Rapid Screening of Micro Fuel Cells for Portable Electronics

PIs: Li Tan, Engineering Mechanics

Zhaoyan Zhang, Mechanical Engineering

University of Nebraska, Lincoln, NE

10/01/07

11/01/06-04/30/07 (also seen in previous report)• Completed geometry and width design for micrometer channels;• Started modeling aspects of micro fuel cells;• Completed fabrication of individual channels with photolithography;• Completed fabrication of micro fuel cell testing array;• Completed fabrication of a testing sample with 4 cells.

05/01/07-09/30/07Fabrication of micro fuel cell arrays• Completed design of micro fuel cell arrays (88 cells);• Completed design/fabrication of three masks for micro channels, inlet/outlet, and electrodes;• Completed fabrication of micro channel arrays (44 cells) on Pyrex glass (1/4 wafer);• Completed fabrication of inlet/outlet on Pyrex.

Performance of Single Fuel Cell• Two different electrolyte membranes (Nafion 117 and 202) were explored.

A novel concept on electrocatalyst support • Initiated a methodology to integrate nanoparticles into fuel cell research.

Research Progress(11/01/06-09/30/07)

Completed 88 Fuel Cell MasksMask I: in/outlets

Channel 3

Mask III: Electrodes

Fabricated In/outlets

Mask II: Flow Channels

Completed Fuel Cell Array (44)

100 um

Pyrex

Mask 2

UV

Pyrex

Pyrex

AuCr

photoresist

Au etching

Cr etching

HF etching

Remove photoresist and Au/Cr

Pho

tore

sist

Chr

omiu

m/G

old

4.8

– 49

wt%

HF

etc

hing

Fuel Cell Array Fabrication Process Flow

• 22 array was used as a base for fuel cell• Two conducting membranes with different thicknesses were tested:

– Nafion® 117 – 183m– Nafion® 212 – 51m

• Nafion® 212 presented better efficiency, as expected due to its thinner nature.

Experimental Measurements of Single Fuel Cell

Nanoparticle (0 dimension)

MicroFiber (1 dimension)

Packed Particles (80 nm)

Uniform 1.5 m

Fiber

Motivation: The surface areas of current catalyst supports are low, challenging to improve the fuel cell performance.

Aim: 3D nanoporous catalyst support.

A Novel Electrocatalyst Support

Summary and Future Work

Confirmed (05/01/07-09/30/07):Fabrication of micro fuel cell arrays• Completed design of micro fuel cell arrays (88 cells);• Completed design/fabrication of three masks for micro channels, inlet/outlet, and

electrodes;• Completed fabrication of micro channel arrays (44 cells) on Pyrex glass (1/4 wafer);• Completed fabrication of inlet/outlet on Pyrex.Performance of Single Fuel Cell• Two different electrolyte membranes (Nafion 117 and 202) were tested.A novel concept on electrocatalyst support • Initiated a methodology to integrate nanoparticles into fuel cell research.

Work Plan (10/01/07-04/30/08):• Explore optimum conditions for fuel cell operation• Prepare a complete micro fuel cell array (88 cells) on Pyrex wafer (d~4”);• Align and integrate in/outlets with flow channels and electrodes;• Explore funding opportunities for the novel electrocatalyst support;• Initiate I-V test for 64-cell.