxygen bubbles as needed, and stopping the oxygen generation when it is not consumed all in a self-regulated fashion. The microstructure of the device is designed such that an electrolytic oxidant comes in contact with an electrocatalyst to generate oxygen bubbles via a reduction reaction. The cathode does not need pressurized gas tank, moving pumps or ambient air to introduce the oxygen and they can therefore be compactly stacked for higher power output. The system operates in a manner free of gravitational forces and thus may be used in non-stationary applications. The monolithic, self-regulating cathode is simple and mechanically robust, and would ideally be coupled with the recently developed monolithic anode (by the authors) that self-pumps the fuel.

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State Of Development

Devices that generate and consume oxygen in a self-regulated manner have been fabricated and tested in electrochemical and visual experiments. Future work will focus on optimizing parameters such as hydrogen peroxide concentration, volume of stored hydrogen peroxide, and cathodic micropocket dimensions. Other future work will strive to implement the cathode into existing self-pumping fuel cells to realize a "true miniature fuel cell" that does not lack oxidant and self-regulates in both anode and cathode.

Background

Despite anticipated promise in high energy densities and efficiency, fuel cells have failed to reach practical applications for portable electronics primarily due to the inability to miniaturize the ancillary parts (e.g., pumps, valves, etc.) needed to operate the fuel cell and package them into a small space without eating up the volume for fuel. Removing all ancillary parts would allow a simpler design for fabrication, a more mechanically robust device, and a system with a higher energy and power density. Recent inventions have produced centimeter-sized fuel cells by removing ancillary parts, but these designs require access to ambient air and thus prevent the feasibility for stacking of the fuel cells for higher power output. In need of active oxygen supply within the fuel cell stacks, presented technology has been devised.

Related Materials

J. I. Hur, D. D. Meng, and C.-J. Kim, "Self-Pumping Membraneless Miniature Fuel Cell with an Air-breathing Fuel-Tolerant Pt Cathode," Journal of Microelectromechanical Systems, Vol. 21, 2012, pp. 476-483.
J.I. Hur and C.-J. Kim, "A Microstructured Cathode for Fuel Cell with Self-Regulated O2 Bubble Creation and Consumption," Proc. IEEE Int. Conf. MEMS, Paris, France, Jan. 2012, pp. 35-38.
J.I. Hur and C.-J. Kim, "Self-Contained Oxygen Supply for Self-Regulating Miniature Fuel Cell," Proc. PowerMEMS, Atlanta, GA, USA, Dec. 2012, pp. 191-194.

Additional Technologies by these Inventors

• Complete Transfer of Liquid Drops by Modification of Nozzle Design
• Micropumping of Liquids by Directional Growth and Selective Venting of Bubbles
• High-speed Switching of Droplet by Electric Meniscus Actuation
• Selective Surface Coating and/or Treatment of Printing Pins
• On-chip, Real-time Feedback Control for Electrical Manipulation of Droplets
• Localized Droplet Heating with Surface Electrodes in Microfluidic Chips
• No-Assembly Devices for Microfluidics Inside a Cavity
• Methods of Restoring and Maintaining Gas Film on Superhydrophobic Surfaces while Underwater
• Membraneless Fuel Cell with Self-Pumped Fuel and Oxidant
• Liquid-Repellent Surfaces Made of Any Materials
• A Low-Profile Flow Shear Sensing Unit
• Method for Commercial Production of Super-Hydrophobic Materials
• Method of Fluid Manipulation By Electrodewetting

Tech ID/UC Case

24166/2012-408-0

Related Cases

2012-408-0

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